1 files changed, 33 insertions, 14 deletions

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 2bb25c3fe2e8..92e8f0a7159c 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -42,16 +42,14 @@ void printk_address(unsigned long address)
 static void
 print_ftrace_graph_addr(unsigned long addr, void *data,
 			const struct stacktrace_ops *ops,
-			struct thread_info *tinfo, int *graph)
+			struct task_struct *task, int *graph)
 {
-	struct task_struct *task;
 	unsigned long ret_addr;
 	int index;
 
 	if (addr != (unsigned long)return_to_handler)
 		return;
 
-	task = tinfo->task;
 	index = task->curr_ret_stack;
 
 	if (!task->ret_stack || index < *graph)
@@ -68,7 +66,7 @@ print_ftrace_graph_addr(unsigned long addr, void *data,
 static inline void
 print_ftrace_graph_addr(unsigned long addr, void *data,
 			const struct stacktrace_ops *ops,
-			struct thread_info *tinfo, int *graph)
+			struct task_struct *task, int *graph)
 { }
 #endif
 
@@ -79,28 +77,36 @@ print_ftrace_graph_addr(unsigned long addr, void *data,
  * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
  */
 
-static inline int valid_stack_ptr(struct thread_info *tinfo,
+static inline int valid_stack_ptr(struct task_struct *task,
 			void *p, unsigned int size, void *end)
 {
-	void *t = tinfo;
+	void *t = task_stack_page(task);
 	if (end) {
 		if (p < end && p >= (end-THREAD_SIZE))
 			return 1;
 		else
 			return 0;
 	}
-	return p > t && p < t + THREAD_SIZE - size;
+	return p >= t && p < t + THREAD_SIZE - size;
 }
 
 unsigned long
-print_context_stack(struct thread_info *tinfo,
+print_context_stack(struct task_struct *task,
 		unsigned long *stack, unsigned long bp,
 		const struct stacktrace_ops *ops, void *data,
 		unsigned long *end, int *graph)
 {
 	struct stack_frame *frame = (struct stack_frame *)bp;
 
-	while (valid_stack_ptr(tinfo, stack, sizeof(*stack), end)) {
+	/*
+	 * If we overflowed the stack into a guard page, jump back to the
+	 * bottom of the usable stack.
+	 */
+	if ((unsigned long)task_stack_page(task) - (unsigned long)stack <
+	    PAGE_SIZE)
+		stack = (unsigned long *)task_stack_page(task);
+
+	while (valid_stack_ptr(task, stack, sizeof(*stack), end)) {
 		unsigned long addr;
 
 		addr = *stack;
@@ -112,7 +118,7 @@ print_context_stack(struct thread_info *tinfo,
 			} else {
 				ops->address(data, addr, 0);
 			}
-			print_ftrace_graph_addr(addr, data, ops, tinfo, graph);
+			print_ftrace_graph_addr(addr, data, ops, task, graph);
 		}
 		stack++;
 	}
@@ -121,7 +127,7 @@ print_context_stack(struct thread_info *tinfo,
 EXPORT_SYMBOL_GPL(print_context_stack);
 
 unsigned long
-print_context_stack_bp(struct thread_info *tinfo,
+print_context_stack_bp(struct task_struct *task,
 		       unsigned long *stack, unsigned long bp,
 		       const struct stacktrace_ops *ops, void *data,
 		       unsigned long *end, int *graph)
@@ -129,7 +135,7 @@ print_context_stack_bp(struct thread_info *tinfo,
 	struct stack_frame *frame = (struct stack_frame *)bp;
 	unsigned long *ret_addr = &frame->return_address;
 
-	while (valid_stack_ptr(tinfo, ret_addr, sizeof(*ret_addr), end)) {
+	while (valid_stack_ptr(task, ret_addr, sizeof(*ret_addr), end)) {
 		unsigned long addr = *ret_addr;
 
 		if (!__kernel_text_address(addr))
@@ -139,7 +145,7 @@ print_context_stack_bp(struct thread_info *tinfo,
 			break;
 		frame = frame->next_frame;
 		ret_addr = &frame->return_address;
-		print_ftrace_graph_addr(addr, data, ops, tinfo, graph);
+		print_ftrace_graph_addr(addr, data, ops, task, graph);
 	}
 
 	return (unsigned long)frame;
@@ -199,6 +205,11 @@ void show_stack(struct task_struct *task, unsigned long *sp)
 	show_stack_log_lvl(task, NULL, sp, bp, "");
 }
 
+void show_stack_regs(struct pt_regs *regs)
+{
+	show_stack_log_lvl(current, regs, (unsigned long *)regs->sp, regs->bp, "");
+}
+
 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
 static int die_owner = -1;
 static unsigned int die_nest_count;
@@ -228,6 +239,8 @@ unsigned long oops_begin(void)
 EXPORT_SYMBOL_GPL(oops_begin);
 NOKPROBE_SYMBOL(oops_begin);
 
+void __noreturn rewind_stack_do_exit(int signr);
+
 void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
 {
 	if (regs && kexec_should_crash(current))
@@ -249,7 +262,13 @@ void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
 		panic("Fatal exception in interrupt");
 	if (panic_on_oops)
 		panic("Fatal exception");
-	do_exit(signr);
+
+	/*
+	 * We're not going to return, but we might be on an IST stack or
+	 * have very little stack space left.  Rewind the stack and kill
+	 * the task.
+	 */
+	rewind_stack_do_exit(signr);
 }
 NOKPROBE_SYMBOL(oops_end);