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[asan] Fix small X86_64 ShadowOffset for non-default shadow scale 

The requirement is that shadow memory must be aligned to page
boundaries (4k in this case).  Use a closed form equation that always
satisfies this requirement.

Differential Revision: https://reviews.llvm.org/D39471

llvm-svn: 318421
This commit is contained in:
Walter Lee 2017-11-16 17:03:00 +00:00
parent dcb9e1b387
commit 8f1545c629
2 changed files with 11 additions and 8 deletions
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3
compiler-rt/lib/asan/asan_mapping.h
View File

@ -139,7 +139,8 @@ static const u64 kDefaultShadowScale = 3;
static const u64 kDefaultShadowSentinel = ~(uptr)0;
static const u64 kDefaultShadowOffset32 = 1ULL << 29; // 0x20000000
static const u64 kDefaultShadowOffset64 = 1ULL << 44;
static const u64 kDefaultShort64bitShadowOffset = 0x7FFF8000; // < 2G.
static const u64 kDefaultShort64bitShadowOffset =
0x7FFFFFFF & (~0xFFFULL << kDefaultShadowScale); // < 2G.
static const u64 kIosShadowOffset32 = 1ULL << 30; // 0x40000000
static const u64 kIosShadowOffset64 = 0x120200000;
static const u64 kIosSimShadowOffset32 = 1ULL << 30;

16
llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
View File

@ -97,7 +97,8 @@ static const uint64_t kDynamicShadowSentinel =
static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
static const uint64_t kIOSSimShadowOffset32 = 1ULL << 30;
static const uint64_t kIOSSimShadowOffset64 = kDefaultShadowOffset64;
static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
static const uint64_t kSmallX86_64ShadowOffsetBase = 0x7FFFFFFF; // < 2G.
static const uint64_t kSmallX86_64ShadowOffsetAlignMask = ~0xFFFULL;
static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
static const uint64_t kSystemZ_ShadowOffset64 = 1ULL << 52;
@ -495,6 +496,11 @@ static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
ShadowMapping Mapping;
Mapping.Scale = kDefaultShadowScale;
if (ClMappingScale.getNumOccurrences() > 0) {
Mapping.Scale = ClMappingScale;
}
if (LongSize == 32) {
if (IsAndroid)
Mapping.Offset = kDynamicShadowSentinel;
@ -528,7 +534,8 @@ static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
if (IsKasan)
Mapping.Offset = kLinuxKasan_ShadowOffset64;
else
Mapping.Offset = kSmallX86_64ShadowOffset;
Mapping.Offset = (kSmallX86_64ShadowOffsetBase &
(kSmallX86_64ShadowOffsetAlignMask << Mapping.Scale));
} else if (IsWindows && IsX86_64) {
Mapping.Offset = kWindowsShadowOffset64;
} else if (IsMIPS64)
@ -548,11 +555,6 @@ static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
Mapping.Offset = kDynamicShadowSentinel;
}
Mapping.Scale = kDefaultShadowScale;
if (ClMappingScale.getNumOccurrences() > 0) {
Mapping.Scale = ClMappingScale;
}
if (ClMappingOffset.getNumOccurrences() > 0) {
Mapping.Offset = ClMappingOffset;
}