[PATCH v2 12/12] x86/crypto: Fix RBP usage in twofish-avx-x86_64-asm_64.S

From: Josh Poimboeuf
Date: Mon Sep 18 2017 - 15:43:02 EST

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

Use R13 instead of RBP. Both are callee-saved registers, so the
substitution is straightforward.

Reported-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Reported-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Tested-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Acked-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
arch/x86/crypto/twofish-avx-x86_64-asm_64.S | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/crypto/twofish-avx-x86_64-asm_64.S b/arch/x86/crypto/twofish-avx-x86_64-asm_64.S
index b3f49d286348..73b471da3622 100644
--- a/arch/x86/crypto/twofish-avx-x86_64-asm_64.S
+++ b/arch/x86/crypto/twofish-avx-x86_64-asm_64.S
@@ -76,8 +76,8 @@
#define RT %xmm14
#define RR %xmm15

-#define RID1 %rbp
-#define RID1d %ebp
+#define RID1 %r13
+#define RID1d %r13d
#define RID2 %rsi
#define RID2d %esi

@@ -259,7 +259,7 @@ __twofish_enc_blk8:

vmovdqu w(CTX), RK1;

- pushq %rbp;
+ pushq %r13;
pushq %rbx;
pushq %rcx;

@@ -282,7 +282,7 @@ __twofish_enc_blk8:

popq %rcx;
popq %rbx;
- popq %rbp;
+ popq %r13;

outunpack_blocks(RC1, RD1, RA1, RB1, RK1, RX0, RY0, RK2);
outunpack_blocks(RC2, RD2, RA2, RB2, RK1, RX0, RY0, RK2);
@@ -301,7 +301,7 @@ __twofish_dec_blk8:

vmovdqu (w+4*4)(CTX), RK1;

- pushq %rbp;
+ pushq %r13;
pushq %rbx;

inpack_blocks(RC1, RD1, RA1, RB1, RK1, RX0, RY0, RK2);
@@ -322,7 +322,7 @@ __twofish_dec_blk8:
vmovdqu (w)(CTX), RK1;

popq %rbx;
- popq %rbp;
+ popq %r13;

outunpack_blocks(RA1, RB1, RC1, RD1, RK1, RX0, RY0, RK2);
outunpack_blocks(RA2, RB2, RC2, RD2, RK1, RX0, RY0, RK2);