xen: rearrange things to fix stackprotector

Make sure the stack-protector segment registers are properly set up
before calling any functions which may have stack-protection compiled
into them.

[ Impact: prevent Xen early-boot crash when stack-protector is enabled ]
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
index 3b767d0..a5b9288 100644 (file)
--- 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 (file)
--- 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