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1 | /* |
2 | * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License version 2 as | |
6 | * published by the Free Software Foundation. | |
7 | * | |
8 | * Vineetg: Aug 2009 | |
9 | * -Moved core context switch macro out of entry.S into this file. | |
10 | * -This is the more "natural" hand written assembler | |
11 | */ | |
12 | ||
ba25915f | 13 | #include <linux/linkage.h> |
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14 | #include <asm/entry.h> /* For the SAVE_* macros */ |
15 | #include <asm/asm-offsets.h> | |
bf90e1ea | 16 | |
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17 | #define KSP_WORD_OFF ((TASK_THREAD + THREAD_KSP) / 4) |
18 | ||
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19 | ;################### Low Level Context Switch ########################## |
20 | ||
21 | .section .sched.text,"ax",@progbits | |
22 | .align 4 | |
23 | .global __switch_to | |
24 | .type __switch_to, @function | |
25 | __switch_to: | |
86effd0d | 26 | CFI_STARTPROC |
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27 | |
28 | /* Save regs on kernel mode stack of task */ | |
29 | st.a blink, [sp, -4] | |
30 | st.a fp, [sp, -4] | |
31 | SAVE_CALLEE_SAVED_KERNEL | |
32 | ||
33 | /* Save the now KSP in task->thread.ksp */ | |
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34 | #if KSP_WORD_OFF <= 255 |
35 | st.as sp, [r0, KSP_WORD_OFF] | |
36 | #else | |
37 | /* Workaround for NR_CPUS=4k as ST.as can only take s9 offset */ | |
38 | add2 r24, r0, KSP_WORD_OFF | |
39 | st sp, [r24] | |
40 | #endif | |
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41 | /* |
42 | * Return last task in r0 (return reg) | |
43 | * On ARC, Return reg = First Arg reg = r0. | |
44 | * Since we already have last task in r0, | |
45 | * don't need to do anything special to return it | |
46 | */ | |
47 | ||
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48 | /* |
49 | * switch to new task, contained in r1 | |
50 | * Temp reg r3 is required to get the ptr to store val | |
51 | */ | |
52 | SET_CURR_TASK_ON_CPU r1, r3 | |
53 | ||
54 | /* reload SP with kernel mode stack pointer in task->thread.ksp */ | |
55 | ld.as sp, [r1, (TASK_THREAD + THREAD_KSP)/4] | |
56 | ||
57 | /* restore the registers */ | |
58 | RESTORE_CALLEE_SAVED_KERNEL | |
59 | ld.ab fp, [sp, 4] | |
60 | ld.ab blink, [sp, 4] | |
61 | j [blink] | |
62 | ||
86effd0d | 63 | END_CFI(__switch_to) |