/*
 * Cryptographic scatter and gather helpers.
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 * Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com>
 * Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */

#ifndef _CRYPTO_SCATTERWALK_H
#define _CRYPTO_SCATTERWALK_H

#include <crypto/algapi.h>
#include <linux/highmem.h>
#include <linux/kernel.h>
#include <linux/scatterlist.h>

static inline void scatterwalk_crypto_chain(struct scatterlist *head,
					    struct scatterlist *sg,
					    int chain, int num)
{
	if (chain) {
		head->length += sg->length;
		sg = sg_next(sg);
	}

	if (sg)
		sg_chain(head, num, sg);
	else
		sg_mark_end(head);
}

static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,
						struct scatter_walk *walk_out)
{
	return !(((sg_page(walk_in->sg) - sg_page(walk_out->sg)) << PAGE_SHIFT) +
		 (int)(walk_in->offset - walk_out->offset));
}

static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
{
	unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
	unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
	return len_this_page > len ? len : len_this_page;
}

static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
					     unsigned int nbytes)
{
	unsigned int len_this_page = scatterwalk_pagelen(walk);
	return nbytes > len_this_page ? len_this_page : nbytes;
}

static inline void scatterwalk_advance(struct scatter_walk *walk,
				       unsigned int nbytes)
{
	walk->offset += nbytes;
}

static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
					       unsigned int alignmask)
{
	return !(walk->offset & alignmask);
}

static inline struct page *scatterwalk_page(struct scatter_walk *walk)
{
	return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
}

static inline void scatterwalk_unmap(void *vaddr)
{
	kunmap_atomic(vaddr);
}

static inline void scatterwalk_start(struct scatter_walk *walk,
				     struct scatterlist *sg)
{
	walk->sg = sg;
	walk->offset = sg->offset;
}

static inline void *scatterwalk_map(struct scatter_walk *walk)
{
	return kmap_atomic(scatterwalk_page(walk)) +
	       offset_in_page(walk->offset);
}

static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out,
					unsigned int more)
{
	if (out) {
		struct page *page;

		page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
		/* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as
		 * PageSlab cannot be optimised away per se due to
		 * use of volatile pointer.
		 */
		if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page))
			flush_dcache_page(page);
	}

	if (more && walk->offset >= walk->sg->offset + walk->sg->length)
		scatterwalk_start(walk, sg_next(walk->sg));
}

static inline void scatterwalk_done(struct scatter_walk *walk, int out,
				    int more)
{
	if (!more || walk->offset >= walk->sg->offset + walk->sg->length ||
	    !(walk->offset & (PAGE_SIZE - 1)))
		scatterwalk_pagedone(walk, out, more);
}

void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
			    size_t nbytes, int out);
void *scatterwalk_map(struct scatter_walk *walk);

void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
			      unsigned int start, unsigned int nbytes, int out);

struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
				     struct scatterlist *src,
				     unsigned int len);

#endif  /* _CRYPTO_SCATTERWALK_H */
class='left'>Lines</th></tr>
lue='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/include/net/caif/cfcnfg.h?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/include/net/caif/cfcnfg.h?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/include/net/caif/cfcnfg.h?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>include/net/caif/cfcnfg.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/net/caif/cfcnfg.h?h=nds-private-remove&amp;id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/include/net/caif/cfcnfg.h?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 'include/net/caif/cfcnfg.h')</div><table summary='diffstat' class='diffstat'>