fpu.c revision 266004 
1/*-
2 * Copyright (C) 1996 Wolfgang Solfrank.
3 * Copyright (C) 1996 TooLs GmbH.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. All advertising materials mentioning features or use of this software
15 *    must display the following acknowledgement:
16 *	This product includes software developed by TooLs GmbH.
17 * 4. The name of TooLs GmbH may not be used to endorse or promote products
18 *    derived from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
26 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
27 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
28 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
29 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 *
31 *	$NetBSD: fpu.c,v 1.5 2001/07/22 11:29:46 wiz Exp $
32 */
33
34#include <sys/cdefs.h>
35__FBSDID("$FreeBSD: stable/10/sys/powerpc/powerpc/fpu.c 266004 2014-05-14 04:42:38Z ian $");
36
37#include <sys/param.h>
38#include <sys/proc.h>
39#include <sys/systm.h>
40#include <sys/limits.h>
41
42#include <machine/fpu.h>
43#include <machine/pcb.h>
44#include <machine/psl.h>
45
46void
47enable_fpu(struct thread *td)
48{
49	int	msr;
50	struct	pcb *pcb;
51	struct	trapframe *tf;
52
53	pcb = td->td_pcb;
54	tf = trapframe(td);
55
56	/*
57	 * Save the thread's FPU CPU number, and set the CPU's current
58	 * FPU thread
59	 */
60	td->td_pcb->pcb_fpcpu = PCPU_GET(cpuid);
61	PCPU_SET(fputhread, td);
62
63	/*
64	 * Enable the FPU for when the thread returns from the exception.
65	 * If this is the first time the FPU has been used by the thread,
66	 * initialise the FPU registers and FPSCR to 0, and set the flag
67	 * to indicate that the FPU is in use.
68	 */
69	pcb->pcb_flags |= PCB_FPU;
70	tf->srr1 |= PSL_FP;
71	if (!(pcb->pcb_flags & PCB_FPREGS)) {
72		memset(&pcb->pcb_fpu, 0, sizeof pcb->pcb_fpu);
73		pcb->pcb_flags |= PCB_FPREGS;
74	}
75
76	/*
77	 * Temporarily enable floating-point so the registers
78	 * can be restored.
79	 */
80	msr = mfmsr();
81	mtmsr(msr | PSL_FP);
82	isync();
83
84	/*
85	 * Load the floating point registers and FPSCR from the PCB.
86	 * (A value of 0xff for mtfsf specifies that all 8 4-bit fields
87	 * of the saved FPSCR are to be loaded from the FPU reg).
88	 */
89	__asm __volatile ("lfd 0,0(%0); mtfsf 0xff,0"
90			  :: "b"(&pcb->pcb_fpu.fpscr));
91
92#define LFP(n)   __asm ("lfd " #n ", 0(%0)" \
93		:: "b"(&pcb->pcb_fpu.fpr[n]));
94	LFP(0);		LFP(1);		LFP(2);		LFP(3);
95	LFP(4);		LFP(5);		LFP(6);		LFP(7);
96	LFP(8);		LFP(9);		LFP(10);	LFP(11);
97	LFP(12);	LFP(13);	LFP(14);	LFP(15);
98	LFP(16);	LFP(17);	LFP(18);	LFP(19);
99	LFP(20);	LFP(21);	LFP(22);	LFP(23);
100	LFP(24);	LFP(25);	LFP(26);	LFP(27);
101	LFP(28);	LFP(29);	LFP(30);	LFP(31);
102#undef LFP
103
104	isync();
105	mtmsr(msr);
106}
107
108void
109save_fpu(struct thread *td)
110{
111	int	msr;
112	struct	pcb *pcb;
113
114	pcb = td->td_pcb;
115
116	/*
117	 * Temporarily re-enable floating-point during the save
118	 */
119	msr = mfmsr();
120	mtmsr(msr | PSL_FP);
121	isync();
122
123	/*
124	 * Save the floating-point registers and FPSCR to the PCB
125	 */
126#define SFP(n)   __asm ("stfd " #n ", 0(%0)" \
127		:: "b"(&pcb->pcb_fpu.fpr[n]));
128	SFP(0);		SFP(1);		SFP(2);		SFP(3);
129	SFP(4);		SFP(5);		SFP(6);		SFP(7);
130	SFP(8);		SFP(9);		SFP(10);	SFP(11);
131	SFP(12);	SFP(13);	SFP(14);	SFP(15);
132	SFP(16);	SFP(17);	SFP(18);	SFP(19);
133	SFP(20);	SFP(21);	SFP(22);	SFP(23);
134	SFP(24);	SFP(25);	SFP(26);	SFP(27);
135	SFP(28);	SFP(29);	SFP(30);	SFP(31);
136#undef SFP
137	__asm __volatile ("mffs 0; stfd 0,0(%0)" :: "b"(&pcb->pcb_fpu.fpscr));
138
139	/*
140	 * Disable floating-point again
141	 */
142	isync();
143	mtmsr(msr);
144
145	/*
146	 * Clear the current fp thread and pcb's CPU id
147	 * XXX should this be left clear to allow lazy save/restore ?
148	 */
149	pcb->pcb_fpcpu = INT_MAX;
150	PCPU_SET(fputhread, NULL);
151}
152
153