x86: Extend #DF debugging aid to 64-bit

It is sometimes very helpful to be able to pinpoint the location which
causes a double fault before it turns into a triple fault and the
machine reboots. We have this for 32-bit already so extend it to 64-bit.
On 64-bit we get the register snapshot at #DF time and not from the
first exception which actually causes the #DF. It should be close
enough, though.

[ hpa: and definitely better than nothing, which is what we have now. ]

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1368093749-31296-1-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 0 insertions, 69 deletions

diff --git a/arch/x86/kernel/doublefault_32.c b/arch/x86/kernel/doublefault_32.c
deleted file mode 100644
index 155a13f33ed8..000000000000
--- a/arch/x86/kernel/doublefault_32.c
+++ /dev/null
@@ -1,69 +0,0 @@
-#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 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),
-	}
-};