]>
Commit | Line | Data |
---|---|---|
bf90e1ea VG |
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> | |
19 | ||
57e26e57 VG |
20 | #define KSP_WORD_OFF ((TASK_THREAD + THREAD_KSP) / 4) |
21 | ||
bf90e1ea VG |
22 | struct task_struct *__sched |
23 | __switch_to(struct task_struct *prev_task, struct task_struct *next_task) | |
24 | { | |
25 | unsigned int tmp; | |
26 | unsigned int prev = (unsigned int)prev_task; | |
27 | unsigned int next = (unsigned int)next_task; | |
bf90e1ea VG |
28 | |
29 | __asm__ __volatile__( | |
30 | /* FP/BLINK save generated by gcc (standard function prologue */ | |
31 | "st.a r13, [sp, -4] \n\t" | |
32 | "st.a r14, [sp, -4] \n\t" | |
33 | "st.a r15, [sp, -4] \n\t" | |
34 | "st.a r16, [sp, -4] \n\t" | |
35 | "st.a r17, [sp, -4] \n\t" | |
36 | "st.a r18, [sp, -4] \n\t" | |
37 | "st.a r19, [sp, -4] \n\t" | |
38 | "st.a r20, [sp, -4] \n\t" | |
39 | "st.a r21, [sp, -4] \n\t" | |
40 | "st.a r22, [sp, -4] \n\t" | |
41 | "st.a r23, [sp, -4] \n\t" | |
42 | "st.a r24, [sp, -4] \n\t" | |
080c3747 | 43 | #ifndef CONFIG_ARC_CURR_IN_REG |
bf90e1ea | 44 | "st.a r25, [sp, -4] \n\t" |
16f9afe6 VG |
45 | #else |
46 | "sub sp, sp, 4 \n\t" /* usual r25 placeholder */ | |
080c3747 | 47 | #endif |
bf90e1ea VG |
48 | |
49 | /* set ksp of outgoing task in tsk->thread.ksp */ | |
57e26e57 | 50 | #if KSP_WORD_OFF <= 255 |
bf90e1ea | 51 | "st.as sp, [%3, %1] \n\t" |
57e26e57 VG |
52 | #else |
53 | /* | |
54 | * Workaround for NR_CPUS=4k | |
55 | * %1 is bigger than 255 (S9 offset for st.as) | |
56 | */ | |
57 | "add2 r24, %3, %1 \n\t" | |
58 | "st sp, [r24] \n\t" | |
59 | #endif | |
bf90e1ea | 60 | |
bf90e1ea VG |
61 | /* |
62 | * setup _current_task with incoming tsk. | |
63 | * optionally, set r25 to that as well | |
64 | * For SMP extra work to get to &_current_task[cpu] | |
65 | * (open coded SET_CURR_TASK_ON_CPU) | |
66 | */ | |
41195d23 | 67 | #ifndef CONFIG_SMP |
bf90e1ea | 68 | "st %2, [@_current_task] \n\t" |
41195d23 VG |
69 | #else |
70 | "lr r24, [identity] \n\t" | |
71 | "lsr r24, r24, 8 \n\t" | |
72 | "bmsk r24, r24, 7 \n\t" | |
73 | "add2 r24, @_current_task, r24 \n\t" | |
74 | "st %2, [r24] \n\t" | |
75 | #endif | |
76 | #ifdef CONFIG_ARC_CURR_IN_REG | |
77 | "mov r25, %2 \n\t" | |
78 | #endif | |
bf90e1ea VG |
79 | |
80 | /* get ksp of incoming task from tsk->thread.ksp */ | |
81 | "ld.as sp, [%2, %1] \n\t" | |
82 | ||
83 | /* start loading it's CALLEE reg file */ | |
84 | ||
080c3747 | 85 | #ifndef CONFIG_ARC_CURR_IN_REG |
bf90e1ea | 86 | "ld.ab r25, [sp, 4] \n\t" |
16f9afe6 VG |
87 | #else |
88 | "add sp, sp, 4 \n\t" | |
080c3747 | 89 | #endif |
bf90e1ea VG |
90 | "ld.ab r24, [sp, 4] \n\t" |
91 | "ld.ab r23, [sp, 4] \n\t" | |
92 | "ld.ab r22, [sp, 4] \n\t" | |
93 | "ld.ab r21, [sp, 4] \n\t" | |
94 | "ld.ab r20, [sp, 4] \n\t" | |
95 | "ld.ab r19, [sp, 4] \n\t" | |
96 | "ld.ab r18, [sp, 4] \n\t" | |
97 | "ld.ab r17, [sp, 4] \n\t" | |
98 | "ld.ab r16, [sp, 4] \n\t" | |
99 | "ld.ab r15, [sp, 4] \n\t" | |
100 | "ld.ab r14, [sp, 4] \n\t" | |
101 | "ld.ab r13, [sp, 4] \n\t" | |
102 | ||
103 | /* last (ret value) = prev : although for ARC it mov r0, r0 */ | |
104 | "mov %0, %3 \n\t" | |
105 | ||
106 | /* FP/BLINK restore generated by gcc (standard func epilogue */ | |
107 | ||
108 | : "=r"(tmp) | |
57e26e57 | 109 | : "n"(KSP_WORD_OFF), "r"(next), "r"(prev) |
bf90e1ea VG |
110 | : "blink" |
111 | ); | |
112 | ||
113 | return (struct task_struct *)tmp; | |
114 | } |