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 --- arch/x86/mm/Makefile | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/x86/mm/Makefile') diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile index eefdeee8a871..72bb3a26c738 100644 --- a/arch/x86/mm/Makefile +++ b/arch/x86/mm/Makefile @@ -1,6 +1,10 @@ obj-y := init.o init_$(BITS).o fault.o ioremap.o extable.o pageattr.o mmap.o \ pat.o pgtable.o gup.o +# Make sure __phys_addr has no stackprotector +nostackp := $(call cc-option, -fno-stack-protector) +CFLAGS_ioremap.o := $(nostackp) + obj-$(CONFIG_SMP) += tlb.o obj-$(CONFIG_X86_32) += pgtable_32.o iomap_32.o -- cgit v1.2.3