linux-kernel - [PATCH v4 1/5] powerpc/mm/slice: Remove intermediate bitmap copy

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>] [thread-next>] [day] [month] [year] [list]

Message-Id: <01e8f783db8f4d4d41df91e0400a8634272b326f.1518226173.git.christophe.leroy@c-s.fr>
Date:   Sat, 10 Feb 2018 13:54:25 +0100 (CET)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Scott Wood <oss@...error.net>, aneesh.kumar@...ux.vnet.ibm.com
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Nicholas Piggin <npiggin@...il.com>
Subject: [PATCH v4 1/5] powerpc/mm/slice: Remove intermediate bitmap copy

bitmap_or() and bitmap_andnot() can work properly with dst identical
to src1 or src2. There is no need of an intermediate result bitmap
that is copied back to dst in a second step.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
---
 v2: New in v2
 v3: patch moved up front of the serie to avoid ephemeral slice_bitmap_copy() function in following patch
 v4: No change

 arch/powerpc/mm/slice.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index 23ec2c5e3b78..98b53d48968f 100644
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -388,21 +388,17 @@ static unsigned long slice_find_area(struct mm_struct *mm, unsigned long len,
 
 static inline void slice_or_mask(struct slice_mask *dst, struct slice_mask *src)
 {
-	DECLARE_BITMAP(result, SLICE_NUM_HIGH);
-
 	dst->low_slices |= src->low_slices;
-	bitmap_or(result, dst->high_slices, src->high_slices, SLICE_NUM_HIGH);
-	bitmap_copy(dst->high_slices, result, SLICE_NUM_HIGH);
+	bitmap_or(dst->high_slices, dst->high_slices, src->high_slices,
+		  SLICE_NUM_HIGH);
 }
 
 static inline void slice_andnot_mask(struct slice_mask *dst, struct slice_mask *src)
 {
-	DECLARE_BITMAP(result, SLICE_NUM_HIGH);
-
 	dst->low_slices &= ~src->low_slices;
 
-	bitmap_andnot(result, dst->high_slices, src->high_slices, SLICE_NUM_HIGH);
-	bitmap_copy(dst->high_slices, result, SLICE_NUM_HIGH);
+	bitmap_andnot(dst->high_slices, dst->high_slices, src->high_slices,
+		      SLICE_NUM_HIGH);
 }
 
 #ifdef CONFIG_PPC_64K_PAGES
-- 
2.13.3