linux-kernel - [PATCH v4 09/21] powerpc/8xx: Optimize verification in FixupDAR

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <20140919083608.3DC9B1AB030@localhost.localdomain>
Date:	Fri, 19 Sep 2014 10:36:08 +0200 (CEST)
From:	Christophe Leroy <christophe.leroy@....fr>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>
CC:	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	Joakim Tjernlund <joakim.tjernlund@...nsmode.se>,
	scottwood@...escale.com
Subject: [PATCH v4 09/21] powerpc/8xx: Optimize verification in FixupDAR

By XORing the upper part of the instruction code, we get a value that can
directly be verified with the second test and we can remove the first test.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>

---
Changes in v2:
- None

Changes in v3:
- None

Changes in v4:
- None

 arch/powerpc/kernel/head_8xx.S |    6 ++----
 1 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index e5a250c..5037420 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -542,10 +542,8 @@ FixupDAR:/* Entry point for dcbx workaround. */
 /* Check if it really is a dcbx instruction. */
 /* dcbt and dcbtst does not generate DTLB Misses/Errors,
  * no need to include them here */
-	srwi	r10, r11, 26	/* check if major OP code is 31 */
-	cmpwi	cr0, r10, 31
-	bne-	141f
-	rlwinm	r10, r11, 0, 21, 30
+	xoris	r10, r11, 0x7c00	/* check if major OP code is 31 */
+	rlwinm	r10, r10, 0, 21, 5
 	cmpwi	cr0, r10, 2028	/* Is dcbz? */
 	beq+	142f
 	cmpwi	cr0, r10, 940	/* Is dcbi? */
-- 
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/