linux-stable.git/include/uapi/linux/bpf.h, branch v5.16.2

bpf: Add alignment padding for "map_extra" + consolidate holes

2021-11-01T21:16:03+00:00

This patch makes 2 changes regarding alignment padding
for the "map_extra" field.

1) In the kernel header, "map_extra" and "btf_value_type_id"
are rearranged to consolidate the hole.

Before:
struct bpf_map {
	...
        u32		max_entries;	/*    36     4	*/
        u32		map_flags;	/*    40     4	*/

        /* XXX 4 bytes hole, try to pack */

        u64		map_extra;	/*    48     8	*/
        int		spin_lock_off;	/*    56     4	*/
        int		timer_off;	/*    60     4	*/
        /* --- cacheline 1 boundary (64 bytes) --- */
        u32		id;		/*    64     4	*/
        int		numa_node;	/*    68     4	*/
	...
        bool		frozen;		/*   117     1	*/

        /* XXX 10 bytes hole, try to pack */

        /* --- cacheline 2 boundary (128 bytes) --- */
	...
        struct work_struct	work;	/*   144    72	*/

        /* --- cacheline 3 boundary (192 bytes) was 24 bytes ago --- */
	struct mutex	freeze_mutex;	/*   216   144 	*/

        /* --- cacheline 5 boundary (320 bytes) was 40 bytes ago --- */
        u64		writecnt; 	/*   360     8	*/

    /* size: 384, cachelines: 6, members: 26 */
    /* sum members: 354, holes: 2, sum holes: 14 */
    /* padding: 16 */
    /* forced alignments: 2, forced holes: 1, sum forced holes: 10 */

} __attribute__((__aligned__(64)));

After:
struct bpf_map {
	...
        u32		max_entries;	/*    36     4	*/
        u64		map_extra;	/*    40     8 	*/
        u32		map_flags;	/*    48     4	*/
        int		spin_lock_off;	/*    52     4	*/
        int		timer_off;	/*    56     4	*/
        u32		id;		/*    60     4	*/

        /* --- cacheline 1 boundary (64 bytes) --- */
        int		numa_node;	/*    64     4	*/
	...
	bool		frozen		/*   113     1  */

        /* XXX 14 bytes hole, try to pack */

        /* --- cacheline 2 boundary (128 bytes) --- */
	...
        struct work_struct	work;	/*   144    72	*/

        /* --- cacheline 3 boundary (192 bytes) was 24 bytes ago --- */
        struct mutex	freeze_mutex;	/*   216   144	*/

        /* --- cacheline 5 boundary (320 bytes) was 40 bytes ago --- */
        u64		writecnt;       /*   360     8	*/

    /* size: 384, cachelines: 6, members: 26 */
    /* sum members: 354, holes: 1, sum holes: 14 */
    /* padding: 16 */
    /* forced alignments: 2, forced holes: 1, sum forced holes: 14 */

} __attribute__((__aligned__(64)));

2) Add alignment padding to the bpf_map_info struct
More details can be found in commit 36f9814a494a ("bpf: fix uapi hole
for 32 bit compat applications")

Signed-off-by: Joanne Koong 
Signed-off-by: Alexei Starovoitov 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20211029224909.1721024-3-joannekoong@fb.com

bpf: Add bpf_kallsyms_lookup_name helper

2021-10-28T23:30:06+00:00

This helper allows us to get the address of a kernel symbol from inside
a BPF_PROG_TYPE_SYSCALL prog (used by gen_loader), so that we can
relocate typeless ksym vars.

Signed-off-by: Kumar Kartikeya Dwivedi 
Signed-off-by: Alexei Starovoitov 
Acked-by: Song Liu 
Link: https://lore.kernel.org/bpf/20211028063501.2239335-2-memxor@gmail.com

bpf: Add bloom filter map implementation

2021-10-28T20:22:49+00:00

This patch adds the kernel-side changes for the implementation of
a bpf bloom filter map.

The bloom filter map supports peek (determining whether an element
is present in the map) and push (adding an element to the map)
operations.These operations are exposed to userspace applications
through the already existing syscalls in the following way:

BPF_MAP_LOOKUP_ELEM -> peek
BPF_MAP_UPDATE_ELEM -> push

The bloom filter map does not have keys, only values. In light of
this, the bloom filter map's API matches that of queue stack maps:
user applications use BPF_MAP_LOOKUP_ELEM/BPF_MAP_UPDATE_ELEM
which correspond internally to bpf_map_peek_elem/bpf_map_push_elem,
and bpf programs must use the bpf_map_peek_elem and bpf_map_push_elem
APIs to query or add an element to the bloom filter map. When the
bloom filter map is created, it must be created with a key_size of 0.

For updates, the user will pass in the element to add to the map
as the value, with a NULL key. For lookups, the user will pass in the
element to query in the map as the value, with a NULL key. In the
verifier layer, this requires us to modify the argument type of
a bloom filter's BPF_FUNC_map_peek_elem call to ARG_PTR_TO_MAP_VALUE;
as well, in the syscall layer, we need to copy over the user value
so that in bpf_map_peek_elem, we know which specific value to query.

A few things to please take note of:
 * If there are any concurrent lookups + updates, the user is
responsible for synchronizing this to ensure no false negative lookups
occur.
 * The number of hashes to use for the bloom filter is configurable from
userspace. If no number is specified, the default used will be 5 hash
functions. The benchmarks later in this patchset can help compare the
performance of using different number of hashes on different entry
sizes. In general, using more hashes decreases both the false positive
rate and the speed of a lookup.
 * Deleting an element in the bloom filter map is not supported.
 * The bloom filter map may be used as an inner map.
 * The "max_entries" size that is specified at map creation time is used
to approximate a reasonable bitmap size for the bloom filter, and is not
otherwise strictly enforced. If the user wishes to insert more entries
into the bloom filter than "max_entries", they may do so but they should
be aware that this may lead to a higher false positive rate.

Signed-off-by: Joanne Koong 
Signed-off-by: Alexei Starovoitov 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20211027234504.30744-2-joannekoong@fb.com

bpf: Add verified_insns to bpf_prog_info and fdinfo

2021-10-21T22:51:47+00:00

This stat is currently printed in the verifier log and not stored
anywhere. To ease consumption of this data, add a field to bpf_prog_aux
so it can be exposed via BPF_OBJ_GET_INFO_BY_FD and fdinfo.

Signed-off-by: Dave Marchevsky 
Signed-off-by: Andrii Nakryiko 
Acked-by: John Fastabend 
Link: https://lore.kernel.org/bpf/20211020074818.1017682-2-davemarchevsky@fb.com

bpf: Add bpf_skc_to_unix_sock() helper

2021-10-21T22:11:06+00:00

The helper is used in tracing programs to cast a socket
pointer to a unix_sock pointer.
The return value could be NULL if the casting is illegal.

Suggested-by: Yonghong Song 
Signed-off-by: Hengqi Chen 
Signed-off-by: Alexei Starovoitov 
Acked-by: Song Liu 
Link: https://lore.kernel.org/bpf/20211021134752.1223426-2-hengqi.chen@gmail.com

bpf: Clarify data_len param in bpf_snprintf and bpf_seq_printf comments

2021-09-17T21:02:06+00:00

Since the data_len in these two functions is a byte len of the preceding
u64 *data array, it must always be a multiple of 8. If this isn't the
case both helpers error out, so let's make the requirement explicit so
users don't need to infer it.

Signed-off-by: Dave Marchevsky 
Signed-off-by: Alexei Starovoitov 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20210917182911.2426606-10-davemarchevsky@fb.com

bpf: Add bpf_trace_vprintk helper

2021-09-17T21:02:05+00:00

This helper is meant to be "bpf_trace_printk, but with proper vararg
support". Follow bpf_snprintf's example and take a u64 pseudo-vararg
array. Write to /sys/kernel/debug/tracing/trace_pipe using the same
mechanism as bpf_trace_printk. The functionality of this helper was
requested in the libbpf issue tracker [0].

[0] Closes: https://github.com/libbpf/libbpf/issues/315

Signed-off-by: Dave Marchevsky 
Signed-off-by: Alexei Starovoitov 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20210917182911.2426606-4-davemarchevsky@fb.com

bpf: Update bpf_get_smp_processor_id() documentation

2021-09-15T20:39:55+00:00

BPF programs run with migration disabled regardless of preemption, as
they are protected by migrate_disable(). Update the uapi documentation
accordingly.

Signed-off-by: Matteo Croce 
Signed-off-by: Daniel Borkmann 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20210914235400.59427-1-mcroce@linux.microsoft.com

bpf: Introduce helper bpf_get_branch_snapshot

2021-09-13T17:53:50+00:00

Introduce bpf_get_branch_snapshot(), which allows tracing pogram to get
branch trace from hardware (e.g. Intel LBR). To use the feature, the
user need to create perf_event with proper branch_record filtering
on each cpu, and then calls bpf_get_branch_snapshot in the bpf function.
On Intel CPUs, VLBR event (raw event 0x1b00) can be use for this.

Signed-off-by: Song Liu 
Signed-off-by: Alexei Starovoitov 
Acked-by: John Fastabend 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20210910183352.3151445-3-songliubraving@fb.com

bpf: Add hardware timestamp field to __sk_buff

2021-09-10T21:19:58+00:00

BPF programs may want to know hardware timestamps if NIC supports
such timestamping.

Expose this data as hwtstamp field of __sk_buff the same way as
gso_segs/gso_size. This field could be accessed from the same
programs as tstamp field, but it's read-only field. Explicit test
to deny access to padding data is added to bpf_skb_is_valid_access.

Also update BPF_PROG_TEST_RUN tests of the feature.

Signed-off-by: Vadim Fedorenko 
Signed-off-by: Daniel Borkmann 
Acked-by: Martin KaFai Lau 
Link: https://lore.kernel.org/bpf/20210909220409.8804-2-vfedorenko@novek.ru