[sanitizer] Add the common FreeBSD AArch64 support

[vitalybuka]

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

1796

how about SANITIZER_NETBSD and solaris?

can you switch to:

#if SANITIZER_FREEBSD && defined(aarch64)
#elif defined(aarch64)
#endif

1894

this exclude other without explanation
for freebsd you don't need to change this line at all?

[andrew]

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

1796

Are they supported in the sanitizers on AArch64? NetBSD doesn't have a __reserved field in its mcontext_t so will fail to build, and I don't see any ports of Solaris to AArch64.

[andrew]

Remove an unneeded SANITIZER_LINUX | SANITIZER_FREEBSD check

[andrew]

Rebase past rename to SANITIZER_APPLE

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

if (&real_pthread_join)
     real_pthread_join(th, nullptr);
 }
 #else
 void *internal_start_thread(void *(*func)(void *), void *arg) { return 0; }
 
 void internal_join_thread(void *th) {}
 #endif
 
-#if defined(__aarch64__)
+#if SANITIZER_LINUX && defined(__aarch64__)
 // Android headers in the older NDK releases miss this definition.
 struct __sanitizer_esr_context {
   struct _aarch64_ctx head;
   uint64_t esr;
 };
 
 static bool Aarch64GetESR(ucontext_t *ucontext, u64 *esr) {
   static const u32 kEsrMagic = 0x45535201;
   u8 *aux = reinterpret_cast<u8 *>(ucontext->uc_mcontext.__reserved);
   while (true) {
     _aarch64_ctx *ctx = (_aarch64_ctx *)aux;
     if (ctx->size == 0) break;
     if (ctx->magic == kEsrMagic) {
       *esr = ((__sanitizer_esr_context *)ctx)->esr;
       return true;
     }
     aux += ctx->size;
   }
   return false;
 }
+#elif SANITIZER_FREEBSD && defined(__aarch64__)
+// FreeBSD doesn't provide ESR in the ucontext.
+static bool Aarch64GetESR(ucontext_t *ucontext, u64 *esr) {
+  return false;
+}
 #endif
 
 using Context = ucontext_t;
 
 SignalContext::WriteFlag SignalContext::GetWriteFlag() const {
   Context *ucontext = (Context *)context;
 #if defined(__x86_64__) || defined(__i386__)
   static const uptr PF_WRITE = 1U << 1;
case 0x3b:  // pcrel
       }
 #endif
   }
   return SignalContext::Unknown;
 #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(__sparc__)
   // Decode the instruction to determine the access type.
   // From OpenSolaris $SRC/uts/sun4/os/trap.c (get_accesstype).
 #if SANITIZER_SOLARIS
#if SANITIZER_NETBSD
   *bp = _UC_MACHINE_FP(ucontext);
   *sp = _UC_MACHINE_SP(ucontext);
 #elif defined(__arm__)
   ucontext_t *ucontext = (ucontext_t*)context;
   *pc = ucontext->uc_mcontext.arm_pc;
   *bp = ucontext->uc_mcontext.arm_fp;
   *sp = ucontext->uc_mcontext.arm_sp;
 #elif defined(__aarch64__)
+# if SANITIZER_FREEBSD
+  ucontext_t *ucontext = (ucontext_t*)context;
+  *pc = ucontext->uc_mcontext.mc_gpregs.gp_elr;
+  *bp = ucontext->uc_mcontext.mc_gpregs.gp_x[29];
+  *sp = ucontext->uc_mcontext.mc_gpregs.gp_sp;
+# else
   ucontext_t *ucontext = (ucontext_t*)context;
   *pc = ucontext->uc_mcontext.pc;
   *bp = ucontext->uc_mcontext.regs[29];
   *sp = ucontext->uc_mcontext.sp;
+# endif
 #elif defined(__hppa__)
   ucontext_t *ucontext = (ucontext_t*)context;
   *pc = ucontext->uc_mcontext.sc_iaoq[0];
   /* GCC uses %r3 whenever a frame pointer is needed.  */
   *bp = ucontext->uc_mcontext.sc_gr[3];
   *sp = ucontext->uc_mcontext.sc_gr[30];
 #elif defined(__x86_64__)
 # if SANITIZER_FREEBSD

compiler-rt/lib/sanitizer_common/sanitizer_syscall_generic.inc

 #if !SANITIZER_NETBSD
 
 #if SANITIZER_FREEBSD || SANITIZER_APPLE || SANITIZER_SOLARIS
 # define SYSCALL(name) SYS_ ## name
 #else
 # define SYSCALL(name) __NR_ ## name
 #endif
 
-#if defined(__x86_64__) && (SANITIZER_FREEBSD || SANITIZER_APPLE)
+#if (defined(__x86_64__) && (SANITIZER_FREEBSD || SANITIZER_APPLE)) || \
+    (defined(__aarch64__) && SANITIZER_FREEBSD)
 # define internal_syscall __syscall
 # else
 # define internal_syscall syscall
 #endif
 
 #endif
 
 bool internal_iserror(uptr retval, int *rverrno) {
   if (retval == (uptr)-1) {
     if (rverrno)
       *rverrno = errno;
     return true;
   } else {
     return false;
   }
 }