[Sanitizers] Disable SANITIZER_CAN_FAST_UNWIND on all SPARC targets

[ro]

Summary

While testing my to-be-submitted Solaris sanitizer support on gcc mainline, I ran into
an issue on Solaris/SPARC (sparc-sun-solaris2.11). Initially libasan.so failed to link:

Undefined                       first referenced
 symbol                             in file
__sanitizer::BufferedStackTrace::FastUnwindStack(unsigned long, unsigned long, unsigned long, unsigned long, unsigned int) /var/gcc/gcc-9.0.0-20181024/11.5-gcc-gas/sparc-sun-solaris2.11/./libsanitizer/asan/.libs/libasan.so

This happens because SANITIZER_CAN_FAST_UNWIND is enabled on non-Linux
SPARC targets (cf. sanitizer_stacktrace.h), but the guard around the SPARCv8-only
definition in sanitizer_stacktrace_sparc.cc only works with clang:

clang predefines sparcv8 on non-Solaris, and sparcv8 only on Solaris
gcc predefines sparcv8 on Solaris, but sparc_v8 on non-Solaris

The attached patch allows for all three variants.

However, disabling SANITIZER_CAN_FAST_UNWIND on all SPARC targets
fixes a couple of testsuite failures in the Solaris asan testsuite, so for now it's better
to keep it disabled everywhere.

This allowed the libsanitizer build to complete and gave reasonable (though slightly
worse than on Solaris/x86) testsuite results.

I'd like to get this into GCC 9, which requires that this patch be accepted upstream
first.

[krytarowski]

There is also sparc and sparc64 support in sanitizers on NetBSD... but I cannot say for now how well it works. For sure we run UBSan and ASan for both of them.

[ro]

In D54099#1293960, @krytarowski wrote:

There is also sparc and sparc64 support in sanitizers on NetBSD... but I cannot say for now how well it works. For sure we run UBSan and ASan for both of them.

I still wonder how this works, though: I've just refreshed my patch for SPARC support in compiler-rt (https://reviews.llvm.org/D40900) and tried
again with patches on top to enable asan on 32-bit sparc in clang and the 32-bit asan tests in compiler-rt (trivial, but not submitted as pointless).

I immediately ran again into build failures of the compiler-rt asan tests:

fatal error: error in backend: Function "main": over-aligned dynamic alloca not supported.
clang-8: error: clang frontend command failed with exit code 70 (use -v to see invocation)

just the same as when I initially had submitted D40900. If you have a way around this, I'm all ears ;-)

I cannot reasonably try sparcv9 on Solaris, though, due to the particular address space layout used there.

However, as I mentioned since about a week an implementation of the TARGET_ASAN_SHADOW_OFFSET hook for sparc has landed in
gcc mainline, where asan works reasonably well.

ubsan should be no problem, admittedly.

[krytarowski]

In D54099#1296841, @ro wrote:

In D54099#1293960, @krytarowski wrote:

There is also sparc and sparc64 support in sanitizers on NetBSD... but I cannot say for now how well it works. For sure we run UBSan and ASan for both of them.

I still wonder how this works, though: I've just refreshed my patch for SPARC support in compiler-rt (https://reviews.llvm.org/D40900) and tried
again with patches on top to enable asan on 32-bit sparc in clang and the 32-bit asan tests in compiler-rt (trivial, but not submitted as pointless).

I immediately ran again into build failures of the compiler-rt asan tests:

fatal error: error in backend: Function "main": over-aligned dynamic alloca not supported.
clang-8: error: clang frontend command failed with exit code 70 (use -v to see invocation)

just the same as when I initially had submitted D40900. If you have a way around this, I'm all ears ;-)

I cannot reasonably try sparcv9 on Solaris, though, due to the particular address space layout used there.

However, as I mentioned since about a week an implementation of the TARGET_ASAN_SHADOW_OFFSET hook for sparc has landed in
gcc mainline, where asan works reasonably well.

ubsan should be no problem, admittedly.

This works with GCC and manually patched libsanitizer (GCC 6.x/7.x) by other developers (mainly Christos Zoulas). The LLVM version is as of now much more advanced, beyond basic support for UBSan and ASan.

I'm personally short on time to work on the GCC part myself.

lib/sanitizer_common/sanitizer_stacktrace.h

 #define SANITIZER_STACKTRACE_H
 
 #include "sanitizer_internal_defs.h"
 
 namespace __sanitizer {
 
 static const u32 kStackTraceMax = 256;
 
-#if SANITIZER_LINUX &&  (defined(__sparc__) || defined(__mips__))
+#if defined(__sparc__) || (SANITIZER_LINUX && defined(__mips__))
 # define SANITIZER_CAN_FAST_UNWIND 0
 #elif SANITIZER_WINDOWS
 # define SANITIZER_CAN_FAST_UNWIND 0
 #elif SANITIZER_OPENBSD
 # define SANITIZER_CAN_FAST_UNWIND 0
 #else
 # define SANITIZER_CAN_FAST_UNWIND 1
 #endif

lib/sanitizer_common/sanitizer_stacktrace_sparc.cc

 // This file is shared between AddressSanitizer and ThreadSanitizer
 // run-time libraries.
 //
 // Implemention of fast stack unwinding for Sparc.
 //===----------------------------------------------------------------------===//
 
 // This file is ported to Sparc v8, but it should be easy to port to
 // Sparc v9.
-#if defined(__sparcv8__)
+#if defined(__sparcv8__) || defined(__sparcv8) || defined(__sparc_v8__)
 
 #include "sanitizer_common.h"
 #include "sanitizer_stacktrace.h"
 
 namespace __sanitizer {
 
 void BufferedStackTrace::FastUnwindStack(uptr pc, uptr bp, uptr stack_top,
                                          uptr stack_bottom, u32 max_depth) {
while (IsValidFrame((uptr)frame, stack_top, bottom) &&
     }
     bottom = (uptr)frame;
     frame = (uhwptr*)frame[14];
   }
 }
 
 }  // namespace __sanitizer
 
-#endif  // !defined(__sparcv8__)
+#endif  // !defined(__sparcv8__) && !defined(__sparcv8) &&
+        // !defined(__sparc_v8__)