LXR linux/arch/mn10300/kernel/fpu.c

   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
  17struct task_struct *fpu_state_owner;
  18#endif
  19
  20/*
  21 * error functions in FPU disabled exception
  22 */
  23asmlinkage 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 */
  34asmlinkage 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 */
  74int 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 */
 119void 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 */
 145int 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 */
 163int 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}
 176