1 /* MN10300 FPU management
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11 #include <asm/uaccess.h>
12 #include <asm/fpu.h>
13 #include <asm/elf.h>
14 #include <asm/exceptions.h>
15 #include <asm/system.h>
16
17 #ifdef CONFIG_LAZY_SAVE_FPU
18 struct task_struct *fpu_state_owner;
19 #endif
20
21 /*
22 * error functions in FPU disabled exception
23 */
fpu_disabled_in_kernel(struct pt_regs * regs)24 asmlinkage void fpu_disabled_in_kernel(struct pt_regs *regs)
25 {
26 die_if_no_fixup("An FPU Disabled exception happened in kernel space\n",
27 regs, EXCEP_FPU_DISABLED);
28 }
29
30 /*
31 * handle an FPU operational exception
32 * - there's a possibility that if the FPU is asynchronous, the signal might
33 * be meant for a process other than the current one
34 */
fpu_exception(struct pt_regs * regs,enum exception_code code)35 asmlinkage void fpu_exception(struct pt_regs *regs, enum exception_code code)
36 {
37 struct task_struct *tsk = current;
38 siginfo_t info;
39 u32 fpcr;
40
41 if (!user_mode(regs))
42 die_if_no_fixup("An FPU Operation exception happened in"
43 " kernel space\n",
44 regs, code);
45
46 if (!is_using_fpu(tsk))
47 die_if_no_fixup("An FPU Operation exception happened,"
48 " but the FPU is not in use",
49 regs, code);
50
51 info.si_signo = SIGFPE;
52 info.si_errno = 0;
53 info.si_addr = (void *) tsk->thread.uregs->pc;
54 info.si_code = FPE_FLTINV;
55
56 unlazy_fpu(tsk);
57
58 fpcr = tsk->thread.fpu_state.fpcr;
59
60 if (fpcr & FPCR_EC_Z)
61 info.si_code = FPE_FLTDIV;
62 else if (fpcr & FPCR_EC_O)
63 info.si_code = FPE_FLTOVF;
64 else if (fpcr & FPCR_EC_U)
65 info.si_code = FPE_FLTUND;
66 else if (fpcr & FPCR_EC_I)
67 info.si_code = FPE_FLTRES;
68
69 force_sig_info(SIGFPE, &info, tsk);
70 }
71
72 /*
73 * save the FPU state to a signal context
74 */
fpu_setup_sigcontext(struct fpucontext * fpucontext)75 int fpu_setup_sigcontext(struct fpucontext *fpucontext)
76 {
77 struct task_struct *tsk = current;
78
79 if (!is_using_fpu(tsk))
80 return 0;
81
82 /* transfer the current FPU state to memory and cause fpu_init() to be
83 * triggered by the next attempted FPU operation by the current
84 * process.
85 */
86 preempt_disable();
87
88 #ifndef CONFIG_LAZY_SAVE_FPU
89 if (tsk->thread.fpu_flags & THREAD_HAS_FPU) {
90 fpu_save(&tsk->thread.fpu_state);
91 tsk->thread.uregs->epsw &= ~EPSW_FE;
92 tsk->thread.fpu_flags &= ~THREAD_HAS_FPU;
93 }
94 #else /* !CONFIG_LAZY_SAVE_FPU */
95 if (fpu_state_owner == tsk) {
96 fpu_save(&tsk->thread.fpu_state);
97 fpu_state_owner->thread.uregs->epsw &= ~EPSW_FE;
98 fpu_state_owner = NULL;
99 }
100 #endif /* !CONFIG_LAZY_SAVE_FPU */
101
102 preempt_enable();
103
104 /* we no longer have a valid current FPU state */
105 clear_using_fpu(tsk);
106
107 /* transfer the saved FPU state onto the userspace stack */
108 if (copy_to_user(fpucontext,
109 &tsk->thread.fpu_state,
110 min(sizeof(struct fpu_state_struct),
111 sizeof(struct fpucontext))))
112 return -1;
113
114 return 1;
115 }
116
117 /*
118 * kill a process's FPU state during restoration after signal handling
119 */
fpu_kill_state(struct task_struct * tsk)120 void fpu_kill_state(struct task_struct *tsk)
121 {
122 /* disown anything left in the FPU */
123 preempt_disable();
124
125 #ifndef CONFIG_LAZY_SAVE_FPU
126 if (tsk->thread.fpu_flags & THREAD_HAS_FPU) {
127 tsk->thread.uregs->epsw &= ~EPSW_FE;
128 tsk->thread.fpu_flags &= ~THREAD_HAS_FPU;
129 }
130 #else /* !CONFIG_LAZY_SAVE_FPU */
131 if (fpu_state_owner == tsk) {
132 fpu_state_owner->thread.uregs->epsw &= ~EPSW_FE;
133 fpu_state_owner = NULL;
134 }
135 #endif /* !CONFIG_LAZY_SAVE_FPU */
136
137 preempt_enable();
138
139 /* we no longer have a valid current FPU state */
140 clear_using_fpu(tsk);
141 }
142
143 /*
144 * restore the FPU state from a signal context
145 */
fpu_restore_sigcontext(struct fpucontext * fpucontext)146 int fpu_restore_sigcontext(struct fpucontext *fpucontext)
147 {
148 struct task_struct *tsk = current;
149 int ret;
150
151 /* load up the old FPU state */
152 ret = copy_from_user(&tsk->thread.fpu_state, fpucontext,
153 min(sizeof(struct fpu_state_struct),
154 sizeof(struct fpucontext)));
155 if (!ret)
156 set_using_fpu(tsk);
157
158 return ret;
159 }
160
161 /*
162 * fill in the FPU structure for a core dump
163 */
dump_fpu(struct pt_regs * regs,elf_fpregset_t * fpreg)164 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpreg)
165 {
166 struct task_struct *tsk = current;
167 int fpvalid;
168
169 fpvalid = is_using_fpu(tsk);
170 if (fpvalid) {
171 unlazy_fpu(tsk);
172 memcpy(fpreg, &tsk->thread.fpu_state, sizeof(*fpreg));
173 }
174
175 return fpvalid;
176 }
177