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espfix code cleanup

PATCH New Stas Sergeev 1 participant 1 message Jul 30, 2006

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Stas Sergeev

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PATCH 1/1 espfix code cleanup

Hi.

The current espfix code used to make problem for some people by its uglyness and the stack switching. The attached patch removes about 2/3 of the mess by utilizing the 32bit stack instead of the 16bit one. I simply patch the base address at gdt so that the kernel esp have the same high word as the user esp.

In case there are no objections - Andrew, could you please apply?

-----
Clean up the espfix code by utilizing the 32bit stack instead of the 16bit one.

Signed-off-by Stas Sergeev <[email protected]>
include/asm-i386/desc.h +0 -4
@@ -4,8 +4,6 @@
 #include <asm/ldt.h>
 #include <asm/segment.h>
 
-#define CPU_16BIT_STACK_SIZE 1024
-
 #ifndef __ASSEMBLY__
 
 #include <linux/preempt.h>

@@ -16,8 +14,6 @@
 
 extern struct desc_struct cpu_gdt_table[GDT_ENTRIES];
 
-DECLARE_PER_CPU(unsigned char, cpu_16bit_stack[CPU_16BIT_STACK_SIZE]);
-
 struct Xgt_desc_struct {
 	unsigned short size;
 	unsigned long address __attribute__((packed));
arch/i386/kernel/head.S +1 -1
@@ -590,7 +590,7 @@
 	.quad 0x00009a000000ffff	/* 0xc0 APM CS 16 code (16 bit) */
 	.quad 0x004092000000ffff	/* 0xc8 APM DS    data */
 
-	.quad 0x0000920000000000	/* 0xd0 - ESPFIX 16-bit SS */
+	.quad 0x00cf92000000ffff	/* 0xd0 - ESPFIX SS */
 	.quad 0x0000000000000000	/* 0xd8 - unused */
 	.quad 0x0000000000000000	/* 0xe0 - unused */
 	.quad 0x0000000000000000	/* 0xe8 - unused */
arch/i386/kernel/traps.c +22 -41

71 lines not on this page · raw message

arch/i386/kernel/entry.S +24 -38

135 lines not on this page · raw message

arch/i386/kernel/cpu/common.c +0 -11
@@ -24,9 +24,6 @@
 DEFINE_PER_CPU(struct Xgt_desc_struct, cpu_gdt_descr);
 EXPORT_PER_CPU_SYMBOL(cpu_gdt_descr);
 
-DEFINE_PER_CPU(unsigned char, cpu_16bit_stack[CPU_16BIT_STACK_SIZE]);
-EXPORT_PER_CPU_SYMBOL(cpu_16bit_stack);
-
 static int cachesize_override __cpuinitdata = -1;
 static int disable_x86_fxsr __cpuinitdata;
 static int disable_x86_serial_nr __cpuinitdata = 1;

@@ -594,7 +591,6 @@
 	struct tss_struct * t = &per_cpu(init_tss, cpu);
 	struct thread_struct *thread = &current->thread;
 	struct desc_struct *gdt;
-	__u32 stk16_off = (__u32)&per_cpu(cpu_16bit_stack, cpu);
 	struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
 
 	if (cpu_test_and_set(cpu, cpu_initialized)) {

@@ -642,13 +638,6 @@
 	 * and set up the GDT descriptor:
 	 */
  	memcpy(gdt, cpu_gdt_table, GDT_SIZE);
-
-	/* Set up GDT entry for 16bit stack */
- 	*(__u64 *)(&gdt[GDT_ENTRY_ESPFIX_SS]) |=
-		((((__u64)stk16_off) << 16) & 0x000000ffffff0000ULL) |
-		((((__u64)stk16_off) << 32) & 0xff00000000000000ULL) |
-		(CPU_16BIT_STACK_SIZE - 1);
-
 	cpu_gdt_descr->size = GDT_SIZE - 1;
  	cpu_gdt_descr->address = (unsigned long)gdt;