From 82bd388bf08329b4e271ef83adca22b3816ff14f Mon Sep 17 00:00:00 2001
From: Doug Rupp <rupp@adacore.com>
Date: Mon, 20 Dec 2021 14:25:30 -0800
Subject: [PATCH] [Ada] vx21.07: stack-checking on ppc

On VxWorks >= 7.2 and 653, signal processing code is expected to clear
the TCB exception count field when returning control back to user code.
This change arranges to do so.  It is believed that this is only an
issue in Kernel mode, and not RTP because there is no exception count
field in RTP mode and no failures have been observed.

gcc/ada/

	* init.c [vxworks] (CLEAR_EXCEPTION_COUNT): New macro.
	(__gnat_clear_exception_count): Remove.
	(__gnat_map_signal): Call CLEAR_EXCEPTION_COUNT().
---
 gcc/ada/init.c | 38 ++++++++++++++++++++++----------------
 1 file changed, 22 insertions(+), 16 deletions(-)

diff --git a/gcc/ada/init.c b/gcc/ada/init.c
index 6b6ed5fb058..9eedffc4a37 100644
--- a/gcc/ada/init.c
+++ b/gcc/ada/init.c
@@ -1758,8 +1758,26 @@ extern size_t vxIntStackOverflowSize;
 #define INT_OVERFLOW_SIZE vxIntStackOverflowSize
 #endif
 
-#ifdef VTHREADS
-#include "private/vThreadsP.h"
+/* VxWorks 653 vThreads expects the field excCnt to be zeroed when a signal is.
+   handled.  The VxWorks version of longjmp does this; GCC's builtin_longjmp
+   doesn't.  A similar issue is present VxWorks 7.2 and affects ZCX as well
+   as builtin_longjmp.  This field only exists in Kernel mode, not RTP.  */
+#if defined(VTHREADS) || (!defined(__RTP__) && (_WRS_VXWORKS_MAJOR >= 7))
+# ifdef VTHREADS
+#  include "private/vThreadsP.h"
+#  define EXCCNT vThreads.excCnt
+# else
+#  include "private/taskLibP.h"
+#  define EXCCNT excCnt
+# endif
+# define CLEAR_EXCEPTION_COUNT()			 \
+  do							 \
+    {							 \
+      WIND_TCB *currentTask = (WIND_TCB *) taskIdSelf(); \
+      currentTask->EXCCNT = 0;				 \
+    } while (0)
+#else
+# define CLEAR_EXCEPTION_COUNT()
 #endif
 
 #ifndef __RTP__
@@ -1835,19 +1853,6 @@ __gnat_reset_guard_page (int sig)
   return FALSE;
 }
 
-/* VxWorks 653 vThreads expects the field excCnt to be zeroed when a signal is.
-   handled. The VxWorks version of longjmp does this; GCC's builtin_longjmp
-   doesn't.  */
-void
-__gnat_clear_exception_count (void)
-{
-#ifdef VTHREADS
-  WIND_TCB *currentTask = (WIND_TCB *) taskIdSelf();
-
-  currentTask->vThreads.excCnt = 0;
-#endif
-}
-
 /* Handle different SIGnal to exception mappings in different VxWorks
    versions.  */
 void
@@ -1959,7 +1964,8 @@ __gnat_map_signal (int sig,
           break;
         }
     }
-  __gnat_clear_exception_count ();
+
+  CLEAR_EXCEPTION_COUNT ();
   Raise_From_Signal_Handler (exception, msg);
 }