linux-kernel - [tip:x86/debug] x86/asm/crypto: Don't use RBP as a scratch register

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Date:	Wed, 24 Feb 2016 21:48:15 -0800
From:	tip-bot for Josh Poimboeuf <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	luto@...capital.net, hpa@...or.com, jpoimboe@...hat.com,
	bp@...en8.de, torvalds@...ux-foundation.org, brgerst@...il.com,
	palves@...hat.com, luto@...nel.org, tglx@...utronix.de,
	namhyung@...il.com, acme@...nel.org, mingo@...nel.org,
	peterz@...radead.org, dvlasenk@...hat.com,
	linux-kernel@...r.kernel.org, bernd@...rovitsch.priv.at,
	chris.j.arges@...onical.com, mmarek@...e.cz,
	akpm@...ux-foundation.org, jslaby@...e.cz
Subject: [tip:x86/debug] x86/asm/crypto: Don't use RBP as a scratch register

Commit-ID:  68874ac3304ade7ed5ebb12af00d6b9bbbca0a16
Gitweb:     http://git.kernel.org/tip/68874ac3304ade7ed5ebb12af00d6b9bbbca0a16
Author:     Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate: Thu, 21 Jan 2016 16:49:18 -0600
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 24 Feb 2016 08:35:42 +0100

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 <jpoimboe@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Bernd Petrovitsch <bernd@...rovitsch.priv.at>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Chris J Arges <chris.j.arges@...onical.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Jiri Slaby <jslaby@...e.cz>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Michal Marek <mmarek@...e.cz>
Cc: Namhyung Kim <namhyung@...il.com>
Cc: Pedro Alves <palves@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: live-patching@...r.kernel.org
Link: http://lkml.kernel.org/r/15a3eb7ebe68e37755927915f45e4f0bde4d18c5.1453405861.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/crypto/sha-mb/sha1_mb_mgr_submit_avx2.S | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/crypto/sha-mb/sha1_mb_mgr_submit_avx2.S b/arch/x86/crypto/sha-mb/sha1_mb_mgr_submit_avx2.S
index a5a14c6..c3b9447 100644
--- a/arch/x86/crypto/sha-mb/sha1_mb_mgr_submit_avx2.S
+++ b/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