From: Menglong Dong <imagedong@xxxxxxxxxxx> By default, libbpf will attach the kprobe/uprobe eBPF program in the latest mode that supported by kernel. In this patch, we add the support to let users manually attach kprobe/uprobe in legacy or perf mode. There are 3 mode that supported by the kernel to attach kprobe/uprobe: LEGACY: create perf event in legacy way and don't use bpf_link PERF: create perf event with perf_event_open() and don't use bpf_link LINK: create perf event with perf_event_open() and use bpf_link Users now can manually choose the mode with bpf_program__attach_uprobe_opts()/bpf_program__attach_kprobe_opts(). Link: https://lore.kernel.org/bpf/20230113093427.1666466-1-imagedong@xxxxxxxxxxx/ Signed-off-by: Menglong Dong <imagedong@xxxxxxxxxxx> --- tools/lib/bpf/libbpf.c | 26 +++++++++++++++++++++++++- tools/lib/bpf/libbpf.h | 19 ++++++++++++++++--- 2 files changed, 41 insertions(+), 4 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index eed5cec6f510..0d20bf1ee301 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -9784,7 +9784,7 @@ struct bpf_link *bpf_program__attach_perf_event_opts(const struct bpf_program *p link->link.dealloc = &bpf_link_perf_dealloc; link->perf_event_fd = pfd; - if (kernel_supports(prog->obj, FEAT_PERF_LINK)) { + if (kernel_supports(prog->obj, FEAT_PERF_LINK) && !opts->no_link) { DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_opts, .perf_event.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0)); @@ -10148,16 +10148,28 @@ bpf_program__attach_kprobe_opts(const struct bpf_program *prog, struct bpf_link *link; size_t offset; bool retprobe, legacy; + enum probe_mode mode; int pfd, err; if (!OPTS_VALID(opts, bpf_kprobe_opts)) return libbpf_err_ptr(-EINVAL); + mode = OPTS_GET(opts, mode, PROBE_MODE_DEFAULT); retprobe = OPTS_GET(opts, retprobe, false); offset = OPTS_GET(opts, offset, 0); pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0); legacy = determine_kprobe_perf_type() < 0; + switch (mode) { + case PROBE_MODE_LEGACY: + legacy = true; + case PROBE_MODE_PERF: + pe_opts.no_link = true; + break; + default: + break; + } + if (!legacy) { pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name, offset, @@ -10817,10 +10829,12 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid, int pfd, err; bool retprobe, legacy; const char *func_name; + enum probe_mode mode; if (!OPTS_VALID(opts, bpf_uprobe_opts)) return libbpf_err_ptr(-EINVAL); + mode = OPTS_GET(opts, mode, PROBE_MODE_DEFAULT); retprobe = OPTS_GET(opts, retprobe, false); ref_ctr_off = OPTS_GET(opts, ref_ctr_offset, 0); pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0); @@ -10849,6 +10863,16 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid, } legacy = determine_uprobe_perf_type() < 0; + switch (mode) { + case PROBE_MODE_LEGACY: + legacy = true; + case PROBE_MODE_PERF: + pe_opts.no_link = true; + break; + default: + break; + } + if (!legacy) { pfd = perf_event_open_probe(true /* uprobe */, retprobe, binary_path, func_offset, pid, ref_ctr_off); diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 8777ff21ea1d..7fb474e036a3 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -451,8 +451,10 @@ struct bpf_perf_event_opts { size_t sz; /* custom user-provided value fetchable through bpf_get_attach_cookie() */ __u64 bpf_cookie; + /* don't use bpf_link when attach eBPF pprogram */ + bool no_link; }; -#define bpf_perf_event_opts__last_field bpf_cookie +#define bpf_perf_event_opts__last_field no_link LIBBPF_API struct bpf_link * bpf_program__attach_perf_event(const struct bpf_program *prog, int pfd); @@ -461,6 +463,13 @@ LIBBPF_API struct bpf_link * bpf_program__attach_perf_event_opts(const struct bpf_program *prog, int pfd, const struct bpf_perf_event_opts *opts); +enum probe_mode { + PROBE_MODE_DEFAULT = 0, /* latest supported by kernel */ + PROBE_MODE_LEGACY, + PROBE_MODE_PERF, + PROBE_MODE_LINK, +}; + struct bpf_kprobe_opts { /* size of this struct, for forward/backward compatiblity */ size_t sz; @@ -470,9 +479,11 @@ struct bpf_kprobe_opts { size_t offset; /* kprobe is return probe */ bool retprobe; + /* kprobe attach mode */ + enum probe_mode mode; size_t :0; }; -#define bpf_kprobe_opts__last_field retprobe +#define bpf_kprobe_opts__last_field mode LIBBPF_API struct bpf_link * bpf_program__attach_kprobe(const struct bpf_program *prog, bool retprobe, @@ -570,9 +581,11 @@ struct bpf_uprobe_opts { * binary_path. */ const char *func_name; + /* uprobe attach mode */ + enum probe_mode mode; size_t :0; }; -#define bpf_uprobe_opts__last_field func_name +#define bpf_uprobe_opts__last_field mode /** * @brief **bpf_program__attach_uprobe()** attaches a BPF program -- 2.39.0
