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x86: Fix oops in identify_cpu() on CPUs without CPUID

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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>
This commit is contained in:
Ondrej Zary 2009-08-11 20:00:11 +02:00 committed by Ingo Molnar
parent fbd8b1819e
commit e8055139d9
1 changed files with 24 additions and 24 deletions
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48
arch/x86/kernel/cpu/common.c
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@ -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;