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Subject[GIT PULL] Fix Xen boot with CONFIG_CC_STACKPROTECTOR
Hi Ingo,

Here's a couple of little changes which prevents an early boot crash
under Xen, due to the stackprotector preamble using segment registers
before they're set up. I only need to disable stackprotector for a
handful of functions, but unfortunately it looks like it can only be
disabled on a per-file basis.

Thanks,
J

The following changes since commit 64f1607ffbbc772685733ea63e6f7f4183df1b16:
Linus Torvalds (1):
Linux 2.6.31-rc6

are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git bugfix

Jeremy Fitzhardinge (2):
x86: make sure load_percpu_segment has no stackprotector
xen: rearrange things to fix stackprotector

arch/x86/kernel/cpu/Makefile | 4 ++++
arch/x86/xen/Makefile | 4 ++++
arch/x86/xen/enlighten.c | 22 ++++++++++------------
3 files changed, 18 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 4e242f9..8b5b9b6 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -7,6 +7,10 @@ ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_common.o = -pg
endif

+# Make sure load_percpu_segment has no stackprotector
+nostackp := $(call cc-option, -fno-stack-protector)
+CFLAGS_common.o := $(nostackp)
+
obj-y := intel_cacheinfo.o addon_cpuid_features.o
obj-y += proc.o capflags.o powerflags.o common.o
obj-y += vmware.o hypervisor.o
diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
index 3b767d0..a5b9288 100644
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -5,6 +5,10 @@ CFLAGS_REMOVE_time.o = -pg
CFLAGS_REMOVE_irq.o = -pg
endif

+# Make sure early boot has no stackprotector
+nostackp := $(call cc-option, -fno-stack-protector)
+CFLAGS_enlighten.o := $(nostackp)
+
obj-y := enlighten.o setup.o multicalls.o mmu.o irq.o \
time.o xen-asm.o xen-asm_$(BITS).o \
grant-table.o suspend.o
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index f09e8c3..edcf72a 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -925,10 +925,6 @@ asmlinkage void __init xen_start_kernel(void)

xen_domain_type = XEN_PV_DOMAIN;

- BUG_ON(memcmp(xen_start_info->magic, "xen-3", 5) != 0);
-
- xen_setup_features();
-
/* Install Xen paravirt ops */
pv_info = xen_info;
pv_init_ops = xen_init_ops;
@@ -937,8 +933,15 @@ asmlinkage void __init xen_start_kernel(void)
pv_apic_ops = xen_apic_ops;
pv_mmu_ops = xen_mmu_ops;

- xen_init_irq_ops();
+#ifdef CONFIG_X86_64
+ /*
+ * Setup percpu state. We only need to do this for 64-bit
+ * because 32-bit already has %fs set properly.
+ */
+ load_percpu_segment(0);
+#endif

+ xen_init_irq_ops();
xen_init_cpuid_mask();

#ifdef CONFIG_X86_LOCAL_APIC
@@ -948,6 +951,8 @@ asmlinkage void __init xen_start_kernel(void)
set_xen_basic_apic_ops();
#endif

+ xen_setup_features();
+
if (xen_feature(XENFEAT_mmu_pt_update_preserve_ad)) {
pv_mmu_ops.ptep_modify_prot_start = xen_ptep_modify_prot_start;
pv_mmu_ops.ptep_modify_prot_commit = xen_ptep_modify_prot_commit;
@@ -955,13 +960,6 @@ asmlinkage void __init xen_start_kernel(void)

machine_ops = xen_machine_ops;

-#ifdef CONFIG_X86_64
- /*
- * Setup percpu state. We only need to do this for 64-bit
- * because 32-bit already has %fs set properly.
- */
- load_percpu_segment(0);
-#endif
/*
* The only reliable way to retain the initial address of the
* percpu gdt_page is to remember it here, so we can go and



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