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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 | * -"C" version of lowest level context switch asm macro called by schedular | |
10 | * gcc doesn't generate the dward CFI info for hand written asm, hence can't | |
11 | * backtrace out of it (e.g. tasks sleeping in kernel). | |
12 | * So we cheat a bit by writing almost similar code in inline-asm. | |
13 | * -This is a hacky way of doing things, but there is no other simple way. | |
14 | * I don't want/intend to extend unwinding code to understand raw asm | |
15 | */ | |
16 | ||
17 | #include <asm/asm-offsets.h> | |
18 | #include <linux/sched.h> | |
b17b0153 | 19 | #include <linux/sched/debug.h> |
86c25466 NC |
20 | #ifdef CONFIG_ARC_PLAT_EZNPS |
21 | #include <plat/ctop.h> | |
22 | #endif | |
bf90e1ea | 23 | |
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24 | #define KSP_WORD_OFF ((TASK_THREAD + THREAD_KSP) / 4) |
25 | ||
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26 | struct task_struct *__sched |
27 | __switch_to(struct task_struct *prev_task, struct task_struct *next_task) | |
28 | { | |
29 | unsigned int tmp; | |
30 | unsigned int prev = (unsigned int)prev_task; | |
31 | unsigned int next = (unsigned int)next_task; | |
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32 | |
33 | __asm__ __volatile__( | |
34 | /* FP/BLINK save generated by gcc (standard function prologue */ | |
35 | "st.a r13, [sp, -4] \n\t" | |
36 | "st.a r14, [sp, -4] \n\t" | |
37 | "st.a r15, [sp, -4] \n\t" | |
38 | "st.a r16, [sp, -4] \n\t" | |
39 | "st.a r17, [sp, -4] \n\t" | |
40 | "st.a r18, [sp, -4] \n\t" | |
41 | "st.a r19, [sp, -4] \n\t" | |
42 | "st.a r20, [sp, -4] \n\t" | |
43 | "st.a r21, [sp, -4] \n\t" | |
44 | "st.a r22, [sp, -4] \n\t" | |
45 | "st.a r23, [sp, -4] \n\t" | |
46 | "st.a r24, [sp, -4] \n\t" | |
080c3747 | 47 | #ifndef CONFIG_ARC_CURR_IN_REG |
bf90e1ea | 48 | "st.a r25, [sp, -4] \n\t" |
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49 | #else |
50 | "sub sp, sp, 4 \n\t" /* usual r25 placeholder */ | |
080c3747 | 51 | #endif |
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52 | |
53 | /* set ksp of outgoing task in tsk->thread.ksp */ | |
57e26e57 | 54 | #if KSP_WORD_OFF <= 255 |
bf90e1ea | 55 | "st.as sp, [%3, %1] \n\t" |
57e26e57 VG |
56 | #else |
57 | /* | |
58 | * Workaround for NR_CPUS=4k | |
59 | * %1 is bigger than 255 (S9 offset for st.as) | |
60 | */ | |
61 | "add2 r24, %3, %1 \n\t" | |
62 | "st sp, [r24] \n\t" | |
63 | #endif | |
bf90e1ea | 64 | |
bf90e1ea VG |
65 | /* |
66 | * setup _current_task with incoming tsk. | |
67 | * optionally, set r25 to that as well | |
68 | * For SMP extra work to get to &_current_task[cpu] | |
69 | * (open coded SET_CURR_TASK_ON_CPU) | |
70 | */ | |
41195d23 | 71 | #ifndef CONFIG_SMP |
bf90e1ea | 72 | "st %2, [@_current_task] \n\t" |
86c25466 NC |
73 | #else |
74 | #ifdef CONFIG_ARC_PLAT_EZNPS | |
75 | "lr r24, [%4] \n\t" | |
76 | #ifndef CONFIG_EZNPS_MTM_EXT | |
77 | "lsr r24, r24, 4 \n\t" | |
78 | #endif | |
41195d23 VG |
79 | #else |
80 | "lr r24, [identity] \n\t" | |
81 | "lsr r24, r24, 8 \n\t" | |
82 | "bmsk r24, r24, 7 \n\t" | |
86c25466 | 83 | #endif |
41195d23 VG |
84 | "add2 r24, @_current_task, r24 \n\t" |
85 | "st %2, [r24] \n\t" | |
86 | #endif | |
87 | #ifdef CONFIG_ARC_CURR_IN_REG | |
88 | "mov r25, %2 \n\t" | |
89 | #endif | |
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90 | |
91 | /* get ksp of incoming task from tsk->thread.ksp */ | |
92 | "ld.as sp, [%2, %1] \n\t" | |
93 | ||
94 | /* start loading it's CALLEE reg file */ | |
95 | ||
080c3747 | 96 | #ifndef CONFIG_ARC_CURR_IN_REG |
bf90e1ea | 97 | "ld.ab r25, [sp, 4] \n\t" |
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98 | #else |
99 | "add sp, sp, 4 \n\t" | |
080c3747 | 100 | #endif |
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101 | "ld.ab r24, [sp, 4] \n\t" |
102 | "ld.ab r23, [sp, 4] \n\t" | |
103 | "ld.ab r22, [sp, 4] \n\t" | |
104 | "ld.ab r21, [sp, 4] \n\t" | |
105 | "ld.ab r20, [sp, 4] \n\t" | |
106 | "ld.ab r19, [sp, 4] \n\t" | |
107 | "ld.ab r18, [sp, 4] \n\t" | |
108 | "ld.ab r17, [sp, 4] \n\t" | |
109 | "ld.ab r16, [sp, 4] \n\t" | |
110 | "ld.ab r15, [sp, 4] \n\t" | |
111 | "ld.ab r14, [sp, 4] \n\t" | |
112 | "ld.ab r13, [sp, 4] \n\t" | |
113 | ||
114 | /* last (ret value) = prev : although for ARC it mov r0, r0 */ | |
115 | "mov %0, %3 \n\t" | |
116 | ||
117 | /* FP/BLINK restore generated by gcc (standard func epilogue */ | |
118 | ||
119 | : "=r"(tmp) | |
57e26e57 | 120 | : "n"(KSP_WORD_OFF), "r"(next), "r"(prev) |
86c25466 NC |
121 | #ifdef CONFIG_ARC_PLAT_EZNPS |
122 | , "i"(CTOP_AUX_LOGIC_GLOBAL_ID) | |
123 | #endif | |
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124 | : "blink" |
125 | ); | |
126 | ||
127 | return (struct task_struct *)tmp; | |
128 | } |