[tsan] Derive the unmangled SP in longjmp with xor key on loongarch64

Introducing xor key to derive unmangled sp is here to follow the way
that the glibc adds support for pointer mangling on loongarch in commit
1c9bc1b6e50293a1b7037a7bfbf835868a55baed.

Reviewed By: SixWeining, wangleiat, xen0n

Differential Revision: https://reviews.llvm.org/D146716

compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp

@@ -66,7 +66,8 @@ extern "C" void *__libc_stack_end;
 void *__libc_stack_end = 0;
 #endif
 
-#if SANITIZER_LINUX && defined(__aarch64__) && !SANITIZER_GO
+#if SANITIZER_LINUX && (defined(__aarch64__) || defined(__loongarch_lp64)) && \
+    !SANITIZER_GO
 # define INIT_LONGJMP_XOR_KEY 1
 #else
 # define INIT_LONGJMP_XOR_KEY 0
@@ -314,7 +315,7 @@ void InitializePlatform() {
     }
 
 #endif
-#if SANITIZER_LINUX && defined(__aarch64__)
+#if SANITIZER_LINUX && (defined(__aarch64__) || defined(__loongarch_lp64))
     // Initialize the xor key used in {sig}{set,long}jump.
     InitializeLongjmpXorKey();
 #endif
@@ -387,8 +388,8 @@ static uptr UnmangleLongJmpSp(uptr mangled_sp) {
 # else
   return mangled_sp;
 # endif
-#elif defined(__loongarch__)
-  return mangled_sp;
+#elif defined(__loongarch_lp64)
+  return mangled_sp ^ longjmp_xor_key;
 #elif defined(__powerpc64__)
   // Reverse of:
   //   ld   r4, -28696(r13)
@@ -452,7 +453,11 @@ static void InitializeLongjmpXorKey() {
 
   // 2. Retrieve vanilla/mangled SP.
   uptr sp;
+#ifdef __loongarch__
+  asm("move  %0, $sp" : "=r" (sp));
+#else
   asm("mov  %0, sp" : "=r" (sp));
+#endif
   uptr mangled_sp = ((uptr *)&env)[LONG_JMP_SP_ENV_SLOT];
 
   // 3. xor SPs to obtain key.