x86/entry: Increase entry_stack size to a full page

[ Upstream commit c7aadc09321d8f9a1d3bd1e6d8a47222ecddf6c5 ]

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>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Tested-by: Marco Elver <elver@google.com>
Link: https://lkml.kernel.org/r/20200618144801.819246178@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 6a87eda9691e4f319f31f0149ff76c0056d11740..56a89519dc144152bfdbd3fd5a6a1faac066744e 100644 (file)
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -344,7 +344,7 @@ struct x86_hw_tss {
 #define INVALID_IO_BITMAP_OFFSET       0x8000
 
 struct entry_stack {
-       unsigned long           words[64];
+       char    stack[PAGE_SIZE];
 };
 
 struct entry_stack_page {