tools/testing/selftests/powerpc/pmu/ebb/ebb_on_willing_child_test.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/powerpc/pmu/ebb/ebb_on_willing_child_test.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/powerpc/pmu/ebb/ebb_on_willing_child_test.c
Extension
.c
Size
1927 bytes
Lines
93
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2014, Michael Ellerman, IBM Corp.
 */

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#include "ebb.h"


/*
 * Tests we can setup an EBB on our child. The child expects this and enables
 * EBBs, which are then delivered to the child, even though the event is
 * created by the parent.
 */

static int victim_child(union pipe read_pipe, union pipe write_pipe)
{
	FAIL_IF(wait_for_parent(read_pipe));

	/* Setup our EBB handler, before the EBB event is created */
	ebb_enable_pmc_counting(1);
	setup_ebb_handler(standard_ebb_callee);
	ebb_global_enable();

	FAIL_IF(notify_parent(write_pipe));

	while (ebb_state.stats.ebb_count < 20) {
		FAIL_IF(core_busy_loop());
	}

	ebb_global_disable();
	ebb_freeze_pmcs();

	dump_ebb_state();

	FAIL_IF(ebb_state.stats.ebb_count == 0);

	return 0;
}

/* Tests we can setup an EBB on our child - if it's expecting it */
int ebb_on_willing_child(void)
{
	union pipe read_pipe, write_pipe;
	struct event event;
	pid_t pid;

	SKIP_IF(!ebb_is_supported());

	FAIL_IF(pipe(read_pipe.fds) == -1);
	FAIL_IF(pipe(write_pipe.fds) == -1);

	pid = fork();
	if (pid == 0) {
		/* NB order of pipes looks reversed */
		exit(victim_child(write_pipe, read_pipe));
	}

	/* Signal the child to setup its EBB handler */
	FAIL_IF(sync_with_child(read_pipe, write_pipe));

	/* Child is running now */

	event_init_named(&event, 0x1001e, "cycles");
	event_leader_ebb_init(&event);

	event.attr.exclude_kernel = 1;
	event.attr.exclude_hv = 1;
	event.attr.exclude_idle = 1;

	FAIL_IF(event_open_with_pid(&event, pid));
	FAIL_IF(ebb_event_enable(&event));

	/* Child show now take EBBs and then exit */
	FAIL_IF(wait_for_child(pid));

	event_close(&event);

	return 0;
}

int main(void)
{

Annotation

Implementation Notes