#ifndef ARCH_PERF_REGS_H
#define ARCH_PERF_REGS_H

#include <stdlib.h>
#include <linux/types.h>
#include <asm/perf_regs.h>

void perf_regs_load(u64 *regs);

#define PERF_REGS_MASK	((1ULL << PERF_REG_ARM64_MAX) - 1)
#define PERF_REGS_MAX	PERF_REG_ARM64_MAX
#define PERF_SAMPLE_REGS_ABI	PERF_SAMPLE_REGS_ABI_64

#define PERF_REG_IP	PERF_REG_ARM64_PC
#define PERF_REG_SP	PERF_REG_ARM64_SP

static inline const char *perf_reg_name(int id)
{
	switch (id) {
	case PERF_REG_ARM64_X0:
		return "x0";
	case PERF_REG_ARM64_X1:
		return "x1";
	case PERF_REG_ARM64_X2:
		return "x2";
	case PERF_REG_ARM64_X3:
		return "x3";
	case PERF_REG_ARM64_X4:
		return "x4";
	case PERF_REG_ARM64_X5:
		return "x5";
	case PERF_REG_ARM64_X6:
		return "x6";
	case PERF_REG_ARM64_X7:
		return "x7";
	case PERF_REG_ARM64_X8:
		return "x8";
	case PERF_REG_ARM64_X9:
		return "x9";
	case PERF_REG_ARM64_X10:
		return "x10";
	case PERF_REG_ARM64_X11:
		return "x11";
	case PERF_REG_ARM64_X12:
		return "x12";
	case PERF_REG_ARM64_X13:
		return "x13";
	case PERF_REG_ARM64_X14:
		return "x14";
	case PERF_REG_ARM64_X15:
		return "x15";
	case PERF_REG_ARM64_X16:
		return "x16";
	case PERF_REG_ARM64_X17:
		return "x17";
	case PERF_REG_ARM64_X18:
		return "x18";
	case PERF_REG_ARM64_X19:
		return "x19";
	case PERF_REG_ARM64_X20:
		return "x20";
	case PERF_REG_ARM64_X21:
		return "x21";
	case PERF_REG_ARM64_X22:
		return "x22";
	case PERF_REG_ARM64_X23:
		return "x23";
	case PERF_REG_ARM64_X24:
		return "x24";
	case PERF_REG_ARM64_X25:
		return "x25";
	case PERF_REG_ARM64_X26:
		return "x26";
	case PERF_REG_ARM64_X27:
		return "x27";
	case PERF_REG_ARM64_X28:
		return "x28";
	case PERF_REG_ARM64_X29:
		return "x29";
	case PERF_REG_ARM64_SP:
		return "sp";
	case PERF_REG_ARM64_LR:
		return "lr";
	case PERF_REG_ARM64_PC:
		return "pc";
	default:
		return NULL;
	}

	return NULL;
}

#endif /* ARCH_PERF_REGS_H */
t.git/tree/kernel/user_namespace.c?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>tree</a><a class='active' href='/cgit.cgi/linux/net-next.git/commit/kernel/user_namespace.c?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>commit</a><a href='/cgit.cgi/linux/net-next.git/diff/kernel/user_namespace.c?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>diff</a></td><td class='form'><form class='right' method='get' action='/cgit.cgi/linux/net-next.git/log/kernel/user_namespace.c'>
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/commit/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/kernel?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>kernel</a>/<a href='/cgit.cgi/linux/net-next.git/commit/kernel/user_namespace.c?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>user_namespace.c</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='h' value='nds-private-remove'/><input type='hidden' name='id' value='39cb2c9a316e77f6dfba96c543e55b6672d5a37e'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option 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/kernel/user_namespace.c?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/kernel/user_namespace.c?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>98fe974ee4e20121253de7f61fc8d01bdb3821c1</a> /<a href='/cgit.cgi/linux/net-next.git/tree/kernel/user_namespace.c?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>kernel/user_namespace.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/kernel/user_namespace.c?h=nds-private-remove&amp;id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/kernel/user_namespace.c?h=nds-private-remove&amp;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/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>Diffstat</a> (limited to 'kernel/user_namespace.c')</div><table summary='diffstat' class='diffstat'>