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[PATCH] i386: cleanup GDT Access

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Now we have an explicit per-cpu GDT variable, we don't need to keep the
descriptors around to use them to find the GDT: expose cpu_gdt directly.

We could go further and make load_gdt() pack the descriptor for us, or even
assume it means "load the current cpu's GDT" which is what it always does.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Rusty Russell
2007-05-02 19:27:11 +02:00
committed by Andi Kleen
parent 141f9cfe0a
commit 4fbb596881
6 changed files with 19 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
arch/i386/kernel/cpu/common.c
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@@ -22,9 +22,6 @@
#include "cpu.h" #include "cpu.h"
DEFINE_PER_CPU(struct Xgt_desc_struct, cpu_gdt_descr);
EXPORT_PER_CPU_SYMBOL(cpu_gdt_descr);
DEFINE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]) = { DEFINE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]) = {
[GDT_ENTRY_KERNEL_CS] = { 0x0000ffff, 0x00cf9a00 }, [GDT_ENTRY_KERNEL_CS] = { 0x0000ffff, 0x00cf9a00 },
[GDT_ENTRY_KERNEL_DS] = { 0x0000ffff, 0x00cf9200 }, [GDT_ENTRY_KERNEL_DS] = { 0x0000ffff, 0x00cf9200 },
@@ -52,6 +49,7 @@ DEFINE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]) = {
[GDT_ENTRY_ESPFIX_SS] = { 0x00000000, 0x00c09200 }, [GDT_ENTRY_ESPFIX_SS] = { 0x00000000, 0x00c09200 },
[GDT_ENTRY_PDA] = { 0x00000000, 0x00c09200 }, /* set in setup_pda */ [GDT_ENTRY_PDA] = { 0x00000000, 0x00c09200 }, /* set in setup_pda */
}; };
EXPORT_PER_CPU_SYMBOL_GPL(cpu_gdt);
DEFINE_PER_CPU(struct i386_pda, _cpu_pda); DEFINE_PER_CPU(struct i386_pda, _cpu_pda);
EXPORT_PER_CPU_SYMBOL(_cpu_pda); EXPORT_PER_CPU_SYMBOL(_cpu_pda);

16
arch/i386/kernel/efi.c
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@@ -69,13 +69,11 @@ static void efi_call_phys_prelog(void) __acquires(efi_rt_lock)
{ {
unsigned long cr4; unsigned long cr4;
unsigned long temp; unsigned long temp;
struct Xgt_desc_struct *cpu_gdt_descr; struct Xgt_desc_struct gdt_descr;
spin_lock(&efi_rt_lock); spin_lock(&efi_rt_lock);
local_irq_save(efi_rt_eflags); local_irq_save(efi_rt_eflags);
cpu_gdt_descr = &per_cpu(cpu_gdt_descr, 0);
/* /*
* If I don't have PSE, I should just duplicate two entries in page * If I don't have PSE, I should just duplicate two entries in page
* directory. If I have PSE, I just need to duplicate one entry in * directory. If I have PSE, I just need to duplicate one entry in
@@ -105,17 +103,19 @@ static void efi_call_phys_prelog(void) __acquires(efi_rt_lock)
*/ */
local_flush_tlb(); local_flush_tlb();
cpu_gdt_descr->address = __pa(cpu_gdt_descr->address); gdt_descr.address = __pa(get_cpu_gdt_table(0));
load_gdt(cpu_gdt_descr); gdt_descr.size = GDT_SIZE - 1;
load_gdt(&gdt_descr);
} }
static void efi_call_phys_epilog(void) __releases(efi_rt_lock) static void efi_call_phys_epilog(void) __releases(efi_rt_lock)
{ {
unsigned long cr4; unsigned long cr4;
struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, 0); struct Xgt_desc_struct gdt_descr;
cpu_gdt_descr->address = (unsigned long)__va(cpu_gdt_descr->address); gdt_descr.address = (unsigned long)get_cpu_gdt_table(0);
load_gdt(cpu_gdt_descr); gdt_descr.size = GDT_SIZE - 1;
load_gdt(&gdt_descr);
cr4 = read_cr4(); cr4 = read_cr4();

3
arch/i386/kernel/entry.S
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@@ -561,8 +561,7 @@ END(syscall_badsys)
#define FIXUP_ESPFIX_STACK \ #define FIXUP_ESPFIX_STACK \
/* since we are on a wrong stack, we cant make it a C code :( */ \ /* since we are on a wrong stack, we cant make it a C code :( */ \
movl %fs:PDA_cpu, %ebx; \ movl %fs:PDA_cpu, %ebx; \
PER_CPU(cpu_gdt_descr, %ebx); \ PER_CPU(cpu_gdt, %ebx); \
movl GDS_address(%ebx), %ebx; \
GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah); \ GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah); \
addl %esp, %eax; \ addl %esp, %eax; \
pushl $__KERNEL_DS; \ pushl $__KERNEL_DS; \

12
arch/i386/kernel/smpboot.c
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@@ -786,13 +786,9 @@ static inline struct task_struct * alloc_idle_task(int cpu)
secondary which will soon come up. */ secondary which will soon come up. */
static __cpuinit void init_gdt(int cpu, struct task_struct *idle) static __cpuinit void init_gdt(int cpu, struct task_struct *idle)
{ {
struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu); struct desc_struct *gdt = get_cpu_gdt_table(cpu);
struct desc_struct *gdt = per_cpu(cpu_gdt, cpu);
struct i386_pda *pda = &per_cpu(_cpu_pda, cpu); struct i386_pda *pda = &per_cpu(_cpu_pda, cpu);
cpu_gdt_descr->address = (unsigned long)gdt;
cpu_gdt_descr->size = GDT_SIZE - 1;
pack_descriptor((u32 *)&gdt[GDT_ENTRY_PDA].a, pack_descriptor((u32 *)&gdt[GDT_ENTRY_PDA].a,
(u32 *)&gdt[GDT_ENTRY_PDA].b, (u32 *)&gdt[GDT_ENTRY_PDA].b,
(unsigned long)pda, sizeof(*pda) - 1, (unsigned long)pda, sizeof(*pda) - 1,
@@ -1187,7 +1183,11 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
* it's on the real one. */ * it's on the real one. */
static inline void switch_to_new_gdt(void) static inline void switch_to_new_gdt(void)
{ {
load_gdt(&per_cpu(cpu_gdt_descr, smp_processor_id())); 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 volatile ("mov %0, %%fs" : : "r" (__KERNEL_PDA) : "memory"); asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_PDA) : "memory");
} }

4
arch/i386/kernel/traps.c
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@@ -1030,9 +1030,7 @@ fastcall void do_spurious_interrupt_bug(struct pt_regs * regs,
fastcall unsigned long patch_espfix_desc(unsigned long uesp, fastcall unsigned long patch_espfix_desc(unsigned long uesp,
unsigned long kesp) unsigned long kesp)
{ {
int cpu = smp_processor_id(); struct desc_struct *gdt = __get_cpu_var(cpu_gdt);
struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
struct desc_struct *gdt = (struct desc_struct *)cpu_gdt_descr->address;
unsigned long base = (kesp - uesp) & -THREAD_SIZE; unsigned long base = (kesp - uesp) & -THREAD_SIZE;
unsigned long new_kesp = kesp - base; unsigned long new_kesp = kesp - base;
unsigned long lim_pages = (new_kesp | (THREAD_SIZE - 1)) >> PAGE_SHIFT; unsigned long lim_pages = (new_kesp | (THREAD_SIZE - 1)) >> PAGE_SHIFT;

7
include/asm-i386/desc.h
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@@ -18,16 +18,13 @@ struct Xgt_desc_struct {
unsigned short pad; unsigned short pad;
} __attribute__ ((packed)); } __attribute__ ((packed));
extern struct Xgt_desc_struct idt_descr;
DECLARE_PER_CPU(struct Xgt_desc_struct, cpu_gdt_descr);
DECLARE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]); DECLARE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]);
extern struct Xgt_desc_struct early_gdt_descr;
static inline struct desc_struct *get_cpu_gdt_table(unsigned int cpu) static inline struct desc_struct *get_cpu_gdt_table(unsigned int cpu)
{ {
return (struct desc_struct *)per_cpu(cpu_gdt_descr, cpu).address; return per_cpu(cpu_gdt, cpu);
} }
extern struct Xgt_desc_struct idt_descr;
extern struct desc_struct idt_table[]; extern struct desc_struct idt_table[];
extern void set_intr_gate(unsigned int irq, void * addr); extern void set_intr_gate(unsigned int irq, void * addr);