1 files changed, 24 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index aa003b13a831..266e4649b1da 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1026,6 +1026,8 @@ __setup("clearcpuid=", setup_disablecpuid);
 
 #ifdef CONFIG_X86_64
 struct desc_ptr idt_descr = { NR_VECTORS * 16 - 1, (unsigned long) idt_table };
+struct desc_ptr nmi_idt_descr = { NR_VECTORS * 16 - 1,
+                                    (unsigned long) nmi_idt_table };
 
 DEFINE_PER_CPU_FIRST(union irq_stack_union,
                      irq_stack_union) __aligned(PAGE_SIZE);
@@ -1090,6 +1092,26 @@ unsigned long kernel_eflags;
  */
 DEFINE_PER_CPU(struct orig_ist, orig_ist);
 
+static DEFINE_PER_CPU(unsigned long, debug_stack_addr);
+DEFINE_PER_CPU(int, debug_stack_usage);
+
+int is_debug_stack(unsigned long addr)
+{
+        return __get_cpu_var(debug_stack_usage) ||
+                (addr <= __get_cpu_var(debug_stack_addr) &&
+                 addr > (__get_cpu_var(debug_stack_addr) - DEBUG_STKSZ));
+}
+
+void debug_stack_set_zero(void)
+{
+        load_idt((const struct desc_ptr *)&nmi_idt_descr);
+}
+
+void debug_stack_reset(void)
+{
+        load_idt((const struct desc_ptr *)&idt_descr);
+}
+
 #else   /* CONFIG_X86_64 */
 
 DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
@@ -1208,6 +1230,8 @@ void __cpuinit cpu_init(void)
                         estacks += exception_stack_sizes[v];
                         oist->ist[v] = t->x86_tss.ist[v] =
                                         (unsigned long)estacks;
+                        if (v == DEBUG_STACK-1)
+                                per_cpu(debug_stack_addr, cpu) = (unsigned long)estacks;
                 }
         }