https://bugs.kde.org/show_bug.cgi?id=452802
Bug ID: 452802
Summary: Handle lld 9+ split RW PT_LOAD segments correctly
Product: valgrind
Version: unspecified
Platform: Other
OS: Other
Status: REPORTED
Severity: major
Priority: NOR
Component: general
Assignee: jsew...@acm.org
Reporter: pjfl...@wanadoo.fr
Target Milestone: ---
Since llvm 9.0.0, lld has produced split RW PT_LOAD segments
ld.bfd and llvm ld before 9.0.0
One RW segment containing
RW PT_LOAD(PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) .data .bss)
llvm lld after 9.0.0
Two RW segments containing
RW PT_LOAD(PT_GNU_RELRO(.data.rel.ro .bss.rel.ro))
RW PT_LOAD(.data. .bss)
Valgrind is hard coded to only read debuginfo for one RW PT_LOAD segment and
ignores the second.
See debuginfo.c line 1269 at the time of writing which contains
line 1269
/* PJF this is true for the 2nd RW PT_LOAD which finds di->have_dinfo from the
1st */
if (di->have_dinfo) {
if (debug)
VG_(dmsg)("di_notify_mmap-4x: "
"ignoring mapping because we already read debuginfo "
"for DebugInfo* %p\n", di);
return 0;
}
I see two possible solutions
1. Add full handling of multiple RW PT_LOAD segments
2. Merge contiguous RW PT_LOAD segments so that they appear like ld.bfd single
RW PT_LOAD segemnts.
I'll start with 2 as it sounds easier to me.
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