diff options
Diffstat (limited to 'arch/arm/lib/clear_user.S')
| -rw-r--r-- | arch/arm/lib/clear_user.S | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/arch/arm/lib/clear_user.S b/arch/arm/lib/clear_user.S new file mode 100644 index 0000000000..8f2c4dbfc5 --- /dev/null +++ b/arch/arm/lib/clear_user.S @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * linux/arch/arm/lib/clear_user.S + * + * Copyright (C) 1995, 1996,1997,1998 Russell King + */ +#include <linux/linkage.h> +#include <asm/assembler.h> +#include <asm/unwind.h> + + .text + +/* Prototype: unsigned long arm_clear_user(void *addr, size_t sz) + * Purpose : clear some user memory + * Params : addr - user memory address to clear + * : sz - number of bytes to clear + * Returns : number of bytes NOT cleared + */ +ENTRY(__clear_user_std) +WEAK(arm_clear_user) +UNWIND(.fnstart) +UNWIND(.save {r1, lr}) + stmfd sp!, {r1, lr} + mov r2, #0 + cmp r1, #4 + blt 2f + ands ip, r0, #3 + beq 1f + cmp ip, #2 + strusr r2, r0, 1 + strusr r2, r0, 1, le + strusr r2, r0, 1, lt + rsb ip, ip, #4 + sub r1, r1, ip @ 7 6 5 4 3 2 1 +1: subs r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7 + strusr r2, r0, 4, pl, rept=2 + bpl 1b + adds r1, r1, #4 @ 3 2 1 0 -1 -2 -3 + strusr r2, r0, 4, pl +2: tst r1, #2 @ 1x 1x 0x 0x 1x 1x 0x + strusr r2, r0, 1, ne, rept=2 + tst r1, #1 @ x1 x0 x1 x0 x1 x0 x1 + it ne @ explicit IT needed for the label +USER( strbtne r2, [r0]) + mov r0, #0 + ldmfd sp!, {r1, pc} +UNWIND(.fnend) +ENDPROC(arm_clear_user) +ENDPROC(__clear_user_std) + + .pushsection .text.fixup,"ax" + .align 0 +9001: ldmfd sp!, {r0, pc} + .popsection + |