[mirror_ubuntu-artful-kernel.git] / arch / mn10300 / kernel / fpu.c

/* 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;
}
Commit	Line	Data
b920de1b DH	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	*/
7c0f6ba6	11	#include <linux/uaccess.h>
3f07c014 IM	12	#include <linux/sched/signal.h>
3f07c014 IM	13
b920de1b DH	14	#include <asm/fpu.h>
	15	#include <asm/elf.h>
	16	#include <asm/exceptions.h>
	17
278d91c4	18	#ifdef CONFIG_LAZY_SAVE_FPU
b920de1b	19	struct task_struct *fpu_state_owner;
278d91c4	20	#endif
b920de1b DH	21
b920de1b DH	22	/*
278d91c4	23	* error functions in FPU disabled exception
b920de1b	24	*/
278d91c4	25	asmlinkage void fpu_disabled_in_kernel(struct pt_regs *regs)
b920de1b	26	{
278d91c4 AT	27	die_if_no_fixup("An FPU Disabled exception happened in kernel space\n",
278d91c4 AT	28	regs, EXCEP_FPU_DISABLED);
b920de1b DH	29	}
	30
	31	/*
	32	* handle an FPU operational exception
	33	* - there's a possibility that if the FPU is asynchronous, the signal might
	34	* be meant for a process other than the current one
	35	*/
	36	asmlinkage void fpu_exception(struct pt_regs *regs, enum exception_code code)
	37	{
278d91c4	38	struct task_struct *tsk = current;
b920de1b	39	siginfo_t info;
278d91c4	40	u32 fpcr;
b920de1b DH	41
	42	if (!user_mode(regs))
	43	die_if_no_fixup("An FPU Operation exception happened in"
	44	" kernel space\n",
	45	regs, code);
	46
278d91c4	47	if (!is_using_fpu(tsk))
b920de1b DH	48	die_if_no_fixup("An FPU Operation exception happened,"
	49	" but the FPU is not in use",
	50	regs, code);
	51
	52	info.si_signo = SIGFPE;
	53	info.si_errno = 0;
	54	info.si_addr = (void *) tsk->thread.uregs->pc;
	55	info.si_code = FPE_FLTINV;
	56
278d91c4	57	unlazy_fpu(tsk);
b920de1b	58
278d91c4 AT	59	fpcr = tsk->thread.fpu_state.fpcr;
	60
	61	if (fpcr & FPCR_EC_Z)
	62	info.si_code = FPE_FLTDIV;
	63	else if (fpcr & FPCR_EC_O)
	64	info.si_code = FPE_FLTOVF;
	65	else if (fpcr & FPCR_EC_U)
	66	info.si_code = FPE_FLTUND;
	67	else if (fpcr & FPCR_EC_I)
	68	info.si_code = FPE_FLTRES;
b920de1b DH	69
	70	force_sig_info(SIGFPE, &info, tsk);
	71	}
	72
	73	/*
	74	* save the FPU state to a signal context
	75	*/
	76	int fpu_setup_sigcontext(struct fpucontext *fpucontext)
	77	{
b920de1b DH	78	struct task_struct *tsk = current;
	79
	80	if (!is_using_fpu(tsk))
	81	return 0;
	82
	83	/* transfer the current FPU state to memory and cause fpu_init() to be
	84	* triggered by the next attempted FPU operation by the current
	85	* process.
	86	*/
	87	preempt_disable();
	88
278d91c4 AT	89	#ifndef CONFIG_LAZY_SAVE_FPU
	90	if (tsk->thread.fpu_flags & THREAD_HAS_FPU) {
	91	fpu_save(&tsk->thread.fpu_state);
	92	tsk->thread.uregs->epsw &= ~EPSW_FE;
	93	tsk->thread.fpu_flags &= ~THREAD_HAS_FPU;
	94	}
	95	#else /* !CONFIG_LAZY_SAVE_FPU */
b920de1b DH	96	if (fpu_state_owner == tsk) {
	97	fpu_save(&tsk->thread.fpu_state);
	98	fpu_state_owner->thread.uregs->epsw &= ~EPSW_FE;
	99	fpu_state_owner = NULL;
	100	}
278d91c4	101	#endif /* !CONFIG_LAZY_SAVE_FPU */
b920de1b DH	102
	103	preempt_enable();
	104
	105	/* we no longer have a valid current FPU state */
	106	clear_using_fpu(tsk);
	107
	108	/* transfer the saved FPU state onto the userspace stack */
	109	if (copy_to_user(fpucontext,
	110	&tsk->thread.fpu_state,
	111	min(sizeof(struct fpu_state_struct),
	112	sizeof(struct fpucontext))))
	113	return -1;
	114
	115	return 1;
b920de1b DH	116	}
	117
	118	/*
	119	* kill a process's FPU state during restoration after signal handling
	120	*/
	121	void fpu_kill_state(struct task_struct *tsk)
	122	{
b920de1b DH	123	/* disown anything left in the FPU */
	124	preempt_disable();
	125
278d91c4 AT	126	#ifndef CONFIG_LAZY_SAVE_FPU
	127	if (tsk->thread.fpu_flags & THREAD_HAS_FPU) {
	128	tsk->thread.uregs->epsw &= ~EPSW_FE;
	129	tsk->thread.fpu_flags &= ~THREAD_HAS_FPU;
	130	}
	131	#else /* !CONFIG_LAZY_SAVE_FPU */
b920de1b DH	132	if (fpu_state_owner == tsk) {
	133	fpu_state_owner->thread.uregs->epsw &= ~EPSW_FE;
	134	fpu_state_owner = NULL;
	135	}
278d91c4	136	#endif /* !CONFIG_LAZY_SAVE_FPU */
b920de1b DH	137
b920de1b DH	138	preempt_enable();
278d91c4	139
b920de1b DH	140	/* we no longer have a valid current FPU state */
	141	clear_using_fpu(tsk);
	142	}
	143
	144	/*
	145	* restore the FPU state from a signal context
	146	*/
	147	int fpu_restore_sigcontext(struct fpucontext *fpucontext)
	148	{
	149	struct task_struct *tsk = current;
	150	int ret;
	151
	152	/* load up the old FPU state */
278d91c4	153	ret = copy_from_user(&tsk->thread.fpu_state, fpucontext,
b920de1b DH	154	min(sizeof(struct fpu_state_struct),
	155	sizeof(struct fpucontext)));
	156	if (!ret)
	157	set_using_fpu(tsk);
	158
	159	return ret;
	160	}
	161
	162	/*
	163	* fill in the FPU structure for a core dump
	164	*/
	165	int dump_fpu(struct pt_regs regs, elf_fpregset_t fpreg)
	166	{
	167	struct task_struct *tsk = current;
	168	int fpvalid;
	169
	170	fpvalid = is_using_fpu(tsk);
	171	if (fpvalid) {
	172	unlazy_fpu(tsk);
	173	memcpy(fpreg, &tsk->thread.fpu_state, sizeof(*fpreg));
	174	}
	175
	176	return fpvalid;
	177	}