vm: Remove kernel stack swapping support, part 3

- Modify PHOLD() to no longer fault in the process.
- Remove _PHOLD_LITE(), which is now the same as _PHOLD(), fix up
consumers.
- Remove faultin()

vm: Remove kernel stack swapping support, part 3

- Modify PHOLD() to no longer fault in the process.
- Remove _PHOLD_LITE(), which is now the same as _PHOLD(), fix up
consumers.
- Remove faultin() and its callees.

Tested by: pho
Reviewed by: imp, kib
Differential Revision: https://reviews.freebsd.org/D46114

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

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

fasttrap: Avoid creating WX mappings

fasttrap instruments certain instructions by overwriting them and
copying the original instruction to some per-thread scratch space which
is executed after the p

fasttrap: Avoid creating WX mappings

fasttrap instruments certain instructions by overwriting them and
copying the original instruction to some per-thread scratch space which
is executed after the probe fires. This trampoline jumps back to the
tracepoint after executing the original instruction.

The created mapping has both write and execute permissions, and so this
mechanism doesn't work when allow_wx is disabled. Work around the
restriction by using proc_rwmem() to write to the trampoline.

Reviewed by: vangyzen
Tested by: Amit <akamit91@hotmail.com>
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34304

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Create sys/reg.h for the common code previously in machine/reg.h

Move the common kernel function signatures from machine/reg.h to a new
sys/reg.h. This is in preperation for adding PT_GETREGSET to p

Create sys/reg.h for the common code previously in machine/reg.h

Move the common kernel function signatures from machine/reg.h to a new
sys/reg.h. This is in preperation for adding PT_GETREGSET to ptrace(2).

Reviewed by: imp, markj
Sponsored by: DARPA, AFRL (original work)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D19830

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amd64: move GDT into PCPU area.

Reviewed by: jhb, markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D22302

MFHead@r345275

MFhead@r344786

Merge ^/head r344549 through r344775.

Fix fasttrap_sig{trap,segv}().

- Don't leak the ksiginfo structure.
- Hold the proc lock when sending a signal in fasttrap_sigsegv().

MFC after: 1 week
Sponsored by: The FreeBSD Foundation

Remove illumos-specific code from the x86 fasttrap_isa.c.

The file has not been touched upstream in over a decade, and the nature
of the code means that a lot of FreeBSD-specific bits are required.

Remove illumos-specific code from the x86 fasttrap_isa.c.

The file has not been touched upstream in over a decade, and the nature
of the code means that a lot of FreeBSD-specific bits are required. Remove
the dead code to improve readability. No functional change intended.

Discussed with: cem
MFC after: 1 week
Sponsored by: The FreeBSD Foundation

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MFhead@r344527

Merge ^/head r344178 through r344512.

Commit a missing piece of r344452.

MFC with: r344452

Fix a tracepoint lookup race in fasttrap_pid_probe().

fasttrap hooks the userspace breakpoint handler; the hook looks up the
breakpoint address in a hash table of tracepoints. It is possible for
th

Fix a tracepoint lookup race in fasttrap_pid_probe().

fasttrap hooks the userspace breakpoint handler; the hook looks up the
breakpoint address in a hash table of tracepoints. It is possible for
the tracepoint to be removed by a different thread in between the
breakpoint trap and the hash table lookup, in which case SIGTRAP gets
delivered to the target process. Fix the problem by adding a
per-process generation counter that gets incremented when a tracepoint
belonging to that process is removed. Then, when a lookup fails, the
trapping instruction is restarted if the thread's counter doesn't match
that of the process.

Reviewed by: cem
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D19273

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Remove very old and unused signal information codes.

These have been supplanted by the MI signal information codes in
<sys/signal.h> since 7.0. The FPE_*_TRAP ones were deprecated even
earlier in 1

Remove very old and unused signal information codes.

These have been supplanted by the MI signal information codes in
<sys/signal.h> since 7.0. The FPE_*_TRAP ones were deprecated even
earlier in 1999.

PR: 226579 (exp-run)
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D14637

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Pass the trap frame to fasttrap hooks.

The DTrace fasttrap entry points expect a struct reg containing the
register values of the calling thread. Perform the conversion in
fasttrap rather than in th

Pass the trap frame to fasttrap hooks.

The DTrace fasttrap entry points expect a struct reg containing the
register values of the calling thread. Perform the conversion in
fasttrap rather than in the trap handler: this reduces the number of
ifdefs and avoids wasting stack space for traps that don't involve
DTrace.

MFC after: 2 weeks

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Merge ^/head r325842 through r325998.

Avoid holding the process in uread() and uwrite().

In general, higher-level code will atomically verify that the process
is not exiting and hold the process. In one case, we were using uwrite()
to c

Avoid holding the process in uread() and uwrite().

In general, higher-level code will atomically verify that the process
is not exiting and hold the process. In one case, we were using uwrite()
to copy a probed instruction to a per-thread scratch space block, but
copyout() can be used for this purpose instead; this change effectively
reverts r227291.

MFC after: 1 week

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MFhead@r313243

Merge ^/head r312720 through r312893.

Fix an off-by-one in an assertion on fasttrap tracepoint sizes.

FASTTRAP_MAX_INSTR_SIZE is the largest valid value of a tracepoint, so
correct the assertion accordingly. This limit was hit with a 15

Fix an off-by-one in an assertion on fasttrap tracepoint sizes.

FASTTRAP_MAX_INSTR_SIZE is the largest valid value of a tracepoint, so
correct the assertion accordingly. This limit was hit with a 15-byte NOP.

Reported by: bdrewery
MFC after: 1 week
Sponsored by: Dell EMC Isilon

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Merge ^/head r308491 through r308841.

Support fetching RFLAGS in fasttrap_getreg().

MFC after: 1 week

Merge ^/head r306303 through 306411.

Move implementations of uread() and uwrite() to the illumos compat layer.

MFC after: 1 week