Commit 5a5c11ee authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'bpf: Add kprobe multi link' 

Jiri Olsa says:

====================

hi,
this patchset adds new link type BPF_TRACE_KPROBE_MULTI that attaches
kprobe program through fprobe API [1] instroduced by Masami.

The fprobe API allows to attach probe on multiple functions at once very
fast, because it works on top of ftrace. On the other hand this limits
the probe point to the function entry or return.

With bpftrace support I see following attach speed:

  # perf stat --null -r 5 ./src/bpftrace -e 'kprobe:x* { } i:ms:1 { exit(); } '
  Attaching 2 probes...
  Attaching 3342 functions
  ...

  1.4960 +- 0.0285 seconds time elapsed  ( +-  1.91% )

v3 changes:
  - based on latest fprobe post from Masami [2]
  - add acks
  - add extra comment to kprobe_multi_link_handler wrt entry ip setup [Masami]
  - keep swap_words_64 static and swap values directly in
    bpf_kprobe_multi_cookie_swap [Andrii]
  - rearrange locking/migrate setup in kprobe_multi_link_prog_run [Andrii]
  - move uapi fields [Andrii]
  - add bpf_program__attach_kprobe_multi_opts function [Andrii]
  - many small test changes [Andrii]
  - added tests for bpf_program__attach_kprobe_multi_opts
  - make kallsyms_lookup_name check for empty string [Andrii]

v2 changes:
  - based on latest fprobe changes [1]
  - renaming the uapi interface to kprobe multi
  - adding support for sort_r to pass user pointer for swap functions
    and using that in cookie support to keep just single functions array
  - moving new link to kernel/trace/bpf_trace.c file
  - using single fprobe callback function for entry and exit
  - using kvzalloc, libbpf_ensure_mem functions
  - adding new k[ret]probe.multi sections instead of using current kprobe
  - used glob_match from test_progs.c, added '?' matching
  - move bpf_get_func_ip verifier inline change to seprate change
  - couple of other minor fixes

Also available at:
  https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
  bpf/kprobe_multi

thanks,
jirka

[1] https://lore.kernel.org/bpf/164458044634.586276.3261555265565111183.stgit@devnote2/
[2] https://lore.kernel.org/bpf/164735281449.1084943.12438881786173547153.stgit@devnote2/


====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents 245d9496 318c812c

include/linux/bpf_types.h

+1 −0
Original line number Diff line number Diff line
@@ -140,3 +140,4 @@ BPF_LINK_TYPE(BPF_LINK_TYPE_XDP, xdp) 
#ifdef CONFIG_PERF_EVENTS

BPF_LINK_TYPE(BPF_LINK_TYPE_PERF_EVENT, perf)

#endif

BPF_LINK_TYPE(BPF_LINK_TYPE_KPROBE_MULTI, kprobe_multi)

include/linux/sort.h

+1 −1
Original line number Diff line number Diff line
@@ -6,7 +6,7 @@ 


void sort_r(void *base, size_t num, size_t size,

	    cmp_r_func_t cmp_func,

	    swap_func_t swap_func,

	    swap_r_func_t swap_func,

	    const void *priv);



void sort(void *base, size_t num, size_t size,

include/linux/trace_events.h

+7 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ struct array_buffer; 
struct tracer;

struct dentry;

struct bpf_prog;

union bpf_attr;



const char *trace_print_flags_seq(struct trace_seq *p, const char *delim,

				  unsigned long flags,
@@ -738,6 +739,7 @@ void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp); 
int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,

			    u32 *fd_type, const char **buf,

			    u64 *probe_offset, u64 *probe_addr);

int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);

#else

static inline unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx)

{
@@ -779,6 +781,11 @@ static inline int bpf_get_perf_event_info(const struct perf_event *event, 
{

	return -EOPNOTSUPP;

}

static inline int

bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)

{

	return -EOPNOTSUPP;

}

#endif



enum {

include/linux/types.h

+1 −0
Original line number Diff line number Diff line
@@ -226,6 +226,7 @@ struct callback_head { 
typedef void (*rcu_callback_t)(struct rcu_head *head);

typedef void (*call_rcu_func_t)(struct rcu_head *head, rcu_callback_t func);



typedef void (*swap_r_func_t)(void *a, void *b, int size, const void *priv);

typedef void (*swap_func_t)(void *a, void *b, int size);



typedef int (*cmp_r_func_t)(const void *a, const void *b, const void *priv);

include/uapi/linux/bpf.h

+14 −0
Original line number Diff line number Diff line
@@ -997,6 +997,7 @@ enum bpf_attach_type { 
	BPF_SK_REUSEPORT_SELECT,

	BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,

	BPF_PERF_EVENT,

	BPF_TRACE_KPROBE_MULTI,

	__MAX_BPF_ATTACH_TYPE

};
@@ -1011,6 +1012,7 @@ enum bpf_link_type { 
	BPF_LINK_TYPE_NETNS = 5,

	BPF_LINK_TYPE_XDP = 6,

	BPF_LINK_TYPE_PERF_EVENT = 7,

	BPF_LINK_TYPE_KPROBE_MULTI = 8,



	MAX_BPF_LINK_TYPE,

};
@@ -1118,6 +1120,11 @@ enum bpf_link_type { 
 */

#define BPF_F_XDP_HAS_FRAGS	(1U << 5)



/* link_create.kprobe_multi.flags used in LINK_CREATE command for

 * BPF_TRACE_KPROBE_MULTI attach type to create return probe.

 */

#define BPF_F_KPROBE_MULTI_RETURN	(1U << 0)



/* When BPF ldimm64's insn[0].src_reg != 0 then this can have

 * the following extensions:

 *
@@ -1475,6 +1482,13 @@ union bpf_attr { 
				 */

				__u64		bpf_cookie;

			} perf_event;

			struct {

				__u32		flags;

				__u32		cnt;

				__aligned_u64	syms;

				__aligned_u64	addrs;

				__aligned_u64	cookies;

			} kprobe_multi;

		};

	} link_create;