Summary:
28c91219c7e 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
# 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)
#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