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authorNicolas Pitre <nico@cam.org>2009-03-08 22:34:45 -0400
committerNicolas Pitre <nico@cam.org>2009-05-29 22:34:45 -0400
commita1f98849fdf2f2fef3ef1c260178cd5fc662b773 (patch)
tree2d6825bc4a9a1eaaaaa7295c337c47b899bc7d72 /arch/arm/lib
parent59a3759d0fe8d969888c741bb33f4946e4d3750d (diff)
[ARM] allow for alternative __copy_to_user/__clear_user implementations
This allows for optional alternative implementations of __copy_to_user and __clear_user, with a possible runtime fallback to the standard version when the alternative provides no gain over that standard version. This is done by making the standard __copy_to_user into a weak alias for the symbol __copy_to_user_std. Same thing for __clear_user. Those two functions are particularly good candidates to have alternative implementations for, since they rely on the STRT instruction which has lower performances than STM instructions on some CPU cores such as the ARM1176 and Marvell Feroceon. Signed-off-by: Nicolas Pitre <nico@marvell.com>
Diffstat (limited to 'arch/arm/lib')
-rw-r--r--arch/arm/lib/clear_user.S3
-rw-r--r--arch/arm/lib/copy_to_user.S3
2 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm/lib/clear_user.S b/arch/arm/lib/clear_user.S
index 4d6bc71231f3..844f56785ebc 100644
--- a/arch/arm/lib/clear_user.S
+++ b/arch/arm/lib/clear_user.S
@@ -18,7 +18,8 @@
18 * : sz - number of bytes to clear 18 * : sz - number of bytes to clear
19 * Returns : number of bytes NOT cleared 19 * Returns : number of bytes NOT cleared
20 */ 20 */
21ENTRY(__clear_user) 21ENTRY(__clear_user_std)
22WEAK(__clear_user)
22 stmfd sp!, {r1, lr} 23 stmfd sp!, {r1, lr}
23 mov r2, #0 24 mov r2, #0
24 cmp r1, #4 25 cmp r1, #4
diff --git a/arch/arm/lib/copy_to_user.S b/arch/arm/lib/copy_to_user.S
index 22f968bbdffd..878820f0a320 100644
--- a/arch/arm/lib/copy_to_user.S
+++ b/arch/arm/lib/copy_to_user.S
@@ -86,7 +86,8 @@
86 86
87 .text 87 .text
88 88
89ENTRY(__copy_to_user) 89ENTRY(__copy_to_user_std)
90WEAK(__copy_to_user)
90 91
91#include "copy_template.S" 92#include "copy_template.S"
92 93