[compiler-rt][asan][hwasan] Refactor shadow setup into sanitizer_common (NFCI)

[tejohnson]

Summary

This refactors some common support related to shadow memory setup from
asan and hwasan into sanitizer_common. This should not only reduce code
duplication but also make these facilities available for new compiler-rt
uses (e.g. heap profiling).

In most cases the separate copies of the code were either identical, or
at least functionally identical. A few notes:

In ProtectGap, the asan version checked the address against an upper
bound (kZeroBaseMaxShadowStart, which is (2^18). I have created a copy
of kZeroBaseMaxShadowStart in hwasan_mapping.h, with the same value, as
it isn't clear why that code should not do the same check. If it
shouldn't, I can remove this and guard this check so that it only
happens for asan.

In asan's InitializeShadowMemory, in the dynamic shadow case it was
setting asan_shadow_memory_dynamic_address to 0 (which then sets both
macro SHADOW_OFFSET as well as macro kLowShadowBeg to 0) before calling
FindDynamicShadowStart(). AFAICT this is only needed because
FindDynamicShadowStart utilizes kHighShadowEnd to
get the shadow size, and kHighShadowEnd is a macro invoking
MEM_TO_SHADOW(kHighMemEnd) which in turn invokes:
(((kHighMemEnd) >> SHADOW_SCALE) + (SHADOW_OFFSET))
I.e. it computes the shadow space needed by kHighMemEnd (the shift), and
adds the offset. Since we only want the shadow space here, the earlier
setting of SHADOW_OFFSET to 0 via asan_shadow_memory_dynamic_address
accomplishes this. In the hwasan version, it simply gets the shadow
space via "MemToShadowSize(kHighMemEnd)", where MemToShadowSize just
does the shift. I've simplified the asan handling to do the same
thing, and therefore was able to remove the setting of the SHADOW_OFFSET
via __asan_shadow_memory_dynamic_address to 0.

[tejohnson]

A couple comments and a question below. Also, what is the best way to test this for mac and win? I tried to find some directions for doing some cross-compiler builds of compiler-rt at least, but couldn't find something clear and definitive.

compiler-rt/lib/asan/asan_linux.cpp

122

The code in asan is multiplying the mmap granularity by 8, whereas the hwasan version shifts it by kShadowScale. I wasn't sure if the 8 here is supposed to be equivalent to a left shift by the shadow scale (which is typically 3 in asan), or is specifically hardcoded separately not using SHADOW_SCALE since it could be something other than 3 in some cases (e.g. 5 for myriad, or user set via ASAN_SHADOW_SCALE). Depending on what was intended here, I would keep the hardcoding of "3" passed to my refactored MapDynamicShadow, or change that to SHADOW_SCALE.

compiler-rt/lib/asan/asan_shadow_setup.cpp

102

See patch description on why I removed this code.

compiler-rt/lib/hwasan/hwasan_mapping.h

40

Copied from the same values in asan. See the patch description for more info. Would it be better to keep a single copy of these values in sanitizer_common?

[kcc]

No strong opinion on whether this needs to be done.
If you feel strong, and if it will help, sure. (you may indeed have to test on various platforms, or rely on the post-commit bots)
OTOH, the new profiler should not require all of these functions, you can probably get away with a custom-tailored variant of MapDynamicShadow.

(Vitaly, please do the review)

compiler-rt/lib/asan/asan_linux.cpp

122

I frankly don't remember :(

[vitalybuka]

compiler-rt/lib/asan/asan_linux.cpp

103

MemToShadowSize(GetHighMemEnd(SHADOW_SCALE))

compiler-rt/lib/hwasan/hwasan.cpp

289

why it's gone?

compiler-rt/lib/sanitizer_common/sanitizer_common.h

123–147

Shadow is specific to only some sanitizers, so I don't like to have it in /sanitizer_common/
Also we have msan/tsan/dfsan with different shadows for which is not clear if we can reuse these functions without exposing more particular sanitizer details. Maybe keeping all shadow code with some redundancy but independent is going to be easier to maintain in long term.

Anyway, if we still go this way, maybe we put code into sanitizer_common/sanitizer_shadow_* files ?

compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp

204

I think it's going to be cleaner if we replace
uptr mmap_alignment_scale, uptr shadow_base_alignment
with
uptr shadow_scale, uptr min_shadow_base_alignment
and adjust calculations accordingly:
const uptr alignment = max(granularity << shadow_scale, min_shadow_base_alignment)

it should be copied into mac and win, even if they use 0 there, for consistency

compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

1083

SHADOW_SCALE is undefined here

1092

kHighShadowEnd and kHighMemEnd are undefined here

1093

because if kHighMemEnd here we need to return mapped size on all platforms :(

compiler-rt/lib/sanitizer_common/sanitizer_win.cpp

351

shadow_size_bytes is not used

353

CHECK_NE

357

kHighShadowEnd is asan constant
probably space_size should be calculated from shadow_size_bytes
same for mac version

[vitalybuka]

compiler-rt/lib/asan/asan_linux.cpp

122

It should be SHADOW_SCALE, myriad works only because it does not use dynamic shadow

[tejohnson]

compiler-rt/lib/asan/asan_linux.cpp

103

The MemToShadowSize facility currently only exists in hwasan, let me go ahead and add it to asan as well (I see I accidentally started referencing it in the asan_mac/win code!).

122

Ok thanks, I'll change the code to use that.

compiler-rt/lib/hwasan/hwasan.cpp

289

It is now embedded in the refactored code (similar to the way asan was doing the madvise calls). See ReserveShadowMemoryRange (the refactored one and the original asan one).

compiler-rt/lib/sanitizer_common/sanitizer_common.h

123–147

Also we have msan/tsan/dfsan with different shadows for which is not clear if we can reuse these functions without exposing more particular sanitizer details. Maybe keeping all shadow code with some redundancy but independent is going to be easier to maintain in long term.

I started to look at trying to coalesce some of the other *san shadow setup code with the *asan versions, but decided to punt on that, at least for now. There are a lot of things that looked similar there too, but not as much as in *asan. As I mentioned in my reply on the RFC just now, it seemed like a good idea to at least common the *asan versions since they were structured somewhat different but essentially functionally the same in almost every way, and it seemed confusing to have multiple versions that aren't obviously duplicates but in fact are.

That being said, I could have the new heap profiler duplicate them (at least the parts that I need) if that is much preferred. I don't technically need ProtectGap for the heap profiler, but it seems like a good thing to use at least while debugging the instrumentation code.

Anyway, if we still go this way, maybe we put code into sanitizer_common/sanitizer_shadow_* files ?

I can do that. There is a small amount of shadow setup code already here, I could move that too.

compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp

204

Sounds good

compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

1083

For this and other comments on the win/mac version, obviously I didn't do a very careful job of moving this code from asan to sanitizer_common. =( Will work on fixing those and need to find a way to at least compile these codes for those platforms to flush out these issues. If you have any pointers on setting up a cross compile of this code on a linux system please let me know.

[vitalybuka]

compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

1083

I have setup to compile on Win. I can try updated patch and fix it up if necessary.
Unfortunately I have no OSX but it should be possible to find someone on the team.
Still there are other platforms where we can only rely on build bots.

[tejohnson]

I have addressed the other comments but not yet moved to any new files (e.g. sanitizer_common/sanitizer_shadow_* as suggested). Will do that as a follow up change so it is easier to see the actual code change diffs between this version and the last. Did you want me to just move the stuff from sanitizer_common.[h,cpp] to new sanitzer_shadow_common.* files, or also out of e.g. sanitizer_win.cpp to sanitizer_shadow_win.cpp, etc?

Also, I did manually force the new functions in sanitizer_win.cpp and sanitizer_mac.cpp to compile to ensure that I fixed all the references, but that's the extent of what I was able to test there so far.

compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

1092

Where it was using kHighShadowEnd we can just recompute from the new high mem (since at this point the offset was 0 so it is just doing the shift). For kHighMemEnd, it is more difficult since this code is updating the value. I didn't find a way around this besides passing in a reference and updating it if needed.

compiler-rt/lib/sanitizer_common/sanitizer_win.cpp

357

Yep, fixed.

[tejohnson]

Address comments

[vitalybuka]

Looks like FUCHSIA is OK and does not call these stuff

compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp

191

UnmapFromTo and MapDynamicShadow must go into sanitizer_linux_libcdep.cpp as libcdep applies to windows/mac and other

compiler-rt/lib/sanitizer_common/sanitizer_win.cpp

356

Max<uptr> and below, or it does not compile on windows
1UL is 32bit here

[vitalybuka]

compiler-rt/lib/hwasan/hwasan_mapping.h

43

Why do we need them in the header? I don't see these constants used outside hwasan_linux.
If this is to pass kHighMemEnd into high_mem_end, then we can make it optional
uptr* high_mem_end = null

compiler-rt/lib/sanitizer_common/sanitizer_common.h

126

Could you please keep this one in asan/hwasan for now.
It looks like a random mem-region related code moved here when the rest is still there.

135

and maybe drop default 0 and make out argument the last one?

Also high_mem_end in this interface looks unrelated. Maybe mapped shadow size? Better to land as is and followup later.

[tejohnson]

compiler-rt/lib/hwasan/hwasan_mapping.h

43

You are right, the constants kZeroBaseShadowStart and kZeroBaseMaxShadowStart are only used in hwasan_linux.cpp, so I can move them there (I put them here initially since they are in asan_mapping.h there).
For kHighMemEnd etc, I made them extern so that they could be passed tp MapDynamicShadow in hwasan_dynamic_shadow.cpp. While that arg is only needed right now on mac, and hwasan is only supporting linux, does it make sense to be consistent (will hwasan ever support mac)?

compiler-rt/lib/sanitizer_common/sanitizer_common.h

126

ok, there is only one call from each of those, so I can move it back.

135

Also high_mem_end in this interface looks unrelated. Maybe mapped shadow size? Better to land as is and followup later.

I'm not sure I understand the comment about it being unrelated, or what you are asking me to do here? Do you mean just change the parameter name?

[tejohnson]

compiler-rt/lib/hwasan/hwasan_mapping.h

43

For now I have moved the kZeroBase* constants to hwasan_linux.h, but left the new externs.

compiler-rt/lib/sanitizer_common/sanitizer_common.h

135

Made the new out parameter last.

[tejohnson]

Address comments

[vitalybuka]

Thank you! LGTM

Windows should work. For the rest we need to rely on bots.

compiler-rt/lib/sanitizer_common/sanitizer_common.h

135

I'm not sure I understand the comment about it being unrelated, or what you are asking me to do here? Do you mean just change the parameter name?

Looking at function interface, it's about shadow. For reader is likely non-intuitive to understand why there is high_mem_end out parameter.
Pure renaming is not going to help. Maybe out parameter with actually mapped side.
Anyway I am not sure what could be a nicer approach for now. So we can keep it as-is and maybe fix later.

btw. it could be nice to write something into high_mem_end, even just 0, on other platforms.

[tejohnson]

In D83247#2154738, @vitalybuka wrote:

Thank you! LGTM

Windows should work. For the rest we need to rely on bots.

Great thanks - did you still want me to move the shadow functions to some new files (e.g. sanitizer_common/sanitizer_shadow_{linux_libcdep, win, mac}.cpp before committing?

compiler-rt/lib/sanitizer_common/sanitizer_common.h

135

btw. it could be nice to write something into high_mem_end, even just 0, on other platforms.

That would actually break things since we are passing in kHighMemEnd, and don't want it reset if it shouldn't change.

[vitalybuka]

In D83247#2154772, @tejohnson wrote:

In D83247#2154738, @vitalybuka wrote:

Thank you! LGTM

Windows should work. For the rest we need to rely on bots.

Great thanks - did you still want me to move the shadow functions to some new files (e.g. sanitizer_common/sanitizer_shadow_{linux_libcdep, win, mac}.cpp before committing?

maybe better to land and fix if anything broken, and maybe move later. I guess I don't mind if we keep them as-is.

[aeubanks]

Hi, I think this is breaking our Android bots: https://crbug.com/1106482

FAILED: lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o
/b/s/w/ir/cache/builder/src/third_party/llvm-build/Release+Asserts/bin/clang++ -DHWASAN_WITH_INTERCEPTORS=1 -I/b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/hwasan/.. --target=aarch64-linux-android21 --sysroot=/b/s/w/ir/cache/builder/src/third_party/android_ndk/toolchains/llvm/prebuilt/linux-x86_64/sysroot --gcc-toolchain=/b/s/w/ir/cache/builder/src/third_party/android_ndk/toolchains/llvm/prebuilt/linux-x86_64 -Wall -std=c++14 -Wno-unused-parameter -O3 -DNDEBUG -fPIC -fno-builtin -fno-exceptions -fomit-frame-pointer -funwind-tables -fno-stack-protector -fno-sanitize=safe-stack -fvisibility=hidden -fno-lto -O3 -gline-tables-only -Wno-gnu -Wno-variadic-macros -Wno-c99-extensions -Wno-non-virtual-dtor -fno-rtti -fPIC -ffreestanding -MD -MT lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o -MF lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o.d -o lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o -c /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp
/b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp:63:3: error: use of undeclared identifier 'UnmapFromTo'

UnmapFromTo(shadow_start + shadow_size, shadow_start + premap_shadow_size);

[tejohnson]

In D83247#2156950, @aeubanks wrote:

Hi, I think this is breaking our Android bots: https://crbug.com/1106482

FAILED: lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o
/b/s/w/ir/cache/builder/src/third_party/llvm-build/Release+Asserts/bin/clang++ -DHWASAN_WITH_INTERCEPTORS=1 -I/b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/hwasan/.. --target=aarch64-linux-android21 --sysroot=/b/s/w/ir/cache/builder/src/third_party/android_ndk/toolchains/llvm/prebuilt/linux-x86_64/sysroot --gcc-toolchain=/b/s/w/ir/cache/builder/src/third_party/android_ndk/toolchains/llvm/prebuilt/linux-x86_64 -Wall -std=c++14 -Wno-unused-parameter -O3 -DNDEBUG -fPIC -fno-builtin -fno-exceptions -fomit-frame-pointer -funwind-tables -fno-stack-protector -fno-sanitize=safe-stack -fvisibility=hidden -fno-lto -O3 -gline-tables-only -Wno-gnu -Wno-variadic-macros -Wno-c99-extensions -Wno-non-virtual-dtor -fno-rtti -fPIC -ffreestanding -MD -MT lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o -MF lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o.d -o lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o -c /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp
/b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp:63:3: error: use of undeclared identifier 'UnmapFromTo'

UnmapFromTo(shadow_start + shadow_size, shadow_start + premap_shadow_size);

Looking...

[tejohnson]

In D83247#2156967, @tejohnson wrote:

In D83247#2156950, @aeubanks wrote:

Hi, I think this is breaking our Android bots: https://crbug.com/1106482

FAILED: lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o
/b/s/w/ir/cache/builder/src/third_party/llvm-build/Release+Asserts/bin/clang++ -DHWASAN_WITH_INTERCEPTORS=1 -I/b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/hwasan/.. --target=aarch64-linux-android21 --sysroot=/b/s/w/ir/cache/builder/src/third_party/android_ndk/toolchains/llvm/prebuilt/linux-x86_64/sysroot --gcc-toolchain=/b/s/w/ir/cache/builder/src/third_party/android_ndk/toolchains/llvm/prebuilt/linux-x86_64 -Wall -std=c++14 -Wno-unused-parameter -O3 -DNDEBUG -fPIC -fno-builtin -fno-exceptions -fomit-frame-pointer -funwind-tables -fno-stack-protector -fno-sanitize=safe-stack -fvisibility=hidden -fno-lto -O3 -gline-tables-only -Wno-gnu -Wno-variadic-macros -Wno-c99-extensions -Wno-non-virtual-dtor -fno-rtti -fPIC -ffreestanding -MD -MT lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o -MF lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o.d -o lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o -c /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp
/b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp:63:3: error: use of undeclared identifier 'UnmapFromTo'

UnmapFromTo(shadow_start + shadow_size, shadow_start + premap_shadow_size);

Looking...

Have a simple fix, just testing it now.

[tejohnson]

In D83247#2157022, @tejohnson wrote:

In D83247#2156967, @tejohnson wrote:

In D83247#2156950, @aeubanks wrote:

Hi, I think this is breaking our Android bots: https://crbug.com/1106482

FAILED: lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o
/b/s/w/ir/cache/builder/src/third_party/llvm-build/Release+Asserts/bin/clang++ -DHWASAN_WITH_INTERCEPTORS=1 -I/b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/hwasan/.. --target=aarch64-linux-android21 --sysroot=/b/s/w/ir/cache/builder/src/third_party/android_ndk/toolchains/llvm/prebuilt/linux-x86_64/sysroot --gcc-toolchain=/b/s/w/ir/cache/builder/src/third_party/android_ndk/toolchains/llvm/prebuilt/linux-x86_64 -Wall -std=c++14 -Wno-unused-parameter -O3 -DNDEBUG -fPIC -fno-builtin -fno-exceptions -fomit-frame-pointer -funwind-tables -fno-stack-protector -fno-sanitize=safe-stack -fvisibility=hidden -fno-lto -O3 -gline-tables-only -Wno-gnu -Wno-variadic-macros -Wno-c99-extensions -Wno-non-virtual-dtor -fno-rtti -fPIC -ffreestanding -MD -MT lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o -MF lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o.d -o lib/hwasan/CMakeFiles/RTHwasan.aarch64.dir/hwasan_dynamic_shadow.cpp.o -c /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp
/b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp:63:3: error: use of undeclared identifier 'UnmapFromTo'

UnmapFromTo(shadow_start + shadow_size, shadow_start + premap_shadow_size);

Looking...

Have a simple fix, just testing it now.

I just committed a fix at c489ae2a8605761d784171ff7152dfc75ab7c064. Please let me know if you are still having any problems.

[aeubanks]

Thanks! I'll let them cycle and let you know if anything is still broken.

[ro]

This patch broke the Solaris/sparcv9 buildbot. Patch posted: [[ https://reviews.llvm.org/D84004 | [compiler-rt][asan] Define MemToShadowSize for sparc64 ]].

Most likely Myriad2 is likewise affected.

[tejohnson]

In D83247#2157632, @ro wrote:

This patch broke the Solaris/sparcv9 buildbot. Patch posted: [[ https://reviews.llvm.org/D84004 | [compiler-rt][asan] Define MemToShadowSize for sparc64 ]].

Most likely Myriad2 is likewise affected.

Thanks for the quick fix. You are right, it looks like a fix is needed for asan_mapping_myriad.h as well (actually I will probably just move the def of this function to a different place in asan_mapping.h to fix all of them). I did not see any bot failures reported to me for either sparc or myriad - is there a myriad bot?

[phosek]

This broke Fuchsia's toolchain build which is now failing with the following error:

FAILED: /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/clang/12.0.0/lib/x86_64-unknown-fuchsia/libclang_rt.ubsan_standalone.so 
: && /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/./bin/clang++ --target=x86_64-unknown-fuchsia --sysroot=/b/s/w/ir/k/cipd/sdk/arch/x64/sysroot -fPIC --target=x86_64-unknown-fuchsia -I/b/s/w/ir/k/cipd/sdk/pkg/fdio/include -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -ffunction-sections -fdata-sections -ffile-prefix-map=/b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/runtimes/runtimes-x86_64-unknown-fuchsia-bins=../recipe_cleanup/clangro8g9J/llvm_build/runtimes/runtimes-x86_64-unknown-fuchsia-bins -ffile-prefix-map=/b/s/w/ir/k/llvm-project/= -no-canonical-prefixes -Wall -std=c++14 -Wno-unused-parameter -O2 -g  -L/b/s/w/ir/k/cipd/sdk/arch/x64/lib    -nodefaultlibs -Wl,-z,text -Wl,-z,defs,-z,now,-z,relro -Wl,--version-script,/b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/runtimes/runtimes-x86_64-unknown-fuchsia-bins/compiler-rt/lib/ubsan/clang_rt.ubsan_standalone-dynamic-x86_64.vers -shared -Wl,-soname,libclang_rt.ubsan_standalone.so -o /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/clang/12.0.0/lib/x86_64-unknown-fuchsia/libclang_rt.ubsan_standalone.so compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_allocator.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_common.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_deadlock_detector1.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_deadlock_detector2.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_errno.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_file.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_flags.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_flag_parser.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_fuchsia.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_libc.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_libignore.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_linux.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_linux_s390.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_mac.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_netbsd.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_openbsd.cpp.obj 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compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_unwind_win.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_diag.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_init.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_flags.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_handlers.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_monitor.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_value.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_cxx.x86_64.dir/ubsan_handlers_cxx.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_cxx.x86_64.dir/ubsan_type_hash.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_cxx.x86_64.dir/ubsan_type_hash_itanium.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_cxx.x86_64.dir/ubsan_type_hash_win.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_standalone.x86_64.dir/ubsan_diag_standalone.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_standalone.x86_64.dir/ubsan_init_standalone.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_standalone.x86_64.dir/ubsan_signals_standalone.cpp.obj compiler-rt/lib/interception/CMakeFiles/RTInterception.x86_64.dir/interception_linux.cpp.obj compiler-rt/lib/interception/CMakeFiles/RTInterception.x86_64.dir/interception_mac.cpp.obj compiler-rt/lib/interception/CMakeFiles/RTInterception.x86_64.dir/interception_win.cpp.obj compiler-rt/lib/interception/CMakeFiles/RTInterception.x86_64.dir/interception_type_test.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_dynamic_version_script_dummy.x86_64.dir/dummy.cpp.obj -L/b/s/w/ir/k/cipd/sdk/arch/x64/lib  -L/b/s/w/ir/k/cipd/sdk/arch/x64/sysroot/lib /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/x86_64-unknown-fuchsia/c++/libunwind.a /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/x86_64-unknown-fuchsia/c++/libc++abi.so.1.0 -lc -lzircon -ldl -lrt -lpthread /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/clang/12.0.0/lib/x86_64-unknown-fuchsia/libclang_rt.builtins.a -lc && :
ld.lld: error: undefined symbol: __sanitizer::MmapFixedSuperNoReserve(unsigned long, unsigned long, char const*)
>>> referenced by sanitizer_common_libcdep.cpp:150 (compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp:150)
>>>               compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_common_libcdep.cpp.obj:(__sanitizer::ReserveShadowMemoryRange(unsigned long, unsigned long, char const*, bool))

ld.lld: error: undefined symbol: __sanitizer::DontDumpShadowMemory(unsigned long, unsigned long)
>>> referenced by sanitizer_common_libcdep.cpp:159 (compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp:159)
>>>               compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_common_libcdep.cpp.obj:(__sanitizer::ReserveShadowMemoryRange(unsigned long, unsigned long, char const*, bool))

ld.lld: error: undefined symbol: __sanitizer::MmapFixedNoReserve(unsigned long, unsigned long, char const*)
>>> referenced by sanitizer_common_libcdep.cpp:151 (compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp:151)
>>>               compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_common_libcdep.cpp.obj:(__sanitizer::ReserveShadowMemoryRange(unsigned long, unsigned long, char const*, bool))
clang++: error: ld.lld command failed with exit code 1 (use -v to see invocation)

That function isn't used on Fuchsia, but it seems like --gc-sections isn't being used here causing the failure. It might be sufficient to just add #if !SANITIZER_FUCHSIA around this function as a workaround.

[tejohnson]

In D83247#2159421, @phosek wrote:

This broke Fuchsia's toolchain build which is now failing with the following error:

FAILED: /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/clang/12.0.0/lib/x86_64-unknown-fuchsia/libclang_rt.ubsan_standalone.so 
: && /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/./bin/clang++ --target=x86_64-unknown-fuchsia --sysroot=/b/s/w/ir/k/cipd/sdk/arch/x64/sysroot -fPIC --target=x86_64-unknown-fuchsia -I/b/s/w/ir/k/cipd/sdk/pkg/fdio/include -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -ffunction-sections -fdata-sections -ffile-prefix-map=/b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/runtimes/runtimes-x86_64-unknown-fuchsia-bins=../recipe_cleanup/clangro8g9J/llvm_build/runtimes/runtimes-x86_64-unknown-fuchsia-bins -ffile-prefix-map=/b/s/w/ir/k/llvm-project/= -no-canonical-prefixes -Wall -std=c++14 -Wno-unused-parameter -O2 -g  -L/b/s/w/ir/k/cipd/sdk/arch/x64/lib    -nodefaultlibs -Wl,-z,text -Wl,-z,defs,-z,now,-z,relro -Wl,--version-script,/b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/runtimes/runtimes-x86_64-unknown-fuchsia-bins/compiler-rt/lib/ubsan/clang_rt.ubsan_standalone-dynamic-x86_64.vers -shared -Wl,-soname,libclang_rt.ubsan_standalone.so -o /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/clang/12.0.0/lib/x86_64-unknown-fuchsia/libclang_rt.ubsan_standalone.so compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_allocator.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_common.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_deadlock_detector1.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_deadlock_detector2.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_errno.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_file.cpp.obj 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compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_unwind_win.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_diag.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_init.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_flags.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_handlers.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_monitor.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_value.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_cxx.x86_64.dir/ubsan_handlers_cxx.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_cxx.x86_64.dir/ubsan_type_hash.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_cxx.x86_64.dir/ubsan_type_hash_itanium.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_cxx.x86_64.dir/ubsan_type_hash_win.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_standalone.x86_64.dir/ubsan_diag_standalone.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_standalone.x86_64.dir/ubsan_init_standalone.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_standalone.x86_64.dir/ubsan_signals_standalone.cpp.obj compiler-rt/lib/interception/CMakeFiles/RTInterception.x86_64.dir/interception_linux.cpp.obj compiler-rt/lib/interception/CMakeFiles/RTInterception.x86_64.dir/interception_mac.cpp.obj compiler-rt/lib/interception/CMakeFiles/RTInterception.x86_64.dir/interception_win.cpp.obj compiler-rt/lib/interception/CMakeFiles/RTInterception.x86_64.dir/interception_type_test.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_dynamic_version_script_dummy.x86_64.dir/dummy.cpp.obj -L/b/s/w/ir/k/cipd/sdk/arch/x64/lib  -L/b/s/w/ir/k/cipd/sdk/arch/x64/sysroot/lib /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/x86_64-unknown-fuchsia/c++/libunwind.a /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/x86_64-unknown-fuchsia/c++/libc++abi.so.1.0 -lc -lzircon -ldl -lrt -lpthread /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/clang/12.0.0/lib/x86_64-unknown-fuchsia/libclang_rt.builtins.a -lc && :
ld.lld: error: undefined symbol: __sanitizer::MmapFixedSuperNoReserve(unsigned long, unsigned long, char const*)
>>> referenced by sanitizer_common_libcdep.cpp:150 (compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp:150)
>>>               compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_common_libcdep.cpp.obj:(__sanitizer::ReserveShadowMemoryRange(unsigned long, unsigned long, char const*, bool))

ld.lld: error: undefined symbol: __sanitizer::DontDumpShadowMemory(unsigned long, unsigned long)
>>> referenced by sanitizer_common_libcdep.cpp:159 (compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp:159)
>>>               compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_common_libcdep.cpp.obj:(__sanitizer::ReserveShadowMemoryRange(unsigned long, unsigned long, char const*, bool))

ld.lld: error: undefined symbol: __sanitizer::MmapFixedNoReserve(unsigned long, unsigned long, char const*)
>>> referenced by sanitizer_common_libcdep.cpp:151 (compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp:151)
>>>               compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_common_libcdep.cpp.obj:(__sanitizer::ReserveShadowMemoryRange(unsigned long, unsigned long, char const*, bool))
clang++: error: ld.lld command failed with exit code 1 (use -v to see invocation)

That function isn't used on Fuchsia, but it seems like --gc-sections isn't being used here causing the failure. It might be sufficient to just add #if !SANITIZER_FUCHSIA around this function as a workaround.

Sorry about that! I see that this code when it was in asan before my patch was guarded by:
#if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
so probably I should guard it the same way here.

Also, while the error above doesn't show any undefs coming from ProtectGap, I'm assuming that will give the same issue as it was moved to the same place and references MmapFixedNoAccess. Both were guarded before in asan and I'll add the guard here and commit shortly. I guess hwasan wasn't built on Fuchscia since it didn't have the guards around its version?

[phosek]

In D83247#2159463, @tejohnson wrote:

Sorry about that! I see that this code when it was in asan before my patch was guarded by:
#if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
so probably I should guard it the same way here.

Also, while the error above doesn't show any undefs coming from ProtectGap, I'm assuming that will give the same issue as it was moved to the same place and references MmapFixedNoAccess. Both were guarded before in asan and I'll add the guard here and commit shortly. I guess hwasan wasn't built on Fuchscia since it didn't have the guards around its version?

Not yet, we plan on porting HWASan to Fuchsia in the next few months.

[tejohnson]

In D83247#2159463, @tejohnson wrote:

In D83247#2159421, @phosek wrote:

This broke Fuchsia's toolchain build which is now failing with the following error:

FAILED: /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/clang/12.0.0/lib/x86_64-unknown-fuchsia/libclang_rt.ubsan_standalone.so 
: && /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/./bin/clang++ --target=x86_64-unknown-fuchsia --sysroot=/b/s/w/ir/k/cipd/sdk/arch/x64/sysroot -fPIC --target=x86_64-unknown-fuchsia -I/b/s/w/ir/k/cipd/sdk/pkg/fdio/include -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -ffunction-sections -fdata-sections -ffile-prefix-map=/b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/runtimes/runtimes-x86_64-unknown-fuchsia-bins=../recipe_cleanup/clangro8g9J/llvm_build/runtimes/runtimes-x86_64-unknown-fuchsia-bins -ffile-prefix-map=/b/s/w/ir/k/llvm-project/= -no-canonical-prefixes -Wall -std=c++14 -Wno-unused-parameter -O2 -g  -L/b/s/w/ir/k/cipd/sdk/arch/x64/lib    -nodefaultlibs -Wl,-z,text -Wl,-z,defs,-z,now,-z,relro -Wl,--version-script,/b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/runtimes/runtimes-x86_64-unknown-fuchsia-bins/compiler-rt/lib/ubsan/clang_rt.ubsan_standalone-dynamic-x86_64.vers -shared -Wl,-soname,libclang_rt.ubsan_standalone.so -o /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/clang/12.0.0/lib/x86_64-unknown-fuchsia/libclang_rt.ubsan_standalone.so compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_allocator.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_common.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_deadlock_detector1.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_deadlock_detector2.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_errno.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_file.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_flags.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_flag_parser.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_fuchsia.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_libc.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_libignore.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_linux.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_linux_s390.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_mac.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_netbsd.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_openbsd.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_persistent_allocator.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_platform_limits_freebsd.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_platform_limits_linux.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_platform_limits_netbsd.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_platform_limits_openbsd.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_platform_limits_posix.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_platform_limits_solaris.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_posix.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_printf.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_procmaps_common.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_procmaps_bsd.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_procmaps_fuchsia.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_procmaps_linux.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_procmaps_mac.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_procmaps_solaris.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_rtems.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_solaris.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_stoptheworld_fuchsia.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_stoptheworld_mac.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_suppressions.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_tls_get_addr.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_thread_registry.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_type_traits.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_win.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommon.x86_64.dir/sanitizer_termination.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_common_libcdep.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_allocator_checks.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_linux_libcdep.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_mac_libcdep.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_posix_libcdep.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_stoptheworld_linux_libcdep.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_stoptheworld_netbsd_libcdep.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonCoverage.x86_64.dir/sancov_flags.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonCoverage.x86_64.dir/sanitizer_coverage_fuchsia.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonCoverage.x86_64.dir/sanitizer_coverage_libcdep_new.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonCoverage.x86_64.dir/sanitizer_coverage_win_sections.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_allocator_report.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_stackdepot.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_stacktrace.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_stacktrace_libcdep.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_stacktrace_printer.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_stacktrace_sparc.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_symbolizer.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_symbolizer_libbacktrace.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_symbolizer_libcdep.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_symbolizer_mac.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_symbolizer_markup.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_symbolizer_posix_libcdep.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_symbolizer_report.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_symbolizer_win.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_unwind_linux_libcdep.cpp.obj compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonSymbolizer.x86_64.dir/sanitizer_unwind_win.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_diag.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_init.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_flags.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_handlers.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_monitor.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan.x86_64.dir/ubsan_value.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_cxx.x86_64.dir/ubsan_handlers_cxx.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_cxx.x86_64.dir/ubsan_type_hash.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_cxx.x86_64.dir/ubsan_type_hash_itanium.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_cxx.x86_64.dir/ubsan_type_hash_win.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_standalone.x86_64.dir/ubsan_diag_standalone.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_standalone.x86_64.dir/ubsan_init_standalone.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_standalone.x86_64.dir/ubsan_signals_standalone.cpp.obj compiler-rt/lib/interception/CMakeFiles/RTInterception.x86_64.dir/interception_linux.cpp.obj compiler-rt/lib/interception/CMakeFiles/RTInterception.x86_64.dir/interception_mac.cpp.obj compiler-rt/lib/interception/CMakeFiles/RTInterception.x86_64.dir/interception_win.cpp.obj compiler-rt/lib/interception/CMakeFiles/RTInterception.x86_64.dir/interception_type_test.cpp.obj compiler-rt/lib/ubsan/CMakeFiles/RTUbsan_dynamic_version_script_dummy.x86_64.dir/dummy.cpp.obj -L/b/s/w/ir/k/cipd/sdk/arch/x64/lib  -L/b/s/w/ir/k/cipd/sdk/arch/x64/sysroot/lib /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/x86_64-unknown-fuchsia/c++/libunwind.a /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/x86_64-unknown-fuchsia/c++/libc++abi.so.1.0 -lc -lzircon -ldl -lrt -lpthread /b/s/w/ir/k/recipe_cleanup/clangro8g9J/llvm_build/lib/clang/12.0.0/lib/x86_64-unknown-fuchsia/libclang_rt.builtins.a -lc && :
ld.lld: error: undefined symbol: __sanitizer::MmapFixedSuperNoReserve(unsigned long, unsigned long, char const*)
>>> referenced by sanitizer_common_libcdep.cpp:150 (compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp:150)
>>>               compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_common_libcdep.cpp.obj:(__sanitizer::ReserveShadowMemoryRange(unsigned long, unsigned long, char const*, bool))

ld.lld: error: undefined symbol: __sanitizer::DontDumpShadowMemory(unsigned long, unsigned long)
>>> referenced by sanitizer_common_libcdep.cpp:159 (compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp:159)
>>>               compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_common_libcdep.cpp.obj:(__sanitizer::ReserveShadowMemoryRange(unsigned long, unsigned long, char const*, bool))

ld.lld: error: undefined symbol: __sanitizer::MmapFixedNoReserve(unsigned long, unsigned long, char const*)
>>> referenced by sanitizer_common_libcdep.cpp:151 (compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp:151)
>>>               compiler-rt/lib/sanitizer_common/CMakeFiles/RTSanitizerCommonLibc.x86_64.dir/sanitizer_common_libcdep.cpp.obj:(__sanitizer::ReserveShadowMemoryRange(unsigned long, unsigned long, char const*, bool))
clang++: error: ld.lld command failed with exit code 1 (use -v to see invocation)

That function isn't used on Fuchsia, but it seems like --gc-sections isn't being used here causing the failure. It might be sufficient to just add #if !SANITIZER_FUCHSIA around this function as a workaround.

Sorry about that! I see that this code when it was in asan before my patch was guarded by:
#if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
so probably I should guard it the same way here.

Also, while the error above doesn't show any undefs coming from ProtectGap, I'm assuming that will give the same issue as it was moved to the same place and references MmapFixedNoAccess. Both were guarded before in asan and I'll add the guard here and commit shortly. I guess hwasan wasn't built on Fuchscia since it didn't have the guards around its version?

Fixed in db15b8ab90793e3707f72e7668c3844922fdf356

[phosek]

In D83247#2159587, @tejohnson wrote:

Fixed in db15b8ab90793e3707f72e7668c3844922fdf356

Thanks for a quick fix, I can confirm that it worked.

compiler-rt/lib/asan/asan_internal.h

 void *AsanTSDGet();
 void AsanTSDSet(void *tsd);
 void PlatformTSDDtor(void *tsd);
 
 void AppendToErrorMessageBuffer(const char *buffer);
 
 void *AsanDlSymNext(const char *sym);
 
-void ReserveShadowMemoryRange(uptr beg, uptr end, const char *name);
-
 // Returns `true` iff most of ASan init process should be skipped due to the
 // ASan library being loaded via `dlopen()`. Platforms may perform any
 // `dlopen()` specific initialization inside this function.
 bool HandleDlopenInit();
 
 // Add convenient macro for interface functions that may be represented as
 // weak hooks.
 #define ASAN_MALLOC_HOOK(ptr, size)                                   \

compiler-rt/lib/asan/asan_linux.cpp

 void InitializePlatformExceptionHandlers() {}
 bool IsSystemHeapAddress (uptr addr) { return false; }
 
 void *AsanDoesNotSupportStaticLinkage() {
   // This will fail to link with -static.
   return &_DYNAMIC;  // defined in link.h
 }
 
-static void UnmapFromTo(uptr from, uptr to) {
-  CHECK(to >= from);
-  if (to == from) return;
-  uptr res = internal_munmap(reinterpret_cast<void *>(from), to - from);
-  if (UNLIKELY(internal_iserror(res))) {
-    Report(
-        "ERROR: AddresSanitizer failed to unmap 0x%zx (%zd) bytes at address "
-        "%p\n",
-        to - from, to - from, from);
-    CHECK("unable to unmap" && 0);
-  }
-}
-
 #if ASAN_PREMAP_SHADOW
-uptr FindPremappedShadowStart() {
+uptr FindPremappedShadowStart(uptr shadow_size_bytes) {
   uptr granularity = GetMmapGranularity();
   uptr shadow_start = reinterpret_cast<uptr>(&__asan_shadow);
   uptr premap_shadow_size = PremapShadowSize();
-  uptr shadow_size = RoundUpTo(kHighShadowEnd, granularity);
+  uptr shadow_size = RoundUpTo(shadow_size_bytes, granularity);
   // We may have mapped too much. Release extra memory.
   UnmapFromTo(shadow_start + shadow_size, shadow_start + premap_shadow_size);
   return shadow_start;
 }
 #endif
 
 uptr FindDynamicShadowStart() {
+  uptr shadow_size_bytes = MemToShadowSize(kHighMemEnd);
 #if ASAN_PREMAP_SHADOW
   if (!PremapShadowFailed())
-    return FindPremappedShadowStart();
+    return FindPremappedShadowStart(shadow_size_bytes);
 #endif
 
-  uptr granularity = GetMmapGranularity();
-  uptr alignment = granularity * 8;
-  uptr left_padding = granularity;
-  uptr shadow_size = RoundUpTo(kHighShadowEnd, granularity);
-  uptr map_size = shadow_size + left_padding + alignment;
-
-  uptr map_start = (uptr)MmapNoAccess(map_size);
-  CHECK_NE(map_start, ~(uptr)0);
-
-  uptr shadow_start = RoundUpTo(map_start + left_padding, alignment);
-  UnmapFromTo(map_start, shadow_start - left_padding);
-  UnmapFromTo(shadow_start + shadow_size, map_start + map_size);
-
-  return shadow_start;
+  return MapDynamicShadow(shadow_size_bytes, SHADOW_SCALE, kHighMemEnd);
 }
 
 void AsanApplyToGlobals(globals_op_fptr op, const void *needle) {
   UNIMPLEMENTED();
 }
 
 #if SANITIZER_ANDROID
 // FIXME: should we do anything for Android?

compiler-rt/lib/asan/asan_mac.cpp

 bool IsSystemHeapAddress (uptr addr) { return false; }
 
 // No-op. Mac does not support static linkage anyway.
 void *AsanDoesNotSupportStaticLinkage() {
   return 0;
 }
 
 uptr FindDynamicShadowStart() {
-  uptr granularity = GetMmapGranularity();
-  uptr alignment = 8 * granularity;
-  uptr left_padding = granularity;
-  uptr space_size = kHighShadowEnd + left_padding;
-
-  uptr largest_gap_found = 0;
-  uptr max_occupied_addr = 0;
-  VReport(2, "FindDynamicShadowStart, space_size = %p\n", space_size);
-  uptr shadow_start =
-      FindAvailableMemoryRange(space_size, alignment, granularity,
-                               &largest_gap_found, &max_occupied_addr);
-  // If the shadow doesn't fit, restrict the address space to make it fit.
-  if (shadow_start == 0) {
-    VReport(
-        2,
-        "Shadow doesn't fit, largest_gap_found = %p, max_occupied_addr = %p\n",
-        largest_gap_found, max_occupied_addr);
-    uptr new_max_vm = RoundDownTo(largest_gap_found << SHADOW_SCALE, alignment);
-    if (new_max_vm < max_occupied_addr) {
-      Report("Unable to find a memory range for dynamic shadow.\n");
-      Report(
-          "space_size = %p, largest_gap_found = %p, max_occupied_addr = %p, "
-          "new_max_vm = %p\n",
-          space_size, largest_gap_found, max_occupied_addr, new_max_vm);
-      CHECK(0 && "cannot place shadow");
-    }
-    RestrictMemoryToMaxAddress(new_max_vm);
-    kHighMemEnd = new_max_vm - 1;
-    space_size = kHighShadowEnd + left_padding;
-    VReport(2, "FindDynamicShadowStart, space_size = %p\n", space_size);
-    shadow_start = FindAvailableMemoryRange(space_size, alignment, granularity,
-                                            nullptr, nullptr);
-    if (shadow_start == 0) {
-      Report("Unable to find a memory range after restricting VM.\n");
-      CHECK(0 && "cannot place shadow after restricting vm");
-    }
-  }
-  CHECK_NE((uptr)0, shadow_start);
-  CHECK(IsAligned(shadow_start, alignment));
-  return shadow_start;
+  return MapDynamicShadow(MemToShadowSize(kHighMemEnd), SHADOW_SCALE,
+                          kHighMemEnd);
 }
 
 // No-op. Mac does not support static linkage anyway.
 void AsanCheckDynamicRTPrereqs() {}
 
 // No-op. Mac does not support static linkage anyway.
 void AsanCheckIncompatibleRT() {}
 

compiler-rt/lib/asan/asan_mapping.h

 #define kShadowGap2Beg (kMidMemBeg ? kMidShadowEnd + 1 : 0)
 #define kShadowGap2End (kMidMemBeg ? kMidMemBeg - 1 : 0)
 
 #define kShadowGap3Beg (kMidMemBeg ? kMidMemEnd + 1 : 0)
 #define kShadowGap3End (kMidMemBeg ? kHighShadowBeg - 1 : 0)
 
 namespace __asan {
 
+static inline uptr MemToShadowSize(uptr size) { return size >> SHADOW_SCALE; }
 static inline bool AddrIsInLowMem(uptr a) {
   PROFILE_ASAN_MAPPING();
   return a <= kLowMemEnd;
 }
 
 static inline bool AddrIsInLowShadow(uptr a) {
   PROFILE_ASAN_MAPPING();
   return a >= kLowShadowBeg && a <= kLowShadowEnd;

compiler-rt/lib/asan/asan_premap_shadow.cpp

 uptr PremapShadowSize() {
   uptr granularity = GetMmapGranularity();
   return RoundUpTo(GetMaxVirtualAddress() >> SHADOW_SCALE, granularity);
 }
 
 // Returns an address aligned to 8 pages, such that one page on the left and
 // PremapShadowSize() bytes on the right of it are mapped r/o.
 uptr PremapShadow() {
-  uptr granularity = GetMmapGranularity();
-  uptr alignment = granularity * 8;
-  uptr left_padding = granularity;
-  uptr shadow_size = PremapShadowSize();
-  uptr map_size = shadow_size + left_padding + alignment;
-
-  uptr map_start = (uptr)MmapNoAccess(map_size);
-  CHECK_NE(map_start, ~(uptr)0);
-
-  uptr shadow_start = RoundUpTo(map_start + left_padding, alignment);
-  uptr shadow_end = shadow_start + shadow_size;
-  internal_munmap(reinterpret_cast<void *>(map_start),
-                  shadow_start - left_padding - map_start);
-  internal_munmap(reinterpret_cast<void *>(shadow_end),
-                  map_start + map_size - shadow_end);
-  return shadow_start;
+  return MapDynamicShadow(PremapShadowSize(), /*mmap_alignment_scale*/ 3,
+                          kHighMemEnd);
 }
 
 bool PremapShadowFailed() {
   uptr shadow = reinterpret_cast<uptr>(&__asan_shadow);
   uptr resolver = reinterpret_cast<uptr>(&__asan_premap_shadow);
   // shadow == resolver is how Android KitKat and older handles ifunc.
   // shadow == 0 just in case.
   if (shadow == 0 || shadow == resolver)

compiler-rt/lib/asan/asan_rtl.cpp

for (uptr i = 0; i < kAsanMappingProfileSize; i++) {
     if (AsanMappingProfile[i] == 0) continue;
     Printf("asan_mapping.h:%zd -- %zd\n", i, AsanMappingProfile[i]);
   }
 }
 
 static void InitializeHighMemEnd() {
 #if !SANITIZER_MYRIAD2
 #if !ASAN_FIXED_MAPPING
-  kHighMemEnd = GetMaxUserVirtualAddress();
-  // Increase kHighMemEnd to make sure it's properly
-  // aligned together with kHighMemBeg:
-  kHighMemEnd |= SHADOW_GRANULARITY * GetMmapGranularity() - 1;
+  kHighMemEnd = GetHighMemEnd(SHADOW_SCALE);
 #endif  // !ASAN_FIXED_MAPPING
   CHECK_EQ((kHighMemBeg % GetMmapGranularity()), 0);
 #endif  // !SANITIZER_MYRIAD2
 }
 
 void PrintAddressSpaceLayout() {
   if (kHighMemBeg) {
     Printf("|| `[%p, %p]` || HighMem    ||\n",

compiler-rt/lib/asan/asan_shadow_setup.cpp

 // InitializeShadowMemory implementation.
 #if !SANITIZER_FUCHSIA && !SANITIZER_RTEMS
 
 #include "asan_internal.h"
 #include "asan_mapping.h"
 
 namespace __asan {
 
-// ---------------------- mmap -------------------- {{{1
-// Reserve memory range [beg, end].
-// We need to use inclusive range because end+1 may not be representable.
-void ReserveShadowMemoryRange(uptr beg, uptr end, const char *name) {
-  CHECK_EQ((beg % GetMmapGranularity()), 0);
-  CHECK_EQ(((end + 1) % GetMmapGranularity()), 0);
-  uptr size = end - beg + 1;
-  DecreaseTotalMmap(size);  // Don't count the shadow against mmap_limit_mb.
-  if (!MmapFixedSuperNoReserve(beg, size, name)) {
-    Report(
-        "ReserveShadowMemoryRange failed while trying to map 0x%zx bytes. "
-        "Perhaps you're using ulimit -v\n",
-        size);
-    Abort();
-  }
-  if (common_flags()->use_madv_dontdump) DontDumpShadowMemory(beg, size);
-}
-
 static void ProtectGap(uptr addr, uptr size) {
   if (!flags()->protect_shadow_gap) {
     // The shadow gap is unprotected, so there is a chance that someone
     // is actually using this memory. Which means it needs a shadow...
     uptr GapShadowBeg = RoundDownTo(MEM_TO_SHADOW(addr), GetPageSizeCached());
     uptr GapShadowEnd =
         RoundUpTo(MEM_TO_SHADOW(addr + size), GetPageSizeCached()) - 1;
     if (Verbosity())
       Printf(
           "protect_shadow_gap=0:"
           " not protecting shadow gap, allocating gap's shadow\n"
           "|| `[%p, %p]` || ShadowGap's shadow ||\n",
           GapShadowBeg, GapShadowEnd);
     ReserveShadowMemoryRange(GapShadowBeg, GapShadowEnd,
                              "unprotected gap shadow");
     return;
   }
-  void *res = MmapFixedNoAccess(addr, size, "shadow gap");
-  if (addr == (uptr)res) return;
-  // A few pages at the start of the address space can not be protected.
-  // But we really want to protect as much as possible, to prevent this memory
-  // being returned as a result of a non-FIXED mmap().
-  if (addr == kZeroBaseShadowStart) {
-    uptr step = GetMmapGranularity();
-    while (size > step && addr < kZeroBaseMaxShadowStart) {
-      addr += step;
-      size -= step;
-      void *res = MmapFixedNoAccess(addr, size, "shadow gap");
-      if (addr == (uptr)res) return;
-    }
-  }
-
-  Report(
-      "ERROR: Failed to protect the shadow gap. "
-      "ASan cannot proceed correctly. ABORTING.\n");
-  DumpProcessMap();
-  Die();
+  __sanitizer::ProtectGap(addr, size, kZeroBaseShadowStart,
+                          kZeroBaseMaxShadowStart);
 }
 
 static void MaybeReportLinuxPIEBug() {
 #if SANITIZER_LINUX && (defined(__x86_64__) || defined(__aarch64__))
   Report("This might be related to ELF_ET_DYN_BASE change in Linux 4.12.\n");
   Report(
       "See https://github.com/google/sanitizers/issues/856 for possible "
       "workarounds.\n");
 #endif
 }
 
 void InitializeShadowMemory() {
   // Set the shadow memory address to uninitialized.
   __asan_shadow_memory_dynamic_address = kDefaultShadowSentinel;
 
   uptr shadow_start = kLowShadowBeg;
   // Detect if a dynamic shadow address must used and find a available location
   // when necessary. When dynamic address is used, the macro |kLowShadowBeg|
   // expands to |__asan_shadow_memory_dynamic_address| which is
   // |kDefaultShadowSentinel|.
   bool full_shadow_is_available = false;
   if (shadow_start == kDefaultShadowSentinel) {
-    __asan_shadow_memory_dynamic_address = 0;
-    CHECK_EQ(0, kLowShadowBeg);
     shadow_start = FindDynamicShadowStart();
     if (SANITIZER_LINUX) full_shadow_is_available = true;
   }
   // Update the shadow memory address (potentially) used by instrumentation.
   __asan_shadow_memory_dynamic_address = shadow_start;
 
   if (kLowShadowBeg) shadow_start -= GetMmapGranularity();
 

compiler-rt/lib/asan/asan_win.cpp

 void *AsanDoesNotSupportStaticLinkage() {
 #if defined(_DEBUG)
 #error Please build the runtime with a non-debug CRT: /MD or /MT
 #endif
   return 0;
 }
 
 uptr FindDynamicShadowStart() {
-  uptr granularity = GetMmapGranularity();
-  uptr alignment = 8 * granularity;
-  uptr left_padding = granularity;
-  uptr space_size = kHighShadowEnd + left_padding;
-  uptr shadow_start = FindAvailableMemoryRange(space_size, alignment,
-                                               granularity, nullptr, nullptr);
-  CHECK_NE((uptr)0, shadow_start);
-  CHECK(IsAligned(shadow_start, alignment));
-  return shadow_start;
+  return MapDynamicShadow(MemToShadowSize(kHighMemEnd), SHADOW_SCALE,
+                          kHighMemEnd);
 }
 
 void AsanCheckDynamicRTPrereqs() {}
 
 void AsanCheckIncompatibleRT() {}
 
 void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
   UNIMPLEMENTED();

compiler-rt/lib/hwasan/hwasan.h

 
 extern int hwasan_inited;
 extern bool hwasan_init_is_running;
 extern int hwasan_report_count;
 
 bool InitShadow();
 void InitPrctl();
 void InitThreads();
-void MadviseShadow();
 void InitializeInterceptors();
 
 void HwasanAllocatorInit();
 
 void *hwasan_malloc(uptr size, StackTrace *stack);
 void *hwasan_calloc(uptr nmemb, uptr size, StackTrace *stack);
 void *hwasan_realloc(void *ptr, uptr size, StackTrace *stack);
 void *hwasan_reallocarray(void *ptr, uptr nmemb, uptr size, StackTrace *stack);

compiler-rt/lib/hwasan/hwasan.cpp

void __hwasan_init() {
 
   InitInstrumentation();
   InitLoadedGlobals();
 
   // Needs to be called here because flags()->random_tags might not have been
   // initialized when InitInstrumentation() was called.
   GetCurrentThread()->InitRandomState();
 
-  MadviseShadow();
-
   SetPrintfAndReportCallback(AppendToErrorMessageBuffer);
   // This may call libc -> needs initialized shadow.
   AndroidLogInit();
 
   InitializeInterceptors();
   InstallDeadlySignalHandlers(HwasanOnDeadlySignal);
   InstallAtExitHandler(); // Needs __cxa_atexit interceptor.
 

compiler-rt/lib/hwasan/hwasan_dynamic_shadow.cpp

 #include "sanitizer_common/sanitizer_posix.h"
 
 #include <elf.h>
 #include <link.h>
 
 // The code in this file needs to run in an unrelocated binary. It should not
 // access any external symbol, including its own non-hidden globals.
 
-namespace __hwasan {
-
-static void UnmapFromTo(uptr from, uptr to) {
-  if (to == from)
-    return;
-  CHECK(to >= from);
-  uptr res = internal_munmap(reinterpret_cast<void *>(from), to - from);
-  if (UNLIKELY(internal_iserror(res))) {
-    Report("ERROR: %s failed to unmap 0x%zx (%zd) bytes at address %p\n",
-           SanitizerToolName, to - from, to - from, from);
-    CHECK("unable to unmap" && 0);
-  }
-}
-
-// Returns an address aligned to kShadowBaseAlignment, such that
-// 2**kShadowBaseAlingment on the left and shadow_size_bytes bytes on the right
-// of it are mapped no access.
-static uptr MapDynamicShadow(uptr shadow_size_bytes) {
-  const uptr granularity = GetMmapGranularity();
-  const uptr min_alignment = granularity << kShadowScale;
-  const uptr alignment = 1ULL << kShadowBaseAlignment;
-  CHECK_GE(alignment, min_alignment);
-
-  const uptr left_padding = 1ULL << kShadowBaseAlignment;
-  const uptr shadow_size =
-      RoundUpTo(shadow_size_bytes, granularity);
-  const uptr map_size = shadow_size + left_padding + alignment;
-
-  const uptr map_start = (uptr)MmapNoAccess(map_size);
-  CHECK_NE(map_start, ~(uptr)0);
-
-  const uptr shadow_start = RoundUpTo(map_start + left_padding, alignment);
-
-  UnmapFromTo(map_start, shadow_start - left_padding);
-  UnmapFromTo(shadow_start + shadow_size, map_start + map_size);
-
-  return shadow_start;
-}
-
-}  // namespace __hwasan
-
 #if SANITIZER_ANDROID
 extern "C" {
 
 INTERFACE_ATTRIBUTE void __hwasan_shadow();
 decltype(__hwasan_shadow)* __hwasan_premap_shadow();
 
 }  // extern "C"
 
 namespace __hwasan {
 
 // Conservative upper limit.
 static uptr PremapShadowSize() {
   return RoundUpTo(GetMaxVirtualAddress() >> kShadowScale,
                    GetMmapGranularity());
 }
 
 static uptr PremapShadow() {
-  return MapDynamicShadow(PremapShadowSize());
+  return MapDynamicShadow(PremapShadowSize(), kShadowScale, kHighMemEnd,
+                          kShadowBaseAlignment);
 }
 
 static bool IsPremapShadowAvailable() {
   const uptr shadow = reinterpret_cast<uptr>(&__hwasan_shadow);
   const uptr resolver = reinterpret_cast<uptr>(&__hwasan_premap_shadow);
   // shadow == resolver is how Android KitKat and older handles ifunc.
   // shadow == 0 just in case.
   return shadow != 0 && shadow != resolver;
if (resolver == reinterpret_cast<ElfW(Addr)>(&__hwasan_premap_shadow)) {
       break;
     }
   }
 }
 
 uptr FindDynamicShadowStart(uptr shadow_size_bytes) {
   if (IsPremapShadowAvailable())
     return FindPremappedShadowStart(shadow_size_bytes);
-  return MapDynamicShadow(shadow_size_bytes);
+  return MapDynamicShadow(shadow_size_bytes, kShadowScale, kHighMemEnd,
+                          kShadowBaseAlignment);
 }
 
 }  // namespace __hwasan
 #else
 namespace __hwasan {
 
 void InitShadowGOT() {}
 
 uptr FindDynamicShadowStart(uptr shadow_size_bytes) {
-  return MapDynamicShadow(shadow_size_bytes);
+  return MapDynamicShadow(shadow_size_bytes, kShadowScale, kHighMemEnd,
+                          kShadowBaseAlignment);
 }
 
 }  // namespace __hwasan
 
 #endif  // SANITIZER_ANDROID

compiler-rt/lib/hwasan/hwasan_linux.cpp

 //    Tested with check-hwasan on aarch64-linux-android.
 #if !SANITIZER_ANDROID
 SANITIZER_INTERFACE_ATTRIBUTE
 THREADLOCAL uptr __hwasan_tls;
 #endif
 
 namespace __hwasan {
 
-static void ReserveShadowMemoryRange(uptr beg, uptr end, const char *name) {
-  CHECK_EQ((beg % GetMmapGranularity()), 0);
-  CHECK_EQ(((end + 1) % GetMmapGranularity()), 0);
-  uptr size = end - beg + 1;
-  DecreaseTotalMmap(size);  // Don't count the shadow against mmap_limit_mb.
-  if (!MmapFixedNoReserve(beg, size, name)) {
-    Report(
-        "ReserveShadowMemoryRange failed while trying to map 0x%zx bytes. "
-        "Perhaps you're using ulimit -v\n",
-        size);
-    Abort();
-  }
-}
-
 static void ProtectGap(uptr addr, uptr size) {
-  if (!size)
-    return;
-  void *res = MmapFixedNoAccess(addr, size, "shadow gap");
-  if (addr == (uptr)res)
-    return;
-  // A few pages at the start of the address space can not be protected.
-  // But we really want to protect as much as possible, to prevent this memory
-  // being returned as a result of a non-FIXED mmap().
-  if (addr == 0) {
-    uptr step = GetMmapGranularity();
-    while (size > step) {
-      addr += step;
-      size -= step;
-      void *res = MmapFixedNoAccess(addr, size, "shadow gap");
-      if (addr == (uptr)res)
-        return;
-    }
-  }
+  __sanitizer::ProtectGap(addr, size, kZeroBaseShadowStart,
+                          kZeroBaseMaxShadowStart);
 
-  Report(
-      "ERROR: Failed to protect shadow gap [%p, %p]. "
-      "HWASan cannot proceed correctly. ABORTING.\n", (void *)addr,
-      (void *)(addr + size));
-  DumpProcessMap();
-  Die();
-}
-
-static uptr kLowMemStart;
-static uptr kLowMemEnd;
-static uptr kLowShadowEnd;
-static uptr kLowShadowStart;
-static uptr kHighShadowStart;
-static uptr kHighShadowEnd;
-static uptr kHighMemStart;
-static uptr kHighMemEnd;
+uptr kLowMemStart;
+uptr kLowMemEnd;
+uptr kLowShadowEnd;
+uptr kLowShadowStart;
+uptr kHighShadowStart;
+uptr kHighShadowEnd;
+uptr kHighMemStart;
+uptr kHighMemEnd;
 
 static void PrintRange(uptr start, uptr end, const char *name) {
   Printf("|| [%p, %p] || %.*s ||\n", (void *)start, (void *)end, 10, name);
 }
 
 static void PrintAddressSpaceLayout() {
   PrintRange(kHighMemStart, kHighMemEnd, "HighMem");
   if (kHighShadowEnd + 1 < kHighMemStart)
static void PrintAddressSpaceLayout() {
   if (kLowMemEnd + 1 < kLowShadowStart)
     PrintRange(kLowMemEnd + 1, kLowShadowStart - 1, "ShadowGap");
   else
     CHECK_EQ(kLowMemEnd + 1, kLowShadowStart);
   PrintRange(kLowMemStart, kLowMemEnd, "LowMem");
   CHECK_EQ(0, kLowMemStart);
 }
 
-static uptr GetHighMemEnd() {
-  // HighMem covers the upper part of the address space.
-  uptr max_address = GetMaxUserVirtualAddress();
-  // Adjust max address to make sure that kHighMemEnd and kHighMemStart are
-  // properly aligned:
-  max_address |= (GetMmapGranularity() << kShadowScale) - 1;
-  return max_address;
-}
-
 static void InitializeShadowBaseAddress(uptr shadow_size_bytes) {
   __hwasan_shadow_memory_dynamic_address =
       FindDynamicShadowStart(shadow_size_bytes);
 }
 
 void InitPrctl() {
 #define PR_SET_TAGGED_ADDR_CTRL 55
 #define PR_GET_TAGGED_ADDR_CTRL 56
#endif
   }
 #undef PR_SET_TAGGED_ADDR_CTRL
 #undef PR_GET_TAGGED_ADDR_CTRL
 #undef PR_TAGGED_ADDR_ENABLE
 }
 
 bool InitShadow() {
   // Define the entire memory range.
-  kHighMemEnd = GetHighMemEnd();
+  kHighMemEnd = GetHighMemEnd(kShadowScale);
 
   // Determine shadow memory base offset.
   InitializeShadowBaseAddress(MemToShadowSize(kHighMemEnd));
 
   // Place the low memory first.
   kLowMemEnd = __hwasan_shadow_memory_dynamic_address - 1;
   kLowMemStart = 0;
 

 void InitThreads() {
   CHECK(__hwasan_shadow_memory_dynamic_address);
   uptr guard_page_size = GetMmapGranularity();
   uptr thread_space_start =
       __hwasan_shadow_memory_dynamic_address - (1ULL << kShadowBaseAlignment);
   uptr thread_space_end =
       __hwasan_shadow_memory_dynamic_address - guard_page_size;
   ReserveShadowMemoryRange(thread_space_start, thread_space_end - 1,
-                           "hwasan threads");
+                           "hwasan threads", /*madvise_shadow*/ false);
   ProtectGap(thread_space_end,
              __hwasan_shadow_memory_dynamic_address - thread_space_end);
   InitThreadList(thread_space_start, thread_space_end - thread_space_start);
 }
 
-static void MadviseShadowRegion(uptr beg, uptr end) {
-  uptr size = end - beg + 1;
-  SetShadowRegionHugePageMode(beg, size);
-  if (common_flags()->use_madv_dontdump)
-    DontDumpShadowMemory(beg, size);
-}
-
-void MadviseShadow() {
-  MadviseShadowRegion(kLowShadowStart, kLowShadowEnd);
-  MadviseShadowRegion(kHighShadowStart, kHighShadowEnd);
-}
-
 bool MemIsApp(uptr p) {
   CHECK(GetTagFromPointer(p) == 0);
   return p >= kHighMemStart || (p >= kLowMemStart && p <= kLowMemEnd);
 }
 
 static void HwasanAtExit(void) {
   if (common_flags()->print_module_map)
     DumpProcessMap();

compiler-rt/lib/hwasan/hwasan_mapping.h

 // || [0x007bbebc8000, 0x007c3ebc7fff] || ShadowGap  ||
 // || [0x007477480000, 0x007bbebc7fff] || LowShadow  ||
 // || [0x000000000000, 0x00747747ffff] || LowMem     ||
 
 // Reasonable values are 4 (for 1/16th shadow) and 6 (for 1/64th).
 constexpr uptr kShadowScale = 4;
 constexpr uptr kShadowAlignment = 1ULL << kShadowScale;
 
+// With the zero shadow base we can not actually map pages starting from 0.
+// This constant is somewhat arbitrary.
+constexpr uptr kZeroBaseShadowStart = 0;
+constexpr uptr kZeroBaseMaxShadowStart = 1 << 18;
+
 namespace __hwasan {
 
+extern uptr kLowMemStart;
+extern uptr kLowMemEnd;
+extern uptr kLowShadowEnd;
+extern uptr kLowShadowStart;
+extern uptr kHighShadowStart;
+extern uptr kHighShadowEnd;
+extern uptr kHighMemStart;
+extern uptr kHighMemEnd;
+
 inline uptr MemToShadow(uptr untagged_addr) {
   return (untagged_addr >> kShadowScale) +
          __hwasan_shadow_memory_dynamic_address;
 }
 inline uptr ShadowToMem(uptr shadow_addr) {
   return (shadow_addr - __hwasan_shadow_memory_dynamic_address) << kShadowScale;
 }
 inline uptr MemToShadowSize(uptr size) {
   return size >> kShadowScale;
 }
 
 bool MemIsApp(uptr p);
 
 }  // namespace __hwasan
 
 #endif  // HWASAN_MAPPING_H

compiler-rt/lib/sanitizer_common/sanitizer_common.h

 void *MmapAlignedOrDieOnFatalError(uptr size, uptr alignment,
                                    const char *mem_type);
 // Disallow access to a memory range.  Use MmapFixedNoAccess to allocate an
 // unaccessible memory.
 bool MprotectNoAccess(uptr addr, uptr size);
 bool MprotectReadOnly(uptr addr, uptr size);
 
 void MprotectMallocZones(void *addr, int prot);
 
+// Get the max address, taking into account alignment due to the mmap
+// granularity and shadow size.
+uptr GetHighMemEnd(uptr shadow_scale);
+
+// Maps shadow_size_bytes of shadow memory and returns shadow address. It will
+// be aligned to the mmap granularity * 2^shadow_scale, or to
+// 2^min_shadow_base_alignment if that is larger. The returned address will
+// have max(2^min_shadow_base_alignment, mmap granularity) on the left, and
+// shadow_size_bytes bytes on the right, mapped no access.
+// The high_mem_end may be updated if the original shadow size doesn't fit.
+uptr MapDynamicShadow(uptr shadow_size_bytes, uptr shadow_scale,
+                      uptr &high_mem_end, uptr min_shadow_base_alignment = 0);
+
+// Reserve memory range [beg, end]. If madvise_shadow is true then apply
+// madvise (e.g. hugepages, core dumping) requested by options.
+void ReserveShadowMemoryRange(uptr beg, uptr end, const char *name,
+                              bool madvise_shadow = true);
+
+// Protect size bytes of memory starting at addr. Also try to protect
+// several pages at the start of the address space as specified by
+// zero_base_shadow_start, at most up to the size or zero_base_max_shadow_start.
+void ProtectGap(uptr addr, uptr size, uptr zero_base_shadow_start,
+                uptr zero_base_max_shadow_start);
+
 // Find an available address space.
 uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding,
                               uptr *largest_gap_found, uptr *max_occupied_addr);
 
 // Used to check if we can map shadow memory to a fixed location.
 bool MemoryRangeIsAvailable(uptr range_start, uptr range_end);
 // Releases memory pages entirely within the [beg, end] address range. Noop if
 // the provided range does not contain at least one entire page.

compiler-rt/lib/sanitizer_common/sanitizer_common.cpp

if (const char *bslash_pos = internal_strrchr(module, '\\'))
       return StripModuleName(bslash_pos + 1);
   }
   if (const char *slash_pos = internal_strrchr(module, '/')) {
     return slash_pos + 1;
   }
   return module;
 }
 
+uptr GetHighMemEnd(uptr shadow_scale) {
+  // HighMem covers the upper part of the address space.
+  uptr max_address = GetMaxUserVirtualAddress();
+  // Adjust max address to make sure that high mem end and high mem start are
+  // properly aligned:
+  max_address |= (GetMmapGranularity() << shadow_scale) - 1;
+  return max_address;
+}
+
 void ReportErrorSummary(const char *error_message, const char *alt_tool_name) {
   if (!common_flags()->print_summary)
     return;
   InternalScopedString buff(kMaxSummaryLength);
   buff.append("SUMMARY: %s: %s",
               alt_tool_name ? alt_tool_name : SanitizerToolName, error_message);
   __sanitizer_report_error_summary(buff.data());
 }

compiler-rt/lib/sanitizer_common/sanitizer_common_libcdep.cpp

uptr ReservedAddressRange::InitAligned(uptr size, uptr align,
   CHECK(IsPowerOfTwo(align));
   if (align <= GetPageSizeCached())
     return Init(size, name);
   uptr start = Init(size + align, name);
   start += align - (start & (align - 1));
   return start;
 }
 
+// Reserve memory range [beg, end].
+// We need to use inclusive range because end+1 may not be representable.
+void ReserveShadowMemoryRange(uptr beg, uptr end, const char *name,
+                              bool madvise_shadow) {
+  CHECK_EQ((beg % GetMmapGranularity()), 0);
+  CHECK_EQ(((end + 1) % GetMmapGranularity()), 0);
+  uptr size = end - beg + 1;
+  DecreaseTotalMmap(size);  // Don't count the shadow against mmap_limit_mb.
+  if (madvise_shadow ? !MmapFixedSuperNoReserve(beg, size, name)
+                     : !MmapFixedNoReserve(beg, size, name)) {
+    Report(
+        "ReserveShadowMemoryRange failed while trying to map 0x%zx bytes. "
+        "Perhaps you're using ulimit -v\n",
+        size);
+    Abort();
+  }
+  if (madvise_shadow && common_flags()->use_madv_dontdump)
+    DontDumpShadowMemory(beg, size);
+}
+
+void ProtectGap(uptr addr, uptr size, uptr zero_base_shadow_start,
+                uptr zero_base_max_shadow_start) {
+  if (!size)
+    return;
+  void *res = MmapFixedNoAccess(addr, size, "shadow gap");
+  if (addr == (uptr)res)
+    return;
+  // A few pages at the start of the address space can not be protected.
+  // But we really want to protect as much as possible, to prevent this memory
+  // being returned as a result of a non-FIXED mmap().
+  if (addr == zero_base_shadow_start) {
+    uptr step = GetMmapGranularity();
+    while (size > step && addr < zero_base_max_shadow_start) {
+      addr += step;
+      size -= step;
+      void *res = MmapFixedNoAccess(addr, size, "shadow gap");
+      if (addr == (uptr)res)
+        return;
+    }
+  }
+
+  Report(
+      "ERROR: Failed to protect the shadow gap. "
+      "%s cannot proceed correctly. ABORTING.\n",
+      SanitizerToolName);
+  DumpProcessMap();
+  Die();
+}
+
+static void UnmapFromTo(uptr from, uptr to) {
+  if (to == from)
+    return;
+  CHECK(to >= from);
+  uptr res = internal_munmap(reinterpret_cast<void *>(from), to - from);
+  if (UNLIKELY(internal_iserror(res))) {
+    Report("ERROR: %s failed to unmap 0x%zx (%zd) bytes at address %p\n",
+           SanitizerToolName, to - from, to - from, from);
+    CHECK("unable to unmap" && 0);
+  }
+}
+
+uptr MapDynamicShadow(uptr shadow_size_bytes, uptr shadow_scale,
+                      UNUSED uptr &high_mem_end,
+                      uptr min_shadow_base_alignment) {
+  const uptr granularity = GetMmapGranularity();
+  const uptr alignment =
+      Max(granularity << shadow_scale, 1UL << min_shadow_base_alignment);
+  const uptr left_padding = Max(granularity, 1UL << min_shadow_base_alignment);
+
+  const uptr shadow_size = RoundUpTo(shadow_size_bytes, granularity);
+  const uptr map_size = shadow_size + left_padding + alignment;
+
+  const uptr map_start = (uptr)MmapNoAccess(map_size);
+  CHECK_NE(map_start, ~(uptr)0);
+
+  const uptr shadow_start = RoundUpTo(map_start + left_padding, alignment);
+
+  UnmapFromTo(map_start, shadow_start - left_padding);
+  UnmapFromTo(shadow_start + shadow_size, map_start + map_size);
+
+  return shadow_start;
+}
+
 }  // namespace __sanitizer
 
 SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_sandbox_on_notify,
                              __sanitizer_sandbox_arguments *args) {
   __sanitizer::PlatformPrepareForSandboxing(args);
   if (__sanitizer::sandboxing_callback)
     __sanitizer::sandboxing_callback();
 }

compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

 # endif
 }
 #endif
 
 uptr GetMaxVirtualAddress() {
   return GetMaxUserVirtualAddress();
 }
 
+uptr MapDynamicShadow(uptr shadow_size_bytes, uptr shadow_scale,
+                      uptr &high_mem_end, uptr min_shadow_base_alignment) {
+  const uptr granularity = GetMmapGranularity();
+  const uptr alignment =
+      Max(granularity << shadow_scale, 1UL << min_shadow_base_alignment);
+  const uptr left_padding = Max(granularity, 1UL << min_shadow_base_alignment);
+
+  uptr space_size = shadow_size_bytes + left_padding;
+
+  uptr largest_gap_found = 0;
+  uptr max_occupied_addr = 0;
+  VReport(2, "FindDynamicShadowStart, space_size = %p\n", space_size);
+  uptr shadow_start =
+      FindAvailableMemoryRange(space_size, alignment, granularity,
+                               &largest_gap_found, &max_occupied_addr);
+  // If the shadow doesn't fit, restrict the address space to make it fit.
+  if (shadow_start == 0) {
+    VReport(
+        2,
+        "Shadow doesn't fit, largest_gap_found = %p, max_occupied_addr = %p\n",
+        largest_gap_found, max_occupied_addr);
+    uptr new_max_vm = RoundDownTo(largest_gap_found << shadow_scale, alignment);
+    if (new_max_vm < max_occupied_addr) {
+      Report("Unable to find a memory range for dynamic shadow.\n");
+      Report(
+          "space_size = %p, largest_gap_found = %p, max_occupied_addr = %p, "
+          "new_max_vm = %p\n",
+          space_size, largest_gap_found, max_occupied_addr, new_max_vm);
+      CHECK(0 && "cannot place shadow");
+    }
+    RestrictMemoryToMaxAddress(new_max_vm);
+    high_mem_end = new_max_vm - 1;
+    space_size = (high_mem_end >> shadow_scale) + left_padding;
+    VReport(2, "FindDynamicShadowStart, space_size = %p\n", space_size);
+    shadow_start = FindAvailableMemoryRange(space_size, alignment, granularity,
+                                            nullptr, nullptr);
+    if (shadow_start == 0) {
+      Report("Unable to find a memory range after restricting VM.\n");
+      CHECK(0 && "cannot place shadow after restricting vm");
+    }
+  }
+  CHECK_NE((uptr)0, shadow_start);
+  CHECK(IsAligned(shadow_start, alignment));
+  return shadow_start;
+}
+
 uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding,
                               uptr *largest_gap_found,
                               uptr *max_occupied_addr) {
   typedef vm_region_submap_short_info_data_64_t RegionInfo;
   enum { kRegionInfoSize = VM_REGION_SUBMAP_SHORT_INFO_COUNT_64 };
   // Start searching for available memory region past PAGEZERO, which is
   // 4KB on 32-bit and 4GB on 64-bit.
   mach_vm_address_t start_address =

compiler-rt/lib/sanitizer_common/sanitizer_win.cpp

 }
 
 bool DontDumpShadowMemory(uptr addr, uptr length) {
   // This is almost useless on 32-bits.
   // FIXME: add madvise-analog when we move to 64-bits.
   return true;
 }
 
+uptr MapDynamicShadow(uptr shadow_size_bytes, uptr shadow_scale,
+                      UNUSED uptr &high_mem_end,
+                      uptr min_shadow_base_alignment) {
+  const uptr granularity = GetMmapGranularity();
+  const uptr alignment =
+      Max(granularity << shadow_scale, 1UL << min_shadow_base_alignment);
+  const uptr left_padding = Max(granularity, 1UL << min_shadow_base_alignment);
+  uptr space_size = shadow_size_bytes + left_padding;
+  uptr shadow_start = FindAvailableMemoryRange(space_size, alignment,
+                                               granularity, nullptr, nullptr);
+  CHECK_NE((uptr)0, shadow_start);
+  CHECK(IsAligned(shadow_start, alignment));
+  return shadow_start;
+}
+
 uptr FindAvailableMemoryRange(uptr size, uptr alignment, uptr left_padding,
                               uptr *largest_gap_found,
                               uptr *max_occupied_addr) {
   uptr address = 0;
   while (true) {
     MEMORY_BASIC_INFORMATION info;
     if (!::VirtualQuery((void*)address, &info, sizeof(info)))
       return 0;