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// SPDX-License-Identifier: GPL-2.0
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/init_task.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/desc.h>
#ifdef CONFIG_X86_32
#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 + MAXMEM)
static void doublefault_fn(void)
{
struct desc_ptr gdt_desc = {0, 0};
unsigned long gdt, tss;
native_store_gdt(&gdt_desc);
gdt = gdt_desc.address;
printk(KERN_EMERG "PANIC: double fault, gdt at %08lx [%d bytes]\n", gdt, gdt_desc.size);
if (ptr_ok(gdt)) {
gdt += GDT_ENTRY_TSS << 3;
tss = get_desc_base((struct desc_struct *)gdt);
printk(KERN_EMERG "double fault, tss at %08lx\n", tss);
if (ptr_ok(tss)) {
struct x86_hw_tss *t = (struct x86_hw_tss *)tss;
printk(KERN_EMERG "eip = %08lx, esp = %08lx\n",
t->ip, t->sp);
printk(KERN_EMERG "eax = %08lx, ebx = %08lx, ecx = %08lx, edx = %08lx\n",
t->ax, t->bx, t->cx, t->dx);
printk(KERN_EMERG "esi = %08lx, edi = %08lx\n",
t->si, t->di);
}
}
for (;;)
cpu_relax();
}
struct tss_struct doublefault_tss __cacheline_aligned = {
.x86_tss = {
.sp0 = STACK_START,
.ss0 = __KERNEL_DS,
.ldt = 0,
.io_bitmap_base = INVALID_IO_BITMAP_OFFSET,
.ip = (unsigned long) doublefault_fn,
/* 0x2 bit is always set */
.flags = X86_EFLAGS_SF | 0x2,
.sp = STACK_START,
.es = __USER_DS,
.cs = __KERNEL_CS,
.ss = __KERNEL_DS,
.ds = __USER_DS,
.fs = __KERNEL_PERCPU,
.__cr3 = __pa_nodebug(swapper_pg_dir),
}
};
/* dummy for do_double_fault() call */
void df_debug(struct pt_regs *regs, long error_code) {}
#else /* !CONFIG_X86_32 */
void df_debug(struct pt_regs *regs, long error_code)
{
pr_emerg("PANIC: double fault, error_code: 0x%lx\n", error_code);
show_regs(regs);
panic("Machine halted.");
}
#endif
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