amd64 pcb.h: use 4 hex digits for pcb flags

Sponsored by: The FreeBSD Foundation
MFC after: 3 days

sys: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl s

sys: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl script.

Sponsored by: Netflix

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sys: Remove $FreeBSD$: one-line .h pattern

Remove /^\s*\*+\s*\$FreeBSD\$.*$\n/

Fix for mis-interpretation of PCB_KERNFPU.

RIght now PCB_KERNFPU is used both as indication that kernel prepared
hardware FPU context to use and that the thread is fpu-kern
thread. This also breaks

Fix for mis-interpretation of PCB_KERNFPU.

RIght now PCB_KERNFPU is used both as indication that kernel prepared
hardware FPU context to use and that the thread is fpu-kern
thread. This also breaks fpu_kern_enter(FPU_KERN_NOCTX), since
fpu_kern_leave() then clears PCB_KERNFPU.

Introduce new flag PCB_KERNFPU_THR which indicates that the thread is
fpu-kern. Do not clear PCB_KERNFPU if fpu-kern thread leaves noctx
fpu region.

Reported and tested by: jhb (amd64)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D25511

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Provide dummy definition of the amd64 struct pcb for -m32 compilation.

I do not see a need in the proper x86/include/pcb.h header.

Reported and tested by: antoine
MFC after: 1 week

PTI: Trap if we returned to userspace with kernel (full) page table
still active.

Map userspace portion of VA in the PTI kernel-mode page table as
non-executable. This way, if we ever miss reloading

PTI: Trap if we returned to userspace with kernel (full) page table
still active.

Map userspace portion of VA in the PTI kernel-mode page table as
non-executable. This way, if we ever miss reloading ucr3 into %cr3 on
the return to usermode, the process traps instead of executing in
potentially vulnerable setup. Catch the condition of such trap and
verify user-mode %cr3, which is saved by page fault handler.

I peek this trick in some article about Linux implementation.

Reviewed by: alc, markj (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 12 days
DIfferential revision: https://reviews.freebsd.org/D13956

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Merge ^/head r325999 through r326131.

sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for

sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

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MFH @ r323558.

MFhead@r322870

Make WRFSBASE and WRGSBASE instructions functional.

Right now, we enable the CR4.FSGSBASE bit on CPUs which support the
facility (Ivy and later), to allow usermode to read fs and gs bases
without sy

Make WRFSBASE and WRGSBASE instructions functional.

Right now, we enable the CR4.FSGSBASE bit on CPUs which support the
facility (Ivy and later), to allow usermode to read fs and gs bases
without syscalls. This bit also controls the write access to bases
from userspace, but WRFSBASE and WRGSBASE instructions currently
cannot be used, because return path from both exceptions or interrupts
overrides bases with the values from pcb.

Supporting the instructions is useful because this means that usermode
can implement green-threads completely in userspace without issuing
syscalls to change all of the machine context.

Support is implemented by saving the fs base and user gs base when
PCB_FULL_IRET flag is set. The flag is set on the context switch,
which potentially causes clobber of the bases due to activation of
another context, and when explicit modification of the user context by
a syscall or exception handler is performed. In particular, the patch
moves setting of the flag before syscalls change context.

The changes to doreti_exit and PUSH_FRAME to clear PCB_FULL_IRET on
entry from userspace can be considered a bug fixes on its own.

Reviewed by: jhb (previous version)
Tested by: pho (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
Differential revision: https://reviews.freebsd.org/D12023

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Merge ^/head r314420 through r314481.

Renumber copyright clause 4

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is

Renumber copyright clause 4

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96

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Merge ^/head r305687 through r305890.

Add FPU_KERN_NOCTX flag to the fpu_kern_enter() function on amd64.

The flag specifies that the block which uses FPU must be executed in
critical section, i.e. take no context switches, and does not

Add FPU_KERN_NOCTX flag to the fpu_kern_enter() function on amd64.

The flag specifies that the block which uses FPU must be executed in
critical section, i.e. take no context switches, and does not need an
FPU save area during the execution.

It is intended to be applied around fast and short code pathes where
save area allocation is impossible or undesirable, due to context or
due to the relative cost of calculation vs. allocation.

Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

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MFH r289384-r293170

Sponsored by: The FreeBSD Foundation

Catch up with head (r291075).

Export various helper variables describing the layout and size of
certain kernel structures for use by debuggers. This mostly aids
in examining cores from a kernel without debug symbols as a debugger

Export various helper variables describing the layout and size of
certain kernel structures for use by debuggers. This mostly aids
in examining cores from a kernel without debug symbols as a debugger
can infer these values if debug symbols are available.

One set of variables describes the layout of 'struct linker_file' to
walk the list of loaded kernel modules.

A second set of variables describes the layout of 'struct proc' and
'struct thread' to walk the list of processes in the kernel and the
threads in each process.

The 'pcb_size' variable is used to index into the stoppcbs[] array.

The 'vm_maxuser_address' is used to distinguish kernel virtual addresses
from user addresses. This doesn't have to be perfect, and
'vm_maxuser_address' is a cheap and simple way to differentiate kernel
pointers from simple values like TIDs and PIDs.

While here, annotate the fields in struct pcb used by kgdb on amd64
and i386 to note that their ABI should be preserved. Annotations for
other platforms will be added in the future.

Reviewed by: kib
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D3773

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Merge from head

Catch up with head, primarily for the 1.14.4.0 firmware.

Merge ^/head r284737 through r285152.

pcb_gs32sd is unused for long time, remove it. Keep the padding in pcb.

Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

Merge from head@274682

Sync to HEAD@r272516.

IFC @r271694