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authorTejun Heo <tj@kernel.org>2009-02-09 22:17:40 +0900
committerIngo Molnar <mingo@elte.hu>2009-02-10 00:42:01 +0100
commit60a5317ff0f42dd313094b88f809f63041568b08 (patch)
tree307dfd9715fbc9ff83c3c3ae3b0e8f03888083f2 /scripts/gcc-x86_32-has-stack-protector.sh
parentccbeed3a05908d201b47b6c3dd1a373138bba566 (diff)
downloadlinux-linaro-stable-60a5317ff0f42dd313094b88f809f63041568b08.tar.gz
x86: implement x86_32 stack protector
Impact: stack protector for x86_32 Implement stack protector for x86_32. GDT entry 28 is used for it. It's set to point to stack_canary-20 and have the length of 24 bytes. CONFIG_CC_STACKPROTECTOR turns off CONFIG_X86_32_LAZY_GS and sets %gs to the stack canary segment on entry. As %gs is otherwise unused by the kernel, the canary can be anywhere. It's defined as a percpu variable. x86_32 exception handlers take register frame on stack directly as struct pt_regs. With -fstack-protector turned on, gcc copies the whole structure after the stack canary and (of course) doesn't copy back on return thus losing all changed. For now, -fno-stack-protector is added to all files which contain those functions. We definitely need something better. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'scripts/gcc-x86_32-has-stack-protector.sh')
-rw-r--r--scripts/gcc-x86_32-has-stack-protector.sh8
1 files changed, 8 insertions, 0 deletions
diff --git a/scripts/gcc-x86_32-has-stack-protector.sh b/scripts/gcc-x86_32-has-stack-protector.sh
new file mode 100644
index 000000000000..4fdf6ce1b062
--- /dev/null
+++ b/scripts/gcc-x86_32-has-stack-protector.sh
@@ -0,0 +1,8 @@
+#!/bin/sh
+
+echo "int foo(void) { char X[200]; return 3; }" | $1 -S -xc -c -O0 -fstack-protector - -o - 2> /dev/null | grep -q "%gs"
+if [ "$?" -eq "0" ] ; then
+ echo y
+else
+ echo n
+fi