1 files changed, 115 insertions, 20 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index e90540a46a0b..0dd0c2c6cae0 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -51,6 +51,7 @@
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 #include <asm/reboot.h>
+#include <asm/stackprotector.h>
 
 #include "xen-ops.h"
 #include "mmu.h"
@@ -215,6 +216,7 @@ static __init void xen_init_cpuid_mask(void)
 			  (1 << X86_FEATURE_ACPI));  /* disable ACPI */
 
 	ax = 1;
+	cx = 0;
 	xen_cpuid(&ax, &bx, &cx, &dx);
 
 	/* cpuid claims we support xsave; try enabling it to see what happens */
@@ -329,18 +331,28 @@ static void xen_load_gdt(const struct desc_ptr *dtr)
 	unsigned long frames[pages];
 	int f;
 
-	/* A GDT can be up to 64k in size, which corresponds to 8192
-	   8-byte entries, or 16 4k pages.. */
+	/*
+	 * A GDT can be up to 64k in size, which corresponds to 8192
+	 * 8-byte entries, or 16 4k pages..
+	 */
 
 	BUG_ON(size > 65536);
 	BUG_ON(va & ~PAGE_MASK);
 
 	for (f = 0; va < dtr->address + size; va += PAGE_SIZE, f++) {
 		int level;
-		pte_t *ptep = lookup_address(va, &level);
+		pte_t *ptep;
 		unsigned long pfn, mfn;
 		void *virt;
 
+		/*
+		 * The GDT is per-cpu and is in the percpu data area.
+		 * That can be virtually mapped, so we need to do a
+		 * page-walk to get the underlying MFN for the
+		 * hypercall.  The page can also be in the kernel's
+		 * linear range, so we need to RO that mapping too.
+		 */
+		ptep = lookup_address(va, &level);
 		BUG_ON(ptep == NULL);
 
 		pfn = pte_pfn(*ptep);
@@ -357,6 +369,44 @@ static void xen_load_gdt(const struct desc_ptr *dtr)
 		BUG();
 }
 
+/*
+ * load_gdt for early boot, when the gdt is only mapped once
+ */
+static __init void xen_load_gdt_boot(const struct desc_ptr *dtr)
+{
+	unsigned long va = dtr->address;
+	unsigned int size = dtr->size + 1;
+	unsigned pages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
+	unsigned long frames[pages];
+	int f;
+
+	/*
+	 * A GDT can be up to 64k in size, which corresponds to 8192
+	 * 8-byte entries, or 16 4k pages..
+	 */
+
+	BUG_ON(size > 65536);
+	BUG_ON(va & ~PAGE_MASK);
+
+	for (f = 0; va < dtr->address + size; va += PAGE_SIZE, f++) {
+		pte_t pte;
+		unsigned long pfn, mfn;
+
+		pfn = virt_to_pfn(va);
+		mfn = pfn_to_mfn(pfn);
+
+		pte = pfn_pte(pfn, PAGE_KERNEL_RO);
+
+		if (HYPERVISOR_update_va_mapping((unsigned long)va, pte, 0))
+			BUG();
+
+		frames[f] = mfn;
+	}
+
+	if (HYPERVISOR_set_gdt(frames, size / sizeof(struct desc_struct)))
+		BUG();
+}
+
 static void load_TLS_descriptor(struct thread_struct *t,
 				unsigned int cpu, unsigned int i)
 {
@@ -580,6 +630,29 @@ static void xen_write_gdt_entry(struct desc_struct *dt, int entry,
 	preempt_enable();
 }
 
+/*
+ * Version of write_gdt_entry for use at early boot-time needed to
+ * update an entry as simply as possible.
+ */
+static __init void xen_write_gdt_entry_boot(struct desc_struct *dt, int entry,
+					    const void *desc, int type)
+{
+	switch (type) {
+	case DESC_LDT:
+	case DESC_TSS:
+		/* ignore */
+		break;
+
+	default: {
+		xmaddr_t maddr = virt_to_machine(&dt[entry]);
+
+		if (HYPERVISOR_update_descriptor(maddr.maddr, *(u64 *)desc))
+			dt[entry] = *(struct desc_struct *)desc;
+	}
+
+	}
+}
+
 static void xen_load_sp0(struct tss_struct *tss,
 			 struct thread_struct *thread)
 {
@@ -713,7 +786,7 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
 	set:
 		base = ((u64)high << 32) | low;
 		if (HYPERVISOR_set_segment_base(which, base) != 0)
-			ret = -EFAULT;
+			ret = -EIO;
 		break;
 #endif
 
@@ -964,6 +1037,23 @@ static const struct machine_ops __initdata xen_machine_ops = {
 	.emergency_restart = xen_emergency_restart,
 };
 
+/*
+ * Set up the GDT and segment registers for -fstack-protector.  Until
+ * we do this, we have to be careful not to call any stack-protected
+ * function, which is most of the kernel.
+ */
+static void __init xen_setup_stackprotector(void)
+{
+	pv_cpu_ops.write_gdt_entry = xen_write_gdt_entry_boot;
+	pv_cpu_ops.load_gdt = xen_load_gdt_boot;
+
+	setup_stack_canary_segment(0);
+	switch_to_new_gdt(0);
+
+	pv_cpu_ops.write_gdt_entry = xen_write_gdt_entry;
+	pv_cpu_ops.load_gdt = xen_load_gdt;
+}
+
 /* First C function to be called on Xen boot */
 asmlinkage void __init xen_start_kernel(void)
 {
@@ -982,13 +1072,28 @@ asmlinkage void __init xen_start_kernel(void)
 	pv_apic_ops = xen_apic_ops;
 	pv_mmu_ops = xen_mmu_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.
+	 * Set up some pagetable state before starting to set any ptes.
 	 */
-	load_percpu_segment(0);
-#endif
+
+	/* Prevent unwanted bits from being set in PTEs. */
+	__supported_pte_mask &= ~_PAGE_GLOBAL;
+	if (!xen_initial_domain())
+		__supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
+
+	__supported_pte_mask |= _PAGE_IOMAP;
+
+	xen_setup_features();
+
+	/* Get mfn list */
+	if (!xen_feature(XENFEAT_auto_translated_physmap))
+		xen_build_dynamic_phys_to_machine();
+
+	/*
+	 * Set up kernel GDT and segment registers, mainly so that
+	 * -fstack-protector code can be executed.
+	 */
+	xen_setup_stackprotector();
 
 	xen_init_irq_ops();
 	xen_init_cpuid_mask();
@@ -1000,8 +1105,6 @@ 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;
@@ -1018,17 +1121,8 @@ asmlinkage void __init xen_start_kernel(void)
 
 	xen_smp_init();
 
-	/* Get mfn list */
-	if (!xen_feature(XENFEAT_auto_translated_physmap))
-		xen_build_dynamic_phys_to_machine();
-
 	pgd = (pgd_t *)xen_start_info->pt_base;
 
-	/* Prevent unwanted bits from being set in PTEs. */
-	__supported_pte_mask &= ~_PAGE_GLOBAL;
-	if (!xen_initial_domain())
-		__supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
-
 #ifdef CONFIG_X86_64
 	/* Work out if we support NX */
 	check_efer();
@@ -1059,6 +1153,7 @@ asmlinkage void __init xen_start_kernel(void)
 	/* set up basic CPUID stuff */
 	cpu_detect(&new_cpu_data);
 	new_cpu_data.hard_math = 1;
+	new_cpu_data.wp_works_ok = 1;
 	new_cpu_data.x86_capability[0] = cpuid_edx(1);
 #endif