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[hwasan] Add fixed_shadow_base flag #73980

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Merged
merged 6 commits into from
Dec 7, 2023
Merged

[hwasan] Add fixed_shadow_base flag #73980

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294ed9b
[hwasan] Add fixed_shadow_base flag
thurstond Nov 30, 2023
48eb300
Change "non-fixed shadow" magic value from 0 to -1, per offline
thurstond Nov 30, 2023
0896aa8
Add test
thurstond Dec 5, 2023
2c9a4b4
clang-format test
thurstond Dec 5, 2023
fc08ffd
Remove MAP_FIXED from mmap in test
thurstond Dec 6, 2023
7005753
Add 'REQUIRES: clang' to testcase
thurstond Dec 7, 2023
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7 changes: 7 additions & 0 deletions compiler-rt/lib/hwasan/hwasan_flags.inc
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Original file line number Diff line number Diff line change
Expand Up @@ -84,3 +84,10 @@ HWASAN_FLAG(bool, malloc_bisect_dump, false,
// are untagged before the call.
HWASAN_FLAG(bool, fail_without_syscall_abi, true,
"Exit if fail to request relaxed syscall ABI.")

HWASAN_FLAG(
uptr, fixed_shadow_base, 0,
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-1, not sure that none will need NULL as a base

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Done

"If non-zero, HWASan will attempt to allocate the shadow at this address, "
"instead of choosing one dynamically."
"Tip: this can be combined with the compiler option, "
"-hwasan-mapping-offset, to optimize the instrumentation.")
10 changes: 8 additions & 2 deletions compiler-rt/lib/hwasan/hwasan_linux.cpp
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Expand Up @@ -106,8 +106,14 @@ static uptr GetHighMemEnd() {
}

static void InitializeShadowBaseAddress(uptr shadow_size_bytes) {
__hwasan_shadow_memory_dynamic_address =
FindDynamicShadowStart(shadow_size_bytes);
// NULL is generally address zero, so it is not a valid location for the
// shadow.
if (flags()->fixed_shadow_base != 0) {
__hwasan_shadow_memory_dynamic_address = flags()->fixed_shadow_base;
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oh,and maybe some test with use of the file?

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probably linux not android only test

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Added compiler-rt/test/hwasan/TestCases/Linux/fixed-shadow.c

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For some reason, for static Android binaries, this branch gets taken

} else {
__hwasan_shadow_memory_dynamic_address =
FindDynamicShadowStart(shadow_size_bytes);
}
}

static void MaybeDieIfNoTaggingAbi(const char *message) {
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