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/* 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 <linux/sched/signal.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;
}
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