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authorNicolas Pitre <nico@cam.org>2005-11-01 19:52:24 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2005-11-01 19:52:24 +0000
commitfadab0943d1c5b652a66858bb99b204fedaad96b (patch)
treeae8f83cd0b6c97ee2120688f3e4f4cfd431b0c3e /arch/arm/lib/copy_to_user.S
parent7549423000fc38d39a8b81c601dea0332c113a42 (diff)
downloadlinux-linaro-stable-fadab0943d1c5b652a66858bb99b204fedaad96b.tar.gz
[ARM] 2948/1: new preemption safe copy_{to|from}_user implementation
Patch from Nicolas Pitre This patch provides a preemption safe implementation of copy_to_user and copy_from_user based on the copy template also used for memcpy. It is enabled unconditionally when CONFIG_PREEMPT=y. Otherwise if the configured architecture is not ARMv3 then it is enabled as well as it gives better performances at least on StrongARM and XScale cores. If ARMv3 is not too affected or if it doesn't matter too much then uaccess.S could be removed altogether. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/lib/copy_to_user.S')
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+/*
+ * linux/arch/arm/lib/copy_to_user.S
+ *
+ * Author: Nicolas Pitre
+ * Created: Sep 29, 2005
+ * Copyright: MontaVista Software, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+/*
+ * Prototype:
+ *
+ * size_t __arch_copy_to_user(void *to, const void *from, size_t n)
+ *
+ * Purpose:
+ *
+ * copy a block to user memory from kernel memory
+ *
+ * Params:
+ *
+ * to = user memory
+ * from = kernel memory
+ * n = number of bytes to copy
+ *
+ * Return value:
+ *
+ * Number of bytes NOT copied.
+ */
+
+ .macro ldr1w ptr reg abort
+ ldr \reg, [\ptr], #4
+ .endm
+
+ .macro ldr4w ptr reg1 reg2 reg3 reg4 abort
+ ldmia \ptr!, {\reg1, \reg2, \reg3, \reg4}
+ .endm
+
+ .macro ldr8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort
+ ldmia \ptr!, {\reg1, \reg2, \reg3, \reg4, \reg5, \reg6, \reg7, \reg8}
+ .endm
+
+ .macro ldr1b ptr reg cond=al abort
+ ldr\cond\()b \reg, [\ptr], #1
+ .endm
+
+ .macro str1w ptr reg abort
+100: strt \reg, [\ptr], #4
+ .section __ex_table, "a"
+ .long 100b, \abort
+ .previous
+ .endm
+
+ .macro str8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort
+ str1w \ptr, \reg1, \abort
+ str1w \ptr, \reg2, \abort
+ str1w \ptr, \reg3, \abort
+ str1w \ptr, \reg4, \abort
+ str1w \ptr, \reg5, \abort
+ str1w \ptr, \reg6, \abort
+ str1w \ptr, \reg7, \abort
+ str1w \ptr, \reg8, \abort
+ .endm
+
+ .macro str1b ptr reg cond=al abort
+100: str\cond\()bt \reg, [\ptr], #1
+ .section __ex_table, "a"
+ .long 100b, \abort
+ .previous
+ .endm
+
+ .macro enter reg1 reg2
+ mov r3, #0
+ stmdb sp!, {r0, r2, r3, \reg1, \reg2}
+ .endm
+
+ .macro exit reg1 reg2
+ add sp, sp, #8
+ ldmfd sp!, {r0, \reg1, \reg2}
+ .endm
+
+ .text
+
+ENTRY(__arch_copy_to_user)
+
+#include "copy_template.S"
+
+ .section .fixup,"ax"
+ .align 0
+ copy_abort_preamble
+ ldmfd sp!, {r1, r2, r3}
+ sub r0, r0, r1
+ rsb r0, r0, r2
+ copy_abort_end
+ .previous
+