Re: [RFC 00/13] perf bpf: Add support to run BEGIN/END code
From: Jiri Olsa
Date: Mon Mar 12 2018 - 07:17:17 EST
adding Alexei and Wang to the loop
On Mon, Mar 12, 2018 at 10:43:00AM +0100, Jiri Olsa wrote:
> hi,
> this is *RFC* and the following patchset is very rough
> and ugly 'prove of concept'-kind-of-toy code. I'm mostly
> interested in opinions about if this could be useful in
> your current eBPF usage.
>
> Currently we can load eBPF code within the record command
> and attach it to event. We have 2 ways of communicating
> the data back to user: bpf-output event that goes to
> perf.data or 'trace_printk' output in tracefs buffer.
>
> AFAICS we're not covering quite large usage base that runs
> code before and once the probe is finished to setup, collect
> and display the collected data.
>
> This patchset is adding support to run BEGIN and END
> code snipets before and after eBPF probe is loaded.
>
> This allow to write 'collecting' code in eBPF object,
> like in the attached example (it's also part of the
> patchset).
>
> This patchset also adds 'bpf' command to ease up the
> loading of eBPF files with options for compilation
> and disassembly of eBPF objects:
>
> $ perf bpf -c samples/syscall-counts.c
> LLVM: dumping samples/syscall-counts.o
>
> $ perf bpf -d samples/syscall-counts.o | head
> Disassembly of raw_syscalls:sys_enter:
> 0: (b7) r1 = 1
> b7 01 00 00 01 00 00 00
> 1: (7b) *(u64 *)(r10 -8) = r1
> 7b 1a f8 ff 00 00 00 00
> 2: (bf) r6 = r10
> ...
>
> $ sudo perf bpf -e samples/syscall-counts.o -a
> BEGIN
> ^CEND
> comm value
> firefox 182
> Socket Thread 8
> InotifyEventThr 26
> xmonad-x86_64-l 405
> ...
>
> The patchset is also available in here:
> https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
> perf/bpf
>
> So far I need following following lines in .perfconfig to run this:
> [llvm]
> kbuild-dir=/home/jolsa/kernel/linux-perf
> clang-opt=-I/home/jolsa/kernel/linux-perf/tools/perf/util
>
>
> thoughts? ;-) thanks,
> jirka
>
>
> Cc: Brendan Gregg <bgregg@xxxxxxxxxxx>
> Cc: Stanislav Kozina <skozina@xxxxxxxxxx>
> Cc: "Frank Ch. Eigler" <fche@xxxxxxxxxx>
> Cc: Will Cohen <wcohen@xxxxxxxxxx>
> Cc: Eugene Syromiatnikov <esyromia@xxxxxxxxxx>
> Cc: Jerome Marchand <jmarchan@xxxxxxxxxx>
>
> ---
> #include <uapi/linux/bpf.h>
> #include <bpf-helpers.h>
> #include <bpf-userfuncs.h>
>
> #define TASK_COMM_LEN 16
>
> char _license[] SEC("license") = "GPL";
> int _version SEC("version") = LINUX_VERSION_CODE;
>
> struct key_t {
> char comm[TASK_COMM_LEN];
> };
>
> struct bpf_map_def SEC("maps") counts_map = {
> .type = BPF_MAP_TYPE_HASH,
> .key_size = sizeof(struct key_t),
> .value_size = sizeof(u64),
> .max_entries = 100,
> };
>
> SEC("raw_syscalls:sys_enter")
> int func(void *ctx)
> {
> u64 *val, one = 1;
> struct key_t key;
> char comm[TASK_COMM_LEN];
>
> bpf_get_current_comm(&key.comm, sizeof(comm));
>
> val = bpf_map_lookup_elem(&counts_map, &key);
> if (val)
> (*val)++;
> else
> bpf_map_update_elem(&counts_map, &key, &one, BPF_NOEXIST);
>
> return 0;
> }
>
> int BEGIN(void)
> {
> print("BEGIN\n");
> return 0;
> }
>
> void END(void)
> {
> struct key_t key = {}, next_key;
> u64 value;
> int i = 0;
>
> print("END\n");
> print("\n comm value\n");
>
> while (bpfu_map_get_next_key(&counts_map, &key, &next_key) == 0) {
> if (bpfu_map_lookup_elem(&counts_map, &next_key, &value))
> continue;
>
> print("%18s %16lu\n", next_key.comm, value);
> key = next_key;
> }
> }
>
> ---
> Jiri Olsa (13):
> lib bpf: Add bpf_program__insns function
> perf tools: Display ebpf compiling command in debug output
> perf tools: Add bpf command
> perf tools: Add bpf__compile function
> perf bpf: Add compile option
> perf bpf: Add disasm option
> libbpf: Make bpf_program__next skip .text section
> libbpf: Collect begin/end .text functions
> libbpf: Add bpf_insn__interpret function
> libbpf: Add bpf_object__run_(begin|end) functions
> perf bpf: Add helper header files
> perf bpf: Run begin/end programs
> perf samples: Add syscall-count.c object
>
> tools/lib/bpf/Build | 2 +-
> tools/lib/bpf/interp.c | 245 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> tools/lib/bpf/libbpf.c | 125 +++++++++++++++++++++++++++++++++++++++++++++++--
> tools/lib/bpf/libbpf.h | 7 +++
> tools/perf/Build | 7 +++
> tools/perf/Makefile.config | 1 +
> tools/perf/builtin-bpf.c | 319 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> tools/perf/builtin.h | 1 +
> tools/perf/command-list.txt | 1 +
> tools/perf/perf.c | 1 +
> tools/perf/samples/syscall-counts.c | 61 ++++++++++++++++++++++++
> tools/perf/util/bpf-helpers.h | 246 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> tools/perf/util/bpf-loader.c | 124 ++++++++++++++++++++++++++++++++++++++++++++-----
> tools/perf/util/bpf-loader.h | 4 ++
> tools/perf/util/bpf-userapi.h | 11 +++++
> tools/perf/util/bpf-userfuncs.h | 19 ++++++++
> tools/perf/util/llvm-utils.c | 14 ++++++
> 17 files changed, 1173 insertions(+), 15 deletions(-)
> create mode 100644 tools/lib/bpf/interp.c
> create mode 100644 tools/perf/builtin-bpf.c
> create mode 100644 tools/perf/samples/syscall-counts.c
> create mode 100644 tools/perf/util/bpf-helpers.h
> create mode 100644 tools/perf/util/bpf-userapi.h
> create mode 100644 tools/perf/util/bpf-userfuncs.h