1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
2 | /* |
3 | * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) |
4 | * |
5 | * Vineetg: Aug 2009 |
6 | * -Moved core context switch macro out of entry.S into this file. |
7 | * -This is the more "natural" hand written assembler |
8 | */ |
9 | |
10 | #include <linux/linkage.h> |
11 | #include <asm/entry.h> /* For the SAVE_* macros */ |
12 | #include <asm/asm-offsets.h> |
13 | |
14 | ; IN |
15 | ; - r0: prev task (also current) |
16 | ; - r1: next task |
17 | ; OUT |
18 | ; - r0: prev task (so r0 not touched) |
19 | |
20 | .section .sched.text,"ax" ,@progbits |
21 | ENTRY_CFI(__switch_to) |
22 | |
23 | /* save kernel stack frame regs of @prev task */ |
24 | push blink |
25 | CFI_DEF_CFA_OFFSET 4 |
26 | CFI_OFFSET r31, -4 |
27 | |
28 | push fp |
29 | CFI_DEF_CFA_OFFSET 8 |
30 | CFI_OFFSET r27, -8 |
31 | |
32 | mov fp, sp |
33 | CFI_DEF_CFA_REGISTER r27 |
34 | |
35 | /* kernel mode callee regs of @prev */ |
36 | SAVE_CALLEE_SAVED_KERNEL |
37 | |
38 | /* |
39 | * save final SP to @prev->thread_info.ksp |
40 | * @prev is "current" so thread_info derived from SP |
41 | */ |
42 | GET_CURR_THR_INFO_FROM_SP r10 |
43 | st sp, [r10, THREAD_INFO_KSP] |
44 | |
45 | /* update @next in _current_task[] and GP register caching it */ |
46 | SET_CURR_TASK_ON_CPU r1, r10 |
47 | |
48 | /* load SP from @next->thread_info.ksp */ |
49 | ld r10, [r1, TASK_THREAD_INFO] |
50 | ld sp, [r10, THREAD_INFO_KSP] |
51 | |
52 | /* restore callee regs, stack frame regs of @next */ |
53 | RESTORE_CALLEE_SAVED_KERNEL |
54 | |
55 | pop fp |
56 | CFI_RESTORE r27 |
57 | CFI_DEF_CFA r28, 4 |
58 | |
59 | pop blink |
60 | CFI_RESTORE r31 |
61 | CFI_DEF_CFA_OFFSET 0 |
62 | |
63 | j [blink] |
64 | END_CFI(__switch_to) |
65 | |