CVS commit: src/lib/libc/gmon

["Rin Okuyama" <rin%netbsd.org@localhost>]

Module Name:    src
Committed By:   rin
Date:           Fri May  6 04:49:13 UTC 2022

Modified Files:
        src/lib/libc/gmon: gmon.c

Log Message:
PR lib/56395
PR toolchain/56771

Fix profiling on CPUs that do not support unaligned memory access;
Allocate objects (referenced from struct gmonparam) with proper
alignments.

For monstartup(), objects are allocated on heap. Break is not
guaranteed to be aligned at all, unlike stack pointer.

For _m_gmon_alloc(), objects are allocated on anonymous memory.
p->tos is not aligned properly in general.

This fixes quasi-random crashes for *_profile tests, at least on
SH-4 and PowerPC 403 [1]. Also, no regression is observed for
others as far as I can see.

This change does not cause any ABI breakage, as long as application
uses proper pointers; use p->tos instead of evil pointer arithmetic
like (struct tostruct *)((char *)p->froms + p->fromssize) [2].

[1] Timeout should be increased for some tests. "pic" variants
still fail as expected. Dynamically-linked binaries also crash in
rtld for SH-4, but this seems different problem...

[2] This example did not work even before, since the order of
froms[] and tos[] is reversed depending on which of monstartup() or
_m_gmon_alloc() is used for allocation.


To generate a diff of this commit:
cvs rdiff -u -r1.36 -r1.37 src/lib/libc/gmon/gmon.c

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