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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>
#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;
BUILD_BUG_ON(sizeof(struct doublefault_stack) != PAGE_SIZE);
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();
}
DEFINE_PER_CPU_PAGE_ALIGNED(struct doublefault_stack, doublefault_stack) = {
.tss = {
/*
* No sp0 or ss0 -- we never run CPL != 0 with this TSS
* active. sp is filled in later.
*/
.ldt = 0,
.io_bitmap_base = IO_BITMAP_OFFSET_INVALID,
.ip = (unsigned long) doublefault_fn,
/* 0x2 bit is always set */
.flags = X86_EFLAGS_SF | 0x2,
.es = __USER_DS,
.cs = __KERNEL_CS,
.ss = __KERNEL_DS,
.ds = __USER_DS,
.fs = __KERNEL_PERCPU,
#ifndef CONFIG_X86_32_LAZY_GS
.gs = __KERNEL_STACK_CANARY,
#endif
.__cr3 = __pa_nodebug(swapper_pg_dir),
},
};
void doublefault_init_cpu_tss(void)
{
unsigned int cpu = smp_processor_id();
struct cpu_entry_area *cea = get_cpu_entry_area(cpu);
/*
* The linker isn't smart enough to initialize percpu variables that
* point to other places in percpu space.
*/
this_cpu_write(doublefault_stack.tss.sp,
(unsigned long)&cea->doublefault_stack.stack +
sizeof(doublefault_stack.stack));
/* Set up doublefault TSS pointer in the GDT */
__set_tss_desc(cpu, GDT_ENTRY_DOUBLEFAULT_TSS,
&get_cpu_entry_area(cpu)->doublefault_stack.tss);
}
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