From e8055139d996e85722984968472868d6dccb1490 Mon Sep 17 00:00:00 2001
From: Ondrej Zary <linux@rainbow-software.org>
Date: Tue, 11 Aug 2009 20:00:11 +0200
Subject: [PATCH] x86: Fix oops in identify_cpu() on CPUs without CPUID
Kernel is broken for x86 CPUs without CPUID since 2.6.28. It
crashes with NULL pointer dereference in identify_cpu():
766 generic_identify(c);
767
768--> if (this_cpu->c_identify)
769 this_cpu->c_identify(c);
this_cpu is NULL. This is because it's only initialized in
get_cpu_vendor() function, which is not called if the CPU has
no CPUID instruction.
Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
LKML-Reference: <200908112000.15993.linux@rainbow-software.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/cpu/common.c | 48 ++++++++++++++++++------------------
1 file changed, 24 insertions(+), 24 deletions(-)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index f1961c07af9a6..5ce60a88027b1 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -59,7 +59,30 @@ void __init setup_cpu_local_masks(void)
alloc_bootmem_cpumask_var(&cpu_sibling_setup_mask);
}
-static const struct cpu_dev *this_cpu __cpuinitdata;
+static void __cpuinit default_init(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_X86_64
+ display_cacheinfo(c);
+#else
+ /* Not much we can do here... */
+ /* Check if at least it has cpuid */
+ if (c->cpuid_level == -1) {
+ /* No cpuid. It must be an ancient CPU */
+ if (c->x86 == 4)
+ strcpy(c->x86_model_id, "486");
+ else if (c->x86 == 3)
+ strcpy(c->x86_model_id, "386");
+ }
+#endif
+}
+
+static const struct cpu_dev __cpuinitconst default_cpu = {
+ .c_init = default_init,
+ .c_vendor = "Unknown",
+ .c_x86_vendor = X86_VENDOR_UNKNOWN,
+};
+
+static const struct cpu_dev *this_cpu __cpuinitdata = &default_cpu;
DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = {
#ifdef CONFIG_X86_64
@@ -332,29 +355,6 @@ void switch_to_new_gdt(int cpu)
static const struct cpu_dev *__cpuinitdata cpu_devs[X86_VENDOR_NUM] = {};
-static void __cpuinit default_init(struct cpuinfo_x86 *c)
-{
-#ifdef CONFIG_X86_64
- display_cacheinfo(c);
-#else
- /* Not much we can do here... */
- /* Check if at least it has cpuid */
- if (c->cpuid_level == -1) {
- /* No cpuid. It must be an ancient CPU */
- if (c->x86 == 4)
- strcpy(c->x86_model_id, "486");
- else if (c->x86 == 3)
- strcpy(c->x86_model_id, "386");
- }
-#endif
-}
-
-static const struct cpu_dev __cpuinitconst default_cpu = {
- .c_init = default_init,
- .c_vendor = "Unknown",
- .c_x86_vendor = X86_VENDOR_UNKNOWN,
-};
-
static void __cpuinit get_model_name(struct cpuinfo_x86 *c)
{
unsigned int *v;
--
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