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1da177e4 LT |
1 | /* |
2 | * r2300_switch.S: R2300 specific task switching code. | |
3 | * | |
4 | * Copyright (C) 1994, 1995, 1996, 1999 by Ralf Baechle | |
5 | * Copyright (C) 1994, 1995, 1996 by Andreas Busse | |
6 | * | |
7 | * Multi-cpu abstraction and macros for easier reading: | |
79add627 | 8 | * Copyright (C) 1996 David S. Miller (davem@davemloft.net) |
1da177e4 LT |
9 | * |
10 | * Further modifications to make this work: | |
11 | * Copyright (c) 1998-2000 Harald Koerfgen | |
12 | */ | |
1da177e4 LT |
13 | #include <asm/asm.h> |
14 | #include <asm/cachectl.h> | |
15 | #include <asm/fpregdef.h> | |
16 | #include <asm/mipsregs.h> | |
048eb582 | 17 | #include <asm/asm-offsets.h> |
1da177e4 LT |
18 | #include <asm/regdef.h> |
19 | #include <asm/stackframe.h> | |
20 | #include <asm/thread_info.h> | |
21 | ||
22 | #include <asm/asmmacro.h> | |
23 | ||
24 | .set mips1 | |
25 | .align 5 | |
26 | ||
27 | /* | |
28 | * Offset to the current process status flags, the first 32 bytes of the | |
29 | * stack are not used. | |
30 | */ | |
31 | #define ST_OFF (_THREAD_SIZE - 32 - PT_SIZE + PT_STATUS) | |
32 | ||
33 | /* | |
34 | * FPU context is saved iff the process has used it's FPU in the current | |
35 | * time slice as indicated by TIF_USEDFPU. In any case, the CU1 bit for user | |
42a3b4f2 | 36 | * space STATUS register should be 0, so that a process *always* starts its |
1da177e4 LT |
37 | * userland with FPU disabled after each context switch. |
38 | * | |
39 | * FPU will be enabled as soon as the process accesses FPU again, through | |
40 | * do_cpu() trap. | |
41 | */ | |
42 | ||
43 | /* | |
44 | * task_struct *resume(task_struct *prev, task_struct *next, | |
70342287 | 45 | * struct thread_info *next_ti, int usedfpu) |
1da177e4 LT |
46 | */ |
47 | LEAF(resume) | |
5323180d AN |
48 | mfc0 t1, CP0_STATUS |
49 | sw t1, THREAD_STATUS(a0) | |
1da177e4 LT |
50 | cpu_save_nonscratch a0 |
51 | sw ra, THREAD_REG31(a0) | |
52 | ||
2dd17030 | 53 | beqz a3, 1f |
1da177e4 | 54 | |
2dd17030 | 55 | PTR_L t3, TASK_THREAD_INFO(a0) |
1da177e4 LT |
56 | |
57 | /* | |
58 | * clear saved user stack CU1 bit | |
59 | */ | |
60 | lw t0, ST_OFF(t3) | |
61 | li t1, ~ST0_CU1 | |
62 | and t0, t0, t1 | |
63 | sw t0, ST_OFF(t3) | |
64 | ||
65 | fpu_save_single a0, t0 # clobbers t0 | |
66 | ||
67 | 1: | |
1400eb65 GF |
68 | |
69 | #if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP) | |
8b3c569a | 70 | PTR_LA t8, __stack_chk_guard |
1400eb65 GF |
71 | LONG_L t9, TASK_STACK_CANARY(a1) |
72 | LONG_S t9, 0(t8) | |
73 | #endif | |
74 | ||
1da177e4 LT |
75 | /* |
76 | * The order of restoring the registers takes care of the race | |
77 | * updating $28, $29 and kernelsp without disabling ints. | |
78 | */ | |
79 | move $28, a2 | |
80 | cpu_restore_nonscratch a1 | |
81 | ||
82 | addiu t1, $28, _THREAD_SIZE - 32 | |
83 | sw t1, kernelsp | |
84 | ||
85 | mfc0 t1, CP0_STATUS /* Do we really need this? */ | |
86 | li a3, 0xff01 | |
87 | and t1, a3 | |
88 | lw a2, THREAD_STATUS(a1) | |
89 | nor a3, $0, a3 | |
90 | and a2, a3 | |
91 | or a2, t1 | |
92 | mtc0 a2, CP0_STATUS | |
93 | move v0, a0 | |
94 | jr ra | |
95 | END(resume) | |
96 | ||
97 | /* | |
98 | * Save a thread's fp context. | |
99 | */ | |
100 | LEAF(_save_fp) | |
101 | fpu_save_single a0, t1 # clobbers t1 | |
102 | jr ra | |
103 | END(_save_fp) | |
104 | ||
105 | /* | |
106 | * Restore a thread's fp context. | |
107 | */ | |
108 | LEAF(_restore_fp) | |
109 | fpu_restore_single a0, t1 # clobbers t1 | |
110 | jr ra | |
111 | END(_restore_fp) | |
112 | ||
113 | /* | |
114 | * Load the FPU with signalling NANS. This bit pattern we're using has | |
115 | * the property that no matter whether considered as single or as double | |
116 | * precision represents signaling NANS. | |
117 | * | |
118 | * We initialize fcr31 to rounding to nearest, no exceptions. | |
119 | */ | |
120 | ||
121 | #define FPU_DEFAULT 0x00000000 | |
122 | ||
123 | LEAF(_init_fpu) | |
124 | mfc0 t0, CP0_STATUS | |
125 | li t1, ST0_CU1 | |
126 | or t0, t1 | |
127 | mtc0 t0, CP0_STATUS | |
128 | ||
129 | li t1, FPU_DEFAULT | |
130 | ctc1 t1, fcr31 | |
131 | ||
132 | li t0, -1 | |
133 | ||
134 | mtc1 t0, $f0 | |
135 | mtc1 t0, $f1 | |
136 | mtc1 t0, $f2 | |
137 | mtc1 t0, $f3 | |
138 | mtc1 t0, $f4 | |
139 | mtc1 t0, $f5 | |
140 | mtc1 t0, $f6 | |
141 | mtc1 t0, $f7 | |
142 | mtc1 t0, $f8 | |
143 | mtc1 t0, $f9 | |
144 | mtc1 t0, $f10 | |
145 | mtc1 t0, $f11 | |
146 | mtc1 t0, $f12 | |
147 | mtc1 t0, $f13 | |
148 | mtc1 t0, $f14 | |
149 | mtc1 t0, $f15 | |
150 | mtc1 t0, $f16 | |
151 | mtc1 t0, $f17 | |
152 | mtc1 t0, $f18 | |
153 | mtc1 t0, $f19 | |
154 | mtc1 t0, $f20 | |
155 | mtc1 t0, $f21 | |
156 | mtc1 t0, $f22 | |
157 | mtc1 t0, $f23 | |
158 | mtc1 t0, $f24 | |
159 | mtc1 t0, $f25 | |
160 | mtc1 t0, $f26 | |
161 | mtc1 t0, $f27 | |
162 | mtc1 t0, $f28 | |
163 | mtc1 t0, $f29 | |
164 | mtc1 t0, $f30 | |
165 | mtc1 t0, $f31 | |
166 | jr ra | |
167 | END(_init_fpu) |