<feed xmlns='http://www.w3.org/2005/Atom'>
<title>user/sven/linux.git/include/linux, branch v5.10.90</title>
<subtitle>Linux Kernel
</subtitle>
<id>https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v5.10.90</id>
<link rel='self' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v5.10.90'/>
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<updated>2022-01-05T11:40:29Z</updated>
<entry>
<title>memblock: fix memblock_phys_alloc() section mismatch error</title>
<updated>2022-01-05T11:40:29Z</updated>
<author>
<name>Jackie Liu</name>
<email>liuyun01@kylinos.cn</email>
</author>
<published>2021-12-17T02:07:54Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=a0e82d5ef992eed30d49f7855eed89773a620ddd'/>
<id>urn:sha1:a0e82d5ef992eed30d49f7855eed89773a620ddd</id>
<content type='text'>
[ Upstream commit d7f55471db2719629f773c2d6b5742a69595bfd3 ]

Fix modpost Section mismatch error in memblock_phys_alloc()

[...]
WARNING: modpost: vmlinux.o(.text.unlikely+0x1dcc): Section mismatch in reference
from the function memblock_phys_alloc() to the function .init.text:memblock_phys_alloc_range()
The function memblock_phys_alloc() references
the function __init memblock_phys_alloc_range().
This is often because memblock_phys_alloc lacks a __init
annotation or the annotation of memblock_phys_alloc_range is wrong.

ERROR: modpost: Section mismatches detected.
Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them.
[...]

memblock_phys_alloc() is a one-line wrapper, make it __always_inline to
avoid these section mismatches.

Reported-by: k2ci &lt;kernel-bot@kylinos.cn&gt;
Suggested-by: Mike Rapoport &lt;rppt@kernel.org&gt;
Signed-off-by: Jackie Liu &lt;liuyun01@kylinos.cn&gt;
[rppt: slightly massaged changelog ]
Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Link: https://lore.kernel.org/r/20211217020754.2874872-1-liu.yun@linux.dev
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>tee: handle lookup of shm with reference count 0</title>
<updated>2021-12-29T11:26:02Z</updated>
<author>
<name>Jens Wiklander</name>
<email>jens.wiklander@linaro.org</email>
</author>
<published>2021-12-09T14:59:37Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=c05d8f66ec3470e5212c4d08c46d6cb5738d600d'/>
<id>urn:sha1:c05d8f66ec3470e5212c4d08c46d6cb5738d600d</id>
<content type='text'>
commit dfd0743f1d9ea76931510ed150334d571fbab49d upstream.

Since the tee subsystem does not keep a strong reference to its idle
shared memory buffers, it races with other threads that try to destroy a
shared memory through a close of its dma-buf fd or by unmapping the
memory.

In tee_shm_get_from_id() when a lookup in teedev-&gt;idr has been
successful, it is possible that the tee_shm is in the dma-buf teardown
path, but that path is blocked by the teedev mutex. Since we don't have
an API to tell if the tee_shm is in the dma-buf teardown path or not we
must find another way of detecting this condition.

Fix this by doing the reference counting directly on the tee_shm using a
new refcount_t refcount field. dma-buf is replaced by using
anon_inode_getfd() instead, this separates the life-cycle of the
underlying file from the tee_shm. tee_shm_put() is updated to hold the
mutex when decreasing the refcount to 0 and then remove the tee_shm from
teedev-&gt;idr before releasing the mutex. This means that the tee_shm can
never be found unless it has a refcount larger than 0.

Fixes: 967c9cca2cc5 ("tee: generic TEE subsystem")
Cc: stable@vger.kernel.org
Reviewed-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Reviewed-by: Lars Persson &lt;larper@axis.com&gt;
Reviewed-by: Sumit Garg &lt;sumit.garg@linaro.org&gt;
Reported-by: Patrik Lantz &lt;patrik.lantz@axis.com&gt;
Signed-off-by: Jens Wiklander &lt;jens.wiklander@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: skip virtio_net_hdr_set_proto if protocol already set</title>
<updated>2021-12-29T11:25:56Z</updated>
<author>
<name>Willem de Bruijn</name>
<email>willemb@google.com</email>
</author>
<published>2021-12-20T14:50:27Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=e00eace2325c4d4715d1001b0e467123d36e6c9a'/>
<id>urn:sha1:e00eace2325c4d4715d1001b0e467123d36e6c9a</id>
<content type='text'>
[ Upstream commit 1ed1d592113959f00cc552c3b9f47ca2d157768f ]

virtio_net_hdr_set_proto infers skb-&gt;protocol from the virtio_net_hdr
gso_type, to avoid packets getting dropped for lack of a proto type.

Its protocol choice is a guess, especially in the case of UFO, where
the single VIRTIO_NET_HDR_GSO_UDP label covers both UFOv4 and UFOv6.

Skip this best effort if the field is already initialized. Whether
explicitly from userspace, or implicitly based on an earlier call to
dev_parse_header_protocol (which is more robust, but was introduced
after this patch).

Fixes: 9d2f67e43b73 ("net/packet: fix packet drop as of virtio gso")
Signed-off-by: Willem de Bruijn &lt;willemb@google.com&gt;
Link: https://lore.kernel.org/r/20211220145027.2784293-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>net: accept UFOv6 packages in virtio_net_hdr_to_skb</title>
<updated>2021-12-29T11:25:56Z</updated>
<author>
<name>Willem de Bruijn</name>
<email>willemb@google.com</email>
</author>
<published>2021-12-20T14:49:01Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=ed05e4dcfba63bcca36ec1d19d099a1ec6b000ec'/>
<id>urn:sha1:ed05e4dcfba63bcca36ec1d19d099a1ec6b000ec</id>
<content type='text'>
[ Upstream commit 7e5cced9ca84df52d874aca6b632f930b3dc5bc6 ]

Skb with skb-&gt;protocol 0 at the time of virtio_net_hdr_to_skb may have
a protocol inferred from virtio_net_hdr with virtio_net_hdr_set_proto.

Unlike TCP, UDP does not have separate types for IPv4 and IPv6. Type
VIRTIO_NET_HDR_GSO_UDP is guessed to be IPv4/UDP. As of the below
commit, UFOv6 packets are dropped due to not matching the protocol as
obtained from dev_parse_header_protocol.

Invert the test to take that L2 protocol field as starting point and
pass both UFOv4 and UFOv6 for VIRTIO_NET_HDR_GSO_UDP.

Fixes: 924a9bc362a5 ("net: check if protocol extracted by virtio_net_hdr_set_proto is correct")
Link: https://lore.kernel.org/netdev/CABcq3pG9GRCYqFDBAJ48H1vpnnX=41u+MhQnayF1ztLH4WX0Fw@mail.gmail.com/
Reported-by: Andrew Melnichenko &lt;andrew@daynix.com&gt;
Signed-off-by: Willem de Bruijn &lt;willemb@google.com&gt;
Link: https://lore.kernel.org/r/20211220144901.2784030-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>PM: runtime: Fix pm_runtime_active() kerneldoc comment</title>
<updated>2021-12-14T10:32:41Z</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2021-12-03T16:19:47Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=bdd8129c66052991f0b5939975e674d669b06a01'/>
<id>urn:sha1:bdd8129c66052991f0b5939975e674d669b06a01</id>
<content type='text'>
commit 444dd878e85fb33fcfb2682cfdab4c236f33ea3e upstream.

The kerneldoc comment of pm_runtime_active() does not reflect the
behavior of the function, so update it accordingly.

Fixes: 403d2d116ec0 ("PM: runtime: Add kerneldoc comments to multiple helpers")
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Reviewed-by: Ulf Hansson &lt;ulf.hansson@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>wait: add wake_up_pollfree()</title>
<updated>2021-12-14T10:32:39Z</updated>
<author>
<name>Eric Biggers</name>
<email>ebiggers@google.com</email>
</author>
<published>2021-12-09T01:04:51Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=8e04c8397bf98235b1aa41153717de7a05e652a2'/>
<id>urn:sha1:8e04c8397bf98235b1aa41153717de7a05e652a2</id>
<content type='text'>
commit 42288cb44c4b5fff7653bc392b583a2b8bd6a8c0 upstream.

Several -&gt;poll() implementations are special in that they use a
waitqueue whose lifetime is the current task, rather than the struct
file as is normally the case.  This is okay for blocking polls, since a
blocking poll occurs within one task; however, non-blocking polls
require another solution.  This solution is for the queue to be cleared
before it is freed, using 'wake_up_poll(wq, EPOLLHUP | POLLFREE);'.

However, that has a bug: wake_up_poll() calls __wake_up() with
nr_exclusive=1.  Therefore, if there are multiple "exclusive" waiters,
and the wakeup function for the first one returns a positive value, only
that one will be called.  That's *not* what's needed for POLLFREE;
POLLFREE is special in that it really needs to wake up everyone.

Considering the three non-blocking poll systems:

- io_uring poll doesn't handle POLLFREE at all, so it is broken anyway.

- aio poll is unaffected, since it doesn't support exclusive waits.
  However, that's fragile, as someone could add this feature later.

- epoll doesn't appear to be broken by this, since its wakeup function
  returns 0 when it sees POLLFREE.  But this is fragile.

Although there is a workaround (see epoll), it's better to define a
function which always sends POLLFREE to all waiters.  Add such a
function.  Also make it verify that the queue really becomes empty after
all waiters have been woken up.

Reported-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211209010455.42744-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers &lt;ebiggers@google.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>bpf, x86: Fix "no previous prototype" warning</title>
<updated>2021-12-14T10:32:36Z</updated>
<author>
<name>Björn Töpel</name>
<email>bjorn@kernel.org</email>
</author>
<published>2021-11-17T12:57:08Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=f26951db84a4074a027aba1840370ceb928ba1a3'/>
<id>urn:sha1:f26951db84a4074a027aba1840370ceb928ba1a3</id>
<content type='text'>
commit f45b2974cc0ae959a4c503a071e38a56bd64372f upstream.

The arch_prepare_bpf_dispatcher function does not have a prototype, and
yields the following warning when W=1 is enabled for the kernel build.

  &gt;&gt; arch/x86/net/bpf_jit_comp.c:2188:5: warning: no previous \
  prototype for 'arch_prepare_bpf_dispatcher' [-Wmissing-prototypes]
        2188 | int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, \
	int num_funcs)
             |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~

Remove the warning by adding a function declaration to include/linux/bpf.h.

Fixes: 75ccbef6369e ("bpf: Introduce BPF dispatcher")
Reported-by: kernel test robot &lt;lkp@intel.com&gt;
Signed-off-by: Björn Töpel &lt;bjorn@kernel.org&gt;
Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Link: https://lore.kernel.org/bpf/20211117125708.769168-1-bjorn@kernel.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>HID: add hid_is_usb() function to make it simpler for USB detection</title>
<updated>2021-12-14T10:32:33Z</updated>
<author>
<name>Greg Kroah-Hartman</name>
<email>gregkh@linuxfoundation.org</email>
</author>
<published>2021-12-01T18:35:01Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=61144329606cb9518642b7d2e940b21eb3214204'/>
<id>urn:sha1:61144329606cb9518642b7d2e940b21eb3214204</id>
<content type='text'>
commit f83baa0cb6cfc92ebaf7f9d3a99d7e34f2e77a8a upstream.

A number of HID drivers already call hid_is_using_ll_driver() but only
for the detection of if this is a USB device or not.  Make this more
obvious by creating hid_is_usb() and calling the function that way.

Also converts the existing hid_is_using_ll_driver() functions to use the
new call.

Cc: Jiri Kosina &lt;jikos@kernel.org&gt;
Cc: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&gt;
Cc: linux-input@vger.kernel.org
Cc: stable@vger.kernel.org
Tested-by: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&gt;
Link: https://lore.kernel.org/r/20211201183503.2373082-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net: annotate data-races on txq-&gt;xmit_lock_owner</title>
<updated>2021-12-08T08:03:25Z</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2021-11-30T17:01:55Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=fa973bf5fd0fda6f0bf9a5d3d403078824dc27ac'/>
<id>urn:sha1:fa973bf5fd0fda6f0bf9a5d3d403078824dc27ac</id>
<content type='text'>
commit 7a10d8c810cfad3e79372d7d1c77899d86cd6662 upstream.

syzbot found that __dev_queue_xmit() is reading txq-&gt;xmit_lock_owner
without annotations.

No serious issue there, let's document what is happening there.

BUG: KCSAN: data-race in __dev_queue_xmit / __dev_queue_xmit

write to 0xffff888139d09484 of 4 bytes by interrupt on cpu 0:
 __netif_tx_unlock include/linux/netdevice.h:4437 [inline]
 __dev_queue_xmit+0x948/0xf70 net/core/dev.c:4229
 dev_queue_xmit_accel+0x19/0x20 net/core/dev.c:4265
 macvlan_queue_xmit drivers/net/macvlan.c:543 [inline]
 macvlan_start_xmit+0x2b3/0x3d0 drivers/net/macvlan.c:567
 __netdev_start_xmit include/linux/netdevice.h:4987 [inline]
 netdev_start_xmit include/linux/netdevice.h:5001 [inline]
 xmit_one+0x105/0x2f0 net/core/dev.c:3590
 dev_hard_start_xmit+0x72/0x120 net/core/dev.c:3606
 sch_direct_xmit+0x1b2/0x7c0 net/sched/sch_generic.c:342
 __dev_xmit_skb+0x83d/0x1370 net/core/dev.c:3817
 __dev_queue_xmit+0x590/0xf70 net/core/dev.c:4194
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4259
 neigh_hh_output include/net/neighbour.h:511 [inline]
 neigh_output include/net/neighbour.h:525 [inline]
 ip6_finish_output2+0x995/0xbb0 net/ipv6/ip6_output.c:126
 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline]
 ip6_finish_output+0x444/0x4c0 net/ipv6/ip6_output.c:201
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip6_output+0x10e/0x210 net/ipv6/ip6_output.c:224
 dst_output include/net/dst.h:450 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 ndisc_send_skb+0x486/0x610 net/ipv6/ndisc.c:508
 ndisc_send_rs+0x3b0/0x3e0 net/ipv6/ndisc.c:702
 addrconf_rs_timer+0x370/0x540 net/ipv6/addrconf.c:3898
 call_timer_fn+0x2e/0x240 kernel/time/timer.c:1421
 expire_timers+0x116/0x240 kernel/time/timer.c:1466
 __run_timers+0x368/0x410 kernel/time/timer.c:1734
 run_timer_softirq+0x2e/0x60 kernel/time/timer.c:1747
 __do_softirq+0x158/0x2de kernel/softirq.c:558
 __irq_exit_rcu kernel/softirq.c:636 [inline]
 irq_exit_rcu+0x37/0x70 kernel/softirq.c:648
 sysvec_apic_timer_interrupt+0x3e/0xb0 arch/x86/kernel/apic/apic.c:1097
 asm_sysvec_apic_timer_interrupt+0x12/0x20

read to 0xffff888139d09484 of 4 bytes by interrupt on cpu 1:
 __dev_queue_xmit+0x5e3/0xf70 net/core/dev.c:4213
 dev_queue_xmit_accel+0x19/0x20 net/core/dev.c:4265
 macvlan_queue_xmit drivers/net/macvlan.c:543 [inline]
 macvlan_start_xmit+0x2b3/0x3d0 drivers/net/macvlan.c:567
 __netdev_start_xmit include/linux/netdevice.h:4987 [inline]
 netdev_start_xmit include/linux/netdevice.h:5001 [inline]
 xmit_one+0x105/0x2f0 net/core/dev.c:3590
 dev_hard_start_xmit+0x72/0x120 net/core/dev.c:3606
 sch_direct_xmit+0x1b2/0x7c0 net/sched/sch_generic.c:342
 __dev_xmit_skb+0x83d/0x1370 net/core/dev.c:3817
 __dev_queue_xmit+0x590/0xf70 net/core/dev.c:4194
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4259
 neigh_resolve_output+0x3db/0x410 net/core/neighbour.c:1523
 neigh_output include/net/neighbour.h:527 [inline]
 ip6_finish_output2+0x9be/0xbb0 net/ipv6/ip6_output.c:126
 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline]
 ip6_finish_output+0x444/0x4c0 net/ipv6/ip6_output.c:201
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip6_output+0x10e/0x210 net/ipv6/ip6_output.c:224
 dst_output include/net/dst.h:450 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 ndisc_send_skb+0x486/0x610 net/ipv6/ndisc.c:508
 ndisc_send_rs+0x3b0/0x3e0 net/ipv6/ndisc.c:702
 addrconf_rs_timer+0x370/0x540 net/ipv6/addrconf.c:3898
 call_timer_fn+0x2e/0x240 kernel/time/timer.c:1421
 expire_timers+0x116/0x240 kernel/time/timer.c:1466
 __run_timers+0x368/0x410 kernel/time/timer.c:1734
 run_timer_softirq+0x2e/0x60 kernel/time/timer.c:1747
 __do_softirq+0x158/0x2de kernel/softirq.c:558
 __irq_exit_rcu kernel/softirq.c:636 [inline]
 irq_exit_rcu+0x37/0x70 kernel/softirq.c:648
 sysvec_apic_timer_interrupt+0x8d/0xb0 arch/x86/kernel/apic/apic.c:1097
 asm_sysvec_apic_timer_interrupt+0x12/0x20
 kcsan_setup_watchpoint+0x94/0x420 kernel/kcsan/core.c:443
 folio_test_anon include/linux/page-flags.h:581 [inline]
 PageAnon include/linux/page-flags.h:586 [inline]
 zap_pte_range+0x5ac/0x10e0 mm/memory.c:1347
 zap_pmd_range mm/memory.c:1467 [inline]
 zap_pud_range mm/memory.c:1496 [inline]
 zap_p4d_range mm/memory.c:1517 [inline]
 unmap_page_range+0x2dc/0x3d0 mm/memory.c:1538
 unmap_single_vma+0x157/0x210 mm/memory.c:1583
 unmap_vmas+0xd0/0x180 mm/memory.c:1615
 exit_mmap+0x23d/0x470 mm/mmap.c:3170
 __mmput+0x27/0x1b0 kernel/fork.c:1113
 mmput+0x3d/0x50 kernel/fork.c:1134
 exit_mm+0xdb/0x170 kernel/exit.c:507
 do_exit+0x608/0x17a0 kernel/exit.c:819
 do_group_exit+0xce/0x180 kernel/exit.c:929
 get_signal+0xfc3/0x1550 kernel/signal.c:2852
 arch_do_signal_or_restart+0x8c/0x2e0 arch/x86/kernel/signal.c:868
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x113/0x190 kernel/entry/common.c:207
 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:300
 do_syscall_64+0x50/0xd0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000 -&gt; 0xffffffff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 28712 Comm: syz-executor.0 Tainted: G        W         5.16.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reported-by: syzbot &lt;syzkaller@googlegroups.com&gt;
Link: https://lore.kernel.org/r/20211130170155.2331929-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>siphash: use _unaligned version by default</title>
<updated>2021-12-08T08:03:23Z</updated>
<author>
<name>Arnd Bergmann</name>
<email>arnd@arndb.de</email>
</author>
<published>2021-11-29T15:39:29Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=ef55f0f8af2b64ddf9e23518bd11475f9fc7e16d'/>
<id>urn:sha1:ef55f0f8af2b64ddf9e23518bd11475f9fc7e16d</id>
<content type='text'>
commit f7e5b9bfa6c8820407b64eabc1f29c9a87e8993d upstream.

On ARM v6 and later, we define CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
because the ordinary load/store instructions (ldr, ldrh, ldrb) can
tolerate any misalignment of the memory address. However, load/store
double and load/store multiple instructions (ldrd, ldm) may still only
be used on memory addresses that are 32-bit aligned, and so we have to
use the CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS macro with care, or we
may end up with a severe performance hit due to alignment traps that
require fixups by the kernel. Testing shows that this currently happens
with clang-13 but not gcc-11. In theory, any compiler version can
produce this bug or other problems, as we are dealing with undefined
behavior in C99 even on architectures that support this in hardware,
see also https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100363.

Fortunately, the get_unaligned() accessors do the right thing: when
building for ARMv6 or later, the compiler will emit unaligned accesses
using the ordinary load/store instructions (but avoid the ones that
require 32-bit alignment). When building for older ARM, those accessors
will emit the appropriate sequence of ldrb/mov/orr instructions. And on
architectures that can truly tolerate any kind of misalignment, the
get_unaligned() accessors resolve to the leXX_to_cpup accessors that
operate on aligned addresses.

Since the compiler will in fact emit ldrd or ldm instructions when
building this code for ARM v6 or later, the solution is to use the
unaligned accessors unconditionally on architectures where this is
known to be fast. The _aligned version of the hash function is
however still needed to get the best performance on architectures
that cannot do any unaligned access in hardware.

This new version avoids the undefined behavior and should produce
the fastest hash on all architectures we support.

Link: https://lore.kernel.org/linux-arm-kernel/20181008211554.5355-4-ard.biesheuvel@linaro.org/
Link: https://lore.kernel.org/linux-crypto/CAK8P3a2KfmmGDbVHULWevB0hv71P2oi2ZCHEAqT=8dQfa0=cqQ@mail.gmail.com/
Reported-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Fixes: 2c956a60778c ("siphash: add cryptographically secure PRF")
Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Reviewed-by: Jason A. Donenfeld &lt;Jason@zx2c4.com&gt;
Acked-by: Ard Biesheuvel &lt;ardb@kernel.org&gt;
Signed-off-by: Jason A. Donenfeld &lt;Jason@zx2c4.com&gt;
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
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