crypto: x86/sha1-avx2 - Fix RBP usage

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>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/arch/x86/crypto/sha1_avx2_x86_64_asm.S b/arch/x86/crypto/sha1_avx2_x86_64_asm.S
index 1eab79c..9f712a7 100644 (file)
--- 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