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Differential D85061

[msan] Respect no_huge_pages_for_shadow.
ClosedPublic

Authored by eugenis on Jul 31 2020, 5:20 PM.

Details

Reviewers
vitalybuka
MaskRay
ckennelly
Commits
rGdc3388b0209d: [msan] Respect no_huge_pages_for_shadow.
Summary

Disable huge pages in the MSan shadow region when
no_huge_pages_for_shadow == true (default).

Diff Detail

Event Timeline

eugenis created this revision.Jul 31 2020, 5:20 PM
Herald added a project: Restricted Project. · View Herald TranscriptJul 31 2020, 5:20 PM
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eugenis requested review of this revision.Jul 31 2020, 5:20 PM
MaskRay accepted this revision.Jul 31 2020, 5:25 PM
MaskRay added a subscriber: MaskRay.

LGTM.

This revision is now accepted and ready to land.Jul 31 2020, 5:25 PM
MaskRay added a comment.Jul 31 2020, 5:26 PM

Is there any way testing this?

eugenis added a comment.Jul 31 2020, 5:28 PM

Testing this would be pretty hard - we'd need to touch a bunch of memory pages, and then somehow wait for the huge page daemon to merge them (or not).

Harbormaster completed remote builds in B66635: Diff 282356.Jul 31 2020, 5:47 PM
ckennelly accepted this revision.Jul 31 2020, 7:03 PM
ckennelly added a subscriber: ckennelly.

We could scan /proc/self/smaps for regions huge page eligibility, but that's probably brittle/annoying.

vitalybuka accepted this revision.Aug 1 2020, 12:49 AM
Closed by commit rGdc3388b0209d: [msan] Respect no_huge_pages_for_shadow. (authored by eugenis). · Explain WhyAug 1 2020, 5:07 PM
This revision was automatically updated to reflect the committed changes.
eugenis added a commit: rGdc3388b0209d: [msan] Respect no_huge_pages_for_shadow..

Revision Contents

PathSize
compiler-rt/
lib/
msan/
2 lines

Diff 282423

compiler-rt/lib/msan/msan_linux.cpp

Show First 20 Lines • Show All 136 Lines • ▼ Show 20 Lines for (unsigned i = 0; i < kMemoryLayoutSize; ++i) {
bool protect = type == MappingDesc::INVALID || bool protect = type == MappingDesc::INVALID ||
(!init_origins && type == MappingDesc::ORIGIN); (!init_origins && type == MappingDesc::ORIGIN);
CHECK(!(map && protect)); CHECK(!(map && protect));
if (!map && !protect) if (!map && !protect)
CHECK(type == MappingDesc::APP); CHECK(type == MappingDesc::APP);
if (map) { if (map) {
if (!CheckMemoryRangeAvailability(start, size)) if (!CheckMemoryRangeAvailability(start, size))
return false; return false;
if (!MmapFixedNoReserve(start, size, kMemoryLayout[i].name)) if (!MmapFixedSuperNoReserve(start, size, kMemoryLayout[i].name))
return false; return false;
if (common_flags()->use_madv_dontdump) if (common_flags()->use_madv_dontdump)
DontDumpShadowMemory(start, size); DontDumpShadowMemory(start, size);
} }
if (protect) { if (protect) {
if (!CheckMemoryRangeAvailability(start, size)) if (!CheckMemoryRangeAvailability(start, size))
return false; return false;
if (!ProtectMemoryRange(start, size, kMemoryLayout[i].name)) if (!ProtectMemoryRange(start, size, kMemoryLayout[i].name))
▲ Show 20 Lines • Show All 109 Lines • Show Last 20 Lines