syscalls: if ptrace(PT_SETREG) occured during syscall, do not do set_syscall_retval()
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Authored by kib on Oct 30 2025, 6:41 PM.

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imp

olce

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andrew
markj
jhb

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rGa6a9d97708ec: kern/subr_syscalls.c: declare 'traced' local variables boolean

Summary

to preserve the register state enforced by debugger.  This is only
relevant for transparent attach to the slow syscalls where sleeps are
not interrupted.

PR:     290008


kern/subr_syscalls.c: declare 'traced' local variables boolean

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rG FreeBSD src repository

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kib created this revision.Oct 30 2025, 6:41 PM

Herald added subscribers: olce, imp. · View Herald TranscriptOct 30 2025, 6:41 PM

That said, I disagree that this is a kernel bug at all.

markj added inline comments.Oct 31 2025, 12:42 PM

sys/kern/subr_syscall.c
119	Don't we need the proc lock here?

Clear TDB_USERWR under proc lock. Do it earlier.

I'm not sure if we should make such a change, but it looks ok to me.

This revision is now accepted and ready to land.Nov 2 2025, 5:48 PM

Closed by commit rGa6a9d97708ec: kern/subr_syscalls.c: declare 'traced' local variables boolean (authored by kib). · Explain WhyNov 2 2025, 9:22 PM

This revision was automatically updated to reflect the committed changes.

kib added a commit: rGa6a9d97708ec: kern/subr_syscalls.c: declare 'traced' local variables boolean.

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kern/

subr_syscall.c

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syscalls: if ptrace(PT_SETREG) occured during syscall, do not do set_syscall_retval()Needs ReviewPublicActions