[PATCH v2 06/12] x86/crypto: Fix RBP usage in sha1_avx2_x86_64_asm.S

From	Josh Poimboeuf <jpoimboe@redhat.com>
Newsgroups	linux.kernel
Subject	[PATCH v2 06/12] x86/crypto: Fix RBP usage in sha1_avx2_x86_64_asm.S
Date	2017-09-18 21:50 +0200
Message-ID	<uradj-2dt-21@gated-at.bofh.it> (permalink)
References	<uradj-2dt-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

Using RBP as a temporary register breaks frame pointer convention and
breaks stack traces when unwinding from an interrupt in the crypto code.

Use R11 instead of RBP.  Since R11 isn't a callee-saved register, it
doesn't need to be saved and restored on the stack.

Reported-by: Eric Biggers <ebiggers@google.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Eric Biggers <ebiggers@google.com>
Acked-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 arch/x86/crypto/sha1_avx2_x86_64_asm.S | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/x86/crypto/sha1_avx2_x86_64_asm.S b/arch/x86/crypto/sha1_avx2_x86_64_asm.S
index 1eab79c9ac48..9f712a7dfd79 100644
--- a/arch/x86/crypto/sha1_avx2_x86_64_asm.S
+++ b/arch/x86/crypto/sha1_avx2_x86_64_asm.S
@@ -89,7 +89,7 @@
 #define	REG_RE	%rdx
 #define	REG_RTA	%r12
 #define	REG_RTB	%rbx
-#define	REG_T1	%ebp
+#define	REG_T1	%r11d
 #define	xmm_mov	vmovups
 #define	avx2_zeroupper	vzeroupper
 #define	RND_F1	1
@@ -637,7 +637,6 @@ _loop3:
 	ENTRY(\name)
 
 	push	%rbx
-	push	%rbp
 	push	%r12
 	push	%r13
 	push	%r14
@@ -673,7 +672,6 @@ _loop3:
 	pop	%r14
 	pop	%r13
 	pop	%r12
-	pop	%rbp
 	pop	%rbx
 
 	ret
-- 
2.13.5

Back to linux.kernel | Previous | Next | Find similar | Unroll thread

Thread

[PATCH v2 06/12] x86/crypto: Fix RBP usage in sha1_avx2_x86_64_asm.S Josh Poimboeuf <jpoimboe@redhat.com> - 2017-09-18 21:50 +0200

csiph-web