[mirror_ubuntu-bionic-kernel.git] / arch / x86 / kernel / tracepoint.c

/*
 * Code for supporting irq vector tracepoints.
 *
 * Copyright (C) 2013 Seiji Aguchi <seiji.aguchi@hds.com>
 *
 */
#include <asm/hw_irq.h>
#include <asm/desc.h>
#include <linux/atomic.h>

atomic_t trace_idt_ctr = ATOMIC_INIT(0);
struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1,
				(unsigned long) trace_idt_table };

/* No need to be aligned, but done to keep all IDTs defined the same way. */
gate_desc trace_idt_table[NR_VECTORS] __page_aligned_bss;

static int trace_irq_vector_refcount;
static DEFINE_MUTEX(irq_vector_mutex);

static void set_trace_idt_ctr(int val)
{
	atomic_set(&trace_idt_ctr, val);
	/* Ensure the trace_idt_ctr is set before sending IPI */
	wmb();
}

static void switch_idt(void *arg)
{
	unsigned long flags;

	local_irq_save(flags);
	load_current_idt();
	local_irq_restore(flags);
}

int trace_irq_vector_regfunc(void)
{
	mutex_lock(&irq_vector_mutex);
	if (!trace_irq_vector_refcount) {
		set_trace_idt_ctr(1);
		smp_call_function(switch_idt, NULL, 0);
		switch_idt(NULL);
	}
	trace_irq_vector_refcount++;
	mutex_unlock(&irq_vector_mutex);
	return 0;
}

void trace_irq_vector_unregfunc(void)
{
	mutex_lock(&irq_vector_mutex);
	trace_irq_vector_refcount--;
	if (!trace_irq_vector_refcount) {
		set_trace_idt_ctr(0);
		smp_call_function(switch_idt, NULL, 0);
		switch_idt(NULL);
	}
	mutex_unlock(&irq_vector_mutex);
}
Commit	Line	Data
cf910e83 SA	1	/*
	2	* Code for supporting irq vector tracepoints.
	3	*
	4	* Copyright (C) 2013 Seiji Aguchi <seiji.aguchi@hds.com>
	5	*
	6	*/
	7	#include <asm/hw_irq.h>
	8	#include <asm/desc.h>
	9	#include <linux/atomic.h>
	10
	11	atomic_t trace_idt_ctr = ATOMIC_INIT(0);
	12	struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1,
	13	(unsigned long) trace_idt_table };
	14
4df05f36 KC	15	/* No need to be aligned, but done to keep all IDTs defined the same way. */
4df05f36 KC	16	gate_desc trace_idt_table[NR_VECTORS] __page_aligned_bss;
cf910e83 SA	17
	18	static int trace_irq_vector_refcount;
	19	static DEFINE_MUTEX(irq_vector_mutex);
	20
	21	static void set_trace_idt_ctr(int val)
	22	{
	23	atomic_set(&trace_idt_ctr, val);
	24	/* Ensure the trace_idt_ctr is set before sending IPI */
	25	wmb();
	26	}
	27
	28	static void switch_idt(void *arg)
	29	{
2b4bc789 SRRH	30	unsigned long flags;
	31
	32	local_irq_save(flags);
cf910e83	33	load_current_idt();
2b4bc789	34	local_irq_restore(flags);
cf910e83 SA	35	}
cf910e83 SA	36
8cf868af	37	int trace_irq_vector_regfunc(void)
cf910e83 SA	38	{
	39	mutex_lock(&irq_vector_mutex);
	40	if (!trace_irq_vector_refcount) {
	41	set_trace_idt_ctr(1);
	42	smp_call_function(switch_idt, NULL, 0);
	43	switch_idt(NULL);
	44	}
	45	trace_irq_vector_refcount++;
	46	mutex_unlock(&irq_vector_mutex);
8cf868af	47	return 0;
cf910e83 SA	48	}
	49
	50	void trace_irq_vector_unregfunc(void)
	51	{
	52	mutex_lock(&irq_vector_mutex);
	53	trace_irq_vector_refcount--;
	54	if (!trace_irq_vector_refcount) {
	55	set_trace_idt_ctr(0);
	56	smp_call_function(switch_idt, NULL, 0);
	57	switch_idt(NULL);
	58	}
	59	mutex_unlock(&irq_vector_mutex);
	60	}