i#1569 AArch64: Implement restarting interrupted system calls.

Review-URL: https://codereview.appspot.com/294630043

core/arch/arch_exports.h

@@ -1741,9 +1741,15 @@ enum {
 #endif
 
     /* Not under defines so we can have code that is less cluttered */
+#ifdef AARCH64
+    INT_LENGTH = 4,
+    SYSCALL_LENGTH = 4,
+    SYSENTER_LENGTH = 4,
+#else
     INT_LENGTH = 2,
     SYSCALL_LENGTH = 2,
     SYSENTER_LENGTH = 2,
+#endif
 };
 
 #define REL32_REACHABLE_OFFS(offs) ((offs) <= INT_MAX && (offs) >= INT_MIN)

core/arch/emit_utils_shared.c

@@ -4577,15 +4577,17 @@ emit_do_syscall_common(dcontext_t *dcontext, generated_code_t *code,
     /* We will call this from handle_system_call, so need prefix on AArch64. */
     APP(&ilist, instr_create_restore_from_tls(dcontext, ENTRY_PC_REG,
                                               ENTRY_PC_SPILL_SLOT));
+    /* XXX: should have a proper patch list entry */
+    *syscall_offs += AARCH64_INSTR_SIZE;
 #endif
 
-#ifdef ARM
+#if defined(ARM) || defined(AARCH64)
     /* We have to save r0 in case the syscall is interrupted.  We can't
      * easily do this from dispatch b/c fcache_enter clobbers some TLS slots.
      */
     APP(&ilist, instr_create_save_to_tls(dcontext, DR_REG_R0, TLS_REG0_SLOT));
     /* XXX: should have a proper patch list entry */
-    *syscall_offs += THUMB_LONG_INSTR_SIZE;
+    *syscall_offs += IF_X64_ELSE(AARCH64_INSTR_SIZE, THUMB_LONG_INSTR_SIZE);
 #endif
 
     /* system call itself -- using same method we've observed OS using */

core/unix/signal.c

@@ -3237,7 +3237,7 @@ adjust_syscall_for_restart(dcontext_t *dcontext, thread_sig_info_t *info, int si
     }
 #ifdef X86
     sc->SC_SYSNUM_REG = sysnum;
-#elif defined(ARM)
+#elif defined(ARM) || defined(AARCH64)
     /* We just need to restore the app's arg to the syscall into r0, which
      * the kernel clobbered with -EINTR.  We stored r0 into TLS.
      */