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[PATCH] i386: Fix UP gdt bugs

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Fixes two problems with the GDT when compiling for uniprocessor:
 - There's no percpu segment, so trying to load its selector into %fs fails.
   Use a null selector instead.
 - The real gdt needs to be loaded at some point.  Do it in cpu_init().

Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Jeremy Fitzhardinge 2007-05-02 19:27:16 +02:00 committed by Andi Kleen
parent 1956c73bb5
commit c5413fbe89
4 changed files with 18 additions and 12 deletions
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13
arch/i386/kernel/cpu/common.c
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@ -638,6 +638,18 @@ struct pt_regs * __devinit idle_regs(struct pt_regs *regs)
return regs;
}
/* Current gdt points %fs at the "master" per-cpu area: after this,
* it's on the real one. */
void switch_to_new_gdt(void)
{
struct Xgt_desc_struct gdt_descr;
gdt_descr.address = (long)get_cpu_gdt_table(smp_processor_id());
gdt_descr.size = GDT_SIZE - 1;
load_gdt(&gdt_descr);
asm("mov %0, %%fs" : : "r" (__KERNEL_PERCPU) : "memory");
}
/*
* cpu_init() initializes state that is per-CPU. Some data is already
* initialized (naturally) in the bootstrap process, such as the GDT
@ -668,6 +680,7 @@ void __cpuinit cpu_init(void)
}
load_idt(&idt_descr);
switch_to_new_gdt();
/*
* Set up and load the per-CPU TSS and LDT

12
arch/i386/kernel/smpboot.c
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@ -1177,18 +1177,6 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
smp_boot_cpus(max_cpus);
}
/* Current gdt points %fs at the "master" per-cpu area: after this,
* it's on the real one. */
static inline void switch_to_new_gdt(void)
{
struct Xgt_desc_struct gdt_descr;
gdt_descr.address = (long)get_cpu_gdt_table(smp_processor_id());
gdt_descr.size = GDT_SIZE - 1;
load_gdt(&gdt_descr);
asm("mov %0, %%fs" : : "r" (__KERNEL_PERCPU) : "memory");
}
void __init native_smp_prepare_boot_cpu(void)
{
unsigned int cpu = smp_processor_id();

1
include/asm-i386/processor.h
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@ -750,6 +750,7 @@ extern void enable_sep_cpu(void);
extern int sysenter_setup(void);
extern void cpu_set_gdt(int);
extern void switch_to_new_gdt(void);
extern void cpu_init(void);
extern int force_mwait;

4
include/asm-i386/segment.h
View File

@ -75,7 +75,11 @@
#define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS * 8)
#define GDT_ENTRY_PERCPU (GDT_ENTRY_KERNEL_BASE + 15)
#ifdef CONFIG_SMP
#define __KERNEL_PERCPU (GDT_ENTRY_PERCPU * 8)
#else
#define __KERNEL_PERCPU 0
#endif
#define GDT_ENTRY_DOUBLEFAULT_TSS 31