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Commit 4fbb5968 authored by Rusty Russell's avatar Rusty Russell Committed by Andi Kleen
Browse files

[PATCH] i386: cleanup GDT Access 



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: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 141f9cfe

arch/i386/kernel/cpu/common.c

+1 −3
Original line number Diff line number Diff line
@@ -22,9 +22,6 @@ 


#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]) = {

	[GDT_ENTRY_KERNEL_CS] = { 0x0000ffff, 0x00cf9a00 },

	[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_PDA] = { 0x00000000, 0x00c09200 }, /* set in setup_pda */

};

EXPORT_PER_CPU_SYMBOL_GPL(cpu_gdt);



DEFINE_PER_CPU(struct i386_pda, _cpu_pda);

EXPORT_PER_CPU_SYMBOL(_cpu_pda);

arch/i386/kernel/efi.c

+8 −8
Original line number Diff line number Diff line
@@ -69,13 +69,11 @@ static void efi_call_phys_prelog(void) __acquires(efi_rt_lock) 
{

	unsigned long cr4;

	unsigned long temp;

	struct Xgt_desc_struct *cpu_gdt_descr;

	struct Xgt_desc_struct gdt_descr;



	spin_lock(&efi_rt_lock);

	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

	 * 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();



	cpu_gdt_descr->address = __pa(cpu_gdt_descr->address);

	load_gdt(cpu_gdt_descr);

	gdt_descr.address = __pa(get_cpu_gdt_table(0));

	gdt_descr.size = GDT_SIZE - 1;

	load_gdt(&gdt_descr);

}



static void efi_call_phys_epilog(void) __releases(efi_rt_lock)

{

	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);

	load_gdt(cpu_gdt_descr);

	gdt_descr.address = (unsigned long)get_cpu_gdt_table(0);

	gdt_descr.size = GDT_SIZE - 1;

	load_gdt(&gdt_descr);



	cr4 = read_cr4();

arch/i386/kernel/entry.S

+1 −2
Original line number Diff line number Diff line
@@ -561,8 +561,7 @@ END(syscall_badsys) 
#define FIXUP_ESPFIX_STACK \

	/* since we are on a wrong stack, we cant make it a C code :( */ \

	movl %fs:PDA_cpu, %ebx; \

	PER_CPU(cpu_gdt_descr, %ebx); \

	movl GDS_address(%ebx), %ebx; \

	PER_CPU(cpu_gdt, %ebx); \

	GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah); \

	addl %esp, %eax; \

	pushl $__KERNEL_DS; \

arch/i386/kernel/smpboot.c

+6 −6
Original line number Diff line number Diff line
@@ -786,13 +786,9 @@ static inline struct task_struct * alloc_idle_task(int cpu) 
   secondary which will soon come up. */

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 = per_cpu(cpu_gdt, cpu);

	struct desc_struct *gdt = get_cpu_gdt_table(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,

			(u32 *)&gdt[GDT_ENTRY_PDA].b,

			(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. */

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");

}

arch/i386/kernel/traps.c

+1 −3
Original line number Diff line number Diff line
@@ -1030,9 +1030,7 @@ fastcall void do_spurious_interrupt_bug(struct pt_regs * regs, 
fastcall unsigned long patch_espfix_desc(unsigned long uesp,

					  unsigned long kesp)

{

	int cpu = smp_processor_id();

	struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);

	struct desc_struct *gdt = (struct desc_struct *)cpu_gdt_descr->address;

	struct desc_struct *gdt = __get_cpu_var(cpu_gdt);

	unsigned long base = (kesp - uesp) & -THREAD_SIZE;

	unsigned long new_kesp = kesp - base;

	unsigned long lim_pages = (new_kesp | (THREAD_SIZE - 1)) >> PAGE_SHIFT;