CVS commit: src

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Thu Apr  4 00:46:30 UTC 2024

Modified Files:
        src/lib/libc/arch/x86_64/gen: __setjmp14.S __sigsetjmp14.S
        src/tests/lib/libc/setjmp: t_sigstack.c

Log Message:
amd64 longjmp: Restore stack first, then signal mask.

Otherwise, a pending signal may be delivered on the wrong stack when
we restore the signal mask.

While here:

- Tidy the code a little bit.
- Sprinkle comments to explain what's going on.
- Use `xorl %eXX,%eXX' instead of `xorq %rXX,%rXX'.
  => Same effect, one byte shorter, breaks dep chain on more uarches.
- Use forward branches for statically predicted not-taken.
  => val==0 is unlikely in longjmp

PR lib/57946


To generate a diff of this commit:
cvs rdiff -u -r1.3 -r1.4 src/lib/libc/arch/x86_64/gen/__setjmp14.S \
    src/lib/libc/arch/x86_64/gen/__sigsetjmp14.S
cvs rdiff -u -r1.7 -r1.8 src/tests/lib/libc/setjmp/t_sigstack.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.