1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * AArch32 user helpers.
4 * Based on the kuser helpers in arch/arm/kernel/entry-armv.S.
5 *
6 * Copyright (C) 2005-2011 Nicolas Pitre <nico@fluxnic.net>
7 * Copyright (C) 2012-2018 ARM Ltd.
8 *
9 * The kuser helpers below are mapped at a fixed address by
10 * aarch32_setup_additional_pages() and are provided for compatibility
11 * reasons with 32 bit (aarch32) applications that need them.
12 *
13 * See Documentation/arch/arm/kernel_user_helpers.rst for formal definitions.
14 */
15
16#include <asm/unistd.h>
17
18 .section .rodata
19 .align 5
20 .globl __kuser_helper_start
21__kuser_helper_start:
22
23__kuser_cmpxchg64: // 0xffff0f60
24 .inst 0xe92d00f0 // push {r4, r5, r6, r7}
25 .inst 0xe1c040d0 // ldrd r4, r5, [r0]
26 .inst 0xe1c160d0 // ldrd r6, r7, [r1]
27 .inst 0xe1b20f9f // 1: ldrexd r0, r1, [r2]
28 .inst 0xe0303004 // eors r3, r0, r4
29 .inst 0x00313005 // eoreqs r3, r1, r5
30 .inst 0x01a23e96 // stlexdeq r3, r6, [r2]
31 .inst 0x03330001 // teqeq r3, #1
32 .inst 0x0afffff9 // beq 1b
33 .inst 0xf57ff05b // dmb ish
34 .inst 0xe2730000 // rsbs r0, r3, #0
35 .inst 0xe8bd00f0 // pop {r4, r5, r6, r7}
36 .inst 0xe12fff1e // bx lr
37
38 .align 5
39__kuser_memory_barrier: // 0xffff0fa0
40 .inst 0xf57ff05b // dmb ish
41 .inst 0xe12fff1e // bx lr
42
43 .align 5
44__kuser_cmpxchg: // 0xffff0fc0
45 .inst 0xe1923f9f // 1: ldrex r3, [r2]
46 .inst 0xe0533000 // subs r3, r3, r0
47 .inst 0x01823e91 // stlexeq r3, r1, [r2]
48 .inst 0x03330001 // teqeq r3, #1
49 .inst 0x0afffffa // beq 1b
50 .inst 0xf57ff05b // dmb ish
51 .inst 0xe2730000 // rsbs r0, r3, #0
52 .inst 0xe12fff1e // bx lr
53
54 .align 5
55__kuser_get_tls: // 0xffff0fe0
56 .inst 0xee1d0f70 // mrc p15, 0, r0, c13, c0, 3
57 .inst 0xe12fff1e // bx lr
58 .rep 5
59 .word 0
60 .endr
61
62__kuser_helper_version: // 0xffff0ffc
63 .word ((__kuser_helper_end - __kuser_helper_start) >> 5)
64 .globl __kuser_helper_end
65__kuser_helper_end:
66

source code of linux/arch/arm64/kernel/kuser32.S