summaryrefslogtreecommitdiffstats
path: root/arch/mn10300/kernel/fpu.c
blob: 2578b7ae7dd55e6a303f4e91c3058ab66ed38c57 (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
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
/* MN10300 FPU management
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */
#include <linux/uaccess.h>
#include <asm/fpu.h>
#include <asm/elf.h>
#include <asm/exceptions.h>

#ifdef CONFIG_LAZY_SAVE_FPU
struct task_struct *fpu_state_owner;
#endif

/*
 * error functions in FPU disabled exception
 */
asmlinkage void fpu_disabled_in_kernel(struct pt_regs *regs)
{
	die_if_no_fixup("An FPU Disabled exception happened in kernel space\n",
			regs, EXCEP_FPU_DISABLED);
}

/*
 * handle an FPU operational exception
 * - there's a possibility that if the FPU is asynchronous, the signal might
 *   be meant for a process other than the current one
 */
asmlinkage void fpu_exception(struct pt_regs *regs, enum exception_code code)
{
	struct task_struct *tsk = current;
	siginfo_t info;
	u32 fpcr;

	if (!user_mode(regs))
		die_if_no_fixup("An FPU Operation exception happened in"
				" kernel space\n",
				regs, code);

	if (!is_using_fpu(tsk))
		die_if_no_fixup("An FPU Operation exception happened,"
				" but the FPU is not in use",
				regs, code);

	info.si_signo = SIGFPE;
	info.si_errno = 0;
	info.si_addr = (void *) tsk->thread.uregs->pc;
	info.si_code = FPE_FLTINV;

	unlazy_fpu(tsk);

	fpcr = tsk->thread.fpu_state.fpcr;

	if (fpcr & FPCR_EC_Z)
		info.si_code = FPE_FLTDIV;
	else if	(fpcr & FPCR_EC_O)
		info.si_code = FPE_FLTOVF;
	else if	(fpcr & FPCR_EC_U)
		info.si_code = FPE_FLTUND;
	else if	(fpcr & FPCR_EC_I)
		info.si_code = FPE_FLTRES;

	force_sig_info(SIGFPE, &info, tsk);
}

/*
 * save the FPU state to a signal context
 */
int fpu_setup_sigcontext(struct fpucontext *fpucontext)
{
	struct task_struct *tsk = current;

	if (!is_using_fpu(tsk))
		return 0;

	/* transfer the current FPU state to memory and cause fpu_init() to be
	 * triggered by the next attempted FPU operation by the current
	 * process.
	 */
	preempt_disable();

#ifndef CONFIG_LAZY_SAVE_FPU
	if (tsk->thread.fpu_flags & THREAD_HAS_FPU) {
		fpu_save(&tsk->thread.fpu_state);
		tsk->thread.uregs->epsw &= ~EPSW_FE;
		tsk->thread.fpu_flags &= ~THREAD_HAS_FPU;
	}
#else /* !CONFIG_LAZY_SAVE_FPU */
	if (fpu_state_owner == tsk) {
		fpu_save(&tsk->thread.fpu_state);
		fpu_state_owner->thread.uregs->epsw &= ~EPSW_FE;
		fpu_state_owner = NULL;
	}
#endif /* !CONFIG_LAZY_SAVE_FPU */

	preempt_enable();

	/* we no longer have a valid current FPU state */
	clear_using_fpu(tsk);

	/* transfer the saved FPU state onto the userspace stack */
	if (copy_to_user(fpucontext,
			 &tsk->thread.fpu_state,
			 min(sizeof(struct fpu_state_struct),
			     sizeof(struct fpucontext))))
		return -1;

	return 1;
}

/*
 * kill a process's FPU state during restoration after signal handling
 */
void fpu_kill_state(struct task_struct *tsk)
{
	/* disown anything left in the FPU */
	preempt_disable();

#ifndef CONFIG_LAZY_SAVE_FPU
	if (tsk->thread.fpu_flags & THREAD_HAS_FPU) {
		tsk->thread.uregs->epsw &= ~EPSW_FE;
		tsk->thread.fpu_flags &= ~THREAD_HAS_FPU;
	}
#else /* !CONFIG_LAZY_SAVE_FPU */
	if (fpu_state_owner == tsk) {
		fpu_state_owner->thread.uregs->epsw &= ~EPSW_FE;
		fpu_state_owner = NULL;
	}
#endif /* !CONFIG_LAZY_SAVE_FPU */

	preempt_enable();

	/* we no longer have a valid current FPU state */
	clear_using_fpu(tsk);
}

/*
 * restore the FPU state from a signal context
 */
int fpu_restore_sigcontext(struct fpucontext *fpucontext)
{
	struct task_struct *tsk = current;
	int ret;

	/* load up the old FPU state */
	ret = copy_from_user(&tsk->thread.fpu_state, fpucontext,
			     min(sizeof(struct fpu_state_struct),
				 sizeof(struct fpucontext)));
	if (!ret)
		set_using_fpu(tsk);

	return ret;
}

/*
 * fill in the FPU structure for a core dump
 */
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpreg)
{
	struct task_struct *tsk = current;
	int fpvalid;

	fpvalid = is_using_fpu(tsk);
	if (fpvalid) {
		unlazy_fpu(tsk);
		memcpy(fpreg, &tsk->thread.fpu_state, sizeof(*fpreg));
	}

	return fpvalid;
}
OpenPOWER on IntegriCloud