[patch 2/5] Add the Kconfig option for the stackprotector feature

[Arjan van de Ven <arjan@linux.intel.com>]

Subject: [patch 2/5] Add the Kconfig option for the stackprotector feature
From: Arjan van de Ven <arjan@linux.intel.com>

This patch adds the config options for -fstack-protector.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
CC: Andi Kleen <ak@suse.de>

---
 arch/x86_64/Kconfig |   25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

Index: linux-2.6.18-rc2-git5-stackprot/arch/x86_64/Kconfig
===================================================================
--- linux-2.6.18-rc2-git5-stackprot.orig/arch/x86_64/Kconfig
+++ linux-2.6.18-rc2-git5-stackprot/arch/x86_64/Kconfig
@@ -522,6 +522,31 @@ config SECCOMP
 
 	  If unsure, say Y. Only embedded should say N here.
 
+config CC_STACKPROTECTOR
+	bool "Enable -fstack-protector buffer overflow detection (EXPRIMENTAL)"
+	depends on EXPERIMENTAL
+	default n
+	help
+	  This option turns on the -fstack-protector GCC feature that is new
+	  in GCC version 4.1. This feature puts, at the beginning of
+	  critical functions, a canary value on the stack just before the return
+	  address, and validates the value just before actually returning.
+	  Stack based buffer overflows that need to overwrite this return
+	  address now also overwrite the canary, which gets detected.
+
+	  NOTE 
+	  This feature requires gcc version 4.2 or above, or a distribution
+	  gcc with the feature backported. For older gcc versions, this is a NOP.
+
+config CC_STACKPROTECTOR_ALL
+	bool "Use stack-protector for all functions"
+	depends on CC_STACKPROTECTOR
+	default n
+	help
+	  Normally, GCC only inserts the canary value protection for
+	  functions that use large-ish on-stack buffers. By enabling
+	  this option, GCC will be asked to do this for ALL functions.
+
 source kernel/Kconfig.hz
 
 config REORDER