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linux/include
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Lorenz Bauer d66423fbe1 bpf: Plug hole in struct bpf_sk_lookup_kern 
As Alexei points out, struct bpf_sk_lookup_kern has two 4-byte holes.
This leads to suboptimal instructions being generated (IPv4, x86):

    1372                    struct bpf_sk_lookup_kern ctx = {
       0xffffffff81b87f30 <+624>:   xor    %eax,%eax
       0xffffffff81b87f32 <+626>:   mov    $0x6,%ecx
       0xffffffff81b87f37 <+631>:   lea    0x90(%rsp),%rdi
       0xffffffff81b87f3f <+639>:   movl   $0x110002,0x88(%rsp)
       0xffffffff81b87f4a <+650>:   rep stos %rax,%es:(%rdi)
       0xffffffff81b87f4d <+653>:   mov    0x8(%rsp),%eax
       0xffffffff81b87f51 <+657>:   mov    %r13d,0x90(%rsp)
       0xffffffff81b87f59 <+665>:   incl   %gs:0x7e4970a0(%rip)
       0xffffffff81b87f60 <+672>:   mov    %eax,0x8c(%rsp)
       0xffffffff81b87f67 <+679>:   movzwl 0x10(%rsp),%eax
       0xffffffff81b87f6c <+684>:   mov    %ax,0xa8(%rsp)
       0xffffffff81b87f74 <+692>:   movzwl 0x38(%rsp),%eax
       0xffffffff81b87f79 <+697>:   mov    %ax,0xaa(%rsp)

Fix this by moving around sport and dport. pahole confirms there
are no more holes:

    struct bpf_sk_lookup_kern {
        u16                        family;       /*     0     2 */
        u16                        protocol;     /*     2     2 */
        __be16                     sport;        /*     4     2 */
        u16                        dport;        /*     6     2 */
        struct {
                __be32             saddr;        /*     8     4 */
                __be32             daddr;        /*    12     4 */
        } v4;                                    /*     8     8 */
        struct {
                const struct in6_addr  * saddr;  /*    16     8 */
                const struct in6_addr  * daddr;  /*    24     8 */
        } v6;                                    /*    16    16 */
        struct sock *              selected_sk;  /*    32     8 */
        bool                       no_reuseport; /*    40     1 */

        /* size: 48, cachelines: 1, members: 8 */
        /* padding: 7 */
        /* last cacheline: 48 bytes */
    };

The assembly also doesn't contain the pesky rep stos anymore:

    1372                    struct bpf_sk_lookup_kern ctx = {
       0xffffffff81b87f60 <+624>:   movzwl 0x10(%rsp),%eax
       0xffffffff81b87f65 <+629>:   movq   $0x0,0xa8(%rsp)
       0xffffffff81b87f71 <+641>:   movq   $0x0,0xb0(%rsp)
       0xffffffff81b87f7d <+653>:   mov    %ax,0x9c(%rsp)
       0xffffffff81b87f85 <+661>:   movzwl 0x38(%rsp),%eax
       0xffffffff81b87f8a <+666>:   movq   $0x0,0xb8(%rsp)
       0xffffffff81b87f96 <+678>:   mov    %ax,0x9e(%rsp)
       0xffffffff81b87f9e <+686>:   mov    0x8(%rsp),%eax
       0xffffffff81b87fa2 <+690>:   movq   $0x0,0xc0(%rsp)
       0xffffffff81b87fae <+702>:   movl   $0x110002,0x98(%rsp)
       0xffffffff81b87fb9 <+713>:   mov    %eax,0xa0(%rsp)
       0xffffffff81b87fc0 <+720>:   mov    %r13d,0xa4(%rsp)

1: https://lore.kernel.org/bpf/CAADnVQKE6y9h2fwX6OS837v-Uf+aBXnT_JXiN_bbo2gitZQ3tA@mail.gmail.com/

Fixes: e9ddbb7707 ("bpf: Introduce SK_LOOKUP program type with a dedicated attach point")
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20200910110248.198326-1-lmb@cloudflare.com
2020-09-10 17:47:50 -07:00
..
acpi ACPI updates for 5.9-rc1 2020-08-03 20:37:22 -07:00
asm-generic iomap: constify ioreadX() iomem argument (as in generic implementation) 2020-08-14 19:56:57 -07:00
clocksource include/: replace HTTP links with HTTPS ones 2020-08-12 10:57:59 -07:00
crypto mm, treewide: rename kzfree() to kfree_sensitive() 2020-08-07 11:33:22 -07:00
drm Linux 5.8 2020-08-11 11:58:31 +10:00
dt-bindings Here's some more updates that missed the last pull request because I 2020-08-12 12:19:49 -07:00
keys It's been a busy cycle for documentation - hopefully the busiest for a 2020-08-04 22:47:54 -07:00
kunit
kvm
linux bpf: Plug hole in struct bpf_sk_lookup_kern 2020-09-10 17:47:50 -07:00
math-emu
media media updates for v5.9-rc1 2020-08-07 13:00:53 -07:00
memory
misc
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-09-01 13:22:59 -07:00
pcmcia
ras
rdma RDMA 5.9 merge window pull request 2020-08-06 16:43:36 -07:00
scsi
soc include/: replace HTTP links with HTTPS ones 2020-08-12 10:57:59 -07:00
sound ALSA: hda: Add dma stop delay variable 2020-08-05 12:27:47 +02:00
target scsi: target: Make iscsit_register_transport() return void 2020-08-04 20:56:56 -04:00
trace Improvements to ext4's block allocator performance for very large file 2020-08-21 11:03:38 -07:00
uapi bpf: Fix formatting in documentation for BPF helpers 2020-09-07 16:31:18 +02:00
vdso lib/vdso: Allow to add architecture-specific vdso data 2020-08-06 10:57:30 +02:00
video
xen xen: branch for v5.9-rc1b 2020-08-14 13:34:37 -07:00