[PATCH 4/7] x86/entry: Increase entry_stack size to a full page

Peter Zijlstra
2020-06-18T14:51:08Z

Marco crashed in bad_iret with a Clang11/KCSAN build due to
overflowing the stack. Now that we run C code on it, expand it to a
full page.

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Reported-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/processor.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -370,7 +370,7 @@ struct x86_hw_tss {
#define IO_BITMAP_OFFSET_INVALID (__KERNEL_TSS_LIMIT + 1)

struct entry_stack {
- unsigned long words[64];
+ char stack[PAGE_SIZE];
};

struct entry_stack_page {