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1 | /* |
2 | * FPU support code, moved here from head.S so that it can be used | |
3 | * by chips which use other head-whatever.S files. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or | |
6 | * modify it under the terms of the GNU General Public License | |
7 | * as published by the Free Software Foundation; either version | |
8 | * 2 of the License, or (at your option) any later version. | |
9 | * | |
10 | */ | |
11 | ||
12 | #include <linux/config.h> | |
b3b8dc6c | 13 | #include <asm/reg.h> |
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14 | #include <asm/page.h> |
15 | #include <asm/mmu.h> | |
16 | #include <asm/pgtable.h> | |
17 | #include <asm/cputable.h> | |
18 | #include <asm/cache.h> | |
19 | #include <asm/thread_info.h> | |
20 | #include <asm/ppc_asm.h> | |
21 | #include <asm/asm-offsets.h> | |
22 | ||
23 | /* | |
24 | * This task wants to use the FPU now. | |
25 | * On UP, disable FP for the task which had the FPU previously, | |
26 | * and save its floating-point registers in its thread_struct. | |
27 | * Load up this task's FP registers from its thread_struct, | |
28 | * enable the FPU for the current task and return to the task. | |
29 | */ | |
b85a046a | 30 | _GLOBAL(load_up_fpu) |
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31 | mfmsr r5 |
32 | ori r5,r5,MSR_FP | |
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33 | SYNC |
34 | MTMSRD(r5) /* enable use of fpu now */ | |
35 | isync | |
36 | /* | |
37 | * For SMP, we don't do lazy FPU switching because it just gets too | |
38 | * horrendously complex, especially when a task switches from one CPU | |
39 | * to another. Instead we call giveup_fpu in switch_to. | |
40 | */ | |
41 | #ifndef CONFIG_SMP | |
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42 | LOADBASE(r3, last_task_used_math) |
43 | tophys(r3,r3) | |
44 | LDL r4,OFF(last_task_used_math)(r3) | |
45 | CMPI 0,r4,0 | |
14cf11af | 46 | beq 1f |
b85a046a | 47 | tophys(r4,r4) |
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48 | addi r4,r4,THREAD /* want last_task_used_math->thread */ |
49 | SAVE_32FPRS(0, r4) | |
50 | mffs fr0 | |
51 | stfd fr0,THREAD_FPSCR-4(r4) | |
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52 | LDL r5,PT_REGS(r4) |
53 | tophys(r5,r5) | |
54 | LDL r4,_MSR-STACK_FRAME_OVERHEAD(r5) | |
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55 | li r10,MSR_FP|MSR_FE0|MSR_FE1 |
56 | andc r4,r4,r10 /* disable FP for previous task */ | |
b85a046a | 57 | STL r4,_MSR-STACK_FRAME_OVERHEAD(r5) |
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58 | 1: |
59 | #endif /* CONFIG_SMP */ | |
60 | /* enable use of FP after return */ | |
b85a046a | 61 | #ifdef CONFIG_PPC32 |
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62 | mfspr r5,SPRN_SPRG3 /* current task's THREAD (phys) */ |
63 | lwz r4,THREAD_FPEXC_MODE(r5) | |
64 | ori r9,r9,MSR_FP /* enable FP for current */ | |
65 | or r9,r9,r4 | |
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66 | #else |
67 | ld r4,PACACURRENT(r13) | |
68 | addi r5,r4,THREAD /* Get THREAD */ | |
69 | ld r4,THREAD_FPEXC_MODE(r5) | |
70 | ori r12,r12,MSR_FP | |
71 | or r12,r12,r4 | |
72 | std r12,_MSR(r1) | |
73 | #endif | |
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74 | lfd fr0,THREAD_FPSCR-4(r5) |
75 | mtfsf 0xff,fr0 | |
76 | REST_32FPRS(0, r5) | |
77 | #ifndef CONFIG_SMP | |
78 | subi r4,r5,THREAD | |
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79 | tovirt(r4,r4) |
80 | STL r4,OFF(last_task_used_math)(r3) | |
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81 | #endif /* CONFIG_SMP */ |
82 | /* restore registers and return */ | |
83 | /* we haven't used ctr or xer or lr */ | |
84 | b fast_exception_return | |
85 | ||
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86 | /* |
87 | * giveup_fpu(tsk) | |
88 | * Disable FP for the task given as the argument, | |
89 | * and save the floating-point registers in its thread_struct. | |
90 | * Enables the FPU for use in the kernel on return. | |
91 | */ | |
b85a046a | 92 | _GLOBAL(giveup_fpu) |
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93 | mfmsr r5 |
94 | ori r5,r5,MSR_FP | |
95 | SYNC_601 | |
96 | ISYNC_601 | |
97 | MTMSRD(r5) /* enable use of fpu now */ | |
98 | SYNC_601 | |
99 | isync | |
b85a046a | 100 | CMPI 0,r3,0 |
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101 | beqlr- /* if no previous owner, done */ |
102 | addi r3,r3,THREAD /* want THREAD of task */ | |
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103 | LDL r5,PT_REGS(r3) |
104 | CMPI 0,r5,0 | |
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105 | SAVE_32FPRS(0, r3) |
106 | mffs fr0 | |
107 | stfd fr0,THREAD_FPSCR-4(r3) | |
108 | beq 1f | |
b85a046a | 109 | LDL r4,_MSR-STACK_FRAME_OVERHEAD(r5) |
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110 | li r3,MSR_FP|MSR_FE0|MSR_FE1 |
111 | andc r4,r4,r3 /* disable FP for previous task */ | |
b85a046a | 112 | STL r4,_MSR-STACK_FRAME_OVERHEAD(r5) |
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113 | 1: |
114 | #ifndef CONFIG_SMP | |
115 | li r5,0 | |
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116 | LOADBASE(r4,last_task_used_math) |
117 | STL r5,OFF(last_task_used_math)(r4) | |
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118 | #endif /* CONFIG_SMP */ |
119 | blr |