x86/asm/crypto: Don't use RBP as a scratch register

The frame pointer (RBP) is getting clobbered in
sha1_mb_mgr_submit_avx2() before a function call, which can mess up
stack traces.  Use R12 instead.

Signed-off-by: Josh Poimboeuf <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Bernd Petrovitsch <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Chris J Arges <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Jiri Slaby <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Michal Marek <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Pedro Alves <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/15a3eb7ebe68e37755927915f45e4f0bde4d18c5.1453405861.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <[email protected]>

arch/x86/crypto/sha-mb/sha1_mb_mgr_submit_avx2.S

@@ -86,8 +86,8 @@ job_rax         = %rax
 len             = %rax
 DWORD_len	= %eax
 
-lane            = %rbp
-tmp3            = %rbp
+lane            = %r12
+tmp3            = %r12
 
 tmp             = %r9
 DWORD_tmp	= %r9d
@@ -99,7 +99,7 @@ lane_data       = %r10
 # arg 2 : rdx : job
 ENTRY(sha1_mb_mgr_submit_avx2)
 	push	%rbx
-	push	%rbp
+	push	%r12
 
 	mov     _unused_lanes(state), unused_lanes
 	mov	unused_lanes, lane
@@ -190,7 +190,7 @@ len_is_0:
 	movl    DWORD_tmp, _result_digest+1*16(job_rax)
 
 return:
-	pop	%rbp
+	pop	%r12
 	pop	%rbx
 	ret