/* Copyright (c) 2016 Facebook
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 */
#define KBUILD_MODNAME "foo"
#include <linux/if_ether.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/in.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <uapi/linux/bpf.h>
#include <net/ip.h>
#include "bpf_helpers.h"

#define DEFAULT_PKTGEN_UDP_PORT 9
#define DEBUG 0

static int tcp(void *data, uint64_t tp_off, void *data_end)
{
	struct tcphdr *tcp = data + tp_off;

	if (tcp + 1 > data_end)
		return 0;
	if (tcp->dest == htons(80) || tcp->source == htons(80))
		return TC_ACT_SHOT;
	return 0;
}

static int udp(void *data, uint64_t tp_off, void *data_end)
{
	struct udphdr *udp = data + tp_off;

	if (udp + 1 > data_end)
		return 0;
	if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT) ||
	    udp->source == htons(DEFAULT_PKTGEN_UDP_PORT)) {
		if (DEBUG) {
			char fmt[] = "udp port 9 indeed\n";

			bpf_trace_printk(fmt, sizeof(fmt));
		}
		return TC_ACT_SHOT;
	}
	return 0;
}

static int parse_ipv4(void *data, uint64_t nh_off, void *data_end)
{
	struct iphdr *iph;
	uint64_t ihl_len;

	iph = data + nh_off;
	if (iph + 1 > data_end)
		return 0;

	if (ip_is_fragment(iph))
		return 0;
	ihl_len = iph->ihl * 4;

	if (iph->protocol == IPPROTO_IPIP) {
		iph = data + nh_off + ihl_len;
		if (iph + 1 > data_end)
			return 0;
		ihl_len += iph->ihl * 4;
	}

	if (iph->protocol == IPPROTO_TCP)
		return tcp(data, nh_off + ihl_len, data_end);
	else if (iph->protocol == IPPROTO_UDP)
		return udp(data, nh_off + ihl_len, data_end);
	return 0;
}

static int parse_ipv6(void *data, uint64_t nh_off, void *data_end)
{
	struct ipv6hdr *ip6h;
	struct iphdr *iph;
	uint64_t ihl_len = sizeof(struct ipv6hdr);
	uint64_t nexthdr;

	ip6h = data + nh_off;
	if (ip6h + 1 > data_end)
		return 0;

	nexthdr = ip6h->nexthdr;

	if (nexthdr == IPPROTO_IPIP) {
		iph = data + nh_off + ihl_len;
		if (iph + 1 > data_end)
			return 0;
		ihl_len += iph->ihl * 4;
		nexthdr = iph->protocol;
	} else if (nexthdr == IPPROTO_IPV6) {
		ip6h = data + nh_off + ihl_len;
		if (ip6h + 1 > data_end)
			return 0;
		ihl_len += sizeof(struct ipv6hdr);
		nexthdr = ip6h->nexthdr;
	}

	if (nexthdr == IPPROTO_TCP)
		return tcp(data, nh_off + ihl_len, data_end);
	else if (nexthdr == IPPROTO_UDP)
		return udp(data, nh_off + ihl_len, data_end);
	return 0;
}

struct vlan_hdr {
	uint16_t h_vlan_TCI;
	uint16_t h_vlan_encapsulated_proto;
};

SEC("varlen")
int handle_ingress(struct __sk_buff *skb)
{
	void *data = (void *)(long)skb->data;
	struct ethhdr *eth = data;
	void *data_end = (void *)(long)skb->data_end;
	uint64_t h_proto, nh_off;

	nh_off = sizeof(*eth);
	if (data + nh_off > data_end)
		return 0;

	h_proto = eth->h_proto;

	if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) {
		struct vlan_hdr *vhdr;

		vhdr = data + nh_off;
		nh_off += sizeof(struct vlan_hdr);
		if (data + nh_off > data_end)
			return 0;
		h_proto = vhdr->h_vlan_encapsulated_proto;
	}
	if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) {
		struct vlan_hdr *vhdr;

		vhdr = data + nh_off;
		nh_off += sizeof(struct vlan_hdr);
		if (data + nh_off > data_end)
			return 0;
		h_proto = vhdr->h_vlan_encapsulated_proto;
	}
	if (h_proto == htons(ETH_P_IP))
		return parse_ipv4(data, nh_off, data_end);
	else if (h_proto == htons(ETH_P_IPV6))
		return parse_ipv6(data, nh_off, data_end);
	return 0;
}
char _license[] SEC("license") = "GPL";
e.h?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>cpuidle.h</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/include/soc/tegra/cpuidle.h?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/include/soc/tegra/cpuidle.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/soc/tegra/cpuidle.h?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>include/soc/tegra/cpuidle.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/soc/tegra/cpuidle.h?h=nds-private-remove&amp;id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/include/soc/tegra/cpuidle.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/soc/tegra/cpuidle.h')</div><table summary='diffstat' class='diffstat'>