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#include <asm/system.h>
  16
  17#ifdef CONFIG_LAZY_SAVE_FPU
  18struct task_struct *fpu_state_owner;
  19#endif
  20
  21/*
  22 * error functions in FPU disabled exception
  23 */
  24asmlinkage 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 */
  35asmlinkage 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 */
  75int 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 */
 120void 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 */
 146int 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 */
 164int 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