Stack checking extensions

This patch adds:

 - Normal builds are done with -fstack-protector (we want to investigate
using -fstack-protector-strong on gcc4.9 but for now we just use that

 - Build with STACK_CHECK=1 will use -fstack-protector-all and -pg and
will check the stack in mcount

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/asm/misc.S b/asm/misc.S
index ccb30d14..00c7f78e 100644
--- a/asm/misc.S
+++ b/asm/misc.S
@@ -17,6 +17,7 @@
 #include <asm-utils.h>
 #include <asm-offsets.h>
 #include <processor.h>
+#include <stack.h>
 
 	.section ".text","ax"
 	.balign	0x10
@@ -41,3 +42,11 @@ trigger_attn:
 	isync
 	attn
 	blr
+
+#ifdef STACK_CHECK_ENABLED
+.global _mcount
+_mcount:
+	mr	%r3,%r1
+	mflr	%r4
+	b	__mcount_stack_check
+#endif