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| /* 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
|
|
