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coral / linux-mtk / 159f597a8bd0f1d7650d5e580c93a2666c9c26d1 / . / arch / ppc / kernel / fpu.S
blob: 6189b26f640f28ece1408e5393258fb3d97d461e [file] [log] [blame]
Paul Mackerras443a8482005-05-01 08:58:40 -0700[diff] [blame]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>
13#include <asm/processor.h>
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/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 */
30 .globl load_up_fpu
31load_up_fpu:
32 mfmsr r5
33 ori r5,r5,MSR_FP
34#ifdef CONFIG_PPC64BRIDGE
35 clrldi r5,r5,1 /* turn off 64-bit mode */
36#endif /* CONFIG_PPC64BRIDGE */
37 SYNC
38 MTMSRD(r5) /* enable use of fpu now */
39 isync
40/*
41 * For SMP, we don't do lazy FPU switching because it just gets too
42 * horrendously complex, especially when a task switches from one CPU
43 * to another. Instead we call giveup_fpu in switch_to.
44 */
45#ifndef CONFIG_SMP
46 tophys(r6,0) /* get __pa constant */
47 addis r3,r6,last_task_used_math@ha
48 lwz r4,last_task_used_math@l(r3)
49 cmpwi 0,r4,0
50 beq 1f
51 add r4,r4,r6
52 addi r4,r4,THREAD /* want last_task_used_math->thread */
53 SAVE_32FPRS(0, r4)
54 mffs fr0
55 stfd fr0,THREAD_FPSCR-4(r4)
56 lwz r5,PT_REGS(r4)
57 add r5,r5,r6
58 lwz r4,_MSR-STACK_FRAME_OVERHEAD(r5)
59 li r10,MSR_FP|MSR_FE0|MSR_FE1
60 andc r4,r4,r10 /* disable FP for previous task */
61 stw r4,_MSR-STACK_FRAME_OVERHEAD(r5)
621:
63#endif /* CONFIG_SMP */
64 /* enable use of FP after return */
65 mfspr r5,SPRN_SPRG3 /* current task's THREAD (phys) */
66 lwz r4,THREAD_FPEXC_MODE(r5)
67 ori r9,r9,MSR_FP /* enable FP for current */
68 or r9,r9,r4
69 lfd fr0,THREAD_FPSCR-4(r5)
70 mtfsf 0xff,fr0
71 REST_32FPRS(0, r5)
72#ifndef CONFIG_SMP
73 subi r4,r5,THREAD
74 sub r4,r4,r6
75 stw r4,last_task_used_math@l(r3)
76#endif /* CONFIG_SMP */
77 /* restore registers and return */
78 /* we haven't used ctr or xer or lr */
79 b fast_exception_return
80
81/*
82 * FP unavailable trap from kernel - print a message, but let
83 * the task use FP in the kernel until it returns to user mode.
84 */
85 .globl KernelFP
86KernelFP:
87 lwz r3,_MSR(r1)
88 ori r3,r3,MSR_FP
89 stw r3,_MSR(r1) /* enable use of FP after return */
90 lis r3,86f@h
91 ori r3,r3,86f@l
92 mr r4,r2 /* current */
93 lwz r5,_NIP(r1)
94 bl printk
95 b ret_from_except
9686: .string "floating point used in kernel (task=%p, pc=%x)\n"
97 .align 4,0
98
99/*
100 * giveup_fpu(tsk)
101 * Disable FP for the task given as the argument,
102 * and save the floating-point registers in its thread_struct.
103 * Enables the FPU for use in the kernel on return.
104 */
105 .globl giveup_fpu
106giveup_fpu:
107 mfmsr r5
108 ori r5,r5,MSR_FP
109 SYNC_601
110 ISYNC_601
111 MTMSRD(r5) /* enable use of fpu now */
112 SYNC_601
113 isync
114 cmpwi 0,r3,0
115 beqlr- /* if no previous owner, done */
116 addi r3,r3,THREAD /* want THREAD of task */
117 lwz r5,PT_REGS(r3)
118 cmpwi 0,r5,0
119 SAVE_32FPRS(0, r3)
120 mffs fr0
121 stfd fr0,THREAD_FPSCR-4(r3)
122 beq 1f
123 lwz r4,_MSR-STACK_FRAME_OVERHEAD(r5)
124 li r3,MSR_FP|MSR_FE0|MSR_FE1
125 andc r4,r4,r3 /* disable FP for previous task */
126 stw r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1271:
128#ifndef CONFIG_SMP
129 li r5,0
130 lis r4,last_task_used_math@ha
131 stw r5,last_task_used_math@l(r4)
132#endif /* CONFIG_SMP */
133 blr