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Subject[PATCH v2 10/12] x86/crypto: Fix RBP usage in sha256-ssse3-asm.S
Date
Using RBP as a temporary register breaks frame pointer convention and
breaks stack traces when unwinding from an interrupt in the crypto code.

Swap the usages of R12 and RBP. Use R12 for the TBL register, and use
RBP to store the pre-aligned stack pointer.

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/sha256-ssse3-asm.S | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/x86/crypto/sha256-ssse3-asm.S b/arch/x86/crypto/sha256-ssse3-asm.S
index 39b83c93e7fd..c6c05ed2c16a 100644
--- a/arch/x86/crypto/sha256-ssse3-asm.S
+++ b/arch/x86/crypto/sha256-ssse3-asm.S
@@ -95,7 +95,7 @@ SRND = %rsi # clobbers INP
c = %ecx
d = %r8d
e = %edx
-TBL = %rbp
+TBL = %r12
a = %eax
b = %ebx

@@ -356,13 +356,13 @@ a = TMP_
ENTRY(sha256_transform_ssse3)
.align 32
pushq %rbx
- pushq %rbp
+ pushq %r12
pushq %r13
pushq %r14
pushq %r15
- pushq %r12
+ pushq %rbp
+ mov %rsp, %rbp

- mov %rsp, %r12
subq $STACK_SIZE, %rsp
and $~15, %rsp

@@ -462,13 +462,12 @@ loop2:

done_hash:

- mov %r12, %rsp
-
- popq %r12
+ mov %rbp, %rsp
+ popq %rbp
popq %r15
popq %r14
popq %r13
- popq %rbp
+ popq %r12
popq %rbx

ret
--
2.13.5
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