summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/kernel/fpu.S
blob: 340730fb8c9110608c8a47b5eb35724170e10d69 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
/*
 *  FPU support code, moved here from head.S so that it can be used
 *  by chips which use other head-whatever.S files.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */

#include <linux/config.h>
#include <asm/reg.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/pgtable.h>
#include <asm/cputable.h>
#include <asm/cache.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>

/*
 * This task wants to use the FPU now.
 * On UP, disable FP for the task which had the FPU previously,
 * and save its floating-point registers in its thread_struct.
 * Load up this task's FP registers from its thread_struct,
 * enable the FPU for the current task and return to the task.
 */
_GLOBAL(load_up_fpu)
	mfmsr	r5
	ori	r5,r5,MSR_FP
	SYNC
	MTMSRD(r5)			/* enable use of fpu now */
	isync
/*
 * For SMP, we don't do lazy FPU switching because it just gets too
 * horrendously complex, especially when a task switches from one CPU
 * to another.  Instead we call giveup_fpu in switch_to.
 */
#ifndef CONFIG_SMP
	LOAD_REG_ADDRBASE(r3, last_task_used_math)
	toreal(r3)
	PPC_LL	r4,ADDROFF(last_task_used_math)(r3)
	PPC_LCMPI	0,r4,0
	beq	1f
	toreal(r4)
	addi	r4,r4,THREAD		/* want last_task_used_math->thread */
	SAVE_32FPRS(0, r4)
	mffs	fr0
	stfd	fr0,THREAD_FPSCR(r4)
	PPC_LL	r5,PT_REGS(r4)
	toreal(r5)
	PPC_LL	r4,_MSR-STACK_FRAME_OVERHEAD(r5)
	li	r10,MSR_FP|MSR_FE0|MSR_FE1
	andc	r4,r4,r10		/* disable FP for previous task */
	PPC_STL	r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#endif /* CONFIG_SMP */
	/* enable use of FP after return */
#ifdef CONFIG_PPC32
	mfspr	r5,SPRN_SPRG3		/* current task's THREAD (phys) */
	lwz	r4,THREAD_FPEXC_MODE(r5)
	ori	r9,r9,MSR_FP		/* enable FP for current */
	or	r9,r9,r4
#else
	ld	r4,PACACURRENT(r13)
	addi	r5,r4,THREAD		/* Get THREAD */
	lwz	r4,THREAD_FPEXC_MODE(r5)
	ori	r12,r12,MSR_FP
	or	r12,r12,r4
	std	r12,_MSR(r1)
#endif
	lfd	fr0,THREAD_FPSCR(r5)
	mtfsf	0xff,fr0
	REST_32FPRS(0, r5)
#ifndef CONFIG_SMP
	subi	r4,r5,THREAD
	fromreal(r4)
	PPC_STL	r4,ADDROFF(last_task_used_math)(r3)
#endif /* CONFIG_SMP */
	/* restore registers and return */
	/* we haven't used ctr or xer or lr */
	b	fast_exception_return

/*
 * giveup_fpu(tsk)
 * Disable FP for the task given as the argument,
 * and save the floating-point registers in its thread_struct.
 * Enables the FPU for use in the kernel on return.
 */
_GLOBAL(giveup_fpu)
	mfmsr	r5
	ori	r5,r5,MSR_FP
	SYNC_601
	ISYNC_601
	MTMSRD(r5)			/* enable use of fpu now */
	SYNC_601
	isync
	PPC_LCMPI	0,r3,0
	beqlr-				/* if no previous owner, done */
	addi	r3,r3,THREAD	        /* want THREAD of task */
	PPC_LL	r5,PT_REGS(r3)
	PPC_LCMPI	0,r5,0
	SAVE_32FPRS(0, r3)
	mffs	fr0
	stfd	fr0,THREAD_FPSCR(r3)
	beq	1f
	PPC_LL	r4,_MSR-STACK_FRAME_OVERHEAD(r5)
	li	r3,MSR_FP|MSR_FE0|MSR_FE1
	andc	r4,r4,r3		/* disable FP for previous task */
	PPC_STL	r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#ifndef CONFIG_SMP
	li	r5,0
	LOAD_REG_ADDRBASE(r4,last_task_used_math)
	PPC_STL	r5,ADDROFF(last_task_used_math)(r4)
#endif /* CONFIG_SMP */
	blr

/*
 * These are used in the alignment trap handler when emulating
 * single-precision loads and stores.
 * We restore and save the fpscr so the task gets the same result
 * and exceptions as if the cpu had performed the load or store.
 */

_GLOBAL(cvt_fd)
	lfd	0,THREAD_FPSCR(r5)	/* load up fpscr value */
	mtfsf	0xff,0
	lfs	0,0(r3)
	stfd	0,0(r4)
	mffs	0
	stfd	0,THREAD_FPSCR(r5)	/* save new fpscr value */
	blr

_GLOBAL(cvt_df)
	lfd	0,THREAD_FPSCR(r5)	/* load up fpscr value */
	mtfsf	0xff,0
	lfd	0,0(r3)
	stfs	0,0(r4)
	mffs	0
	stfd	0,THREAD_FPSCR(r5)	/* save new fpscr value */
	blr
OpenPOWER on IntegriCloud