/*
 * Copyright 2014, Michael Ellerman, IBM Corp.
 * Licensed under GPLv2.
 */

#define _GNU_SOURCE	/* For CPU_ZERO etc. */

#include <errno.h>
#include <sched.h>
#include <setjmp.h>
#include <stdlib.h>
#include <sys/wait.h>

#include "utils.h"
#include "lib.h"


int bind_to_cpu(int cpu)
{
	cpu_set_t mask;

	printf("Binding to cpu %d\n", cpu);

	CPU_ZERO(&mask);
	CPU_SET(cpu, &mask);

	return sched_setaffinity(0, sizeof(mask), &mask);
}

#define PARENT_TOKEN	0xAA
#define CHILD_TOKEN	0x55

int sync_with_child(union pipe read_pipe, union pipe write_pipe)
{
	char c = PARENT_TOKEN;

	FAIL_IF(write(write_pipe.write_fd, &c, 1) != 1);
	FAIL_IF(read(read_pipe.read_fd, &c, 1) != 1);
	if (c != CHILD_TOKEN) /* sometimes expected */
		return 1;

	return 0;
}

int wait_for_parent(union pipe read_pipe)
{
	char c;

	FAIL_IF(read(read_pipe.read_fd, &c, 1) != 1);
	FAIL_IF(c != PARENT_TOKEN);

	return 0;
}

int notify_parent(union pipe write_pipe)
{
	char c = CHILD_TOKEN;

	FAIL_IF(write(write_pipe.write_fd, &c, 1) != 1);

	return 0;
}

int notify_parent_of_error(union pipe write_pipe)
{
	char c = ~CHILD_TOKEN;

	FAIL_IF(write(write_pipe.write_fd, &c, 1) != 1);

	return 0;
}

int wait_for_child(pid_t child_pid)
{
	int rc;

	if (waitpid(child_pid, &rc, 0) == -1) {
		perror("waitpid");
		return 1;
	}

	if (WIFEXITED(rc))
		rc = WEXITSTATUS(rc);
	else
		rc = 1; /* Signal or other */

	return rc;
}

int kill_child_and_wait(pid_t child_pid)
{
	kill(child_pid, SIGTERM);

	return wait_for_child(child_pid);
}

static int eat_cpu_child(union pipe read_pipe, union pipe write_pipe)
{
	volatile int i = 0;

	/*
	 * We are just here to eat cpu and die. So make sure we can be killed,
	 * and also don't do any custom SIGTERM handling.
	 */
	signal(SIGTERM, SIG_DFL);

	notify_parent(write_pipe);
	wait_for_parent(read_pipe);

	/* Soak up cpu forever */
	while (1) i++;

	return 0;
}

pid_t eat_cpu(int (test_function)(void))
{
	union pipe read_pipe, write_pipe;
	int cpu, rc;
	pid_t pid;

	cpu = pick_online_cpu();
	FAIL_IF(cpu < 0);
	FAIL_IF(bind_to_cpu(cpu));

	if (pipe(read_pipe.fds) == -1)
		return -1;

	if (pipe(write_pipe.fds) == -1)
		return -1;

	pid = fork();
	if (pid == 0)
		exit(eat_cpu_child(write_pipe, read_pipe));

	if (sync_with_child(read_pipe, write_pipe)) {
		rc = -1;
		goto out;
	}

	printf("main test running as pid %d\n", getpid());

	rc = test_function();
out:
	kill(pid, SIGKILL);

	return rc;
}

struct addr_range libc, vdso;

int parse_proc_maps(void)
{
	unsigned long start, end;
	char execute, name[128];
	FILE *f;
	int rc;

	f = fopen("/proc/self/maps", "r");
	if (!f) {
		perror("fopen");
		return -1;
	}

	do {
		/* This skips line with no executable which is what we want */
		rc = fscanf(f, "%lx-%lx %*c%*c%c%*c %*x %*d:%*d %*d %127s\n",
			    &start, &end, &execute, name);
		if (rc <= 0)
			break;

		if (execute != 'x')
			continue;

		if (strstr(name, "libc")) {
			libc.first = start;
			libc.last = end - 1;
		} else if (strstr(name, "[vdso]")) {
			vdso.first = start;
			vdso.last = end - 1;
		}
	} while(1);

	fclose(f);

	return 0;
}

#define PARANOID_PATH	"/proc/sys/kernel/perf_event_paranoid"

bool require_paranoia_below(int level)
{
	long current;
	char *end, buf[16];
	FILE *f;
	bool rc;

	rc = false;

	f = fopen(PARANOID_PATH, "r");
	if (!f) {
		perror("fopen");
		goto out;
	}

	if (!fgets(buf, sizeof(buf), f)) {
		printf("Couldn't read " PARANOID_PATH "?\n");
		goto out_close;
	}

	current = strtol(buf, &end, 10);

	if (end == buf) {
		printf("Couldn't parse " PARANOID_PATH "?\n");
		goto out_close;
	}

	if (current >= level)
		goto out_close;

	rc = true;
out_close:
	fclose(f);
out:
	return rc;
}

tion value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-29 13:50:06 -0800</td></tr>
<tr><th>committer</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-29 13:50:06 -0800</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/perf/scripts/perl?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/tools/perf/scripts/perl?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>98fe974ee4e20121253de7f61fc8d01bdb3821c1</a> /<a href='/cgit.cgi/linux/net-next.git/tree/tools/perf/scripts/perl?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>tools/perf/scripts/perl</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/tools/perf/scripts/perl?id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/tools/perf/scripts/perl?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e&amp;id2=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>diff</a>)</td></tr></table>
<div class='commit-subject'>drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()</div><div class='commit-msg'>I've seen this trigger twice now, where the i915_gem_object_to_ggtt()
call in intel_unpin_fb_obj() returns NULL, resulting in an oops
immediately afterwards as the (inlined) call to i915_vma_unpin_fence()
tries to dereference it.

It seems to be some race condition where the object is going away at
shutdown time, since both times happened when shutting down the X
server.  The call chains were different:

 - VT ioctl(KDSETMODE, KD_TEXT):

    intel_cleanup_plane_fb+0x5b/0xa0 [i915]
    drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper]
    intel_atomic_commit_tail+0x749/0xfe0 [i915]
    intel_atomic_commit+0x3cb/0x4f0 [i915]
    drm_atomic_commit+0x4b/0x50 [drm]
    restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper]
    drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper]
    drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper]
    intel_fbdev_set_par+0x18/0x70 [i915]
    fb_set_var+0x236/0x460
    fbcon_blank+0x30f/0x350
    do_unblank_screen+0xd2/0x1a0
    vt_ioctl+0x507/0x12a0
    tty_ioctl+0x355/0xc30
    do_vfs_ioctl+0xa3/0x5e0
    SyS_ioctl+0x79/0x90
    entry_SYSCALL_64_fastpath+0x13/0x94

 - i915 unpin_work workqueue:

    intel_unpin_work_fn+0x58/0x140 [i915]
    process_one_work+0x1f1/0x480
    worker_thread+0x48/0x4d0
    kthread+0x101/0x140

and this patch purely papers over the issue by adding a NULL pointer
check and a WARN_ON_ONCE() to avoid the oops that would then generally
make the machine unresponsive.

Other callers of i915_gem_object_to_ggtt() seem to also check for the
returned pointer being NULL and warn about it, so this clearly has
happened before in other places.

[ Reported it originally to the i915 developers on Jan 8, applying the
  ugly workaround on my own now after triggering the problem for the
  second time with no feedback.

  This is likely to be the same bug reported as

     https://bugs.freedesktop.org/show_bug.cgi?id=98829
     https://bugs.freedesktop.org/show_bug.cgi?id=99134

  which has a patch for the underlying problem, but it hasn't gotten to
  me, so I'm applying the workaround. ]

Cc: Daniel Vetter &lt;daniel.vetter@intel.com&gt;
Cc: Jani Nikula &lt;jani.nikula@linux.intel.com&gt;
Cc: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Cc: Chris Wilson &lt;chris@chris-wilson.co.uk&gt;
Cc: Maarten Lankhorst &lt;maarten.lankhorst@linux.intel.com&gt;
Cc: Tvrtko Ursulin &lt;tvrtko.ursulin@intel.com&gt;
Cc: Imre Deak &lt;imre.deak@intel.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>Diffstat</a> (limited to 'tools/perf/scripts/perl')</div><table summary='diffstat' class='diffstat'>