[linux-2.6-block.git] / arch / arm64 / kernel / fpsimd.c

/*
 * FP/SIMD context switching and fault handling
 *
 * Copyright (C) 2012 ARM Ltd.
 * Author: Catalin Marinas <catalin.marinas@arm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/cpu.h>
#include <linux/cpu_pm.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/hardirq.h>

#include <asm/fpsimd.h>
#include <asm/cputype.h>

#define FPEXC_IOF	(1 << 0)
#define FPEXC_DZF	(1 << 1)
#define FPEXC_OFF	(1 << 2)
#define FPEXC_UFF	(1 << 3)
#define FPEXC_IXF	(1 << 4)
#define FPEXC_IDF	(1 << 7)

/*
 * In order to reduce the number of times the FPSIMD state is needlessly saved
 * and restored, we need to keep track of two things:
 * (a) for each task, we need to remember which CPU was the last one to have
 *     the task's FPSIMD state loaded into its FPSIMD registers;
 * (b) for each CPU, we need to remember which task's userland FPSIMD state has
 *     been loaded into its FPSIMD registers most recently, or whether it has
 *     been used to perform kernel mode NEON in the meantime.
 *
 * For (a), we add a 'cpu' field to struct fpsimd_state, which gets updated to
 * the id of the current CPU everytime the state is loaded onto a CPU. For (b),
 * we add the per-cpu variable 'fpsimd_last_state' (below), which contains the
 * address of the userland FPSIMD state of the task that was loaded onto the CPU
 * the most recently, or NULL if kernel mode NEON has been performed after that.
 *
 * With this in place, we no longer have to restore the next FPSIMD state right
 * when switching between tasks. Instead, we can defer this check to userland
 * resume, at which time we verify whether the CPU's fpsimd_last_state and the
 * task's fpsimd_state.cpu are still mutually in sync. If this is the case, we
 * can omit the FPSIMD restore.
 *
 * As an optimization, we use the thread_info flag TIF_FOREIGN_FPSTATE to
 * indicate whether or not the userland FPSIMD state of the current task is
 * present in the registers. The flag is set unless the FPSIMD registers of this
 * CPU currently contain the most recent userland FPSIMD state of the current
 * task.
 *
 * For a certain task, the sequence may look something like this:
 * - the task gets scheduled in; if both the task's fpsimd_state.cpu field
 *   contains the id of the current CPU, and the CPU's fpsimd_last_state per-cpu
 *   variable points to the task's fpsimd_state, the TIF_FOREIGN_FPSTATE flag is
 *   cleared, otherwise it is set;
 *
 * - the task returns to userland; if TIF_FOREIGN_FPSTATE is set, the task's
 *   userland FPSIMD state is copied from memory to the registers, the task's
 *   fpsimd_state.cpu field is set to the id of the current CPU, the current
 *   CPU's fpsimd_last_state pointer is set to this task's fpsimd_state and the
 *   TIF_FOREIGN_FPSTATE flag is cleared;
 *
 * - the task executes an ordinary syscall; upon return to userland, the
 *   TIF_FOREIGN_FPSTATE flag will still be cleared, so no FPSIMD state is
 *   restored;
 *
 * - the task executes a syscall which executes some NEON instructions; this is
 *   preceded by a call to kernel_neon_begin(), which copies the task's FPSIMD
 *   register contents to memory, clears the fpsimd_last_state per-cpu variable
 *   and sets the TIF_FOREIGN_FPSTATE flag;
 *
 * - the task gets preempted after kernel_neon_end() is called; as we have not
 *   returned from the 2nd syscall yet, TIF_FOREIGN_FPSTATE is still set so
 *   whatever is in the FPSIMD registers is not saved to memory, but discarded.
 */
static DEFINE_PER_CPU(struct fpsimd_state *, fpsimd_last_state);

/*
 * Trapped FP/ASIMD access.
 */
void do_fpsimd_acc(unsigned int esr, struct pt_regs *regs)
{
	/* TODO: implement lazy context saving/restoring */
	WARN_ON(1);
}

/*
 * Raise a SIGFPE for the current process.
 */
void do_fpsimd_exc(unsigned int esr, struct pt_regs *regs)
{
	siginfo_t info;
	unsigned int si_code = 0;

	if (esr & FPEXC_IOF)
		si_code = FPE_FLTINV;
	else if (esr & FPEXC_DZF)
		si_code = FPE_FLTDIV;
	else if (esr & FPEXC_OFF)
		si_code = FPE_FLTOVF;
	else if (esr & FPEXC_UFF)
		si_code = FPE_FLTUND;
	else if (esr & FPEXC_IXF)
		si_code = FPE_FLTRES;

	memset(&info, 0, sizeof(info));
	info.si_signo = SIGFPE;
	info.si_code = si_code;
	info.si_addr = (void __user *)instruction_pointer(regs);

	send_sig_info(SIGFPE, &info, current);
}

void fpsimd_thread_switch(struct task_struct *next)
{
	/*
	 * Save the current FPSIMD state to memory, but only if whatever is in
	 * the registers is in fact the most recent userland FPSIMD state of
	 * 'current'.
	 */
	if (current->mm && !test_thread_flag(TIF_FOREIGN_FPSTATE))
		fpsimd_save_state(&current->thread.fpsimd_state);

	if (next->mm) {
		/*
		 * If we are switching to a task whose most recent userland
		 * FPSIMD state is already in the registers of *this* cpu,
		 * we can skip loading the state from memory. Otherwise, set
		 * the TIF_FOREIGN_FPSTATE flag so the state will be loaded
		 * upon the next return to userland.
		 */
		struct fpsimd_state *st = &next->thread.fpsimd_state;

		if (__this_cpu_read(fpsimd_last_state) == st
		    && st->cpu == smp_processor_id())
			clear_ti_thread_flag(task_thread_info(next),
					     TIF_FOREIGN_FPSTATE);
		else
			set_ti_thread_flag(task_thread_info(next),
					   TIF_FOREIGN_FPSTATE);
	}
}

void fpsimd_flush_thread(void)
{
	memset(&current->thread.fpsimd_state, 0, sizeof(struct fpsimd_state));
	set_thread_flag(TIF_FOREIGN_FPSTATE);
}

/*
 * Save the userland FPSIMD state of 'current' to memory, but only if the state
 * currently held in the registers does in fact belong to 'current'
 */
void fpsimd_preserve_current_state(void)
{
	preempt_disable();
	if (!test_thread_flag(TIF_FOREIGN_FPSTATE))
		fpsimd_save_state(&current->thread.fpsimd_state);
	preempt_enable();
}

/*
 * Load the userland FPSIMD state of 'current' from memory, but only if the
 * FPSIMD state already held in the registers is /not/ the most recent FPSIMD
 * state of 'current'
 */
void fpsimd_restore_current_state(void)
{
	preempt_disable();
	if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
		struct fpsimd_state *st = &current->thread.fpsimd_state;

		fpsimd_load_state(st);
		this_cpu_write(fpsimd_last_state, st);
		st->cpu = smp_processor_id();
	}
	preempt_enable();
}

/*
 * Load an updated userland FPSIMD state for 'current' from memory and set the
 * flag that indicates that the FPSIMD register contents are the most recent
 * FPSIMD state of 'current'
 */
void fpsimd_update_current_state(struct fpsimd_state *state)
{
	preempt_disable();
	fpsimd_load_state(state);
	if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
		struct fpsimd_state *st = &current->thread.fpsimd_state;

		this_cpu_write(fpsimd_last_state, st);
		st->cpu = smp_processor_id();
	}
	preempt_enable();
}

/*
 * Invalidate live CPU copies of task t's FPSIMD state
 */
void fpsimd_flush_task_state(struct task_struct *t)
{
	t->thread.fpsimd_state.cpu = NR_CPUS;
}

#ifdef CONFIG_KERNEL_MODE_NEON

static DEFINE_PER_CPU(struct fpsimd_partial_state, hardirq_fpsimdstate);
static DEFINE_PER_CPU(struct fpsimd_partial_state, softirq_fpsimdstate);

/*
 * Kernel-side NEON support functions
 */
void kernel_neon_begin_partial(u32 num_regs)
{
	if (in_interrupt()) {
		struct fpsimd_partial_state *s = this_cpu_ptr(
			in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);

		BUG_ON(num_regs > 32);
		fpsimd_save_partial_state(s, roundup(num_regs, 2));
	} else {
		/*
		 * Save the userland FPSIMD state if we have one and if we
		 * haven't done so already. Clear fpsimd_last_state to indicate
		 * that there is no longer userland FPSIMD state in the
		 * registers.
		 */
		preempt_disable();
		if (current->mm &&
		    !test_and_set_thread_flag(TIF_FOREIGN_FPSTATE))
			fpsimd_save_state(&current->thread.fpsimd_state);
		this_cpu_write(fpsimd_last_state, NULL);
	}
}
EXPORT_SYMBOL(kernel_neon_begin_partial);

void kernel_neon_end(void)
{
	if (in_interrupt()) {
		struct fpsimd_partial_state *s = this_cpu_ptr(
			in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
		fpsimd_load_partial_state(s);
	} else {
		preempt_enable();
	}
}
EXPORT_SYMBOL(kernel_neon_end);

#endif /* CONFIG_KERNEL_MODE_NEON */

#ifdef CONFIG_CPU_PM
static int fpsimd_cpu_pm_notifier(struct notifier_block *self,
				  unsigned long cmd, void *v)
{
	switch (cmd) {
	case CPU_PM_ENTER:
		if (current->mm && !test_thread_flag(TIF_FOREIGN_FPSTATE))
			fpsimd_save_state(&current->thread.fpsimd_state);
		this_cpu_write(fpsimd_last_state, NULL);
		break;
	case CPU_PM_EXIT:
		if (current->mm)
			set_thread_flag(TIF_FOREIGN_FPSTATE);
		break;
	case CPU_PM_ENTER_FAILED:
	default:
		return NOTIFY_DONE;
	}
	return NOTIFY_OK;
}

static struct notifier_block fpsimd_cpu_pm_notifier_block = {
	.notifier_call = fpsimd_cpu_pm_notifier,
};

static void fpsimd_pm_init(void)
{
	cpu_pm_register_notifier(&fpsimd_cpu_pm_notifier_block);
}

#else
static inline void fpsimd_pm_init(void) { }
#endif /* CONFIG_CPU_PM */

#ifdef CONFIG_HOTPLUG_CPU
static int fpsimd_cpu_hotplug_notifier(struct notifier_block *nfb,
				       unsigned long action,
				       void *hcpu)
{
	unsigned int cpu = (long)hcpu;

	switch (action) {
	case CPU_DEAD:
	case CPU_DEAD_FROZEN:
		per_cpu(fpsimd_last_state, cpu) = NULL;
		break;
	}
	return NOTIFY_OK;
}

static struct notifier_block fpsimd_cpu_hotplug_notifier_block = {
	.notifier_call = fpsimd_cpu_hotplug_notifier,
};

static inline void fpsimd_hotplug_init(void)
{
	register_cpu_notifier(&fpsimd_cpu_hotplug_notifier_block);
}

#else
static inline void fpsimd_hotplug_init(void) { }
#endif

/*
 * FP/SIMD support code initialisation.
 */
static int __init fpsimd_init(void)
{
	u64 pfr = read_cpuid(ID_AA64PFR0_EL1);

	if (pfr & (0xf << 16)) {
		pr_notice("Floating-point is not implemented\n");
		return 0;
	}
	elf_hwcap |= HWCAP_FP;

	if (pfr & (0xf << 20))
		pr_notice("Advanced SIMD is not implemented\n");
	else
		elf_hwcap |= HWCAP_ASIMD;

	fpsimd_pm_init();
	fpsimd_hotplug_init();

	return 0;
}
late_initcall(fpsimd_init);
Commit	Line	Data
53631b54 CM	1	/*
	2	* FP/SIMD context switching and fault handling
	3	*
	4	* Copyright (C) 2012 ARM Ltd.
	5	* Author: Catalin Marinas <catalin.marinas@arm.com>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program. If not, see <http://www.gnu.org/licenses/>.
	18	*/
	19
32365e64	20	#include <linux/cpu.h>
fb1ab1ab	21	#include <linux/cpu_pm.h>
53631b54 CM	22	#include <linux/kernel.h>
	23	#include <linux/init.h>
	24	#include <linux/sched.h>
	25	#include <linux/signal.h>
4cfb3613	26	#include <linux/hardirq.h>
53631b54 CM	27
	28	#include <asm/fpsimd.h>
	29	#include <asm/cputype.h>
	30
	31	#define FPEXC_IOF (1 << 0)
	32	#define FPEXC_DZF (1 << 1)
	33	#define FPEXC_OFF (1 << 2)
	34	#define FPEXC_UFF (1 << 3)
	35	#define FPEXC_IXF (1 << 4)
	36	#define FPEXC_IDF (1 << 7)
	37
005f78cd AB	38	/*
	39	* In order to reduce the number of times the FPSIMD state is needlessly saved
	40	* and restored, we need to keep track of two things:
	41	* (a) for each task, we need to remember which CPU was the last one to have
	42	* the task's FPSIMD state loaded into its FPSIMD registers;
	43	* (b) for each CPU, we need to remember which task's userland FPSIMD state has
	44	* been loaded into its FPSIMD registers most recently, or whether it has
	45	* been used to perform kernel mode NEON in the meantime.
	46	*
	47	* For (a), we add a 'cpu' field to struct fpsimd_state, which gets updated to
	48	* the id of the current CPU everytime the state is loaded onto a CPU. For (b),
	49	* we add the per-cpu variable 'fpsimd_last_state' (below), which contains the
	50	* address of the userland FPSIMD state of the task that was loaded onto the CPU
	51	* the most recently, or NULL if kernel mode NEON has been performed after that.
	52	*
	53	* With this in place, we no longer have to restore the next FPSIMD state right
	54	* when switching between tasks. Instead, we can defer this check to userland
	55	* resume, at which time we verify whether the CPU's fpsimd_last_state and the
	56	* task's fpsimd_state.cpu are still mutually in sync. If this is the case, we
	57	* can omit the FPSIMD restore.
	58	*
	59	* As an optimization, we use the thread_info flag TIF_FOREIGN_FPSTATE to
	60	* indicate whether or not the userland FPSIMD state of the current task is
	61	* present in the registers. The flag is set unless the FPSIMD registers of this
	62	* CPU currently contain the most recent userland FPSIMD state of the current
	63	* task.
	64	*
	65	* For a certain task, the sequence may look something like this:
	66	* - the task gets scheduled in; if both the task's fpsimd_state.cpu field
	67	* contains the id of the current CPU, and the CPU's fpsimd_last_state per-cpu
	68	* variable points to the task's fpsimd_state, the TIF_FOREIGN_FPSTATE flag is
	69	* cleared, otherwise it is set;
	70	*
	71	* - the task returns to userland; if TIF_FOREIGN_FPSTATE is set, the task's
	72	* userland FPSIMD state is copied from memory to the registers, the task's
	73	* fpsimd_state.cpu field is set to the id of the current CPU, the current
	74	* CPU's fpsimd_last_state pointer is set to this task's fpsimd_state and the
	75	* TIF_FOREIGN_FPSTATE flag is cleared;
	76	*
	77	* - the task executes an ordinary syscall; upon return to userland, the
	78	* TIF_FOREIGN_FPSTATE flag will still be cleared, so no FPSIMD state is
	79	* restored;
	80	*
	81	* - the task executes a syscall which executes some NEON instructions; this is
	82	* preceded by a call to kernel_neon_begin(), which copies the task's FPSIMD
	83	* register contents to memory, clears the fpsimd_last_state per-cpu variable
	84	* and sets the TIF_FOREIGN_FPSTATE flag;
	85	*
	86	* - the task gets preempted after kernel_neon_end() is called; as we have not
	87	* returned from the 2nd syscall yet, TIF_FOREIGN_FPSTATE is still set so
	88	* whatever is in the FPSIMD registers is not saved to memory, but discarded.
	89	*/
	90	static DEFINE_PER_CPU(struct fpsimd_state *, fpsimd_last_state);
	91
53631b54 CM	92	/*
	93	* Trapped FP/ASIMD access.
	94	*/
	95	void do_fpsimd_acc(unsigned int esr, struct pt_regs *regs)
	96	{
	97	/* TODO: implement lazy context saving/restoring */
	98	WARN_ON(1);
	99	}
	100
	101	/*
	102	* Raise a SIGFPE for the current process.
	103	*/
	104	void do_fpsimd_exc(unsigned int esr, struct pt_regs *regs)
	105	{
	106	siginfo_t info;
	107	unsigned int si_code = 0;
	108
	109	if (esr & FPEXC_IOF)
	110	si_code = FPE_FLTINV;
	111	else if (esr & FPEXC_DZF)
	112	si_code = FPE_FLTDIV;
	113	else if (esr & FPEXC_OFF)
	114	si_code = FPE_FLTOVF;
	115	else if (esr & FPEXC_UFF)
	116	si_code = FPE_FLTUND;
	117	else if (esr & FPEXC_IXF)
	118	si_code = FPE_FLTRES;
	119
	120	memset(&info, 0, sizeof(info));
	121	info.si_signo = SIGFPE;
	122	info.si_code = si_code;
	123	info.si_addr = (void __user *)instruction_pointer(regs);
	124
	125	send_sig_info(SIGFPE, &info, current);
	126	}
	127
	128	void fpsimd_thread_switch(struct task_struct *next)
	129	{
005f78cd AB	130	/*
	131	* Save the current FPSIMD state to memory, but only if whatever is in
	132	* the registers is in fact the most recent userland FPSIMD state of
	133	* 'current'.
	134	*/
	135	if (current->mm && !test_thread_flag(TIF_FOREIGN_FPSTATE))
53631b54	136	fpsimd_save_state(&current->thread.fpsimd_state);
005f78cd AB	137
	138	if (next->mm) {
	139	/*
	140	* If we are switching to a task whose most recent userland
	141	* FPSIMD state is already in the registers of this cpu,
	142	* we can skip loading the state from memory. Otherwise, set
	143	* the TIF_FOREIGN_FPSTATE flag so the state will be loaded
	144	* upon the next return to userland.
	145	*/
	146	struct fpsimd_state *st = &next->thread.fpsimd_state;
	147
	148	if (__this_cpu_read(fpsimd_last_state) == st
	149	&& st->cpu == smp_processor_id())
	150	clear_ti_thread_flag(task_thread_info(next),
	151	TIF_FOREIGN_FPSTATE);
	152	else
	153	set_ti_thread_flag(task_thread_info(next),
	154	TIF_FOREIGN_FPSTATE);
	155	}
53631b54 CM	156	}
	157
	158	void fpsimd_flush_thread(void)
	159	{
	160	memset(&current->thread.fpsimd_state, 0, sizeof(struct fpsimd_state));
005f78cd	161	set_thread_flag(TIF_FOREIGN_FPSTATE);
53631b54 CM	162	}
53631b54 CM	163
c51f9269	164	/*
005f78cd AB	165	* Save the userland FPSIMD state of 'current' to memory, but only if the state
005f78cd AB	166	* currently held in the registers does in fact belong to 'current'
c51f9269 AB	167	*/
	168	void fpsimd_preserve_current_state(void)
	169	{
	170	preempt_disable();
005f78cd AB	171	if (!test_thread_flag(TIF_FOREIGN_FPSTATE))
005f78cd AB	172	fpsimd_save_state(&current->thread.fpsimd_state);
c51f9269 AB	173	preempt_enable();
	174	}
	175
	176	/*
005f78cd AB	177	* Load the userland FPSIMD state of 'current' from memory, but only if the
	178	* FPSIMD state already held in the registers is /not/ the most recent FPSIMD
	179	* state of 'current'
	180	*/
	181	void fpsimd_restore_current_state(void)
	182	{
	183	preempt_disable();
	184	if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
	185	struct fpsimd_state *st = &current->thread.fpsimd_state;
	186
	187	fpsimd_load_state(st);
	188	this_cpu_write(fpsimd_last_state, st);
	189	st->cpu = smp_processor_id();
	190	}
	191	preempt_enable();
	192	}
	193
	194	/*
	195	* Load an updated userland FPSIMD state for 'current' from memory and set the
	196	* flag that indicates that the FPSIMD register contents are the most recent
	197	* FPSIMD state of 'current'
c51f9269 AB	198	*/
	199	void fpsimd_update_current_state(struct fpsimd_state *state)
	200	{
	201	preempt_disable();
	202	fpsimd_load_state(state);
005f78cd AB	203	if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
	204	struct fpsimd_state *st = &current->thread.fpsimd_state;
	205
	206	this_cpu_write(fpsimd_last_state, st);
	207	st->cpu = smp_processor_id();
	208	}
c51f9269 AB	209	preempt_enable();
	210	}
	211
005f78cd AB	212	/*
	213	* Invalidate live CPU copies of task t's FPSIMD state
	214	*/
	215	void fpsimd_flush_task_state(struct task_struct *t)
	216	{
	217	t->thread.fpsimd_state.cpu = NR_CPUS;
	218	}
	219
4cfb3613 AB	220	#ifdef CONFIG_KERNEL_MODE_NEON
4cfb3613 AB	221
190f1ca8 AB	222	static DEFINE_PER_CPU(struct fpsimd_partial_state, hardirq_fpsimdstate);
	223	static DEFINE_PER_CPU(struct fpsimd_partial_state, softirq_fpsimdstate);
	224
4cfb3613 AB	225	/*
	226	* Kernel-side NEON support functions
	227	*/
190f1ca8	228	void kernel_neon_begin_partial(u32 num_regs)
4cfb3613	229	{
190f1ca8 AB	230	if (in_interrupt()) {
	231	struct fpsimd_partial_state *s = this_cpu_ptr(
	232	in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
4cfb3613	233
190f1ca8 AB	234	BUG_ON(num_regs > 32);
	235	fpsimd_save_partial_state(s, roundup(num_regs, 2));
	236	} else {
	237	/*
	238	* Save the userland FPSIMD state if we have one and if we
	239	* haven't done so already. Clear fpsimd_last_state to indicate
	240	* that there is no longer userland FPSIMD state in the
	241	* registers.
	242	*/
	243	preempt_disable();
	244	if (current->mm &&
	245	!test_and_set_thread_flag(TIF_FOREIGN_FPSTATE))
	246	fpsimd_save_state(&current->thread.fpsimd_state);
	247	this_cpu_write(fpsimd_last_state, NULL);
	248	}
4cfb3613	249	}
190f1ca8	250	EXPORT_SYMBOL(kernel_neon_begin_partial);
4cfb3613 AB	251
	252	void kernel_neon_end(void)
	253	{
190f1ca8 AB	254	if (in_interrupt()) {
	255	struct fpsimd_partial_state *s = this_cpu_ptr(
	256	in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
	257	fpsimd_load_partial_state(s);
	258	} else {
	259	preempt_enable();
	260	}
4cfb3613 AB	261	}
	262	EXPORT_SYMBOL(kernel_neon_end);
	263
	264	#endif /* CONFIG_KERNEL_MODE_NEON */
	265
fb1ab1ab LP	266	#ifdef CONFIG_CPU_PM
	267	static int fpsimd_cpu_pm_notifier(struct notifier_block *self,
	268	unsigned long cmd, void *v)
	269	{
	270	switch (cmd) {
	271	case CPU_PM_ENTER:
005f78cd	272	if (current->mm && !test_thread_flag(TIF_FOREIGN_FPSTATE))
fb1ab1ab	273	fpsimd_save_state(&current->thread.fpsimd_state);
7c68a9cc	274	this_cpu_write(fpsimd_last_state, NULL);
fb1ab1ab LP	275	break;
	276	case CPU_PM_EXIT:
	277	if (current->mm)
005f78cd	278	set_thread_flag(TIF_FOREIGN_FPSTATE);
fb1ab1ab LP	279	break;
	280	case CPU_PM_ENTER_FAILED:
	281	default:
	282	return NOTIFY_DONE;
	283	}
	284	return NOTIFY_OK;
	285	}
	286
	287	static struct notifier_block fpsimd_cpu_pm_notifier_block = {
	288	.notifier_call = fpsimd_cpu_pm_notifier,
	289	};
	290
	291	static void fpsimd_pm_init(void)
	292	{
	293	cpu_pm_register_notifier(&fpsimd_cpu_pm_notifier_block);
	294	}
	295
	296	#else
	297	static inline void fpsimd_pm_init(void) { }
	298	#endif /* CONFIG_CPU_PM */
	299
32365e64 JL	300	#ifdef CONFIG_HOTPLUG_CPU
	301	static int fpsimd_cpu_hotplug_notifier(struct notifier_block *nfb,
	302	unsigned long action,
	303	void *hcpu)
	304	{
	305	unsigned int cpu = (long)hcpu;
	306
	307	switch (action) {
	308	case CPU_DEAD:
	309	case CPU_DEAD_FROZEN:
	310	per_cpu(fpsimd_last_state, cpu) = NULL;
	311	break;
	312	}
	313	return NOTIFY_OK;
	314	}
	315
	316	static struct notifier_block fpsimd_cpu_hotplug_notifier_block = {
	317	.notifier_call = fpsimd_cpu_hotplug_notifier,
	318	};
	319
	320	static inline void fpsimd_hotplug_init(void)
	321	{
	322	register_cpu_notifier(&fpsimd_cpu_hotplug_notifier_block);
	323	}
	324
	325	#else
	326	static inline void fpsimd_hotplug_init(void) { }
	327	#endif
	328
53631b54 CM	329	/*
	330	* FP/SIMD support code initialisation.
	331	*/
	332	static int __init fpsimd_init(void)
	333	{
	334	u64 pfr = read_cpuid(ID_AA64PFR0_EL1);
	335
	336	if (pfr & (0xf << 16)) {
	337	pr_notice("Floating-point is not implemented\n");
	338	return 0;
	339	}
	340	elf_hwcap \|= HWCAP_FP;
	341
	342	if (pfr & (0xf << 20))
	343	pr_notice("Advanced SIMD is not implemented\n");
	344	else
	345	elf_hwcap \|= HWCAP_ASIMD;
	346
fb1ab1ab	347	fpsimd_pm_init();
32365e64	348	fpsimd_hotplug_init();
fb1ab1ab	349
53631b54 CM	350	return 0;
	351	}
	352	late_initcall(fpsimd_init);