| 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
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| 2 | /* |
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| 3 | * linux/arch/arm/lib/clear_user.S |
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| 4 | * |
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| 5 | * Copyright (C) 1995, 1996,1997,1998 Russell King |
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| 6 | */ |
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| 7 | #include <linux/linkage.h> |
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| 8 | #include <asm/assembler.h> |
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| 9 | #include <asm/unwind.h> |
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| 10 | |
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| 11 | .text |
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| 12 | |
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| 13 | /* Prototype: unsigned long arm_clear_user(void *addr, size_t sz) |
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| 14 | * Purpose : clear some user memory |
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| 15 | * Params : addr - user memory address to clear |
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| 16 | * : sz - number of bytes to clear |
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| 17 | * Returns : number of bytes NOT cleared |
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| 18 | */ |
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| 19 | ENTRY(__clear_user_std) |
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| 20 | WEAK(arm_clear_user) |
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| 21 | UNWIND(.fnstart) |
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| 22 | UNWIND(.save {r1, lr}) |
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| 23 | stmfd sp!, {r1, lr} |
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| 24 | mov r2, #0 |
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| 25 | cmp r1, #4 |
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| 26 | blt 2f |
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| 27 | ands ip, r0, #3 |
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| 28 | beq 1f |
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| 29 | cmp ip, #2 |
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| 30 | strusr r2, r0, 1 |
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| 31 | strusr r2, r0, 1, le |
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| 32 | strusr r2, r0, 1, lt |
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| 33 | rsb ip, ip, #4 |
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| 34 | sub r1, r1, ip @ 7 6 5 4 3 2 1 |
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| 35 | 1: subs r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7 |
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| 36 | strusr r2, r0, 4, pl, rept=2 |
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| 37 | bpl 1b |
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| 38 | adds r1, r1, #4 @ 3 2 1 0 -1 -2 -3 |
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| 39 | strusr r2, r0, 4, pl |
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| 40 | 2: tst r1, #2 @ 1x 1x 0x 0x 1x 1x 0x |
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| 41 | strusr r2, r0, 1, ne, rept=2 |
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| 42 | tst r1, #1 @ x1 x0 x1 x0 x1 x0 x1 |
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| 43 | it ne @ explicit IT needed for the label |
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| 44 | USER( strbtne r2, [r0]) |
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| 45 | mov r0, #0 |
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| 46 | ldmfd sp!, {r1, pc} |
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| 47 | UNWIND(.fnend) |
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| 48 | ENDPROC(arm_clear_user) |
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| 49 | ENDPROC(__clear_user_std) |
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| 50 | |
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| 51 | .pushsection .text.fixup,"ax" |
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| 52 | .align 0 |
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| 53 | 9001: ldmfd sp!, {r0, pc} |
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| 54 | .popsection |
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| 55 | |
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| 56 | |
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