1 files changed, 70 insertions, 0 deletions
diff --git a/arch/i386/kernel/doublefault_32.c b/arch/i386/kernel/doublefault_32.c
new file mode 100644
index 0000000..40978af
--- /dev/null
+++ b/arch/i386/kernel/doublefault_32.c
@@ -0,0 +1,70 @@
+#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 + MAXMEM)
+
+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(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 = *(u16 *)(gdt+2);
+		tss += *(u8 *)(gdt+4) << 16;
+		tss += *(u8 *)(gdt+7) << 24;
+		printk(KERN_EMERG "double fault, tss at %08lx\n", tss);
+
+		if (ptr_ok(tss)) {
+			struct i386_hw_tss *t = (struct i386_hw_tss *)tss;
+
+			printk(KERN_EMERG "eip = %08lx, esp = %08lx\n", t->eip, t->esp);
+
+			printk(KERN_EMERG "eax = %08lx, ebx = %08lx, ecx = %08lx, edx = %08lx\n",
+				t->eax, t->ebx, t->ecx, t->edx);
+			printk(KERN_EMERG "esi = %08lx, edi = %08lx\n",
+				t->esi, t->edi);
+		}
+	}
+
+	for (;;)
+		cpu_relax();
+}
+
+struct tss_struct doublefault_tss __cacheline_aligned = {
+	.x86_tss = {
+		.esp0		= STACK_START,
+		.ss0		= __KERNEL_DS,
+		.ldt		= 0,
+		.io_bitmap_base	= INVALID_IO_BITMAP_OFFSET,
+
+		.eip		= (unsigned long) doublefault_fn,
+		/* 0x2 bit is always set */
+		.eflags		= X86_EFLAGS_SF | 0x2,
+		.esp		= STACK_START,
+		.es		= __USER_DS,
+		.cs		= __KERNEL_CS,
+		.ss		= __KERNEL_DS,
+		.ds		= __USER_DS,
+		.fs		= __KERNEL_PERCPU,
+
+		.__cr3		= __pa(swapper_pg_dir)
+	}
+};