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authorVivek Goyal <vgoyal@in.ibm.com>2005-06-25 14:58:13 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-25 16:24:52 -0700
commit4d55476c3f889e0f30d88e22da4682b5f10394ff (patch)
tree097c222aea3243596762e7c3b0fa02ba94d60fde /arch/i386
parent625f1c8219d95300ed32e4c67eb62a50ded095ba (diff)
[PATCH] kdump: NMI handler segment selector, stack pointer fix
CPU does not save ss and esp on stack if execution was already in kernel mode at the time of NMI occurrence. This leads to saving of erractic values for ss and esp. This patch fixes the issue. Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/i386')
-rw-r--r--arch/i386/kernel/crash.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/i386/kernel/crash.c b/arch/i386/kernel/crash.c
index 3645ad7ac20..31e077bb0ca 100644
--- a/arch/i386/kernel/crash.c
+++ b/arch/i386/kernel/crash.c
@@ -112,7 +112,20 @@ static atomic_t waiting_for_crash_ipi;
static int crash_nmi_callback(struct pt_regs *regs, int cpu)
{
+ struct pt_regs fixed_regs;
local_irq_disable();
+
+ /* CPU does not save ss and esp on stack if execution is already
+ * running in kernel mode at the time of NMI occurrence. This code
+ * fixes it.
+ */
+ if (!user_mode(regs)) {
+ memcpy(&fixed_regs, regs, sizeof(*regs));
+ fixed_regs.esp = (unsigned long)&(regs->esp);
+ __asm__ __volatile__("xorl %eax, %eax;");
+ __asm__ __volatile__ ("movw %%ss, %%ax;" :"=a"(fixed_regs.xss));
+ regs = &fixed_regs;
+ }
crash_save_this_cpu(regs, cpu);
disable_local_APIC();
atomic_dec(&waiting_for_crash_ipi);