From 4f14ef87b2fba9718c1a88b9ed9ca7ba111d60da Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue, 22 Sep 2009 08:10:43 +0000
Subject: Fix crash of stackoverflow2 on x86_64-linux.

---
diff --git a/src/sigsegv.h.in b/src/sigsegv.h.in
index 85f337d..6b8e4c7 100644
--- a/src/sigsegv.h.in
+++ b/src/sigsegv.h.in
@@ -121,9 +121,11 @@ typedef void (*stackoverflow_handler_t) (int emergency, stackoverflow_context_t
 /*
  * Installs a stack overflow handler.
  * The extra_stack argument is a pointer to a pre-allocated area used as a
- * stack for executing the handler. It is typically allocated by use of
- * `alloca' during `main'. Its size should be sufficiently large.
- * The following code determines an appropriate size:
+ * stack for executing the handler. It typically comes from a static variable
+ * or from heap-allocated memoty; placing it on the main stack may fail on
+ * some operating systems.
+ * Its size, passed in extra_stack_size, should be sufficiently large.  The
+ * following code determines an appropriate size:
  *   #include <signal.h>
  *   #ifndef SIGSTKSZ         / * glibc defines SIGSTKSZ for this purpose * /
  *   # define SIGSTKSZ 16384  / * on most platforms, 16 KB are sufficient * /
diff --git a/tests/stackoverflow1.c b/tests/stackoverflow1.c
index 0970e79..23eff58 100644
--- a/tests/stackoverflow1.c
+++ b/tests/stackoverflow1.c
@@ -88,12 +88,13 @@ recurse (volatile int n)
   return *recurse_1 (n, &n);
 }
 
+/* glibc says: Users should use SIGSTKSZ as the size of user-supplied
+   buffers.  */
+char mystack[2 * SIGSTKSZ];
+
 int
 main ()
 {
-  /* glibc says: Users should use SIGSTKSZ as the size of user-supplied
-     buffers.  */
-  char mystack[SIGSTKSZ];
   sigset_t emptyset;
 
 #if HAVE_SETRLIMIT && defined RLIMIT_STACK
diff --git a/tests/stackoverflow2.c b/tests/stackoverflow2.c
index 2475bf2..4a07c66 100644
--- a/tests/stackoverflow2.c
+++ b/tests/stackoverflow2.c
@@ -109,12 +109,13 @@ recurse (volatile int n)
   return *recurse_1 (n, &n);
 }
 
+/* glibc says: Users should use SIGSTKSZ as the size of user-supplied
+   buffers.  */
+char mystack[2 * SIGSTKSZ];
+
 int
 main ()
 {
-  /* glibc says: Users should use SIGSTKSZ as the size of user-supplied
-     buffers.  */
-  char mystack[SIGSTKSZ];
   sigset_t emptyset;
   void *p;
 
--
cgit v0.8.2.1
diff -up libsigsegv-2.6/m4/sigaltstack-longjmp.m4.stack2 libsigsegv-2.6/m4/sigaltstack-longjmp.m4
--- libsigsegv-2.6/m4/sigaltstack-longjmp.m4.stack2	2008-08-24 15:40:16.000000000 -0500
+++ libsigsegv-2.6/m4/sigaltstack-longjmp.m4	2009-09-22 13:26:07.552664938 -0500
@@ -51,9 +51,9 @@ int recurse (volatile int n)
   int sum = 0;
   return *recurse_1 (n, &sum);
 }
+char mystack[2 * SIGSTKSZ];
 int main ()
 {
-  char mystack[SIGSTKSZ];
   stack_t altstack;
   struct sigaction action;
   sigset_t emptyset;
diff -up libsigsegv-2.6/m4/sigaltstack.m4.stack2 libsigsegv-2.6/m4/sigaltstack.m4
--- libsigsegv-2.6/m4/sigaltstack.m4.stack2	2008-08-24 15:41:10.000000000 -0500
+++ libsigsegv-2.6/m4/sigaltstack.m4	2009-09-22 13:25:47.462666140 -0500
@@ -71,9 +71,10 @@ int recurse (volatile int n)
   int sum = 0;
   return *recurse_1 (n, &sum);
 }
+char mystack[2 * SIGSTKSZ];
+
 int main ()
 {
-  char mystack[SIGSTKSZ];
   stack_t altstack;
   struct sigaction action;
 #if defined HAVE_SETRLIMIT && defined RLIMIT_STACK
diff -up libsigsegv-2.6/m4/sigaltstack-siglongjmp.m4.stack2 libsigsegv-2.6/m4/sigaltstack-siglongjmp.m4
--- libsigsegv-2.6/m4/sigaltstack-siglongjmp.m4.stack2	2008-08-24 15:40:49.000000000 -0500
+++ libsigsegv-2.6/m4/sigaltstack-siglongjmp.m4	2009-09-22 13:26:43.994665249 -0500
@@ -49,9 +49,9 @@ int recurse (volatile int n)
   int sum = 0;
   return *recurse_1 (n, &sum);
 }
+char mystack[2 * SIGSTKSZ];
 int main ()
 {
-  char mystack[SIGSTKSZ];
   stack_t altstack;
   struct sigaction action;
 #ifdef __BEOS__