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