xref: /illumos-gate/usr/src/man/man5/proc.5 (revision a14132db566b083c26658ccbf0a1ba8885fc5c27)

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.Dd May 8, 2023
.Dt PROC 5
.Os
.Sh NAME
.Nm proc
.Nd /proc, the process file system
.Sh DESCRIPTION
.Pa /proc
is a file system that provides access to the state of each process
and light-weight process (lwp) in the system.
The name of each entry in the
.Pa /proc
directory is a decimal number corresponding to a process-ID.
These entries are themselves subdirectories.
Access to process state is provided by additional files contained within each
subdirectory; the hierarchy is described more completely below.
In this document,
.Dq Pa /proc file
refers to a non-directory file within the hierarchy rooted at
.Pa /proc .
The owner of each
.Pa /proc
file and subdirectory is determined by the user-ID of the process.
.Pp
.Pa /proc
can be mounted on any mount point, in addition to the standard
.Pa /proc
mount point, and can be mounted several places at once.
Such additional mounts are allowed in order to facilitate the confinement of
processes to subtrees of the file system via
.Xr chroot 2
and yet allow such processes access to commands like
.Xr ps 1 .
.Pp
Standard system calls are used to access
.Pa /proc
files:
.Xr open 2 ,
.Xr close 2 ,
.Xr read 2 ,
and
.Xr write 2
(including
.Xr readv 2 ,
.Xr writev 2 ,
.Xr pread 2 ,
and
.Xr pwrite 2 ) .
Most files describe process state and can only be opened for reading.
.Pa ctl
and
.Pa lwpctl
(control) files permit manipulation of process state and can only be opened for
writing.
.Pa as
(address space) files contain the image of the running process and can be
opened for both reading and writing.
An open for writing allows process control; a read-only open allows inspection
but not control.
In this document, we refer to the process as open for reading or writing if
any of its associated
.Pa /proc
files is open for reading or writing.
.Pp
In general, more than one process can open the same
.Pa /proc
file at the same time. \fIExclusive\fR \fIopen\fR is an advisory mechanism provided to
allow controlling processes to avoid collisions with each other.
A process can obtain exclusive control of a target process, with respect to
other cooperating processes, if it successfully opens any
.Pa /proc
file in the target process for writing (the
.Pa as
or
.Pa ctl
files, or the
.Pa lwpctl
file of any lwp) while specifying
.Sy O_EXCL
in the
.Xr open 2 .
Such an open will fail if the target process is already open for writing (that
is, if an
.Pa as ,
.Pa ctl ,
or
.Pa lwpctl
file is already open for writing).
There can be any number of concurrent read-only opens;
.Sy O_EXCL
is ignored on opens for reading.
It is recommended that the first open for writing by a controlling
process use the
.Sy O_EXCL
flag; multiple controlling processes usually result in chaos.
.Pp
If a process opens one of its own
.Pa /proc
files for writing, the open
succeeds regardless of
.Sy O_EXCL
and regardless of whether some other process has the process open for writing.
Self-opens do not count when another process attempts an exclusive open.
(A process cannot exclude a debugger by opening itself for writing and the
application of a debugger cannot prevent a process from opening itself.)
All self-opens for writing are forced to be close-on-exec (see the
.Sy F_SETFD
operation of
.Xr fcntl 2 ) .
.Pp
Data may be transferred from or to any locations in the address space of the
traced process by applying
.Xr lseek 2
to position the
.Pa as
file at the virtual address of interest followed by
.Xr read 2
or
.Xr write 2
(or by using
.Xr pread 2
or
.Xr pwrite 2
for the combined operation).
The address-map files
.Pa /proc/ Ns Em pid Ns Pa /map
and
.Pa /proc/ Ns Em pid Ns Pa /xmap
can be read to determine the accessible areas (mappings) of the address space.
.Sy I/O
transfers may span contiguous mappings.
An
.Sy I/O
request extending into an unmapped area is truncated at the boundary.
A write request beginning at an unmapped virtual address fails with
.Er EIO ;
a read request beginning at an unmapped virtual address returns zero (an
end-of-file indication).
.Pp
Information and control operations are provided through additional files.
.In procfs.h
contains definitions of data structures and message formats
used with these files.
Some of these definitions involve the use of sets of flags.
The set types
.Sy sigset_t ,
.Sy fltset_t ,
and
.Sy sysset_t
correspond, respectively, to signal, fault, and system call enumerations
defined in
.In sys/signal.h ,
.In sys/fault.h ,
and
.In sys/syscall.h .
Each set type is large enough to hold flags for its own enumeration.
Although they are of different sizes, they have a common
structure and can be manipulated by these macros:
.Bd -literal -offset indent
prfillset(&set);             /* turn on all flags in set */
premptyset(&set);            /* turn off all flags in set */
praddset(&set, flag);        /* turn on the specified flag */
prdelset(&set, flag);        /* turn off the specified flag */
r = prismember(&set, flag);  /* != 0 iff flag is turned on */
.Ed
.Pp
One of
.Fn prfillset
or
.Fn premptyset
must be used to initialize
.Fa set
before it is used in any other operation.
.Fa flag
must be a member of the enumeration corresponding to
.Fa set .
.Pp
Every process contains at least one
.Em light-weight process ,
or
.Sy lwp .
Each lwp represents a flow of execution that is independently scheduled by the
operating system.
All lwps in a process share its address space as well as many other attributes.
Through the use of
.Pa lwpctl
and
.Pa ctl
files as described below, it is possible to affect individual lwps in a
process or to affect all of them at once, depending on the operation.
.Pp
When the process has more than one lwp, a representative lwp is chosen by the
system for certain process status files and control operations.
The representative lwp is a stopped lwp only if all of the process's lwps are
stopped; is stopped on an event of interest only if all of the lwps are so
stopped (excluding
.Sy PR_SUSPENDED
lwps); is in a
.Sy PR_REQUESTED
stop only if there are no other events of interest to be found; or, failing
everything else, is in a
.Sy PR_SUSPENDED
stop (implying that the process is deadlocked).
See the description of the
.Pa status
file for definitions of stopped states.
See the
.Sy PCSTOP
control operation for the definition of
.Dq event of interest .
.Pp
The representative lwp remains fixed (it will be chosen again on the next
operation) as long as all of the lwps are stopped on events of interest or are
in a
.Sy PR_SUSPENDED
stop and the
.Sy PCRUN
control operation is not applied to any of them.
.Pp
When applied to the process control file, every
.Pa /proc
control operation
that must act on an lwp uses the same algorithm to choose which lwp to act
upon.
Together with synchronous stopping (see
.Sy PCSET ) ,
this enables a debugger to control a multiple-lwp process using only the
process-level status and control files if it so chooses.
More fine-grained control can be achieved using the lwp-specific files.
.Pp
The system supports two process data models, the traditional 32-bit data model
in which ints, longs and pointers are all 32 bits wide (the ILP32 data model),
and on some platforms the 64-bit data model in which longs and pointers, but
not ints, are 64 bits in width (the LP64 data model).
In the LP64 data model some system data types, notably
.Sy size_t ,
.Sy off_t ,
.Sy time_t
and
.Sy dev_t ,
grow from 32 bits to 64 bits as well.
.Pp
The
.Pa /proc
interfaces described here are available to both 32-bit and
64-bit controlling processes.
However, many operations attempted by a 32-bit
controlling process on a 64-bit target process will fail with
.Er EOVERFLOW
because the address space range of a 32-bit process cannot encompass a 64-bit
process or because the data in some 64-bit system data type cannot be
compressed to fit into the corresponding 32-bit type without loss of
information.
Operations that fail in this circumstance include reading and
writing the address space, reading the address-map files, and setting the
target process's registers.
There is no restriction on operations applied by a
64-bit process to either a 32-bit or a 64-bit target processes.
.Pp
The format of the contents of any
.Pa /proc
file depends on the data model of the observer (the controlling process), not
on the data model of the target process.
A 64-bit debugger does not have to translate the information it reads from a
.Pa /proc
file for a 32-bit process from 32-bit format to 64-bit format.
However, it usually has to be aware of the data model of the target process.
The
.Sy pr_dmodel
field of the
.Pa status
files indicates the target process's data model.
.Pp
To help deal with system data structures that are read from 32-bit processes, a
64-bit controlling program can be compiled with the C preprocessor symbol
.Dv _SYSCALL32
defined before system header files are included.
This makes explicit 32-bit fixed-width data structures (like
.Sy struct stat32 )
visible to the 64-bit program.
See
.Xr types32.h 3HEAD .
.Sh DIRECTORY STRUCTURE
At the top level, the directory
.Pa /proc
contains entries each of which names an existing process in the system.
These entries are themselves directories.
Except where otherwise noted, the files described below can be
opened for reading only.
In addition, if a process becomes a
.Em zombie
(one that has exited but whose parent has not yet performed a
.Xr wait 3C
upon it), most of its associated
.Pa /proc
files disappear from the hierarchy; subsequent attempts to open them, or to
read or write files opened before the process exited, will elicit the error
.Er ENOENT .
.Pp
Although process state and consequently the contents of
.Pa /proc
files can change from instant to instant, a single
.Xr read 2
of a
.Pa /proc
file is guaranteed to return a sane representation of state; that is, the read
will be atomic with respect to the state of the process.
No such guarantee applies to successive reads applied to a
.Pa /proc
file for a running process.
In addition, atomicity is not guaranteed for
.Sy I/O
applied to the
.Pa as
(address-space) file for a running process or for a process whose address space
contains memory shared by another running process.
.Pp
A number of structure definitions are used to describe the files.
These structures may grow by the addition of elements at the end in future
releases of the system and it is not legitimate for a program to assume that
they will not.
.Sh STRUCTURE OF Pa /proc/ Ns Em pid
A given directory
.Pa /proc/ Ns Em pid
contains the following entries.
A process can use the invisible alias
.Pa /proc/self
if it wishes to open one of its own
.Pa /proc
files (invisible in the sense that the name
.Dq self
does not appear in a directory listing of
.Pa /proc
obtained from
.Xr ls 1 ,
.Xr getdents 2 ,
or
.Xr readdir 3C ) .
.Ss contracts
A directory containing references to the contracts held by the process.
Each entry is a symlink to the contract's directory under
.Pa /system/contract .
See
.Xr contract 5 .
.Ss as
Contains the address-space image of the process; it can be opened for both
reading and writing.
.Xr lseek 2
is used to position the file at the virtual address of interest and then the
address space can be examined or changed through
.Xr read 2
or
.Xr write 2
(or by using
.Xr pread 2
or
.Xr pwrite 2
for the combined operation).
.Ss ctl
A write-only file to which structured messages are written directing the system
to change some aspect of the process's state or control its behavior in some
way.
The seek offset is not relevant when writing to this file.
Individual lwps also have associated
.Pa lwpctl
files in the lwp subdirectories.
A control message may be written either to the process's
.Pa ctl
file or to a specific
.Pa lwpctl
file with operation-specific effects.
The effect of a control message is immediately reflected in the state of the
process visible through appropriate status and information files.
The types of control messages are described in detail later.
See
.Sx CONTROL MESSAGES .
.Ss status
Contains state information about the process and the representative lwp.
The file contains a
.Sy pstatus
structure which contains an embedded
.Sy lwpstatus
structure for the representative lwp, as follows:
.Bd -literal -offset 2
typedef struct pstatus {
     int pr_flags;            /* flags (see below) */
     int pr_nlwp;             /* number of active lwps in the process */
     int pr_nzomb;            /* number of zombie lwps in the process */
     pid_tpr_pid;             /* process id */
     pid_tpr_ppid;            /* parent process id */
     pid_tpr_pgid;            /* process group id */
     pid_tpr_sid;             /* session id */
     id_t pr_aslwpid;         /* obsolete */
     id_t pr_agentid;         /* lwp-id of the agent lwp, if any */
     sigset_t pr_sigpend;     /* set of process pending signals */
     uintptr_t pr_brkbase;    /* virtual address of the process heap */
     size_t pr_brksize;       /* size of the process heap, in bytes */
     uintptr_t pr_stkbase;    /* virtual address of the process stack */
     size_tpr_stksize;        /* size of the process stack, in bytes */
     timestruc_t pr_utime;    /* process user cpu time */
     timestruc_t pr_stime;    /* process system cpu time */
     timestruc_t pr_cutime;   /* sum of children's user times */
     timestruc_t pr_cstime;   /* sum of children's system times */
     sigset_t pr_sigtrace;    /* set of traced signals */
     fltset_t pr_flttrace;    /* set of traced faults */
     sysset_t pr_sysentry;    /* set of system calls traced on entry */
     sysset_t pr_sysexit;     /* set of system calls traced on exit */
     char pr_dmodel;          /* data model of the process */
     taskid_t pr_taskid;      /* task id */
     projid_t pr_projid;      /* project id */
     zoneid_t pr_zoneid;      /* zone id */
     lwpstatus_t pr_lwp;      /* status of the representative lwp */
} pstatus_t;
.Ed
.Pp
.Sy pr_flags
is a bit-mask holding the following process flags.
For convenience, it also contains the lwp flags for the representative lwp,
described later.
.Bl -tag -width "PR_MSACCT" -offset indent
.It Sy PR_ISSYS
process is a system process (see
.Sx PCSTOP ) .
.It Sy PR_VFORKP
process is the parent of a vforked child (see
.Sx PCWATCH ) .
.It Sy PR_FORK
process has its inherit-on-fork mode set (see
.Sx PCSET ) .
.It Sy PR_RLC
process has its run-on-last-close mode set (see
.Sx PCSET ) .
.It Sy PR_KLC
process has its kill-on-last-close mode set (see
.Sx PCSET ) .
.It Sy PR_ASYNC
process has its asynchronous-stop mode set (see
.Sx PCSET ) .
.It Sy PR_MSACCT
Set by default in all processes to indicate that microstate accounting is
enabled.
However, this flag has been deprecated and no longer has any effect.
Microstate accounting may not be disabled; however, it is still possible to
toggle the flag.
.It Sy PR_MSFORK
Set by default in all processes to indicate that microstate accounting will be
enabled for processes that this parent
.Xr fork 2 Ns s .
However, this flag has been deprecated and no longer has any effect.
It is possible to toggle this flag; however, it is not possible to disable
microstate accounting.
.It Sy PR_BPTADJ
process has its breakpoint adjustment mode set (see
.Sx PCSET ) .
.It Sy PR_PTRACE
process has its ptrace-compatibility mode set (see
.Sx PCSET ) .
.El
.Pp
.Sy pr_nlwp
is the total number of active lwps in the process.
.Sy pr_nzomb
is the total number of zombie lwps in the process.
A zombie lwp is a non-detached lwp that has terminated but has not been reaped
with
.Xr thr_join 3C
or
.Xr pthread_join 3C .
.Pp
.Sy pr_pid ,
.Sy pr_ppi ,
.Sy pr_pgid ,
and
.Sy pr_sid
are, respectively, the process ID, the ID of the process's parent, the
process's process group ID, and the process's session ID.
.Pp
.Sy pr_aslwpid
is obsolete and is always zero.
.Pp
.Sy pr_agentid
is the lwp-ID for the
.Pa /proc
agent lwp (see the
.Sx PCAGENT
control operation).
It is zero if there is no agent lwp in the process.
.Pp
.Sy pr_sigpend
identifies asynchronous signals pending for the process.
.Pp
.Sy pr_brkbase
is the virtual address of the process heap and
.Sy pr_brksize
is its size in bytes.
The address formed by the sum of these values is the process
.Sy break
(see
.Xr brk 2 ) .
.Sy pr_stkbase
and
.Sy pr_stksize
are, respectively, the virtual address of the process stack and its size in
bytes.
(Each lwp runs on a separate stack; the distinguishing characteristic of the
process stack is that the operating system will grow it when necessary.)
.Pp
.Sy pr_utime ,
.Sy pr_stime ,
.Sy pr_cutime ,
.Sy and pr_cstime
are, respectively, the user
.Sy CPU
and system
.Sy CPU
time consumed by the process, and the cumulative user
.Sy CPU
and system
.Sy CPU
time consumed by the process's children, in seconds and nanoseconds.
.Pp
.Sy pr_sigtrace
and
.Sy pr_flttrace
contain, respectively, the set of signals and the set of hardware faults that
are being traced (see
.Sx PCSTRACE
and
.Sx PCSFAULT ) .
.Pp
.Sy pr_sysentry
and
.Sy pr_sysexit
contain, respectively, the sets of system calls being traced on entry and exit
(see
.Sx PCSENTRY
and
.Sx PCSEXIT ) .
.Pp
.Sy pr_dmodel
indicates the data model of the process.
Possible values are:
.Bl -tag -width "PR_MODEL_NATIVE" -offset indent
.It Sy PR_MODEL_ILP32
process data model is ILP32.
.It Sy PR_MODEL_LP64
process data model is LP64.
.It Sy PR_MODEL_NATIVE
process data model is native.
.El
.Pp
The
.Sy pr_taskid ,
.Sy pr_projid ,
and
.Sy pr_zoneid
fields contain respectively, the numeric
.Sy ID Ns s
of the task, project, and zone in which the process was running.
.Pp
The constant
.Sy PR_MODEL_NATIVE
reflects the data model of the controlling process,
.Em that is ,
its value is
.Sy PR_MODEL_ILP32
or
.Sy PR_MODEL_LP64
according to whether the controlling process has been
compiled as a 32-bit program or a 64-bit program, respectively.
.Pp
.Sy pr_lwp
contains the status information for the representative lwp:
.Bd -literal -offset 2
typedef struct lwpstatus {
  int pr_flags;              /* flags (see below) */
  id_t pr_lwpid;             /* specific lwp identifier */
  short pr_why;              /* reason for lwp stop, if stopped */
  short pr_what;             /* more detailed reason */
  short pr_cursig;           /* current signal, if any */
  siginfo_t pr_info;         /* info associated with signal or fault */
  sigset_t pr_lwppend;       /* set of signals pending to the lwp */
  sigset_t pr_lwphold;       /* set of signals blocked by the lwp */
  struct sigaction pr_action;/* signal action for current signal */
  stack_t pr_altstack;       /* alternate signal stack info */
  uintptr_t pr_oldcontext;   /* address of previous ucontext */
  short pr_syscall;          /* system call number (if in syscall) */
  short pr_nsysarg;          /* number of arguments to this syscall */
  int pr_errno;              /* errno for failed syscall */
  long pr_sysarg[PRSYSARGS]; /* arguments to this syscall */
  long pr_rval1;             /* primary syscall return value */
  long pr_rval2;             /* second syscall return value, if any */
  char pr_clname[PRCLSZ];    /* scheduling class name */
  timestruc_t pr_tstamp;     /* real-time time stamp of stop */
  timestruc_t pr_utime;      /* lwp user cpu time */
  timestruc_t pr_stime;      /* lwp system cpu time */
  uintptr_t pr_ustack;       /* stack boundary data (stack_t) address */
  ulong_t pr_instr;          /* current instruction */
  prgregset_t pr_reg;        /* general registers */
  prfpregset_t pr_fpreg;     /* floating-point registers */
} lwpstatus_t;
.Ed
.Pp
.Sy pr_flags
is a bit-mask holding the following lwp flags.
For convenience, it also contains the process flags, described previously.
.Bl -tag -width "PR_STOPPED" -offset indent
.It Sy PR_STOPPED
The lwp is stopped.
.It Sy PR_ISTOP
The lwp is stopped on an event of interest (see
.Sx PCSTOP ) .
.It Sy PR_DSTOP
The lwp has a stop directive in effect (see
.Sx PCSTOP ) .
.It Sy PR_STEP
The lwp has a single-step directive in effect (see
.Sx PCRUN ) .
.It Sy PR_ASLEEP
The lwp is in an interruptible sleep within a system call.
.It Sy PR_PCINVAL
The lwp's current instruction
.Pq Sy pr_instr
is undefined.
.It Sy PR_DETACH
This is a detached lwp (see
.Xr pthread_create 3C
and
.Xr pthread_join 3C ) .
.It Sy PR_DAEMON
This is a daemon lwp (see
.Xr pthread_create 3C ) .
.It Sy PR_ASLWP
This flag is obsolete and is never set.
.It Sy PR_AGENT
This is the
.Pa /proc
agent lwp for the process.
.El
.Pp
.Sy pr_lwpid
names the specific lwp.
.Pp
.Sy pr_why
.Sy and
pr_what
together describe, for a stopped lwp, the reason for the stop.
Possible values of
.Sy pr_why
and the associated
.Sy pr_what
are:
.Bl -tag -width "PR_JOBCONTROL" -offset left
.It Sy PR_REQUESTED
indicates that the stop occurred in response to a stop directive, normally
because
.Sy PCSTOP
was applied or because another lwp stopped on an event of interest and the
asynchronous-stop flag (see
.Sx PCSET )
was not set for the process.
.Sy pr_what
is unused in this case.
.It Sy PR_SIGNALLED
indicates that the lwp stopped on receipt of a signal (see
.Sx PCSTRACE ) ;
.Sy pr_what
holds the signal number that caused the stop (for a newly-stopped
lwp, the same value is in
.Sy pr_cursig ) .
.It Sy PR_FAULTED
indicates that the lwp stopped on incurring a hardware fault (see
.Sx PCSFAULT ) ;
.Sy pr_what
holds the fault number that caused the stop.
.It Sy PR_SYSENTRY
.It Sy PR_SYSEXIT
indicate a stop on entry to or exit from a system call (see
.Sx PCSENTRY
and
.Sx PCSEXIT ) ;
.Sy pr_what
holds the system call number.
.It Sy PR_JOBCONTROL
indicates that the lwp stopped due to the default action of a job control stop
signal (see
.Xr sigaction 2 ) ;
.Sy pr_what
holds the stopping signal number.
.It Sy PR_SUSPENDED
indicates that the lwp stopped due to internal synchronization of lwps within
the process.
.Sy pr_what
is unused in this case.
.El
.Pp
.Sy pr_cursig
names the current signal, that is, the next signal to be delivered to the lwp,
if any.
.Sy pr_info ,
when the lwp is in a
.Sy PR_SIGNALLED
or
.Sy PR_FAULTED
stop, contains additional information pertinent to the particular signal or
fault (see
.In sys/siginfo.h ) .
.Pp
.Sy pr_lwppend
identifies any synchronous or directed signals pending for the lwp.
.Sy pr_lwphold
identifies those signals whose delivery is being blocked by the lwp (the
signal mask).
.Pp
.Sy pr_action
contains the signal action information pertaining to the current signal (see
.Xr sigaction 2 ) ;
it is undefined if
.Sy pr_cursig
is zero.
.Sy pr_altstack
contains the alternate signal stack information for the lwp (see
.Xr sigaltstack 2 ) .
.Pp
.Sy pr_oldcontext ,
if not zero, contains the address on the lwp stack of a
.Sy ucontext
structure describing the previous user-level context (see
.Xr ucontext.h 3HEAD ) .
It is non-zero only if the lwp is executing in the context of a signal handler.
.Pp
.Sy pr_syscall
is the number of the system call, if any, being executed by
the lwp; it is non-zero if and only if the lwp is stopped on
.Sy PR_SYSENTRY
or
.Sy PR_SYSEXIT ,
or is asleep within a system call
.Pf ( Sy PR_ASLEEP
is set).
If
.Sy pr_syscall
is non-zero,
.Sy pr_nsysarg
is the number of arguments to the system call and
.Sy pr_sysarg
contains the actual arguments.
.Pp
.Sy pr_rval1 ,
.Sy pr_rval2 ,
and
.Sy pr_errno
are defined only if the lwp
is stopped on
.Sy PR_SYSEXIT
or if the
.Sy PR_VFORKP
flag is set.
If
.Sy pr_errno
is zero,
.Sy pr_rval1
and
.Sy pr_rval2
contain the return values from the system call.
Otherwise,
.Sy pr_errno
contains the error number for the failing system call (see
.In sys/errno.h ) .
.Pp
.Sy pr_clname
contains the name of the lwp's scheduling class.
.Pp
.Sy pr_tstamp ,
if the lwp is stopped, contains a time stamp marking when the
lwp stopped, in real time seconds and nanoseconds since an arbitrary time in
the past.
.Pp
.Sy pr_utime
is the amount of user level CPU time used by this LWP.
.Pp
.Sy pr_stime
is the amount of system level CPU time used by this LWP.
.Pp
.Sy pr_ustack
is the virtual address of the
.Sy stack_t
that contains the stack boundaries for this LWP.
See
.Xr getustack 2
and
.Xr _stack_grow 3C .
.Pp
.Sy pr_instr
contains the machine instruction to which the lwp's program counter refers.
The amount of data retrieved from the process is machine-dependent.
On SPARC based machines, it is a 32-bit word.
On x86-based machines, it is a single byte.
In general, the size is that of the machine's smallest instruction.
If
.Sy PR_PCINVAL
is set,
.Sy pr_instr
is undefined; this occurs whenever the lwp is not stopped or when the program
counter refers to an invalid virtual address.
.Pp
.Sy pr_reg
is an array holding the contents of a stopped lwp's general registers.
.Bl -tag -offset left -width "SPARC V8 (32-bit)"
.It Sy SPARC
On SPARC-based machines, the predefined constants
.Sy R_G0
\&.\&.\&.
.Sy R_G7 ,
.Sy R_O0
\&.\&.\&.
.Sy R_O7 ,
.Sy R_L0
\&.\&.\&.
.Sy R_L7 ,
.Sy R_I0
\&.\&.\&.
.Sy R_I7 ,
.Sy R_PC ,
.Sy R_nPC ,
and
.Sy R_Y
can be used as indices to refer to the corresponding registers; previous
register windows can be read from their overflow locations on the stack
(however, see the
.Pa gwindows
file in the
.Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid
subdirectory).
.It Sy SPARC V8 (32-bit)
For SPARC V8 (32-bit) controlling processes, the predefined constants
.Sy R_PSR ,
.Sy R_WIM ,
and
.Sy R_TBR
can be used as indices to refer to the corresponding special registers.
For SPARC V9 (64-bit) controlling processes, the predefined constants
.Sy R_CCR ,
.Sy R_ASI ,
and
.Sy R_FPRS
can be used as indices to refer to the corresponding special registers.
.It Sy x86 (32-bit)
For 32-bit x86 processes, the predefined constants listed belowcan be used as
indices to refer to the corresponding registers.
.Bl -tag -width "TRAPNO" -offset indent -compact
.It SS
.It UESP
.It EFL
.It CS
.It EIP
.It ERR
.It TRAPNO
.It EAX
.It ECX
.It EDX
.It EBX
.It ESP
.It EBP
.It ESI
.It EDI
.It DS
.It ES
.It GS
.El
.Pp
The preceding constants are listed in
.In sys/regset.h .
.Pp
Note that a 32-bit process can run on an x86 64-bit system, using the constants
listed above.
.It Sy x86 (64-bit)
To read the registers of a 32-
.Em or
a 64-bit process, a 64-bit x86 process should use the predefined constants
listed below.
.Bl -tag -width "REG_TRAPNO" -offset indent -compact
.It REG_GSBASE
.It REG_FSBASE
.It REG_DS
.It REG_ES
.It REG_GS
.It REG_FS
.It REG_SS
.It REG_RSP
.It REG_RFL
.It REG_CS
.It REG_RIP
.It REG_ERR
.It REG_TRAPNO
.It REG_RAX
.It REG_RCX
.It REG_RDX
.It REG_RBX
.It REG_RBP
.It REG_RSI
.It REG_RDI
.It REG_R8
.It REG_R9
.It REG_R10
.It REG_R11
.It REG_R12
.It REG_R13
.It REG_R14
.It REG_R15
.El
.Pp
The preceding constants are listed in
.In sys/regset.h .
.El
.Pp
.Sy pr_fpreg
is a structure holding the contents of the floating-point registers.
.Pp
SPARC registers, both general and floating-point, as seen by a 64-bit
controlling process are the V9 versions of the registers, even if the target
process is a 32-bit (V8) process.
V8 registers are a subset of the V9 registers.
.Pp
If the lwp is not stopped, all register values are undefined.
.Ss psinfo
Contains miscellaneous information about the process and the representative lwp
needed by the
.Xr ps 1
command.
.Sy psinfo
remains accessible after a process becomes a
.Em zombie .
The file contains a
.Sy psinfo
structure which contains an embedded
.Sy lwpsinfo
structure for the representative lwp, as follows:
.Bd -literal -offset 2
typedef struct psinfo {
    int pr_flag;             /* process flags (DEPRECATED: see below) */
    int pr_nlwp;             /* number of active lwps in the process */
    int pr_nzomb;            /* number of zombie lwps in the process */
    pid_t pr_pid;            /* process id */
    pid_t pr_ppid;           /* process id of parent */
    pid_t pr_pgid;           /* process id of process group leader */
    pid_t pr_sid;            /* session id */
    uid_t pr_uid;            /* real user id */
    uid_t pr_euid;           /* effective user id */
    gid_t pr_gid;            /* real group id */
    gid_t pr_egid;           /* effective group id */
    uintptr_t pr_addr;       /* address of process */
    size_t pr_size;          /* size of process image in Kbytes */
    size_t pr_rssize;        /* resident set size in Kbytes */
    dev_t pr_ttydev;         /* controlling tty device (or PRNODEV) */
    ushort_t pr_pctcpu;      /* % of recent cpu time used by all lwps */
    ushort_t pr_pctmem;      /* % of system memory used by process */
    timestruc_t pr_start;    /* process start time, from the epoch */
    timestruc_t pr_time;     /* cpu time for this process */
    timestruc_t pr_ctime;    /* cpu time for reaped children */
    char pr_fname[PRFNSZ];   /* name of exec'ed file */
    char pr_psargs[PRARGSZ]; /* initial characters of arg list */
    int pr_wstat;            /* if zombie, the wait() status */
    int pr_argc;             /* initial argument count */
    uintptr_t pr_argv;       /* address of initial argument vector */
    uintptr_t pr_envp;       /* address of initial environment vector */
    char pr_dmodel;          /* data model of the process */
    taskid_t pr_taskid;      /* task id */
    projid_t pr_projid;      /* project id */
    poolid_t pr_poolid;      /* pool id */
    zoneid_t pr_zoneid;      /* zone id */
    ctid_t pr_contract;      /* process contract id */
    lwpsinfo_t pr_lwp;       /* information for representative lwp */
} psinfo_t;
.Ed
.Pp
Some of the entries in
.Sy psinfo ,
such as
.Sy pr_addr ,
refer to internal kernel data structures and should not be expected to retain
their meanings across different versions of the operating system.
.Pp
.Sy psinfo_t.pr_flag
is a deprecated interface that should no longer be used.
Applications currently relying on the
.Sy SSYS
bit in
.Sy pr_flag
should migrate to checking
.Sy PR_ISSYS
in the
.Sy pstatus
structure's
.Sy pr_flags
field.
.Pp
.Sy pr_pctcpu
and
.Sy pr_pctmem
are 16-bit binary fractions in the range 0.0 to 1.0 with the binary point to
the right of the high-order bit (1.0 == 0x8000).
.Sy pr_pctcpu
is the summation over all lwps in the process.
.Pp
.Sy pr_lwp
contains the
.Xr ps 1
information for the representative lwp.
If the process is a
.Em zombie ,
.Sy pr_nlwp ,
.Sy pr_nzomb ,
and
.Sy pr_lwp.pr_lwpid
are zero and the other fields of
.Sy pr_lwp
are undefined:
.Bd -literal -offset 2
typedef struct lwpsinfo {
    int pr_flag;             /* lwp flags (DEPRECATED: see below) */
    id_t pr_lwpid;           /* lwp id */
    uintptr_t pr_addr;       /* internal address of lwp */
    uintptr_t pr_wchan;      /* wait addr for sleeping lwp */
    char pr_stype;           /* synchronization event type */
    char pr_state;           /* numeric lwp state */
    char pr_sname;           /* printable character for pr_state */
    char pr_nice;            /* nice for cpu usage */
    short pr_syscall;        /* system call number (if in syscall) */
    char pr_oldpri;          /* pre-SVR4, low value is high priority */
    char pr_cpu;             /* pre-SVR4, cpu usage for scheduling */
    int pr_pri;              /* priority, high value = high priority */
    ushort_t pr_pctcpu;      /* % of recent cpu time used by this lwp */
    timestruc_t pr_start;    /* lwp start time, from the epoch */
    timestruc_t pr_time;     /* cpu time for this lwp */
    char pr_clname[PRCLSZ];  /* scheduling class name */
    char pr_name[PRFNSZ];    /* name of system lwp */
    processorid_t pr_onpro;  /* processor which last ran this lwp */
    processorid_t pr_bindpro;/* processor to which lwp is bound */
    psetid_t pr_bindpset;    /* processor set to which lwp is bound */
    lgrp_id_t pr_lgrp;       /* home lgroup */
} lwpsinfo_t;
.Ed
.Pp
Some of the entries in
.Sy lwpsinfo ,
such as
.Sy pr_addr ,
.Sy pr_wchan ,
.Sy pr_stype ,
.Sy pr_state ,
and
.Sy pr_name ,
refer to internal kernel data structures and should not be expected to retain
their meanings across different versions of the operating system.
.Pp
.Sy lwpsinfo_t.pr_flag
is a deprecated interface that should no longer be used.
.Pp
.Sy pr_pctcpu
is a 16-bit binary fraction, as described above.
It represents the
.Sy CPU
time used by the specific lwp.
On a multi-processor machine, the maximum value is 1/N, where N is the number
of
.Sy CPU Ns s .
.Pp
.Sy pr_contract
is the id of the process contract of which the process is a member.
See
.Xr contract 5
and
.Xr process 5 .
.Ss cred
Contains a description of the credentials associated with the process:
.Bd -literal -offset 2
typedef struct prcred {
	uid_t pr_euid;      /* effective user id */
	uid_t pr_ruid;      /* real user id */
	uid_t pr_suid;      /* saved user id (from exec) */
	gid_t pr_egid;      /* effective group id */
	gid_t pr_rgid;      /* real group id */
	gid_t pr_sgid;      /* saved group id (from exec) */
	int pr_ngroups;     /* number of supplementary groups */
	gid_t pr_groups[1]; /* array of supplementary groups */
} prcred_t;
.Ed
.Pp
The array of associated supplementary groups in
.Sy pr_groups
 is of variable
length; the
.Sy cred
file contains all of the supplementary groups.
.Sy pr_ngroups
indicates the number of supplementary groups. (See also the
.Sy PCSCRED
and
.Sy PCSCREDX
control operations.)
.Ss priv
Contains a description of the privileges associated with the process:
.Bd -literal -offset 2
typedef struct prpriv {
     uint32_t        pr_nsets;      /* number of privilege set */
     uint32_t        pr_setsize;    /* size of privilege set */
     uint32_t        pr_infosize;   /* size of supplementary data */
     priv_chunk_t    pr_sets[1];    /* array of sets */
} prpriv_t;
.Ed
.Pp
The actual dimension of the
.Sy pr_sets Ns []
field is
.D1 pr_sets[pr_nsets][pr_setsize]
.Pp
which is followed by additional information about the process state
.Sy pr_infosize
bytes in size.
.Pp
The full size of the structure can be computed using
.Fn PRIV_PRPRIV_SIZE "prpriv_t *" .
.Ss secflags
This file contains the security-flags of the process.
It contains a description of the security flags associated with the process.
.Bd -literal -offset 2
typedef struct prsecflags {
	uint32_t pr_version;		/* ABI Versioning of this structure */
	secflagset_t pr_effective;	/* Effective flags */
	secflagset_t pr_inherit;	/* Inheritable flags */
	secflagset_t pr_lower;		/* Lower flags */
	secflagset_t pr_upper;		/* Upper flags */
} prsecflags_t;
.Ed
.Pp
The
.Sy pr_version
field is a version number for the structure, currently
.Sy PRSECFLAGS_VERSION_1 .
.Ss sigact
Contains an array of
.Sy sigaction structures
describing the current dispositions of all signals associated with the traced
process (see
.Xr sigaction 2 ) .
Signal numbers are displaced by 1 from array indices, so that the action for
signal number
.Va n
appears in position
.Va n Ns -1
of the array.
.Ss auxv
Contains the initial values of the process's aux vector in an array of
.Sy auxv_t
structures (see
.In sys/auxv.h ) .
The values are those that were passed by the operating system as startup
information to the dynamic linker.
.Ss ldt
This file exists only on x86-based machines.
It is non-empty only if the process has established a local descriptor table
.Pq Sy LDT .
If non-empty, the file contains the array of currently active
.Sy LDT
entries in an array of elements of type
.Vt struct ssd ,
defined in
.In sys/sysi86.h ,
one element for each active
.Sy LDT
entry.
.Ss map, xmap
Contain information about the virtual address map of the process.
The map file contains an array of
.Sy prmap
structures while the xmap file contains an
array of
.Sy prxmap
structures.
Each structure describes a contiguous virtual
address region in the address space of the traced process:
.Bd -literal -offset 2
typedef struct prmap {
	uintptr_tpr_vaddr;         /* virtual address of mapping */
	size_t pr_size;            /* size of mapping in bytes */
	char pr_mapname[PRMAPSZ];  /* name in /proc/pid/object */
	offset_t pr_offset;        /* offset into mapped object, if any */
	int pr_mflags;             /* protection and attribute flags */
	int pr_pagesize;           /* pagesize for this mapping in bytes */
	int pr_shmid;              /* SysV shared memory identifier */
} prmap_t;
.Ed
.Bd -literal -offset 2
typedef struct prxmap {
	uintptr_t pr_vaddr;        /* virtual address of mapping */
	size_t pr_size;            /* size of mapping in bytes */
	char pr_mapname[PRMAPSZ];  /* name in /proc/pid/object */
	offset_t pr_offset;        /* offset into mapped object, if any */
	int pr_mflags;             /* protection and attribute flags */
	int pr_pagesize;           /* pagesize for this mapping in bytes */
	int pr_shmid;              /* SysV shared memory identifier */
	dev_t pr_dev;              /* device of mapped object, if any */
	uint64_t pr_ino;           /* inode of mapped object, if any */
	size_t pr_rss;             /* pages of resident memory */
	size_t pr_anon;            /* pages of resident anonymous memory */
	size_t pr_locked;          /* pages of locked memory */
	uint64_t pr_hatpagesize;   /* pagesize of mapping */
} prxmap_t;
.Ed
.Pp
.Sy pr_vaddr
is the virtual address of the mapping within the traced process and
.Sy pr_size
is its size in bytes.
.Sy pr_mapname ,
if it does not contain a null string, contains the name of a file in the
.Sy object
directory (see below) that can be opened read-only to obtain a file descriptor
for the mapped file associated with the mapping.
This enables a debugger to find object file symbol tables without having to
know the real path names of the executable file and shared libraries of
the process.
.Sy pr_offset
is the 64-bit offset within the mapped file (if any) to which the virtual
address is mapped.
.Pp
.Sy pr_mflags
is a bit-mask of protection and attribute flags:
.Bl -tag -width "MA_NORESERVE" -offset left
.It Sy MA_READ
mapping is readable by the traced process.
.It Sy MA_WRITE
mapping is writable by the traced process.
.It Sy MA_EXEC
mapping is executable by the traced process.
.It Sy MA_SHARED
mapping changes are shared by the mapped object.
.It Sy MA_ISM
mapping is intimate shared memory (shared MMU resources)
.It Sy MAP_NORESERVE
mapping does not have swap space reserved (mapped with MAP_NORESERVE)
.It Sy MA_SHM
mapping System V shared memory
.El
.Pp
A contiguous area of the address space having the same underlying mapped object
may appear as multiple mappings due to varying read, write, and execute
attributes.
The underlying mapped object does not change over the range of a
single mapping.
An
.Sy I/O
operation to a mapping marked
.Sy MA_SHARED
fails if applied at a virtual address not corresponding to a valid page in the
underlying mapped object.
A write to a
.Sy MA_SHARED
mapping that is not marked
.Sy MA_WRITE
fails.
Reads and writes to private mappings always succeed.
Reads and writes to unmapped addresses fail.
.Pp
.Sy pr_pagesize
is the page size for the mapping, currently always the system pagesize.
.Pp
.Sy pr_shmid
is the shared memory identifier, if any, for the mapping.
Its value is \-1
if the mapping is not System V shared memory.
See
.Xr shmget 2 .
.Pp
.Sy pr_dev
is the device of the mapped object, if any, for the mapping.
Its value is
.Sy PRNODEV
.Pq \-1
if the mapping does not have a device.
.Pp
.Sy pr_ino
is the inode of the mapped object, if any, for the mapping.
Its contents are only valid if
.Sy pr_dev
is not
.Sy PRNODEV .
.Pp
.Sy pr_rss
is the number of resident pages of memory for the mapping.
The number of resident bytes for the mapping may be determined by multiplying
.Sy pr_rss
by the page size given by
.Sy pr_pagesize .
.Pp
.Sy pr_anon
is the number of resident anonymous memory pages (pages which are
private to this process) for the mapping.
.Pp
.Sy pr_locked
is the number of locked pages for the mapping.
Pages which are locked are always resident in memory.
.Pp
.Sy pr_hatpagesize
is the size, in bytes, of the
.Sy HAT
.Pq Sy MMU
translation for the mapping.
.Sy pr_hatpagesize
may be different than
.Sy pr_pagesize .
The possible values are hardware architecture specific, and
may change over a mapping's lifetime.
.Ss rmap
Contains information about the reserved address ranges of the process.
The file contains an array of
.Sy prmap
structures, as defined above for the
.Sy map
file.
Each structure describes a contiguous virtual address region in the
address space of the traced process that is reserved by the system in the sense
that an
.Xr mmap 2
system call that does not specify
.Sy MAP_FIXED
will not use any part of it for the new mapping.
Examples of such reservations include the address ranges reserved for the
process stack and the individual thread stacks of a multi-threaded process.
.Ss cwd
A symbolic link to the process's current working directory.
See
.Xr chdir 2 .
A
.Xr readlink 2
of
.Pa /proc/ Ns Em pid Ns Pa /cwd
yields a null string.
However, it can be opened, listed, and searched as a directory, and can be the
target of
.Xr chdir 2 .
.Ss root
A symbolic link to the process's root directory.
.Pa /proc/ Ns Em pid Ns Pa /root
can differ from the system root directory if the process or one of its
ancestors executed
.Xr chroot 2
as super user.
It has the same semantics as
.Pa /proc/ Ns Em pid Ns Pa /cwd .
.Ss fd
A directory containing references to the open files of the process.
Each entry is a decimal number corresponding to an open file descriptor in the
process.
.Pp
If an entry refers to a regular file, it can be opened with normal file system
semantics but, to ensure that the controlling process cannot gain greater
access than the controlled process, with no file access modes other than its
read/write open modes in the controlled process.
If an entry refers to a directory, it can be accessed with the same semantics
as
.Pa /proc/ Ns Em pid Ns Pa /cwd .
An attempt to open any other type of entry fails with
.Er EACCES .
.Ss fdinfo
A directory containing information about each of the process's open files.
Each entry is a decimal number corresponding to an open file descriptor in the
process.
Each file contains a
.Sy prfdinfo_t
structure defined as follows:
.Bd -literal -offset 2
typedef struct prfdinfo {
    int     pr_fd;          /* file descriptor number */
    mode_t  pr_mode;        /* (see st_mode in stat(2)) */
    uint64_t pr_ino;        /* inode number */
    uint64_t pr_size;       /* file size */
    int64_t pr_offset;      /* current offset of file descriptor */
    uid_t   pr_uid;         /* owner's user id */
    gid_t   pr_gid;         /* owner's group id */
    major_t pr_major;       /* major number of device containing file */
    minor_t pr_minor;       /* minor number of device containing file */
    major_t pr_rmajor;      /* major number (if special file) */
    minor_t pr_rminor;      /* minor number (if special file) */
    int     pr_fileflags;   /* (see F_GETXFL in fcntl(2)) */
    int     pr_fdflags;     /* (see F_GETFD in fcntl(2)) */
    short   pr_locktype;    /* (see F_GETLK in fcntl(2)) */
    pid_t   pr_lockpid;     /* process holding file lock (see F_GETLK) */
    int     pr_locksysid;   /* sysid of locking process (see F_GETLK) */
    pid_t   pr_peerpid;     /* peer process (socket, door) */
    int     pr_filler[25];  /* reserved for future use */
    char    pr_peername[PRFNSZ]; /* peer process name */
#if __STDC_VERSION__ >= 199901L
    char    pr_misc[];      /* self describing structures */
#else
    char    pr_misc[1];
#endif
} prfdinfo_t;
.Ed
.Pp
The
.Sy pr_misc
element points to a list of additional miscellaneous data items, each of which
has a header of type
.Sy pr_misc_header_t
specifying the size and type, and some data which immediately follow
the header.
.Bd -literal -offset 2
typedef struct pr_misc_header {
    uint_t          pr_misc_size;
    uint_t          pr_misc_type;
} pr_misc_header_t;
.Ed
.Pp
The
.Sy pr_misc_size
field is the sum of the sizes of the header and the associated data and any
trailing padding bytes which will be set to zero.
The end of the list is indicated by a header with a zero size and a type with
all bits set.
.Pp
The following miscellaneous data types can be present:
.Bl -tag -width "PR_SOCKOPT_TCP_CONGESTION" -offset left
.It Sy PR_PATHNAME
The file descriptor's path in the filesystem.
This is a NUL-terminated sequence of characters.
.It Sy PR_SOCKETNAME
A
.Sy sockaddr
structure representing the local socket name for this file descriptor, as
would be returned by calling
.Fn getsockname
within the process.
.It Sy PR_PEERSOCKNAME
A
.Sy sockaddr
structure representing the peer socket name for this file descriptor, as
would be returned by calling
.Fn getpeername
within the process.
.It Sy PR_SOCKOPTS_BOOL_OPTS
An unsigned integer which has bits set corresponding to options which are
set on the underlying socket.
The following bits may be set:
.Bl -tag -width "PR_SO_PASSIVE_CONNECT"
.It Sy PR_SO_DEBUG
.It Sy PR_SO_REUSEADDR
.It Sy PR_SO_REUSEPORT
.It Sy PR_SO_KEEPALIVE
.It Sy PR_SO_DONTROUTE
.It Sy PR_SO_BROADCAST
.It Sy PR_SO_OOBINLINE
.It Sy PR_SO_DGRAM_ERRIND
.It Sy PR_SO_ALLZONES
.It Sy PR_SO_MAC_EXEMPT
.It Sy PR_SO_EXCLBIND
.It Sy PR_SO_PASSIVE_CONNECT
.It Sy PR_SO_ACCEPTCONN
.It Sy PR_UDP_NAT_T_ENDPOINT
.It Sy PR_SO_VRRP
.It Sy PR_SO_MAC_IMPLICIT
.El
.It Sy PR_SOCKOPT_LINGER
A
.Sy struct linger
as would be returned by calling
.Fn getsockopt SO_LINGER
within the process.
.It Sy PR_SOCKOPT_SNDBUF
The data that would be returned by calling
.Fn getsockopt SO_SNDBUF
within the process.
.It Sy PR_SOCKOPT_RCVBUF
The data that would be returned by calling
.Fn getsockopt SO_RCVBUF
within the process.
.It Sy PR_SOCKOPT_IP_NEXTHOP
The data that would be returned by calling
.Fn getsockopt IPPROTO_IP IP_NEXTHOP
within the process.
.It Sy PR_SOCKOPT_IPV6_NEXTHOP
The data that would be returned by calling
.Fn getsockopt IPPROTO_IPV6 IPV6_NEXTHOP
within the process.
.It Sy PR_SOCKOPT_TYPE
The data that would be returned by calling
.Fn getsockopt SO_TYPE
within the process.
.It Sy PR_SOCKOPT_TCP_CONGESTION
For TCP sockets, the data that would be returned by calling
.Fn getsockopt IPPROTO_TCP TCP_CONGESTION
within the process.
This is a NUL-terminated character array containing the name of the congestion
algorithm in use for the socket.
.It Sy PR_SOCKFILTERS_PRIV
Private data relating to up to the first 32 socket filters pushed on this
descriptor.
.El
.Ss object
A directory containing read-only files with names corresponding to the
.Sy pr_mapname
entries in the
.Sy map
and
.Sy pagedata
files.
Opening such a file yields a file descriptor for the underlying mapped file
associated with an address-space mapping in the process.
The file name
.Pa a.out
appears in the directory as an alias for the process's executable file.
.Pp
The
.Pa object
directory makes it possible for a controlling process to gain
access to the object file and any shared libraries (and consequently the symbol
tables) without having to know the actual path names of the executable files.
.Ss path
A directory containing symbolic links to files opened by the process.
The directory includes one entry for
.Pa cwd
and
.Pa root .
The directory also contains a numerical entry for each file descriptor in the
.Pa fd
directory, and entries matching those in the
.Pa object
directory.
If this information is not available, any attempt to read the contents of the
symbolic link will fail.
This is most common for files that do not exist in the filesystem namespace
(such as
.Sy FIFO Ns s
and sockets), but can also happen for regular files.
For the file descriptor entries, the path may be different from the one
used by the process to open the file.
.Ss pagedata
Opening the page data file enables tracking of address space references and
modifications on a per-page basis.
.Pp
A
.Xr read 2
of the page data file descriptor returns structured page data
and atomically clears the page data maintained for the file by the system.
That is to say, each read returns data collected since the last read; the
first read returns data collected since the file was opened.
When the call completes, the read buffer contains the following structure as
its header and thereafter contains a number of section header structures and
associated byte arrays that must be accessed by walking linearly through the
buffer.
.Bd -literal -offset 2
typedef struct prpageheader {
    timestruc_t pr_tstamp; /* real time stamp, time of read() */
    ulong_t pr_nmap;       /* number of address space mappings */
    ulong_t pr_npage;      /* total number of pages */
} prpageheader_t;
.Ed
.Pp
The header is followed by
.Sy "pr_nmap prasmap"
structures and associated data arrays.
The
.Sy prasmap
structure contains the following elements:
.Bd -literal -offset 2
typedef struct prasmap {
    uintptr_t pr_vaddr;        /* virtual address of mapping */
    ulong_t pr_npage;          /* number of pages in mapping */
    char pr_mapname[PRMAPSZ];  /* name in /proc/pid/object */
    offset_t pr_offset;        /* offset into mapped object, if any */
    int pr_mflags;             /* protection and attribute flags */
    int pr_pagesize;           /* pagesize for this mapping in bytes */
    int pr_shmid;              /* SysV shared memory identifier */
} prasmap_t;
.Ed
.Pp
Each section header is followed by
.Sy pr_npage
bytes, one byte for each page in the mapping, plus 0-7 null bytes at the end
so that the next
.Sy prasmap
structure begins on an eight-byte aligned boundary.
Each data byte may contain these flags:
.Bl -tag -width "PG_REFERENCED" -offset 2
.It Sy PG_REFERENCED
page has been referenced.
.It Sy PG_MODIFIED
page has been modified.
.El
.Pp
If the read buffer is not large enough to contain all of the page data, the
read fails with
.Er E2BIG
and the page data is not cleared.
The required size of the read buffer can be determined through
.Xr fstat 2 .
Application of
.Xr lseek 2
to the page data file descriptor is ineffective; every read
starts from the beginning of the file.
Closing the page data file descriptor
terminates the system overhead associated with collecting the data.
.Pp
More than one page data file descriptor for the same process can be opened, up
to a system-imposed limit per traced process.
A read of one does not affect the data being collected by the system for the
others.
An open of the page data file will fail with
.Er ENOMEM
if the system-imposed limit would be exceeded.
.Ss watch
Contains an array of
.Vt prwatch
structures, one for each watched area established by the
.Sy PCWATCH
control operation.
See
.Sx PCWATCH
for details.
.Ss usage
Contains process usage information described by a
.Vt prusage
structure which contains at least the following fields:
.Bd -literal -offset 2
typedef struct prusage {
    id_t pr_lwpid;           /* lwp id.  0: process or defunct */
    int pr_count;            /* number of contributing lwps */
    timestruc_t pr_tstamp;   /* real time stamp, time of read() */
    timestruc_t pr_create;   /* process/lwp creation time stamp */
    timestruc_t pr_term;     /* process/lwp termination time stamp */
    timestruc_t pr_rtime;    /* total lwp real (elapsed) time */
    timestruc_t pr_utime;    /* user level CPU time */
    timestruc_t pr_stime;    /* system call CPU time */
    timestruc_t pr_ttime;    /* other system trap CPU time */
    timestruc_t pr_tftime;   /* text page fault sleep time */
    timestruc_t pr_dftime;   /* data page fault sleep time */
    timestruc_t pr_kftime;   /* kernel page fault sleep time */
    timestruc_t pr_ltime;    /* user lock wait sleep time */
    timestruc_t pr_slptime;  /* all other sleep time */
    timestruc_t pr_wtime;    /* wait-cpu (latency) time */
    timestruc_t pr_stoptime; /* stopped time */
    ulong_t pr_minf;         /* minor page faults */
    ulong_t pr_majf;         /* major page faults */
    ulong_t pr_nswap;        /* swaps */
    ulong_t pr_inblk;        /* input blocks */
    ulong_t pr_oublk;        /* output blocks */
    ulong_t pr_msnd;         /* messages sent */
    ulong_t pr_mrcv;         /* messages received */
    ulong_t pr_sigs;         /* signals received */
    ulong_t pr_vctx;         /* voluntary context switches */
    ulong_t pr_ictx;         /* involuntary context switches */
    ulong_t pr_sysc;         /* system calls */
    ulong_t pr_ioch;         /* chars read and written */
} prusage_t;
.Ed
.Pp
Microstate accounting is now continuously enabled.
While this information was
previously an estimate, if microstate accounting were not enabled, the current
information is now never an estimate represents time the process has spent in
various states.
.Ss lstatus
Contains a
.Vt prheader
structure followed by an array of
.Vt lwpstatus
structures, one for each active lwp in the process (see also
.Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid Ns Pa /lwpstatus ,
below).
The
.Vt prheader
structure describes the number and size of the array entries that follow.
.Bd -literal -offset 2
typedef struct prheader {
    long pr_nent;        /* number of entries */
    size_t pr_entsize;   /* size of each entry, in bytes */
} prheader_t;
.Ed
.Pp
The
.Vt lwpstatus
structure may grow by the addition of elements at the end in future releases
of the system.
Programs must use
.Sy pr_entsize
in the file header to index through the array.
These comments apply to all
.Pa /proc
files that include a
.Vt prheader
structure
.Pf ( Pa lpsinfo
and
.Pa lusage ,
below).
.Ss lpsinfo
Contains a
.Vt prheader
structure followed by an array of
.Vt lwpsinfo
structures, one for eachactive and zombie lwp in the process.
See also
.Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid Ns Pa /lwpsinfo ,
below.
.Ss lusage
Contains a
.Vt prheader
structure followed by an array of
.Vt prusage
structures, one for each active lwp in the process, plus an additional element
at the beginning that contains the summation over all defunct lwps (lwps that
once existed but no longer exist in the process).
Excluding the
.Sy pr_lwpid ,
.Sy pr_tstamp ,
.Sy pr_create ,
and
.Sy pr_term
entries, the entry-by-entry summation over all these structures is the
definition of the process usage information obtained from the
.Pa usage
file. (See also
.Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid Ns Pa /lwpusage ,
below.)
.Ss lwp
A directory containing entries each of which names an active or zombie lwp
within the process.
These entries are themselves directories containing additional files as
described below.
Only the
.Pa lwpsinfo
file exists in the directory of a zombie lwp.
.Sh "STRUCTURE OF" Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid
A given directory
.Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid
contains the following entries:
.Ss lwpctl
Write-only control file.
The messages written to this file affect the specific
lwp rather than the representative lwp, as is the case for the process's
.Pa ctl
file.
.Ss lwpname
A buffer of
.Dv THREAD_NAME_MAX
bytes representing the LWP name; the buffer is
zero-filled if the thread name is shorter than the buffer.
If no thread name is set, the buffer contains the empty string.
A read with a buffer shorter than
.Dv THREAD_NAME_MAX
bytes is not guaranteed to be NUL-terminated.
Writing to this file will set the LWP name for the specific lwp.
This file may not be present in older operating system versions.
.Dv THREAD_NAME_MAX
may increase in the future; clients should be prepared for this.
.Ss lwpstatus
lwp-specific state information.
This file contains the
.Vt lwpstatus
structure for the specific lwp as described above for the representative lwp in
the process's
.Pa status
file.
.Ss lwpsinfo
lwp-specific
.Xr ps 1
information.
This file contains the
.Vt lwpsinfo
structure for the specific lwp as described above for the representative lwp in
the process's
.Pa psinfo
file.
The
.Pa lwpsinfo
file remains accessible after an lwp becomes a zombie.
.Ss lwpusage
This file contains the
.Vt prusage
structure for the specific lwp as described above for the process's
.Pa usage
file.
.Ss gwindows
This file exists only on SPARC based machines.
If it is non-empty, it contains a
.Vt gwindows_t
structure, defined in
.In sys/regset.h ,
with the values of those SPARC register windows that could not be stored on
the stack when the lwp stopped.
Conditions under which register windows are not stored on the
stack are: the stack pointer refers to nonexistent process memory or the stack
pointer is improperly aligned.
If the lwp is not stopped or if there are no
register windows that could not be stored on the stack, the file is empty (the
usual case).
.Ss xregs
Extra state registers.
The extra state register set is architecture dependent;
this file is empty if the system does not support extra state registers.
If the file is non-empty, it contains an architecture dependent structure of
type
.Vt prxregset_t ,
defined in
.In procfs.h ,
with the values of the lwp's extra state registers.
If the lwp is not stopped, all register values are undefined.
See also the
.Sx PCSXREG
control operation, below.
Reading this data currently requires that the process be stopped.
.Ss asrs
This file exists only for 64-bit SPARC V9 processes.
It contains an
.Vt asrset_t
structure, defined in
.In sys/regset.h ,
containing the values of the lwp's platform-dependent ancillary state registers.
If the lwp is not stopped, all register values are undefined.
See also the
.Sx PCSASRS
control operation, below.
.Ss spymaster
For an agent lwp (see
.Sx PCAGENT ) ,
this file contains a
.Vt psinfo_t
structure that corresponds to the process that created the agent lwp at the
time the agent was created.
This structure is identical to that retrieved via the
.Pa psinfo
file, with one modification: the
.Sy pr_time
field does not correspond to the CPU time for the process, but rather to the
creation time of the agent lwp.
.Ss templates
A directory which contains references to the active templates for the lwp,
named by the contract type.
Changes made to an active template descriptor do
not affect the original template which was activated, though they do affect the
active template.
It is not possible to activate an active template descriptor.
See
.Xr contract 5 .
.Sh ARCHITECTURE-SPECIFIC STRUCTURES
.Ss x86
While the x86
.Vt prxregset_t
structure is opaque to consumers, it is made up of several different
components due to the fact that different x86 processors enumerate
different architectural extensions.
.Pp
The structure begins with a header, the
.Vt prxregset_hdr_t ,
which is followed by a number of different information sections which
describe different possible extended registers.
Each of those is covered by a
.Vt prxregset_info_t ,
and then finally there are different data payloads that represent each
extended register.
.Pp
The number of different informational entries varies from system to
system based on the set of architectural features that the system
supports and the corresponding OS enablement for them.
This structure is built around the idea of the x86
.Sy xsave
structure.
That is, there is a central header which describes a bit-vector of what
extended features are present and have valid state.
.Pp
Each x86 xregs file begins with the
.Vt prxregset_hdr_t
which looks like:
.Bd -literal -offset 2
typedef struct prxregset_hdr {
	uint32_t	pr_type;
	uint32_t	pr_size;
	uint32_t	pr_flags;
	uint32_t	pr_pad[4];
	uint32_t	pr_ninfo;
	prxregset_info_t pr_info[];
} prxregset_hdr_t;
.Ed
.Pp
The
.Fa pr_type
member is always set to
.Dv PR_TYPE_XSAVE .
This is used to indicate the type of file that is present.
There may be different file types in the future on x86 so this value
should always be checked.
If it is not
.Dv PR_TYPE_XSAVE
then the rest of the structure may look different.
The
.Fa pr_size
member indicates the size in bytes of the overall structure.
The
.Fa pr_flags
and
.Fa pr_pad
values are currently reserved for future use.
They will be set to zero right now when read and must be set to zero when
writing the data.
The
.Fa pr_ninfo
member indicates the number of informational items are present in
.Fa pr_info.
There will be one informational item for each register set that exists.
.Pp
The
.Fa pr_info
member points to an array of informational members.
These immediately follow the structure, though the
.Fa pr_info
member may not be available directly if not in an environment compatible with
some C99 features.
Each
.Vt prxregset_info_t
structure looks like:
.Bd -literal -offset 2
typedef struct prxregset_info {
	uint32_t pri_type;
	uint32_t pri_flags;
	uint32_t pri_size;
	uint32_t pri_offset;
} prxregset_info_t;
.Ed
.Pp
The
.Fa pri_type
member is used to indicate the type of data and its format that this represents.
Types are listed below.
The
.Fa pri_flags
member is used to indicate future extensions or information about these items.
Right now, these are all zero.
The
.Fa pri_size
member indicates the size in bytes of the type's data.
The
.Fa pri_offset
member indicates the offset to the start of the data section from the beginning
of the xregs file.
That is an offset of 0 would be the first byte of the
.Vt prxregset_hdr_t .
.Pp
The following types of structures and their corresponding data structures are
currently defined:
.Bl -tag -width Ds
.It Dv PRX_INFO_XCR - Vt prxregset_xcr_t
This structure provides read-only access to understanding the CPU's settings for
this thread.
In particular, it lets you see what is set in the x86 %xcr0 register which is
the extended feature control register and controls what extended features the
CPU actually uses.
It also contains the x86 extended feature disable MSR which controls features
that are ignored.
The
.Vt prxregset_xcr_t
looks like:
.Bd -literal -offset -indent
typedef struct prxregset_xcr {
	uint64_t	prx_xcr_xcr0;
	uint64_t	prx_xcr_xfd;
	uint64_t	prx_xcr_pad[2];
} prxregset_xcr_t;
.Ed
.Pp
When setting the xregs, this entry can be left out.
If it is included, it must match the existing entries, otherwise an error will
be generated.
.It Dv PRX_INFO_XSAVE - Vt prxregset_xsave_t
This structure represents the same as the actual Intel xsave structure, which
has both the traditional XMM state that comes from the fxsave instruction and
then also contains the xsave header itself.
The structure varies between 32-bit and 64-bit applications.
The structure itself looks like:
.Bd -literal
typedef struct prxregset_xsave {
	uint16_t	prx_fx_fcw;
	uint16_t	prx_fx_fsw;
	uint16_t	prx_fx_fctw;	/* compressed tag word */
	uint16_t	prx_fx_fop;
#if defined(__amd64)
	uint64_t	prx_fx_rip;
	uint64_t	prx_fx_rdp;
#else
	uint32_t	prx_fx_eip;
	uint16_t	prx_fx_cs;
	uint16_t	__prx_fx_ign0;
	uint32_t	prx_fx_dp;
	uint16_t	prx_fx_ds;
	uint16_t	__prx_fx_ign1;
#endif
	uint32_t	prx_fx_mxcsr;
	uint32_t	prx_fx_mxcsr_mask;
	union {
		uint16_t prx_fpr_16[5];	/* 80-bits of x87 state */
		u_longlong_t prx_fpr_mmx;	/* 64-bit mmx register */
		uint32_t _prx__fpr_pad[4];	/* (pad out to 128-bits) */
	} fx_st[8];
#if defined(__amd64)
	upad128_t	prx_fx_xmm[16];	/* 128-bit registers */
	upad128_t	__prx_fx_ign2[6];
#else
	upad128_t	prx_fx_xmm[8];	/* 128-bit registers */
	upad128_t	__prx_fx_ign2[14];
#endif
	uint64_t	prx_xsh_xstate_bv;
	uint64_t	prx_xsh_xcomp_bv;
	uint64_t	prx_xsh_reserved[6];
} prxregset_xsave_t;
.Ed
.Pp
In the classical fxsave portion of the structure, most of the members follow the
same meaning and match their presence in the fpregs file and their use as
discussed in the Intel and AMD software developer manuals.
The one exception is that when setting the
.Fa prx_fx_mxcsr
member reserved bits that are set will be masked off and ignored.
.Pp
The most notable fields to consider here right now are the last few members
which are part of the xsave header itself.
In particular, the
.Fa prx_xsh_xstate_bv
component is used to track the actual features whose content are valid.
When reading the registers, if a given entry is not valid, the register state
will write out the informational entry in its default state.
When setting the extended registers, this notes which features will be loaded
from their default state
.Pq as defined by Intel and AMD's manuals
and which will be loaded from the informational entries.
If a bit is set in the
.Fa prx_xsh_xstate_bv
entry, then it must be present as its own informational entry otherwise a write
will fail.
If an informational entry is present in a write, but not set in the
.Fa prx_xsh_xstate_bv
then its contents will be ignored.
.Pp
The xregs format currently does not support any compressed items being specified
nor does it specify any, so the
.Fa prx_xsh_xcomp_bv
member will be always set to zero and it and the reserved members
.Fa prx_xsh_reserved
must all be left as zero.
.It Dv PRX_INFO_YMM - Vt prxregset_ymm_t
This structure contains the upper 128-bits of the first 16 %ymm registers
.Pq 8 for 32-bit applications .
To construct a full vector register, it must be combined with the
.Fa prx_fx_xmm
member of the
.Dv PRX_INFO_XSAVE
data.
In 32-bit applications, the reserved registers must be written as zero.
The structure itself looks like:
.Bd -literal -offset 2
typedef struct prxregset_ymm {
#if defined(__amd64)
	upad128_t	prx_ymm[16];
#else
	upad128_t	prx_ymm[8];
	upad128_t	prx_rsvd[8];
#endif
} prxregset_ymm_t;
.Ed
.It Dv PRX_INFO_OPMASK - Vt prxregset_opmask_t
This structure represents one portion of Intel's AVX-512 state: the 8 64-bit
mask registers, %k0 through %k7.
The structure looks like:
.Bd -literal -offset 2
typedef struct prxregset_opmask {
	uint64_t	prx_opmask[8];
} prxregset_opmask_t;
.Ed
.It Dv PRX_INFO_ZMM - Vt prxregset_zmm_t
This structure represents one portion of Intel's AVX-512 state: the upper
256 bits of the 512-bit %zmm0 through %zmm15 registers.
Bits 0-127 are found in the
.Fa prx_fx_xmm
member of the
.Dv PRX_INFO_XSAVE
data and bits 128-255 are found in the
.Fa prx_ymm
member of the
.Dv PRX_INFO_YMM .
32-bit applications only have access to %zmm0 through %zmm7.
This structure looks like:
.Bd -literal -offset 2
typedef struct prxregset_zmm {
#if defined(__amd64)
	upad256_t	prx_zmm[16];
#else
	upad256_t	prx_zmm[8];
	upad256_t	prx_rsvd[8];
#endif
} prxregset_zmm_t;
.Ed
.It Dv PRX_INFO_HI_ZMM - Vt prxregset_hi_zmm_t
This structure represents the third portion of Intel's AVX-512 state: the
additional 16 512-bit registers that are available to 64-bit applications, but
not 32-bit applications.
This represents %zmm16 through %zmm31.
This structure looks like:
.Bd -literal -offset indent
typedef struct prxregset_hi_zmm {
#if defined(__amd64)
	upad512_t	prx_hi_zmm[16];
#else
	upad512_t	prx_rsvd[16];
#endif
} prxregset_hi_zmm_t;
.Pp
Unlike the other lower %zmm registers of %zmm0 through %zmm15, this contains the
entire 512-bit register in one spot and there is no need to look at other
information items to reconstitute the entire vector.
.Ed
.Pp
When setting the extended registers, at least the
.Dv PRX_INFO_XSAVE
component must be present.
None of the component offsets may overlap with the
.Vt prxregset_hdr_t
or any of the
.Vt prxregset_info_t
structures.
When constructing the overall payload, it is expected that the various
structures start with their naturally expected alignment, which is most
often 16 bytes
.Po
that is the value that the C
.Fn alignof
keyword will return
.Pc .
The structures that we use are all multiples of 16 bytes to make this easier.
Note, when reading the x86 xregs file, the kernel will write out these
structures with increased alignment beyond the natural alignment of the
structure.
The kernel does this so that the structure's data may be more easily used
directly by x86 instructions that require alignment such as vmovdqu64.
.El
.Sh CONTROL MESSAGES
Process state changes are effected through messages written to a process's
.Sy ctl
file or to an individual lwp's
.Sy lwpctl
file.
All control messages consist of a
.Sy long
that names the specific operation followed by
additional data containing the operand, if any.
.Pp
Multiple control messages may be combined in a single
.Xr write 2
(or
.Xr writev 2 )
to a control file, but no partial writes are permitted.
That is, each control message, operation code plus operand, if any, must be
presented in its entirety to the
.Xr write 2
and not in pieces over several system calls.
If a control operation fails, no subsequent operations contained in the same
.Xr write 2
are attempted.
.Pp
Descriptions of the allowable control messages follow.
In all cases, writing a message to a control file for a process or lwp that
has terminated elicits the error
.Er ENOENT .
.Ss PCSTOP PCDSTOP PCWSTOP PCTWSTOP
When applied to the process control file,
.Sy PCSTOP
directs all lwps to stop and waits for them to stop,
.Sy PCDSTOP
directs all lwps to stop without waiting for them to stop, and
.Sy PCWSTOP
simply waits for all lwps to stop.
When applied to an lwp control file,
.Sy PCSTOP
directs the specific lwp to stop and waits until it has stopped,
.Sy PCDSTOP
directs the specific lwp to stop without waiting for it to stop, and
.Sy PCWSTOP
simply waits for the specific lwp to stop.
When applied to an lwp control file,
.Sy PCSTOP
and
.Sy PCWSTOP
complete when the lwp stops on an event of interest, immediately
if already so stopped; when applied to the process control file, they complete
when every lwp has stopped either on an event of interest or on a
.Sy PR_SUSPENDED
stop.
.Pp
.Sy PCTWSTOP
is identical to
.Sy PCWSTOP
except that it enables the operation to time out, to avoid waiting forever for
a process or lwp that may never stop on an event of interest.
.Sy PCTWSTOP
takes a
.Sy long
operand specifying a number of milliseconds; the wait will terminate
successfully after the specified number of milliseconds even if the process or
lwp has not stopped; a timeout value of zero makes the operation identical to
.Sy PCWSTOP .
.Pp
An
.Dq event of interest
is either a
.Sy PR_REQUESTED
stop or a stop that has been specified in the process's tracing flags (set by
.Sy PCSTRACE ,
.Sy PCSFAULT ,
.Sy PCSENTRY ,
and
.Sy PCSEXIT ) .
.Sy PR_JOBCONTROL
and
.Sy PR_SUSPENDED
stops are specifically not events of interest.
(An lwp may stop twice due to a stop signal, first showing
.Sy PR_SIGNALLED
if the signal is traced and again showing
.Sy PR_JOBCONTROL
if the lwp is set running without clearing the signal.)
If
.Sy PCSTOP
or
.Sy PCDSTOP
is applied to an
lwp that is stopped, but not on an event of interest, the stop directive takes
effect when the lwp is restarted by the competing mechanism.
At that time, the lwp enters a
.Sy PR_REQUESTED
stop before executing any user-level code.
.Pp
A write of a control message that blocks is interruptible by a signal so that,
for example, an
.Xr alarm 2
can be set to avoid waiting forever for a
process or lwp that may never stop on an event of interest.
If
.Sy PCSTOP
is interrupted, the lwp stop directives remain in effect even though the
.Xr write 2
returns an error.
(Use of
.Sy PCTWSTOP
with a non-zero timeout is recommended over
.Sy PCWSTOP
with an
.Xr alarm 2 . )
.Pp
A system process (indicated by the
.Sy PR_ISSYS
flag) never executes at user level, has no user-level address space visible
through
.Pa /proc ,
and cannot be stopped.
Applying one of these operations to a system process or any of its
lwps elicits the error
.Er EBUSY .
.Ss PCRUN
Make an lwp runnable again after a stop.
This operation takes a
.Vt long
operand containing zero or more of the following flags:
.Bl -tag -width "PRSABORT" -offset left
.It Sy PRCSIG
clears the current signal, if any (see
.Sx PCCSIG ) .
.It Sy PRCFAULT
clears the current fault, if any (see
.Sx PCCFAULT ) .
.It Sy PRSTEP
directs the lwp to execute a single machine instruction.
On completion of the instruction, a trace trap occurs.
If
.Sy FLTTRACE
is being traced, the lwp stops; otherwise, it is sent
.Sy SIGTRAP .
If
.Sy SIGTRAP
is being traced and is not blocked, the lwp stops.
When the lwp stops on an event of interest,
the single-step directive is cancelled, even if the stop occurs before the
instruction is executed.
This operation requires hardware and operating system
support and may not be implemented on all processors.
It is implemented on SPARC and x86-based machines.
.It Sy PRSABORT
is meaningful only if the lwp is in a
.Sy PR_SYSENTRY
stop or is marked
.Sy PR_ASLEEP ;
it instructs the lwp to abort execution of the system call (see
.Sx PCSENTRY
and
.Sx PCSEXIT ) .
.It Sy PRSTOP
directs the lwp to stop again as soon as possible after resuming execution (see
.Sx PCDSTOP ) .
In particular, if the lwp is stopped on
.Sy PR_SIGNALLED
or
.Sy PR_FAULTED ,
the next stop will show
.Sy PR_REQUESTED ,
no other stop
will have intervened, and the lwp will not have executed any user-level code.
.El
.Pp
When applied to an lwp control file,
.Sy PCRUN
clears any outstanding
directed-stop request and makes the specific lwp runnable.
The operation fails with
.Er EBUSY
if the specific lwp is not stopped on an event of interest or
has not been directed to stop or if the agent lwp exists and this is not the
agent lwp (see
.Sx PCAGENT ) .
.Pp
When applied to the process control file, a representative lwp is chosen for
the operation as described for
.Pa /proc/ Ns Em pid Ns Pa /status .
The operation fails with
.Er EBUSY
if the representative lwp is not stopped on an
event of interest or has not been directed to stop or if the agent lwp exists.
If
.Sy PRSTEP
or
.Sy PRSTOP
was requested, the representative lwp is made
runnable and its outstanding directed-stop request is cleared; otherwise all
outstanding directed-stop requests are cleared and, if it was stopped on an
event of interest, the representative lwp is marked
.Sy PR_REQUESTED .
If, as a consequence, all lwps are in the
.Sy PR_REQUESTED
or
.Sy PR_SUSPENDED
stop state, all lwps showing
.Sy PR_REQUESTED
are made runnable.
.Ss PCSTRACE
Define a set of signals to be traced in the process.
The receipt of one of these signals by an lwp causes the lwp to stop.
The set of signals is defined using an operand
.Sy sigset_t
contained in the control message.
Receipt of
.Sy SIGKILL
cannot be traced; if specified, it is silently ignored.
.Pp
If a signal that is included in an lwp's held signal set (the signal mask) is
sent to the lwp, the signal is not received and does not cause a stop until it
is removed from the held signal set, either by the lwp itself or by setting the
held signal set with
.Sy PCSHOLD .
.Ss PCCSIG
The current signal, if any, is cleared from the specific or representative lwp.
.Ss PCSSIG
The current signal and its associated signal information for the specific or
representative lwp are set according to the contents of the operand
.Vt siginfo
structure (see
.In sys/siginfo.h ) .
If the specified signal number is zero, the current signal is cleared.
The semantics of this operation are different from those of
.Xr kill 2
in that the signal is delivered to the lwp immediately after execution is
resumed (even if it is being blocked) and an additional
.Sy PR_SIGNALLED
stop does not intervene even if the signal is traced.
Setting the current signal to
.Sy SIGKILL
terminates the process immediately.
.Ss PCKILL
If applied to the process control file, a signal is sent to the process with
semantics identical to those of
.Xr kill 2
If applied to an lwp control file, a directed signal is sent to the specific
lwp.
The signal is named in a
.Vt long
operand contained in the message.
Sending
.Sy SIGKILL
terminates the process immediately.
.Ss PCUNKILL
A signal is deleted, that is, it is removed from the set of pending signals.
If applied to the process control file, the signal is deleted from the process's
pending signals.
If applied to an lwp control file, the signal is deleted from
the lwp's pending signals.
The current signal (if any) is unaffected.
The signal is named in a
.Sy long
operand in the control message.
It is an error
.Pq Er EINVAL
to attempt to delete
.Sy SIGKILL .
.Ss PCSHOLD
Set the set of held signals for the specific or representative lwp (signals
whose delivery will be blocked if sent to the lwp).
The set of signals is specified with a
.Vt sigset_t
operand.
.Sy SIGKILL
and
.Sy SIGSTOP
cannot be held; if specified, they are silently ignored.
.Ss PCSFAULT
Define a set of hardware faults to be traced in the process.
On incurring one of these faults, an lwp stops.
The set is defined via the operand
.Vt fltset_t
structure.
Fault names are defined in
.In sys/fault.h
and include the following.
Some of these may not occur on all processors; there may
be processor-specific faults in addition to these.
.Bl -tag -width "FLTACCESS" -offset indent
.It Sy FLTILL
illegal instruction
.It Sy FLTPRIV
privileged instruction
.It Sy FLTBPT
breakpoint trap
.It Sy FLTTRACE
trace trap (single-step)
.It Sy FLTWATCH
watchpoint trap
.It Sy FLTACCESS
memory access fault (bus error)
.It Sy FLTBOUNDS
memory bounds violation
.It Sy FLTIOVF
integer overflow
.It Sy FLTIZDIV
integer zero divide
.It Sy FLTFPE
floating-point exception
.It Sy FLTSTACK
unrecoverable stack fault
.It Sy FLTPAGE
recoverable page fault
.El
.Pp
When not traced, a fault normally results in the posting of a signal to the lwp
that incurred the fault.
If an lwp stops on a fault, the signal is posted to
the lwp when execution is resumed unless the fault is cleared by
.Sy PCCFAULT
or by the
.Sy PRCFAULT
option of
.Sy PCRUN .
.Sy FLTPAGE
is an exception; no signal is posted.
The
.Sy pr_info
field in the
.Vt lwpstatus
structure identifies the signal to be sent and contains machine-specific
information about the fault.
.Ss PCCFAULT
The current fault, if any, is cleared; the associated signal will not be sent
to the specific or representative lwp.
.Ss PCSENTRY PCSEXIT
These control operations instruct the process's lwps to stop on entry to or
exit from specified system calls.
The set of system calls to be traced is defined via an operand
.Vt sysset_t
structure.
.Pp
When entry to a system call is being traced, an lwp stops after having begun
the call to the system but before the system call arguments have been fetched
from the lwp.
When exit from a system call is being traced, an lwp stops on completion of
the system call just prior to checking for signals and returning to user level.
At this point, all return values have been stored into the lwp's registers.
.Pp
If an lwp is stopped on entry to a system call
.Pq Sy PR_SYSENTRY
or when sleeping in an interruptible system call
.Pf ( Sy PR_ASLEEP
is set), it may be instructed to go directly to system call exit by specifying
the
.Sy PRSABORT
flag in a
.Sy PCRUN
control message.
Unless exit from the system call is being traced, the lwp returns to user
level showing
.Er EINTR .
.Ss PCWATCH
Set or clear a watched area in the controlled process from a
.Vt prwatch
structure operand:
.Bd -literal -offset 2
typedef struct prwatch {
    uintptr_t pr_vaddr;  /* virtual address of watched area */
    size_t pr_size;      /* size of watched area in bytes */
    int pr_wflags;       /* watch type flags */
} prwatch_t;
.Ed
.Pp
.Sy pr_vaddr
specifies the virtual address of an area of memory to be watched
in the controlled process.
.Sy pr_size
specifies the size of the area, in bytes.
.Sy pr_wflags
specifies the type of memory access to be monitored as a
bit-mask of the following flags:
.Bl -tag -width "WA_TRAPAFTER" -offset indent
.It Sy WA_READ
read access
.It Sy WA_WRITE
write access
.It Sy WA_EXEC
execution access
.It Sy WA_TRAPAFTER
trap after the instruction completes
.El
.Pp
If
.Sy pr_wflags
is non-empty, a watched area is established for the virtual
address range specified by
.Sy pr_vaddr
and
.Sy pr_size .
If
.Sy pr_wflags
is empty, any previously-established watched area starting at the specified
virtual address is cleared;
.Sy pr_size
is ignored.
.Pp
A watchpoint is triggered when an lwp in the traced process makes a memory
reference that covers at least one byte of a watched area and the memory
reference is as specified in
.Sy pr_wflags .
When an lwp triggers a watchpoint, it incurs a watchpoint trap.
If
.Sy FLTWATCH
is being traced, the lwp stops; otherwise, it is sent a
.Sy SIGTRAP
signal; if
.Sy SIGTRAP
is being traced and is not blocked, the lwp stops.
.Pp
The watchpoint trap occurs before the instruction completes unless
.Sy WA_TRAPAFTER
was specified, in which case it occurs after the instruction completes.
If it occurs before completion, the memory is not modified.
If it occurs after completion, the memory is modified (if the access is a write
access).
.Pp
Physical i/o is an exception for watchpoint traps.
In this instance, there is no guarantee that memory before the watched area
has already been modified (or in the case of
.Sy WA_TRAPAFTER ,
that the memory following the watched area
has not been modified) when the watchpoint trap occurs and the lwp stops.
.Pp
.Sy pr_info
in the
.Vt lwpstatus
structure contains information pertinent to the watchpoint trap.
In particular, the
.Sy si_addr
field contains the
virtual address of the memory reference that triggered the watchpoint, and the
.Sy si_code
field contains one of
.Sy TRAP_RWATCH ,
.Sy TRAP_WWATCH ,
or
.Sy TRAP_XWATCH ,
indicating read, write, or execute access, respectively.
The
.Sy si_trapafter
field is zero unless
.Sy WA_TRAPAFTER
is in effect for this watched area; non-zero indicates that the current
instruction is not the instruction that incurred the watchpoint trap.
The
.Sy si_pc
field contains the virtual address of the instruction that incurred the trap.
.Pp
A watchpoint trap may be triggered while executing a system call that makes
reference to the traced process's memory.
The lwp that is executing the system call incurs the watchpoint trap while
still in the system call.
If it stops as a result, the
.Vt lwpstatus
structure contains the system call number and its arguments.
If the lwp does not stop, or if it is set running again without
clearing the signal or fault, the system call fails with
.Er EFAULT .
If
.Sy WA_TRAPAFTER
was specified, the memory reference will have completed and
the memory will have been modified (if the access was a write access) when the
watchpoint trap occurs.
.Pp
If more than one of
.Sy WA_READ ,
.Sy WA_WRITE ,
and
.Sy WA_EXEC
is specified for a watched area, and a single instruction incurs more than one
of the specified types, only one is reported when the watchpoint trap occurs.
The precedence is
.Sy WA_EXEC ,
.Sy WA_READ ,
.Sy WA_WRITE
.Pf ( Sy WA_EXEC
and
.Sy WA_READ
take precedence over
.Sy WA_WRITE ) ,
unless
.Sy WA_TRAPAFTER
was specified, in which case it is
.Sy WA_WRITE ,
.Sy WA_READ ,
.Sy WA_EXEC
.Pf ( Sy WA_WRITE
takes precedence).
.Pp
.Sy PCWATCH
fails with
.Er EINVAL
if an attempt is made to specify overlapping watched areas or if
.Sy pr_wflags
contains flags other than those specified above.
It fails with
.Er ENOMEM
if an attempt is made to establish more watched areas than the system can
support (the system can support thousands).
.Pp
The child of a
.Xr vfork 2
borrows the parent's address space.
When a
.Xr vfork 2
is executed by a traced process, all watched areas established
for the parent are suspended until the child terminates or performs an
.Xr exec 2 .
Any watched areas established independently in the child are
cancelled when the parent resumes after the child's termination or
.Xr exec 2 .
.Sy PCWATCH
fails with
.Er EBUSY
if applied to the parent of a
.Xr vfork 2
before the child has terminated or performed an
.Xr exec 2 .
The
.Sy PR_VFORKP
flag is set in the
.Sy pstatus
structure for such a parent process.
.Pp
Certain accesses of the traced process's address space by the operating system
are immune to watchpoints.
The initial construction of a signal stack frame when a signal is delivered to
an lwp will not trigger a watchpoint trap even if the new frame covers watched
areas of the stack.
Once the signal handler is entered, watchpoint traps occur normally.
On SPARC based machines, register window overflow and underflow will not
trigger watchpoint traps, even if the register window save areas cover watched
areas of the stack.
.Pp
Watched areas are not inherited by child processes, even if the traced
process's inherit-on-fork mode,
.Sy PR_FORK ,
is set (see
.Sy PCSET ,
below).
All watched areas are cancelled when the traced process performs a successful
.Xr exec 2 .
.Ss PCSET PCUNSET
.Sy PCSET
sets one or more modes of operation for the traced process.
.Sy PCUNSET
unsets these modes.
The modes to be set or unset are specified by flags in an operand
.Sy long
in the control message:
.Bl -tag -offset left -width "PR_MSFORK"
.It Sy PR_FORK
(inherit-on-fork): When set, the process's tracing flags and its
inherit-on-fork mode are inherited by the child of a
.Xr fork 2 ,
.Xr fork1 2 ,
or
.Xr vfork 2 .
When unset, child processes start with all tracing flags cleared.
.It Sy PR_RLC
(run-on-last-close): When set and the last writable
.Pa /proc
file descriptor referring to the traced process or any of its lwps is closed,
all of the process's tracing flags and watched areas are cleared, any
outstanding stop directives are canceled, and if any lwps are stopped on
events of interest, they are set running as though
.Sy PCRUN
had been applied to them.
When unset, the process's tracing flags and watched areas are retained and
lwps are not set running on last close.
.It Sy PR_KLC
(kill-on-last-close): When set and the last writable
.Pa /proc
file descriptor referring to the traced process or any of its lwps is closed,
the process is terminated with
.Sy SIGKILL .
.It Sy PR_ASYNC
(asynchronous-stop): When set, a stop on an event of interest by one lwp does
not directly affect any other lwp in the process.
When unset and an lwp stops on an event of interest other than
.Sy PR_REQUESTED ,
all other lwps in the process are directed to stop.
.It Sy PR_MSACCT
(microstate accounting): Microstate accounting is now continuously enabled.
This flag is deprecated and no longer has any effect upon microstate
accounting.
Applications may toggle this flag; however, microstate accounting
will remain enabled regardless.
.It Sy PR_MSFORK
(inherit microstate accounting): All processes now inherit microstate
accounting, as it is continuously enabled.
This flag has been deprecated and its use no longer has any effect upon the
behavior of microstate accounting.
.It Sy PR_BPTADJ
(breakpoint trap pc adjustment): On x86-based machines, a breakpoint trap
leaves the program counter (the
.Sy EIP )
referring to the breakpointed instruction plus one byte.
When
.Sy PR_BPTADJ
is set, the system will adjust the program counter back to the location of the
breakpointed instruction when the lwp stops on a breakpoint.
This flag has no effect on SPARC based machines, where breakpoint traps leave
the program counter referring to the breakpointed instruction.
.It Sy PR_PTRACE
(ptrace-compatibility): When set, a stop on an event of interest by the traced
process is reported to the parent of the traced process by
.Xr wait 3C ,
.Sy SIGTRAP
is sent to the traced process when it executes a successful
.Xr exec 2 ,
setuid/setgid flags are not honored for execs performed by the
traced process, any exec of an object file that the traced process cannot read
fails, and the process dies when its parent dies.
This mode is deprecated; it is provided only to allow
.Xr ptrace 3C
to be implemented as a library function using
.Pa /proc .
.El
.Pp
It is an error
.Pq Er EINVAL
to specify flags other than those described above
or to apply these operations to a system process.
The current modes are reported in the
.Sy pr_flags
field of
.Pa /proc/ Ns Em pid Ns Pa /status
and
.Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwp Ns Pa /lwpstatus .
.Ss PCSREG
Set the general registers for the specific or representative lwp according to
the operand
.Vt prgregset_t
structure.
.Pp
On SPARC based systems, only the condition-code bits of the processor-status
register (R_PSR) of SPARC V8 (32-bit) processes can be modified by
.Sy PCSREG .
Other privileged registers cannot be modified at all.
.Pp
On x86-based systems, only certain bits of the flags register (EFL) can be
modified by
.Sy PCSREG :
these include the condition codes, direction-bit, and overflow-bit.
.Pp
.Sy PCSREG
fails with
.Er EBUSY
if the lwp is not stopped on an event of interest.
.Ss PCSVADDR
Set the address at which execution will resume for the specific or
representative lwp from the operand
.Vt long .
On SPARC based systems, both %pc and %npc are set, with %npc set to the
instruction following the virtual address.
On x86-based systems, only %eip is set.
.Sy PCSVADDR
fails with
.Er EBUSY
if the lwp is not stopped on an event of interest.
.Ss PCSFPREG
Set the floating-point registers for the specific or representative lwp
according to the operand
.Vt prfpregset_t
structure.
An error
.Pq Er EINVAL
is returned if the system does not support floating-point operations (no
floating-point hardware and the system does not emulate floating-point machine
instructions).
.Sy PCSFPREG
fails with
.Er EBUSY
if the lwp is not stopped on an event of interest.
.Ss PCSXREG
Set the extra state registers for the specific or representative lwp according
to the architecture-dependent operand
.Vt prxregset_t
structure.
An error
.Pq Er EINVAL
is returned if the system does not support extra state registers or the register
state is invalid.
.Sy PCSXREG
fails with
.Er EBUSY
if the lwp is not stopped on an event of interest.
.Ss PCSASRS
Set the ancillary state registers for the specific or representative lwp
according to the SPARC V9 platform-dependent operand
.Vt asrset_t
structure.
An error
.Pq Er EINVAL
is returned if either the target process or the
controlling process is not a 64-bit SPARC V9 process.
Most of the ancillary state registers are privileged registers that cannot be
modified.
Only those that can be modified are set; all others are silently ignored.
.Sy PCSASRS
fails with
.Er EBUSY
if the lwp is not stopped on an event of interest.
.Ss PCAGENT
Create an agent lwp in the controlled process with register values from the
operand
.Vt prgregset_t
structure (see
.Sy PCSREG ,
above).
The agent lwp is created in the stopped state showing
.Sy PR_REQUESTED
and with its held signal set (the signal mask) having all signals except
.Sy SIGKILL
and
.Sy SIGSTOP
blocked.
.Pp
The
.Sy PCAGENT
operation fails with
.Er EBUSY
unless the process is fully stopped via
.Pa /proc ,
that is, unless all of the lwps in the process are
stopped either on events of interest or on
.Sy PR_SUSPENDED ,
or are stopped on
.Sy PR_JOBCONTROL
and have been directed to stop via
.Sy PCDSTOP .
It fails with
.Er EBUSY
if an agent lwp already exists.
It fails with
.Er ENOMEM
if system resources for creating new lwps have been exhausted.
.Pp
Any
.Sy PCRUN
operation applied to the process control file or to the control
file of an lwp other than the agent lwp fails with
.Er EBUSY
as long as the agent lwp exists.
The agent lwp must be caused to terminate by executing the
.Sy SYS_lwp_exit
system call trap before the process can be restarted.
.Pp
Once the agent lwp is created, its lwp-ID can be found by reading the process
status file.
To facilitate opening the agent lwp's control and status files,
the directory name
.Pa /proc/ Ns Em pid Ns Pa /lwp/agent
is accepted for lookup operations as an invisible alias for
.Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid ,
.Em lwpid
being the lwp-ID of the agent lwp (invisible in the sense that the name
.Dq agent
does not appear in a directory listing of
.Pa /proc/ Ns Em pid Ns Pa /lwp
obtained from
.Xr ls 1 ,
.Xr getdents 2 ,
or
.Xr readdir 3C .
.Pp
The purpose of the agent lwp is to perform operations in the controlled process
on behalf of the controlling process: to gather information not directly
available via
.Pa /proc
files, or in general to make the process change state
in ways not directly available via
.Pa /proc
control operations.
To make use of an agent lwp, the controlling process must be capable of making
it execute system calls (specifically, the
.Sy SYS_lwp_exit
system call trap).
The register values given to the agent lwp on creation are typically the
registers of the representative lwp, so that the agent lwp can use its stack.
.Pp
If the controlling process neglects to force the agent lwp to execute the
.Sy SYS_lwp_exit
system call (due to either logic error or fatal failure on
the part of the controlling process), the agent lwp will remain in the target
process.
For purposes of being able to debug these otherwise rogue agents,
information as to the creator of the agent lwp is reflected in that lwp's
.Pa spymaster
file in
.Pa /proc .
Should the target process generate a core
dump with the agent lwp in place, this information will be available via the
.Sy NT_SPYMASTER
note in the core file (see
.Xr core 5 ) .
.Pp
The agent lwp is not allowed to execute any variation of the
.Sy SYS_fork
or
.Sy SYS_exec
system call traps.
Attempts to do so yield
.Er ENOTSUP
to the agent lwp.
.Pp
Symbolic constants for system call trap numbers like
.Sy SYS_lwp_exit
and
.Sy SYS_lwp_create
can be found in the header file
.In sys/syscall.h .
.Ss PCREAD PCWRITE
Read or write the target process's address space via a
.Vt priovec
structure operand:
.Bd -literal -offset 2
typedef struct priovec {
    void *pio_base;      /* buffer in controlling process */
    size_t pio_len;      /* size of read/write request in bytes */
    off_t pio_offset;    /* virtual address in target process */
} priovec_t;
.Ed
.Pp
These operations have the same effect as
.Xr pread 2
and
.Xr pwrite 2 ,
respectively, of the target process's address space file.
The difference is that more than one
.Sy PCREAD
or
.Sy PCWRITE
control operation can be
written to the control file at once, and they can be interspersed with other
control operations in a single write to the control file.
This is useful, for example, when planting many breakpoint instructions in
the process's address space, or when stepping over a breakpointed instruction.
Unlike
.Xr pread 2
and
.Xr pwrite 2 ,
no provision is made for partial reads or writes; if the
operation cannot be performed completely, it fails with
.Er EIO .
.Ss PCNICE
The traced process's
.Xr nice 2
value is incremented by the amount in the
operand
.Vt long .
Only a process with the
.Brq Sy PRIV_PROC_PRIOCNTL
privilege asserted in its effective set can better a process's priority in this
way, but any user may lower the priority.
This operation is not meaningful for all scheduling classes.
.Ss PCSCRED
Set the target process credentials to the values contained in the
.Vt prcred_t
structure operand (see
.Pa /proc/ Ns Em pid Ns Pa /cred ) .
The
effective, real, and saved user-IDs and group-IDs of the target process are
set.
The target process's supplementary groups are not changed; the
.Sy pr_ngroups
and
.Sy pr_groups
members of the structure operand are ignored.
Only the privileged processes can perform this operation; for all
others it fails with
.Er EPERM .
.Ss PCSCREDX
Operates like
.Sy PCSCRED
but also sets the supplementary groups; the length
of the data written with this control operation should be "sizeof
.Pq Vt prcred_t
+ sizeof
.Pq Vt gid_t
* (#groups - 1)".
.Ss PCSPRIV
Set the target process privilege to the values contained in the
.Vt prpriv_t
operand (see
.Pa /proc/pid/priv ) .
The effective, permitted, inheritable, and
limit sets are all changed.
Privilege flags can also be set.
The process is made privilege aware unless it can relinquish privilege awareness.
See
.Xr privileges 7 .
.Pp
The limit set of the target process cannot be grown.
The other privilege sets must be subsets of the intersection of the effective set
of the calling process with the new limit set of the target process or subsets of
the original values of the sets in the target process.
.Pp
If any of the above restrictions are not met,
.Er EPERM
is returned.
If the structure written is improperly formatted,
.Er EINVAL
is returned.
.Sh PROGRAMMING NOTES
For security reasons, except for the
.Sy psinfo ,
.Sy usage ,
.Sy lpsinfo ,
.Sy lusage ,
.Sy lwpsinfo ,
and
.Sy lwpusage
files, which are world-readable, and except for privileged processes, an open
of a
.Pa /proc
file fails unless both the user-ID and group-ID of the caller match those of
the traced process and the process's object file is readable by the caller.
The effective set of the caller is a superset of both the inheritable and the
permitted set of the target process.
The limit set of the caller is a superset of the limit set of the target
process.
Except for the world-readable files just mentioned, files corresponding to
setuid and setgid processes can be opened only by the appropriately privileged
process.
.Pp
A process that is missing the basic privilege
.Brq Sy PRIV_PROC_INFO
cannot see any processes under
.Pa /proc
that it cannot send a signal to.
.Pp
A process that has
.Brq Sy PRIV_PROC_OWNER
asserted in its effective set can open any file for reading.
To manipulate or control a process, the controlling process must have at least
as many privileges in its effective set as the target process has in its
effective, inheritable, and permitted sets.
The limit set of the controlling process must be a superset of the limit set
of the target process.
Additional restrictions apply if any of the uids of the target process are 0.
See
.Xr privileges 7 .
.Pp
Even if held by a privileged process, an open process or lwp file descriptor
(other than file descriptors for the world-readable files) becomes invalid if
the traced process performs an
.Xr exec 2
of a setuid/setgid object file or
an object file that the traced process cannot read.
Any operation performed on an invalid file descriptor, except
.Xr close 2 ,
fails with
.Er EAGAIN .
In this situation, if any tracing flags are set and the process or any lwp
file descriptor is open for writing, the process will have been directed to
stop and its run-on-last-close flag will have been set (see
.Sx PCSET ) .
This enables a controlling process (if it has permission) to reopen the
.Pa /proc
files to get new valid file descriptors, close the invalid file descriptors,
unset the run-on-last-close flag (if desired), and proceed.
Just closing the invalid file descriptors causes the traced process to resume
execution with all tracing flags cleared.
Any process not currently open for writing via
.Pa /proc ,
but that has left-over tracing flags from a previous open, and that executes
a setuid/setgid or unreadable object file, will not be stopped but will have
all its tracing flags cleared.
.Pp
To wait for one or more of a set of processes or lwps to stop or terminate,
.Pa /proc
file descriptors (other than those obtained by opening the
.Pa cwd
or
.Pa root
directories or by opening files in the
.Pa fd
or
.Pa object
directories) can be used in a
.Xr poll 2
system call.
When requested and returned, either of the polling events
.Sy POLLPRI
or
.Sy POLLWRNORM
indicates that the process or lwp stopped on an event of
interest.
Although they cannot be requested, the polling events
.Sy POLLHUP ,
.Sy POLLERR ,
and
.Sy POLLNVAL
may be returned.
.Sy POLLHUP
indicates that the process or lwp has terminated.
.Sy POLLERR
indicates that the file descriptor has become invalid.
.Sy POLLNVAL
is returned immediately if
.Sy POLLPRI
or
.Sy POLLWRNORM
is requested on a file descriptor referring to a system process (see
.Sx  PCSTOP ) .
The requested events may be empty to wait simply for termination.
.Sh FILES
.Bl -tag -compact -width Ds
.It Pa /proc
directory (list of processes)
.It Pa /proc/ Ns Em pid
specific process directory
.It Pa /proc/self
alias for a process's own directory
.It Pa /proc/ Ns Em pid Ns Pa /as
address space file
.It Pa /proc/ Ns Em pid Ns Pa /ctl
process control file
.It Pa /proc/ Ns Em pid Ns Pa /status
process status
.It Pa /proc/ Ns Em pid Ns Pa /lstatus
array of lwp status structs
.It Pa /proc/ Ns Em pid Ns Pa /psinfo
process
.Xr ps 1
info
.It Pa /proc/ Ns Em pid Ns Pa /lpsinfo
array of lwp
.Xr ps 1
info structs
.It Pa /proc/ Ns Em pid Ns Pa /map
address space map
.It Pa /proc/ Ns Em pid Ns Pa /xmap
extended address space map
.It Pa /proc/ Ns Em pid Ns Pa /rmap
reserved address map
.It Pa /proc/ Ns Em pid Ns Pa /cred
process credentials
.It Pa /proc/ Ns Em pid Ns Pa /priv
process privileges
.It Pa /proc/ Ns Em pid Ns Pa /sigact
process signal actions
.It Pa /proc/ Ns Em pid Ns Pa /auxv
process aux vector
.It Pa /proc/ Ns Em pid Ns Pa /ldt
process
.Sy LDT
(x86 only)
.It Pa /proc/ Ns Em pid Ns Pa /usage
process usage
.It Pa /proc/ Ns Em pid Ns Pa /lusage
array of lwp usage structs
.It Pa /proc/ Ns Em pid Ns Pa /path
symbolic links to process open files
.It Pa /proc/ Ns Em pid Ns Pa /pagedata
process page data
.It Pa /proc/ Ns Em pid Ns Pa /watch
active watchpoints
.It Pa /proc/ Ns Em pid Ns Pa /cwd
alias for the current working directory
.It Pa /proc/ Ns Em pid Ns Pa /root
alias for the root directory
.It Pa /proc/ Ns Em pid Ns Pa /fd
directory (list of open files)
.It Pa /proc/ Ns Em pid Ns Pa /fd/*
aliases for process's open files
.It Pa /proc/ Ns Em pid Ns Pa /object
directory (list of mapped files)
.It Pa /proc/ Ns Em pid Ns Pa /object/a.out
alias for process's executable file
.It Pa /proc/ Ns Em pid Ns Pa /object/*
aliases for other mapped files
.It Pa /proc/ Ns Em pid Ns Pa /lwp
directory (list of lwps)
.It Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid
specific lwp directory
.It Pa /proc/ Ns Em pid Ns Pa /lwp/agent
alias for the agent lwp directory
.It Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid Ns Pa /lwpctl
lwp control file
.It Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid Ns Pa /lwpstatus
lwp status
.It Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid Ns Pa /lwpsinfo
lwp
.Xr ps 1
info
.It Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid Ns Pa /lwpusage
lwp usage
.It Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid Ns Pa /gwindows
register windows (SPARC only)
.It Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid Ns Pa /xregs
extra state registers
.It Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid Ns Pa /asrs
ancillary state registers (SPARC V9 only)
.It Pa /proc/ Ns Em pid Ns Pa /lwp/ Ns Em lwpid Ns Pa /spymaster
For an agent LWP, the controlling process
.El
.Sh DIAGNOSTICS
Errors that can occur in addition to the errors normally associated with file
system access:
.Bl -tag -width "EOVERFLOW" -offset left
.It Er E2BIG
Data to be returned in a
.Xr read 2
of the page data file exceeds the size of the read buffer provided by the
caller.
.It Er EACCES
An attempt was made to examine a process that ran under a different uid than
the controlling process and
.Brq Sy PRIV_PROC_OWNER
was not asserted in the effective set.
.It Er EAGAIN
The traced process has performed an
.Xr exec 2
of a setuid/setgid object
file or of an object file that it cannot read; all further operations on the
process or lwp file descriptor (except
.Xr close 2 )
elicit this error.
.It Er EBUSY
.Sy PCSTOP ,
.Sy PCDSTOP ,
.Sy PCWSTOP , or
.Sy PCTWSTOP
was applied to a system process; an exclusive
.Xr open 2
was attempted on a
.Pa /proc
file for a process already open for writing;
.Sy PCRUN ,
.Sy PCSREG ,
.Sy PCSVADDR ,
.Sy PCSFPREG ,
or
.Sy PCSXREG
was applied to a process or
lwp not stopped on an event of interest; an attempt was made to mount
.Pa /proc
when it was already mounted;
.Sy PCAGENT
was applied to a process
that was not fully stopped or that already had an agent lwp.
.It Er EINVAL
In general, this means that some invalid argument was supplied to a system
call.
A non-exhaustive list of conditions eliciting this error includes: a
control message operation code is undefined; an out-of-range signal number was
specified with
.Sy PCSSIG ,
.Sy PCKILL ,
or
.Sy PCUNKILL ;
.Sy SIGKILL
was specified with
.Sy PCUNKILL ;
.Sy PCSFPREG
was applied on a system that does not support floating-point operations;
.Sy PCSXREG
was applied on a system that does not support extra state registers.
.It Er EINTR
A signal was received by the controlling process while waiting for the traced
process or lwp to stop via
.Sy PCSTOP ,
.Sy PCWSTOP ,
or
.Sy PCTWSTOP .
.It Er EIO
A
.Xr write 2
was attempted at an illegal address in the traced process.
.It Er ENOENT
The traced process or lwp has terminated after being opened.
The basic privilege
.Brq Sy PRIV_PROC_INFO
is not asserted in the effective set of the calling process and the calling
process cannot send a signal to the target process.
.It Er ENOMEM
The system-imposed limit on the number of page data file descriptors was
reached on an open of
.Pa /proc/ Ns Em pid Ns Pa /pagedata ;
an attempt was made
with
.Sy PCWATCH
to establish more watched areas than the system can support;
the
.Sy PCAGENT
operation was issued when the system was out of resources for
creating lwps.
.It Er ENOSYS
An attempt was made to perform an unsupported operation (such as
.Xr creat 2 ,
.Xr link 2 ,
or
.Xr unlink 2 )
on an entry in
.Pa /proc .
.It Er EOVERFLOW
A 32-bit controlling process attempted to read or write the
.Pa as
file or attempted to read the
.Pa map ,
.Pa rmap ,
or
.Pa pagedata
file of a 64-bit target process.
A 32-bit controlling process attempted to apply one of the
control operations
.Sy PCSREG ,
.Sy PCSXREG ,
.Sy PCSVADDR ,
.Sy PCWATCH ,
.Sy PCAGENT ,
.Sy PCREAD ,
.Sy PCWRITE
to a 64-bit target process.
.It Er EPERM
The process that issued the
.Sy PCSCRED
or
.Sy PCSCREDX
operation did not have the
.Brq Sy PRIV_PROC_SETID
privilege asserted in its effective set, or
the process that issued the
.Sy PCNICE
operation did not have the
.Brq Sy PRIV_PROC_PRIOCNTL
in its effective set.
.Pp
An attempt was made to control a process of which the E, P, and I privilege
sets were not a subset of the effective set of the controlling process or the
limit set of the controlling process is not a superset of limit set of the
controlled process.
.Pp
Any of the uids of the target process are
.Sy 0
or an attempt was made to change any of the uids to
.Sy 0
using
.Sy PCSCRED
and the security policy imposed additional restrictions.
See
.Xr privileges 7 .
.El
.Sh SEE ALSO
.Xr ls 1 ,
.Xr ps 1 ,
.Xr alarm 2 ,
.Xr brk 2 ,
.Xr chdir 2 ,
.Xr chroot 2 ,
.Xr close 2 ,
.Xr creat 2 ,
.Xr dup 2 ,
.Xr exec 2 ,
.Xr fcntl 2 ,
.Xr fork 2 ,
.Xr fork1 2 ,
.Xr fstat 2 ,
.Xr getdents 2 ,
.Xr getustack 2 ,
.Xr kill 2 ,
.Xr lseek 2 ,
.Xr mmap 2 ,
.Xr nice 2 ,
.Xr open 2 ,
.Xr poll 2 ,
.Xr pread 2 ,
.Xr pwrite 2 ,
.Xr read 2 ,
.Xr readlink 2 ,
.Xr readv 2 ,
.Xr shmget 2 ,
.Xr sigaction 2 ,
.Xr sigaltstack 2 ,
.Xr vfork 2 ,
.Xr write 2 ,
.Xr writev 2 ,
.Xr _stack_grow 3C ,
.Xr pthread_create 3C ,
.Xr pthread_join 3C ,
.Xr ptrace 3C ,
.Xr readdir 3C ,
.Xr thr_create 3C ,
.Xr thr_join 3C ,
.Xr wait 3C ,
.Xr siginfo.h 3HEAD ,
.Xr signal.h 3HEAD ,
.Xr types32.h 3HEAD ,
.Xr ucontext.h 3HEAD ,
.Xr contract 5 ,
.Xr core 5 ,
.Xr process 5 ,
.Xr lfcompile 7 ,
.Xr privileges 7 ,
.Xr security-flags 7 ,
.Xr chroot 8
.Sh NOTES
Descriptions of structures in this document include only interesting structure
elements, not filler and padding fields, and may show elements out of order for
descriptive clarity.
The actual structure definitions are contained in
.In procfs.h .
.Sh BUGS
Because the old
.Xr ioctl 2 Ns -based
version of
.Pa /proc
is currently supported for binary compatibility with old applications, the
top-level directory for a process,
.Pa /proc/ Ns Em pid ,
is not world-readable, but it is world-searchable.
Thus, anyone can open
.Pa /proc/ Ns Em pid Ns Pa /psinfo
even though
.Xr ls 1
applied to
.Pa /proc/ Ns Em pid
will fail for anyone but the owner or an appropriately privileged process.
Support for the old
.Xr ioctl 2 Ns -based
version of
.Pa /proc
will be dropped in a future release, at which time the top-level directory for
a process will be made world-readable.
.Pp
On SPARC based machines, the types
.Sy gregset_t
and
.Sy fpregset_t
defined in
.In sys/regset.h
are similar to but not the same as the types
.Sy prgregset_t
and
.Sy prfpregset_t
defined in
.In procfs.h .