linux/arch/i386/kernel/doublefault.c
Zachary Amsden 4d37e7e3fd [PATCH] i386: inline assembler: cleanup and encapsulate descriptor and task register management
i386 inline assembler cleanup.

This change encapsulates descriptor and task register management.  Also,
it is possible to improve assembler generation in two cases; savesegment
may store the value in a register instead of a memory location, which
allows GCC to optimize stack variables into registers, and MOV MEM, SEG
is always a 16-bit write to memory, making the casting in math-emu
unnecessary.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-05 00:06:11 -07:00

65 lines
1.6 KiB
C

#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/init_task.h>
#include <linux/fs.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/desc.h>
#define DOUBLEFAULT_STACKSIZE (1024)
static unsigned long doublefault_stack[DOUBLEFAULT_STACKSIZE];
#define STACK_START (unsigned long)(doublefault_stack+DOUBLEFAULT_STACKSIZE)
#define ptr_ok(x) ((x) > PAGE_OFFSET && (x) < PAGE_OFFSET + 0x1000000)
static void doublefault_fn(void)
{
struct Xgt_desc_struct gdt_desc = {0, 0};
unsigned long gdt, tss;
store_gdt(&gdt_desc);
gdt = gdt_desc.address;
printk("double fault, gdt at %08lx [%d bytes]\n", gdt, gdt_desc.size);
if (ptr_ok(gdt)) {
gdt += GDT_ENTRY_TSS << 3;
tss = *(u16 *)(gdt+2);
tss += *(u8 *)(gdt+4) << 16;
tss += *(u8 *)(gdt+7) << 24;
printk("double fault, tss at %08lx\n", tss);
if (ptr_ok(tss)) {
struct tss_struct *t = (struct tss_struct *)tss;
printk("eip = %08lx, esp = %08lx\n", t->eip, t->esp);
printk("eax = %08lx, ebx = %08lx, ecx = %08lx, edx = %08lx\n",
t->eax, t->ebx, t->ecx, t->edx);
printk("esi = %08lx, edi = %08lx\n",
t->esi, t->edi);
}
}
for (;;) /* nothing */;
}
struct tss_struct doublefault_tss __cacheline_aligned = {
.esp0 = STACK_START,
.ss0 = __KERNEL_DS,
.ldt = 0,
.io_bitmap_base = INVALID_IO_BITMAP_OFFSET,
.eip = (unsigned long) doublefault_fn,
.eflags = X86_EFLAGS_SF | 0x2, /* 0x2 bit is always set */
.esp = STACK_START,
.es = __USER_DS,
.cs = __KERNEL_CS,
.ss = __KERNEL_DS,
.ds = __USER_DS,
.__cr3 = __pa(swapper_pg_dir)
};