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Another seemingly-small but critical change imported from 2.4.0-ppc:

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don't read symbols from sections with w permissions.  For some reason
ppc-linux maps executables three times, not twice as on x86, and if
the w flag is ignored, we wind up reading debug info twice, getting
wrong redirections, and then it all goes to hell in a handbasket.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@4139
This commit is contained in:
Julian Seward
2005-07-09 10:36:25 +00:00
parent eeb4b800cd
commit 2aa48b8c3a
1 changed files with 42 additions and 21 deletions
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63
coregrind/m_aspacemgr/aspacemgr.c
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@@ -787,37 +787,58 @@ VG_(map_file_segment)( Addr addr, SizeT len,
/* If this mapping is of the beginning of a file, isn't part of
Valgrind, is at least readable and seems to contain an object
file, then try reading symbols from it.
Getting this heuristic right is critical. On x86-linux,
objects are typically mapped twice:
1b8fb000-1b8ff000 r-xp 00000000 08:02 4471477 vgpreload_memcheck.so
1b8ff000-1b900000 rw-p 00004000 08:02 4471477 vgpreload_memcheck.so
whereas ppc32-linux mysteriously does this:
118a6000-118ad000 r-xp 00000000 08:05 14209428 vgpreload_memcheck.so
118ad000-118b6000 ---p 00007000 08:05 14209428 vgpreload_memcheck.so
118b6000-118bd000 rwxp 00000000 08:05 14209428 vgpreload_memcheck.so
The third mapping should not be considered to have executable code in.
Therefore a test which works for both is: r and x and NOT w. Reading
symbols from the rwx segment -- which overlaps the r-x segment in the
file -- causes the redirection mechanism to redirect to addresses in
that third segment, which is wrong and causes crashes.
*/
if (s->seginfo == NULL
&& ( (addr+len < VG_(valgrind_base) || addr > VG_(valgrind_last))
|| is_stage2
)
&& (flags & (SF_MMAP|SF_NOSYMS)) == SF_MMAP
) {
if (off == 0
&& s->fnIdx != -1
&& (prot & (VKI_PROT_READ|VKI_PROT_EXEC)) == (VKI_PROT_READ|VKI_PROT_EXEC)
&& len >= VKI_PAGE_SIZE
&& VG_(is_object_file)((void *)addr)
) {
if (off == 0
&& s->fnIdx != -1
/* r, x are set */
&& (prot & (VKI_PROT_READ|VKI_PROT_EXEC)) == (VKI_PROT_READ|VKI_PROT_EXEC)
/* w is clear */
&& (prot & VKI_PROT_WRITE) == 0
/* other checks .. */
&& len >= VKI_PAGE_SIZE
&& VG_(is_object_file)((void *)addr) ) {
s->seginfo = VG_(read_seg_symbols)(s->addr, s->len, s->offset,
s->filename);
} else if (flags & SF_MMAP) {
#if 0
const SegInfo *info;
/* Otherwise see if an existing SegInfo applies to this Segment */
for(info = VG_(next_seginfo)(NULL);
info != NULL;
info = VG_(next_seginfo)(info)) {
if (VG_(seg_overlaps)(s, VG_(seg_start)(info), VG_(seg_size)(info)))
{
s->seginfo = (SegInfo *)info;
VG_(seginfo_incref)((SegInfo *)info);
}
}
#endif
}
//else
//if (flags & SF_MMAP) {
// const SegInfo *info;
//
// /* Otherwise see if an existing SegInfo applies to this Segment */
// for(info = VG_(next_seginfo)(NULL);
// info != NULL;
// info = VG_(next_seginfo)(info)) {
// if (VG_(seg_overlaps)(s, VG_(seg_start)(info), VG_(seg_size)(info)))
// {
// s->seginfo = (SegInfo *)info;
// VG_(seginfo_incref)((SegInfo *)info);
// }
// }
//}
}
/* clean up */