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Disable interception of sigaltstack on i386 macOS. 

Summary:
28c91219c7 introduced an interceptor for `sigaltstack`. It turns out this
broke `setjmp` on i386 macOS. This is because the implementation of `setjmp` on
i386 macOS is written in assembly and makes the assumption that the call to
`sigaltstack` does not clobber any registers.  Presumably that assumption was
made because it's a system call.  In particular `setjmp`  assumes that before
and after the call that `%ecx` will contain a pointer the `jmp_buf`. The
current interceptor breaks this assumption because it's written in C++ and
`%ecx` is not a callee-saved register. This could be fixed by writing a
trampoline interceptor to the existing interceptor in assembly that
ensures all the registers are preserved. However, this is a lot of work
for very little gain. Instead this patch just disables the interceptor
on i386 macOS.

For other Darwin architectures it currently appears to be safe to intercept
`sigaltstack` using the current implementation because:

* `setjmp` for x86_64 saves the pointer `jmp_buf` to the stack before calling `sigaltstack`.
* `setjmp` for armv7/arm64/arm64_32/arm64e appears to not call `sigaltstack` at all.

This patch should unbreak (once they are re-enabled) the following
tests:

```
AddressSanitizer-Unit :: ./Asan-i386-calls-Test/AddressSanitizer.LongJmpTest
AddressSanitizer-Unit :: ./Asan-i386-calls-Test/AddressSanitizer.SigLongJmpTest
AddressSanitizer-Unit :: ./Asan-i386-inline-Test/AddressSanitizer.LongJmpTest
AddressSanitizer-Unit :: ./Asan-i386-inline-Test/AddressSanitizer.SigLongJmpTest
AddressSanitizer-i386-darwin :: TestCases/longjmp.cpp
```

This patch introduces a `SANITIZER_I386` macro for convenience.

rdar://problem/62141412

Reviewers: kubamracek, yln, eugenis

Subscribers: kristof.beyls, #sanitizers, llvm-commits

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D82691
This commit is contained in:
Dan Liew 2020-06-26 16:14:22 -07:00
parent 5e9b16b67f
commit 888951aaca
2 changed files with 10 additions and 1 deletions
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6
compiler-rt/lib/sanitizer_common/sanitizer_platform.h
View File

@ -132,6 +132,12 @@
# define SANITIZER_X32 0
#endif
#if defined(__i386__) || defined(_M_IX86)
# define SANITIZER_I386 1
#else
# define SANITIZER_I386 0
#endif
#if defined(__mips__)
# define SANITIZER_MIPS 1
# if defined(__mips64)

5
compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
View File

@ -597,7 +597,10 @@
#define SANITIZER_INTERCEPT_QSORT \
(SI_POSIX && !SI_IOSSIM && !SI_WATCHOS && !SI_TVOS && !SI_ANDROID)
#define SANITIZER_INTERCEPT_QSORT_R (SI_LINUX && !SI_ANDROID)
#define SANITIZER_INTERCEPT_SIGALTSTACK SI_POSIX
// sigaltstack on i386 macOS cannot be intercepted due to setjmp()
// calling it and assuming that it does not clobber registers.
#define SANITIZER_INTERCEPT_SIGALTSTACK \
(SI_POSIX && !(SANITIZER_MAC && SANITIZER_I386))
#define SANITIZER_INTERCEPT_UNAME (SI_POSIX && !SI_FREEBSD)
#define SANITIZER_INTERCEPT___XUNAME SI_FREEBSD