From 577eebeae34d340685d8985dfdb7dfe337c511e8 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Thu, 27 Aug 2009 12:46:35 -0700 Subject: xen: make -fstack-protector work under Xen -fstack-protector uses a special per-cpu "stack canary" value. gcc generates special code in each function to test the canary to make sure that the function's stack hasn't been overrun. On x86-64, this is simply an offset of %gs, which is the usual per-cpu base segment register, so setting it up simply requires loading %gs's base as normal. On i386, the stack protector segment is %gs (rather than the usual kernel percpu %fs segment register). This requires setting up the full kernel GDT and then loading %gs accordingly. We also need to make sure %gs is initialized when bringing up secondary cpus too. To keep things consistent, we do the full GDT/segment register setup on both architectures. Because we need to avoid -fstack-protected code before setting up the GDT and because there's no way to disable it on a per-function basis, several files need to have stack-protector inhibited. [ Impact: allow Xen booting with stack-protector enabled ] Signed-off-by: Jeremy Fitzhardinge --- drivers/xen/Makefile | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/xen') diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index ec2a39b1e26f..7c284342f30f 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -1,6 +1,9 @@ obj-y += grant-table.o features.o events.o manage.o obj-y += xenbus/ +nostackp := $(call cc-option, -fno-stack-protector) +CFLAGS_features.o := $(nostackp) + obj-$(CONFIG_HOTPLUG_CPU) += cpu_hotplug.o obj-$(CONFIG_XEN_XENCOMM) += xencomm.o obj-$(CONFIG_XEN_BALLOON) += balloon.o -- cgit v1.2.2