ada-x86-android.patch

diff -rup gcc-6.4.0/gcc/ada/init.c gcc-6.4.0-new/gcc/ada/init.c
--- gcc-6.4.0/gcc/ada/init.c	2015-11-25 07:16:44.605929000 -0800
+++ gcc-6.4.0-new/gcc/ada/init.c	2018-10-28 21:43:17.804437431 -0700
@@ -2510,8 +2510,45 @@ __gnat_adjust_context_for_raise (int sig
 {
   mcontext_t *mcontext = &((ucontext_t *) ucontext)->uc_mcontext;
 
+  /* On the i386 and x86-64 architectures, stack checking is performed by
+     means of probes with moving stack pointer, that is to say the probed
+     address is always the value of the stack pointer.  Upon hitting the
+     guard page, the stack pointer therefore points to an inaccessible
+     address and an alternate signal stack is needed to run the handler.
+     But there is an additional twist: on these architectures, the EH
+     return code writes the address of the handler at the target CFA's
+     value on the stack before doing the jump.  As a consequence, if
+     there is an active handler in the frame whose stack has overflowed,
+     the stack pointer must nevertheless point to an accessible address
+     by the time the EH return is executed.
+
+     We therefore adjust the saved value of the stack pointer by the size
+     of one page + a small dope of 4 words, in order to make sure that it
+     points to an accessible address in case it's used as the target CFA.
+     The stack checking code guarantees that this address is unused by the
+     time this happens.  */
+
+#if defined (__i386__)
+  unsigned long *pc = (unsigned long *)mcontext->gregs[REG_EIP];
+  /* The pattern is "orl $0x0,(%esp)" for a probe in 32-bit mode.  */
+  if (signo == SIGSEGV && pc && *pc == 0x00240c83)
+    mcontext->gregs[REG_ESP] += 4096 + 4 * sizeof (unsigned long);
+#elif defined (__x86_64__)
+  unsigned long long *pc = (unsigned long long *)mcontext->gregs[REG_RIP];
+  if (signo == SIGSEGV && pc
+      /* The pattern is "orq $0x0,(%rsp)" for a probe in 64-bit mode.  */
+      && ((*pc & 0xffffffffffLL) == 0x00240c8348LL
+	  /* The pattern may also be "orl $0x0,(%esp)" for a probe in
+	     x32 mode.  */
+	  || (*pc & 0xffffffffLL) == 0x00240c83LL))
+    mcontext->gregs[REG_RSP] += 4096 + 4 * sizeof (unsigned long);
+#elif defined (__ia64__)
+  /* ??? The IA-64 unwinder doesn't compensate for signals.  */
+  mcontext->sc_ip++;
+#elif defined (__ARMEL__)
   /* ARM Bump has to be an even number because of odd/even architecture.  */
-  ((mcontext_t *) mcontext)->arm_pc += 2;
+  mcontext->arm_pc+=2;
+#endif
 }
 
 static void
@@ -2552,8 +2589,12 @@ __gnat_error_handler (int sig, siginfo_t
 {
   __gnat_adjust_context_for_raise (sig, ucontext);
 
+  #if defined (__ARMEL__)
   __gnat_sigtramp (sig, (void *) si, (void *) ucontext,
 		   (__sigtramphandler_t *)&__gnat_map_signal);
+  #else
+  __gnat_map_signal (sig, si, ucontext);
+  #endif
 }
 
 /* This must be in keeping with System.OS_Interface.Alternate_Stack_Size.  */