Commit 5a3cf869 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Ingo Molnar

x86/dumpstack: Fix interrupt and exception stack boundary checks

On x86_64, the double fault exception stack is located immediately after
the interrupt stack in memory.  This causes confusion in the unwinder
when it tries to unwind through an empty interrupt stack, where the
stack pointer points to the address bordering the two stacks.  The
unwinder incorrectly thinks it's running on the double fault stack.

Fix this kind of stack border confusion by never considering the
beginning address of an exception or interrupt stack to be part of the
stack.
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Fixes: 5fe599e0 ("x86/dumpstack: Add support for unwinding empty IRQ stacks")
Link: http://lkml.kernel.org/r/bcc142160a5104de5c354c21c394c93a0173943f.1499786555.git.jpoimboe@redhat.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent b0529bec
...@@ -37,7 +37,7 @@ static bool in_hardirq_stack(unsigned long *stack, struct stack_info *info) ...@@ -37,7 +37,7 @@ static bool in_hardirq_stack(unsigned long *stack, struct stack_info *info)
* This is a software stack, so 'end' can be a valid stack pointer. * This is a software stack, so 'end' can be a valid stack pointer.
* It just means the stack is empty. * It just means the stack is empty.
*/ */
if (stack < begin || stack > end) if (stack <= begin || stack > end)
return false; return false;
info->type = STACK_TYPE_IRQ; info->type = STACK_TYPE_IRQ;
...@@ -62,7 +62,7 @@ static bool in_softirq_stack(unsigned long *stack, struct stack_info *info) ...@@ -62,7 +62,7 @@ static bool in_softirq_stack(unsigned long *stack, struct stack_info *info)
* This is a software stack, so 'end' can be a valid stack pointer. * This is a software stack, so 'end' can be a valid stack pointer.
* It just means the stack is empty. * It just means the stack is empty.
*/ */
if (stack < begin || stack > end) if (stack <= begin || stack > end)
return false; return false;
info->type = STACK_TYPE_SOFTIRQ; info->type = STACK_TYPE_SOFTIRQ;
......
...@@ -55,7 +55,7 @@ static bool in_exception_stack(unsigned long *stack, struct stack_info *info) ...@@ -55,7 +55,7 @@ static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
begin = end - (exception_stack_sizes[k] / sizeof(long)); begin = end - (exception_stack_sizes[k] / sizeof(long));
regs = (struct pt_regs *)end - 1; regs = (struct pt_regs *)end - 1;
if (stack < begin || stack >= end) if (stack <= begin || stack >= end)
continue; continue;
info->type = STACK_TYPE_EXCEPTION + k; info->type = STACK_TYPE_EXCEPTION + k;
...@@ -78,7 +78,7 @@ static bool in_irq_stack(unsigned long *stack, struct stack_info *info) ...@@ -78,7 +78,7 @@ static bool in_irq_stack(unsigned long *stack, struct stack_info *info)
* This is a software stack, so 'end' can be a valid stack pointer. * This is a software stack, so 'end' can be a valid stack pointer.
* It just means the stack is empty. * It just means the stack is empty.
*/ */
if (stack < begin || stack > end) if (stack <= begin || stack > end)
return false; return false;
info->type = STACK_TYPE_IRQ; info->type = STACK_TYPE_IRQ;
......
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