| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1 | /* |
| 2 | * linux/arch/arm/lib/clear_user.S |
| 3 | * |
| 4 | * Copyright (C) 1995, 1996,1997,1998 Russell King |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License version 2 as |
| 8 | * published by the Free Software Foundation. |
| 9 | */ |
| 10 | #include <linux/linkage.h> |
| 11 | #include <asm/assembler.h> |
| 12 | #include <asm/unwind.h> |
| 13 | |
| 14 | .text |
| 15 | |
| 16 | /* Prototype: unsigned long arm_clear_user(void *addr, size_t sz) |
| 17 | * Purpose : clear some user memory |
| 18 | * Params : addr - user memory address to clear |
| 19 | * : sz - number of bytes to clear |
| 20 | * Returns : number of bytes NOT cleared |
| 21 | */ |
| 22 | ENTRY(__clear_user_std) |
| 23 | WEAK(arm_clear_user) |
| 24 | UNWIND(.fnstart) |
| 25 | UNWIND(.save {r1, lr}) |
| 26 | stmfd sp!, {r1, lr} |
| 27 | mov r2, #0 |
| 28 | cmp r1, #4 |
| 29 | blt 2f |
| 30 | ands ip, r0, #3 |
| 31 | beq 1f |
| 32 | cmp ip, #2 |
| 33 | strusr r2, r0, 1 |
| 34 | strusr r2, r0, 1, le |
| 35 | strusr r2, r0, 1, lt |
| 36 | rsb ip, ip, #4 |
| 37 | sub r1, r1, ip @ 7 6 5 4 3 2 1 |
| 38 | 1: subs r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7 |
| 39 | strusr r2, r0, 4, pl, rept=2 |
| 40 | bpl 1b |
| 41 | adds r1, r1, #4 @ 3 2 1 0 -1 -2 -3 |
| 42 | strusr r2, r0, 4, pl |
| 43 | 2: tst r1, #2 @ 1x 1x 0x 0x 1x 1x 0x |
| 44 | strusr r2, r0, 1, ne, rept=2 |
| 45 | tst r1, #1 @ x1 x0 x1 x0 x1 x0 x1 |
| 46 | it ne @ explicit IT needed for the label |
| 47 | USER( strnebt r2, [r0]) |
| 48 | mov r0, #0 |
| 49 | ldmfd sp!, {r1, pc} |
| 50 | UNWIND(.fnend) |
| 51 | ENDPROC(arm_clear_user) |
| 52 | ENDPROC(__clear_user_std) |
| 53 | |
| 54 | .pushsection .text.fixup,"ax" |
| 55 | .align 0 |
| 56 | 9001: ldmfd sp!, {r0, pc} |
| 57 | .popsection |
| 58 | |