[sanitizer] Add the settings of Read and Write flags in SignalContext for LoongArch

[tangyouling]

Summary

The bit-30 in this __flags means the address error is due to memory load, and the
bit-31 means the address error is due to memory store. (see SC_ADDRERR_RD
and SC_ADDRERR_WR in kernel arch/loongarch/include/uapi/asm/sigcontext.h).

illegal_write_test.cpp and illegal_read_test.cpp have been tested and passed.

[tangyouling]

The signal is caused by a READ memory access,

$ ./test/sanitizer_common/asan-loongarch64-Linux/Posix/Output/illegal_read_test.cpp.tmp
AddressSanitizer:DEADLYSIGNAL
=================================================================
==3114306==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x555558803104 bp 0x7ffffbd391a0 sp 0x7ffffbd39160 T0)
==3114306==The signal is caused by a READ memory access.
==3114306==Hint: address points to the zero page.
    #0 0x555558803104 in main /home/loongson/llvm-work/llvm-project-test2/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Posix/illegal_read_test.cpp:13:7
    #1 0x7ffff1a09678  (/usr/lib64/libc.so.6+0x25678)
    #2 0x7ffff1a09764 in __libc_start_main (/usr/lib64/libc.so.6+0x25764)
    #3 0x55555871eac4  (/home/loongson/llvm-work/llvm-project-test2/llvm-project/build_crt/test/sanitizer_common/asan-loongarch64-Linux/Posix/Output/illegal_read_test.cpp.tmp+0x26ac4)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /home/loongson/llvm-work/llvm-project-test2/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Posix/illegal_read_test.cpp:13:7 in main
==3114306==ABORTING

The signal is caused by a WRITE memory access,

$ ./test/sanitizer_common/asan-loongarch64-Linux/Posix/Output/illegal_write_test.cpp.tmp 
AddressSanitizer:DEADLYSIGNAL
=================================================================
==3114308==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x5555579c70c8 bp 0x7ffffba24c50 sp 0x7ffffba24c10 T0)
==3114308==The signal is caused by a WRITE memory access.
==3114308==Hint: address points to the zero page.
    #0 0x5555579c70c8 in main /home/loongson/llvm-work/llvm-project-test2/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Posix/illegal_write_test.cpp:12:9
    #1 0x7ffff07b9678  (/usr/lib64/libc.so.6+0x25678)
    #2 0x7ffff07b9764 in __libc_start_main (/usr/lib64/libc.so.6+0x25764)
    #3 0x5555578e2a84  (/home/loongson/llvm-work/llvm-project-test2/llvm-project/build_crt/test/sanitizer_common/asan-loongarch64-Linux/Posix/Output/illegal_write_test.cpp.tmp+0x26a84)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /home/loongson/llvm-work/llvm-project-test2/llvm-project/compiler-rt/test/sanitizer_common/TestCases/Posix/illegal_write_test.cpp:12:9 in main
==3114308==ABORTING

[SixWeining]

LGTM but wait for others.

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

1963

don-t-use-else-after-a-return

https://llvm.org/docs/CodingStandards.html#don-t-use-else-after-a-return

[tangyouling]

Don’t use else after a return.

[xen0n]

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

1961

Define static const u32 SC_ADDRERR_RD and similarly SC_ADDRERR_WR to avoid magic numbers, as the other arches did.

[tangyouling]

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

1961

Define static const u32 SC_ADDRERR_RD and similarly SC_ADDRERR_WR to avoid magic numbers, as the other arches did.

I will use the definition in /usr/include/asm/sigcontext.h directly, if redefined will conflict.

/home/loongson/llvm-work/llvm-project-test2/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp:1959:20: error: expected ')'
/usr/include/asm/sigcontext.h:17:25: note: expanded from macro 'SC_ADDRERR_RD'
#define SC_ADDRERR_RD           (1 << 30)
                                 ^
/home/loongson/llvm-work/llvm-project-test2/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp:1959:20: note: to match this '('
/usr/include/asm/sigcontext.h:17:24: note: expanded from macro 'SC_ADDRERR_RD'
#define SC_ADDRERR_RD           (1 << 30)
                                ^
/home/loongson/llvm-work/llvm-project-test2/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp:1960:20: error: expected unqualified-id
  static const u32 SC_ADDRERR_WR = 1U << 31;
                   ^
/usr/include/asm/sigcontext.h:19:25: note: expanded from macro 'SC_ADDRERR_WR'
#define SC_ADDRERR_WR           (1 << 31)

[tangyouling]

Use the SC_ADDRERR_RD and SC_ADDRERR_WR macros in /usr/include/asm/sigcontext.h directly.

[xen0n]

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

1963

Missing space after if.

[tangyouling]

Add the missing space after if.

[XiaodongLoong]

What is the kernel version that support this flags? Maybe give a link on Github?

[xry111]

In D137231#3904351, @XiaodongLoong wrote:

What is the kernel version that support this flags? Maybe give a link on Github?

These flags are there since the day one LoongArch support was added into the kernel:
https://git.kernel.org/torvalds/c/c6f2f3e2c80e

[tangyouling]

In D137231#3904351, @XiaodongLoong wrote:

What is the kernel version that support this flags? Maybe give a link on Github?

Upstream kernel supports from the beginning,
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/diff/?id=b74baf4ad05b5ebe3152592fb2fa80d51681392a

[xen0n]

Should be good LoongArch-wise.

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

#elif defined(__arm__)
   static const uptr FSR_WRITE = 1U << 11;
   uptr fsr = ucontext->uc_mcontext.error_code;
   return fsr & FSR_WRITE ? Write : Read;
 #elif defined(__aarch64__)
   static const u64 ESR_ELx_WNR = 1U << 6;
   u64 esr;
   if (!Aarch64GetESR(ucontext, &esr)) return Unknown;
   return esr & ESR_ELx_WNR ? Write : Read;
+#elif defined(__loongarch__)
+  u32 flags = ucontext->uc_mcontext.__flags;
+  if (flags & SC_ADDRERR_RD)
+    return SignalContext::Read;
+  if (flags & SC_ADDRERR_WR)
+    return SignalContext::Write;
+  return SignalContext::Unknown;
 #elif defined(__sparc__)
   // Decode the instruction to determine the access type.
   // From OpenSolaris $SRC/uts/sun4/os/trap.c (get_accesstype).
 #if SANITIZER_SOLARIS
   uptr pc = ucontext->uc_mcontext.gregs[REG_PC];
 #else
   // Historical BSDism here.
   struct sigcontext *scontext = (struct sigcontext *)context;