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author | Evgeniy Stepanov <eugeni.stepanov@gmail.com> | 2017-11-10 22:27:48 +0000 |
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committer | Evgeniy Stepanov <eugeni.stepanov@gmail.com> | 2017-11-10 22:27:48 +0000 |
commit | 8357d02f2d4f6c22202fb25f3b4c97fb2b893ec9 (patch) | |
tree | 0d96828a1cf600d29c8d473da77d633ec7b166c5 /lib/asan/asan_linux.cc | |
parent | 55dee3e7a884bf78e0f8932ff7eaac6f614866fa (diff) |
[asan] Use dynamic shadow on 32-bit Android.
Summary:
The following kernel change has moved ET_DYN base to 0x4000000 on arm32:
https://marc.info/?l=linux-kernel&m=149825162606848&w=2
Switch to dynamic shadow base to avoid such conflicts in the future.
Reserve shadow memory in an ifunc resolver, but don't use it in the instrumentation
until PR35221 is fixed. This will eventually let use save one load per function.
Reviewers: kcc
Subscribers: aemerson, srhines, kubamracek, kristof.beyls, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D39393
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@317943 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/asan/asan_linux.cc')
-rw-r--r-- | lib/asan/asan_linux.cc | 32 |
1 files changed, 30 insertions, 2 deletions
diff --git a/lib/asan/asan_linux.cc b/lib/asan/asan_linux.cc index a949a9888..902c64cc4 100644 --- a/lib/asan/asan_linux.cc +++ b/lib/asan/asan_linux.cc @@ -17,6 +17,7 @@ #include "asan_interceptors.h" #include "asan_internal.h" +#include "asan_premap_shadow.h" #include "asan_thread.h" #include "sanitizer_common/sanitizer_flags.h" #include "sanitizer_common/sanitizer_freebsd.h" @@ -81,10 +82,37 @@ void *AsanDoesNotSupportStaticLinkage() { return &_DYNAMIC; // defined in link.h } +#if ASAN_PREMAP_SHADOW uptr FindDynamicShadowStart() { - UNREACHABLE("FindDynamicShadowStart is not available"); - return 0; + uptr granularity = GetMmapGranularity(); + uptr shadow_start = reinterpret_cast<uptr>(&__asan_shadow); + uptr shadow_size = PremapShadowSize(); + UnmapOrDie((void *)(shadow_start - granularity), shadow_size + granularity); + // MmapNoAccess does not touch TotalMmap, but UnmapOrDie decreases it. + // Compensate. + IncreaseTotalMmap(shadow_size + granularity); + return shadow_start; } +#else +uptr FindDynamicShadowStart() { + uptr granularity = GetMmapGranularity(); + uptr alignment = granularity * 8; + uptr left_padding = granularity; + uptr shadow_size = kHighShadowEnd + left_padding; + uptr map_size = shadow_size + alignment; + + uptr map_start = (uptr)MmapNoAccess(map_size); + CHECK_NE(map_start, ~(uptr)0); + + uptr shadow_start = RoundUpTo(map_start, alignment); + UnmapOrDie((void *)map_start, map_size); + // MmapNoAccess does not touch TotalMmap, but UnmapOrDie decreases it. + // Compensate. + IncreaseTotalMmap(map_size); + + return shadow_start; +} +#endif void AsanApplyToGlobals(globals_op_fptr op, const void *needle) { UNIMPLEMENTED(); |