| Message ID | 20230222230141.1729048-3-namhyung@kernel.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | BPF |
| Headers | show |
| Series | perf record: Implement BPF sample filter (v3) | expand |
On 23/02/23 01:01, Namhyung Kim wrote: > The BPF program will be attached to a perf_event and be triggered when > it overflows. It'd iterate the filters map and compare the sample > value according to the expression. If any of them fails, the sample > would be dropped. > > Also it needs to have the corresponding sample data for the expression > so it compares data->sample_flags with the given value. To access the > sample data, it uses the bpf_cast_to_kern_ctx() kfunc which was added > in v6.2 kernel. > > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > --- > tools/perf/Makefile.perf | 2 +- > tools/perf/util/bpf-filter.c | 64 ++++++++++ > tools/perf/util/bpf-filter.h | 24 ++-- > tools/perf/util/bpf_skel/sample-filter.h | 24 ++++ > tools/perf/util/bpf_skel/sample_filter.bpf.c | 126 +++++++++++++++++++ > tools/perf/util/evsel.h | 7 +- > 6 files changed, 235 insertions(+), 12 deletions(-) > create mode 100644 tools/perf/util/bpf_skel/sample-filter.h > create mode 100644 tools/perf/util/bpf_skel/sample_filter.bpf.c > > diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf > index bac9272682b7..474af4adea95 100644 > --- a/tools/perf/Makefile.perf > +++ b/tools/perf/Makefile.perf > @@ -1047,7 +1047,7 @@ SKELETONS := $(SKEL_OUT)/bpf_prog_profiler.skel.h > SKELETONS += $(SKEL_OUT)/bperf_leader.skel.h $(SKEL_OUT)/bperf_follower.skel.h > SKELETONS += $(SKEL_OUT)/bperf_cgroup.skel.h $(SKEL_OUT)/func_latency.skel.h > SKELETONS += $(SKEL_OUT)/off_cpu.skel.h $(SKEL_OUT)/lock_contention.skel.h > -SKELETONS += $(SKEL_OUT)/kwork_trace.skel.h > +SKELETONS += $(SKEL_OUT)/kwork_trace.skel.h $(SKEL_OUT)/sample_filter.skel.h > > $(SKEL_TMP_OUT) $(LIBAPI_OUTPUT) $(LIBBPF_OUTPUT) $(LIBPERF_OUTPUT) $(LIBSUBCMD_OUTPUT) $(LIBSYMBOL_OUTPUT): > $(Q)$(MKDIR) -p $@ > diff --git a/tools/perf/util/bpf-filter.c b/tools/perf/util/bpf-filter.c > index 6b1148fcfb0e..e1b1a5343bad 100644 > --- a/tools/perf/util/bpf-filter.c > +++ b/tools/perf/util/bpf-filter.c > @@ -1,10 +1,74 @@ > // SPDX-License-Identifier: GPL-2.0 > #include <stdlib.h> > > +#include <bpf/bpf.h> > +#include <linux/err.h> > +#include <internal/xyarray.h> > + > +#include "util/debug.h" > +#include "util/evsel.h" > + > #include "util/bpf-filter.h" > #include "util/bpf-filter-flex.h" > #include "util/bpf-filter-bison.h" > > +#include "bpf_skel/sample-filter.h" > +#include "bpf_skel/sample_filter.skel.h" > + > +#define FD(e, x, y) (*(int *)xyarray__entry(e->core.fd, x, y)) > + > +int perf_bpf_filter__prepare(struct evsel *evsel) > +{ > + int i, x, y, fd; > + struct sample_filter_bpf *skel; > + struct bpf_program *prog; > + struct bpf_link *link; > + struct perf_bpf_filter_expr *expr; > + > + skel = sample_filter_bpf__open_and_load(); > + if (!skel) { > + pr_err("Failed to load perf sample-filter BPF skeleton\n"); > + return -1; > + } > + > + i = 0; > + fd = bpf_map__fd(skel->maps.filters); > + list_for_each_entry(expr, &evsel->bpf_filters, list) { > + struct perf_bpf_filter_entry entry = { > + .op = expr->op, > + .flags = expr->sample_flags, > + .value = expr->val, > + }; > + bpf_map_update_elem(fd, &i, &entry, BPF_ANY); > + i++; > + } > + > + prog = skel->progs.perf_sample_filter; > + for (x = 0; x < xyarray__max_x(evsel->core.fd); x++) { > + for (y = 0; y < xyarray__max_y(evsel->core.fd); y++) { > + link = bpf_program__attach_perf_event(prog, FD(evsel, x, y)); > + if (IS_ERR(link)) { > + pr_err("Failed to attach perf sample-filter program\n"); > + return PTR_ERR(link); > + } > + } > + } > + evsel->bpf_skel = skel; > + return 0; > +} > + > +int perf_bpf_filter__destroy(struct evsel *evsel) > +{ > + struct perf_bpf_filter_expr *expr, *tmp; > + > + list_for_each_entry_safe(expr, tmp, &evsel->bpf_filters, list) { > + list_del(&expr->list); > + free(expr); > + } > + sample_filter_bpf__destroy(evsel->bpf_skel); > + return 0; > +} > + > struct perf_bpf_filter_expr *perf_bpf_filter_expr__new(unsigned long sample_flags, > enum perf_bpf_filter_op op, > unsigned long val) > diff --git a/tools/perf/util/bpf-filter.h b/tools/perf/util/bpf-filter.h > index fd5b1164a322..6077930073f9 100644 > --- a/tools/perf/util/bpf-filter.h > +++ b/tools/perf/util/bpf-filter.h > @@ -4,15 +4,7 @@ > > #include <linux/list.h> > > -enum perf_bpf_filter_op { > - PBF_OP_EQ, > - PBF_OP_NEQ, > - PBF_OP_GT, > - PBF_OP_GE, > - PBF_OP_LT, > - PBF_OP_LE, > - PBF_OP_AND, > -}; > +#include "bpf_skel/sample-filter.h" > > struct perf_bpf_filter_expr { > struct list_head list; > @@ -21,16 +13,30 @@ struct perf_bpf_filter_expr { > unsigned long val; > }; > > +struct evsel; > + > #ifdef HAVE_BPF_SKEL > struct perf_bpf_filter_expr *perf_bpf_filter_expr__new(unsigned long sample_flags, > enum perf_bpf_filter_op op, > unsigned long val); > int perf_bpf_filter__parse(struct list_head *expr_head, const char *str); > +int perf_bpf_filter__prepare(struct evsel *evsel); > +int perf_bpf_filter__destroy(struct evsel *evsel); > + > #else /* !HAVE_BPF_SKEL */ > + > static inline int perf_bpf_filter__parse(struct list_head *expr_head __maybe_unused, > const char *str __maybe_unused) > { > return -ENOSYS; Any reason for ENOSYS instead of say EOPNOTSUPP? > } > +static inline int perf_bpf_filter__prepare(struct evsel *evsel) Needs __maybe_unused on the parameters > +{ > + return -ENOSYS; > +} > +static inline int perf_bpf_filter__destroy(struct evsel *evsel) Needs __maybe_unused on the parameters > +{ > + return -ENOSYS; > +} > #endif /* HAVE_BPF_SKEL*/ > #endif /* PERF_UTIL_BPF_FILTER_H */ > \ No newline at end of file > diff --git a/tools/perf/util/bpf_skel/sample-filter.h b/tools/perf/util/bpf_skel/sample-filter.h > new file mode 100644 > index 000000000000..862060bfda14 > --- /dev/null > +++ b/tools/perf/util/bpf_skel/sample-filter.h > @@ -0,0 +1,24 @@ > +#ifndef PERF_UTIL_BPF_SKEL_SAMPLE_FILTER_H > +#define PERF_UTIL_BPF_SKEL_SAMPLE_FILTER_H > + > +#define MAX_FILTERS 32 > + > +/* supported filter operations */ > +enum perf_bpf_filter_op { > + PBF_OP_EQ, > + PBF_OP_NEQ, > + PBF_OP_GT, > + PBF_OP_GE, > + PBF_OP_LT, > + PBF_OP_LE, > + PBF_OP_AND > +}; > + > +/* BPF map entry for filtering */ > +struct perf_bpf_filter_entry { > + enum perf_bpf_filter_op op; > + __u64 flags; > + __u64 value; > +}; > + > +#endif /* PERF_UTIL_BPF_SKEL_SAMPLE_FILTER_H */ > \ No newline at end of file > diff --git a/tools/perf/util/bpf_skel/sample_filter.bpf.c b/tools/perf/util/bpf_skel/sample_filter.bpf.c > new file mode 100644 > index 000000000000..c07256279c3e > --- /dev/null > +++ b/tools/perf/util/bpf_skel/sample_filter.bpf.c > @@ -0,0 +1,126 @@ > +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > +// Copyright (c) 2023 Google > +#include "vmlinux.h" > +#include <bpf/bpf_helpers.h> > +#include <bpf/bpf_tracing.h> > +#include <bpf/bpf_core_read.h> > + > +#include "sample-filter.h" > + > +/* BPF map that will be filled by user space */ > +struct filters { > + __uint(type, BPF_MAP_TYPE_ARRAY); > + __type(key, int); > + __type(value, struct perf_bpf_filter_entry); > + __uint(max_entries, MAX_FILTERS); > +} filters SEC(".maps"); > + > +int dropped; > + > +void *bpf_cast_to_kern_ctx(void *) __ksym; > + > +/* new kernel perf_sample_data definition */ > +struct perf_sample_data___new { > + __u64 sample_flags; > +} __attribute__((preserve_access_index)); > + > +/* helper function to return the given perf sample data */ > +static inline __u64 perf_get_sample(struct bpf_perf_event_data_kern *kctx, > + struct perf_bpf_filter_entry *entry) > +{ > + struct perf_sample_data___new *data = (void *)kctx->data; > + > + if (!bpf_core_field_exists(data->sample_flags) || > + (data->sample_flags & entry->flags) == 0) > + return 0; > + > + switch (entry->flags) { > + case PERF_SAMPLE_IP: > + return kctx->data->ip; > + case PERF_SAMPLE_ID: > + return kctx->data->id; > + case PERF_SAMPLE_TID: > + return kctx->data->tid_entry.tid; > + case PERF_SAMPLE_CPU: > + return kctx->data->cpu_entry.cpu; > + case PERF_SAMPLE_TIME: > + return kctx->data->time; > + case PERF_SAMPLE_ADDR: > + return kctx->data->addr; > + case PERF_SAMPLE_PERIOD: > + return kctx->data->period; > + case PERF_SAMPLE_TRANSACTION: > + return kctx->data->txn; > + case PERF_SAMPLE_WEIGHT: > + return kctx->data->weight.full; > + case PERF_SAMPLE_PHYS_ADDR: > + return kctx->data->phys_addr; > + case PERF_SAMPLE_CODE_PAGE_SIZE: > + return kctx->data->code_page_size; > + case PERF_SAMPLE_DATA_PAGE_SIZE: > + return kctx->data->data_page_size; > + default: > + break; > + } > + return 0; > +} > + > +/* BPF program to be called from perf event overflow handler */ > +SEC("perf_event") > +int perf_sample_filter(void *ctx) > +{ > + struct bpf_perf_event_data_kern *kctx; > + struct perf_bpf_filter_entry *entry; > + __u64 sample_data; > + int i; > + > + kctx = bpf_cast_to_kern_ctx(ctx); > + > + for (i = 0; i < MAX_FILTERS; i++) { > + int key = i; /* needed for verifier :( */ > + > + entry = bpf_map_lookup_elem(&filters, &key); > + if (entry == NULL) > + break; > + sample_data = perf_get_sample(kctx, entry); > + > + switch (entry->op) { > + case PBF_OP_EQ: > + if (!(sample_data == entry->value)) > + goto drop; > + break; > + case PBF_OP_NEQ: > + if (!(sample_data != entry->value)) > + goto drop; > + break; > + case PBF_OP_GT: > + if (!(sample_data > entry->value)) > + goto drop; > + break; > + case PBF_OP_GE: > + if (!(sample_data >= entry->value)) > + goto drop; > + break; > + case PBF_OP_LT: > + if (!(sample_data < entry->value)) > + goto drop; > + break; > + case PBF_OP_LE: > + if (!(sample_data <= entry->value)) > + goto drop; > + break; > + case PBF_OP_AND: > + if (!(sample_data & entry->value)) > + goto drop; > + break; > + } > + } > + /* generate sample data */ > + return 1; > + > +drop: > + __sync_fetch_and_add(&dropped, 1); > + return 0; > +} > + > +char LICENSE[] SEC("license") = "Dual BSD/GPL"; > diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h > index 24cb807ef6ce..6845642485ec 100644 > --- a/tools/perf/util/evsel.h > +++ b/tools/perf/util/evsel.h > @@ -151,8 +151,10 @@ struct evsel { > */ > struct bpf_counter_ops *bpf_counter_ops; > > - /* for perf-stat -b */ > - struct list_head bpf_counter_list; > + union { > + struct list_head bpf_counter_list; /* for perf-stat -b */ > + struct list_head bpf_filters; /* for perf-record --filter */ > + }; > > /* for perf-stat --use-bpf */ > int bperf_leader_prog_fd; > @@ -160,6 +162,7 @@ struct evsel { > union { > struct bperf_leader_bpf *leader_skel; > struct bperf_follower_bpf *follower_skel; > + void *bpf_skel; > }; > unsigned long open_flags; > int precise_ip_original;
Hi Adrian, Thanks for your feedback! On Tue, Mar 7, 2023 at 5:04 AM Adrian Hunter <adrian.hunter@intel.com> wrote: > > On 23/02/23 01:01, Namhyung Kim wrote: > > The BPF program will be attached to a perf_event and be triggered when > > it overflows. It'd iterate the filters map and compare the sample > > value according to the expression. If any of them fails, the sample > > would be dropped. > > > > Also it needs to have the corresponding sample data for the expression > > so it compares data->sample_flags with the given value. To access the > > sample data, it uses the bpf_cast_to_kern_ctx() kfunc which was added > > in v6.2 kernel. > > > > Signed-off-by: Namhyung Kim <namhyung@kernel.org> [SNIP] > > diff --git a/tools/perf/util/bpf-filter.h b/tools/perf/util/bpf-filter.h > > index fd5b1164a322..6077930073f9 100644 > > --- a/tools/perf/util/bpf-filter.h > > +++ b/tools/perf/util/bpf-filter.h > > @@ -4,15 +4,7 @@ > > > > #include <linux/list.h> > > > > -enum perf_bpf_filter_op { > > - PBF_OP_EQ, > > - PBF_OP_NEQ, > > - PBF_OP_GT, > > - PBF_OP_GE, > > - PBF_OP_LT, > > - PBF_OP_LE, > > - PBF_OP_AND, > > -}; > > +#include "bpf_skel/sample-filter.h" > > > > struct perf_bpf_filter_expr { > > struct list_head list; > > @@ -21,16 +13,30 @@ struct perf_bpf_filter_expr { > > unsigned long val; > > }; > > > > +struct evsel; > > + > > #ifdef HAVE_BPF_SKEL > > struct perf_bpf_filter_expr *perf_bpf_filter_expr__new(unsigned long sample_flags, > > enum perf_bpf_filter_op op, > > unsigned long val); > > int perf_bpf_filter__parse(struct list_head *expr_head, const char *str); > > +int perf_bpf_filter__prepare(struct evsel *evsel); > > +int perf_bpf_filter__destroy(struct evsel *evsel); > > + > > #else /* !HAVE_BPF_SKEL */ > > + > > static inline int perf_bpf_filter__parse(struct list_head *expr_head __maybe_unused, > > const char *str __maybe_unused) > > { > > return -ENOSYS; > > Any reason for ENOSYS instead of say EOPNOTSUPP? No specific reason. I can change it to EOPNOTSUPP. > > > } > > +static inline int perf_bpf_filter__prepare(struct evsel *evsel) > > Needs __maybe_unused on the parameters Sure. > > > +{ > > + return -ENOSYS; > > +} > > +static inline int perf_bpf_filter__destroy(struct evsel *evsel) > > Needs __maybe_unused on the parameters Will do. Thanks, Namhyung
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf index bac9272682b7..474af4adea95 100644 --- a/tools/perf/Makefile.perf +++ b/tools/perf/Makefile.perf @@ -1047,7 +1047,7 @@ SKELETONS := $(SKEL_OUT)/bpf_prog_profiler.skel.h SKELETONS += $(SKEL_OUT)/bperf_leader.skel.h $(SKEL_OUT)/bperf_follower.skel.h SKELETONS += $(SKEL_OUT)/bperf_cgroup.skel.h $(SKEL_OUT)/func_latency.skel.h SKELETONS += $(SKEL_OUT)/off_cpu.skel.h $(SKEL_OUT)/lock_contention.skel.h -SKELETONS += $(SKEL_OUT)/kwork_trace.skel.h +SKELETONS += $(SKEL_OUT)/kwork_trace.skel.h $(SKEL_OUT)/sample_filter.skel.h $(SKEL_TMP_OUT) $(LIBAPI_OUTPUT) $(LIBBPF_OUTPUT) $(LIBPERF_OUTPUT) $(LIBSUBCMD_OUTPUT) $(LIBSYMBOL_OUTPUT): $(Q)$(MKDIR) -p $@ diff --git a/tools/perf/util/bpf-filter.c b/tools/perf/util/bpf-filter.c index 6b1148fcfb0e..e1b1a5343bad 100644 --- a/tools/perf/util/bpf-filter.c +++ b/tools/perf/util/bpf-filter.c @@ -1,10 +1,74 @@ // SPDX-License-Identifier: GPL-2.0 #include <stdlib.h> +#include <bpf/bpf.h> +#include <linux/err.h> +#include <internal/xyarray.h> + +#include "util/debug.h" +#include "util/evsel.h" + #include "util/bpf-filter.h" #include "util/bpf-filter-flex.h" #include "util/bpf-filter-bison.h" +#include "bpf_skel/sample-filter.h" +#include "bpf_skel/sample_filter.skel.h" + +#define FD(e, x, y) (*(int *)xyarray__entry(e->core.fd, x, y)) + +int perf_bpf_filter__prepare(struct evsel *evsel) +{ + int i, x, y, fd; + struct sample_filter_bpf *skel; + struct bpf_program *prog; + struct bpf_link *link; + struct perf_bpf_filter_expr *expr; + + skel = sample_filter_bpf__open_and_load(); + if (!skel) { + pr_err("Failed to load perf sample-filter BPF skeleton\n"); + return -1; + } + + i = 0; + fd = bpf_map__fd(skel->maps.filters); + list_for_each_entry(expr, &evsel->bpf_filters, list) { + struct perf_bpf_filter_entry entry = { + .op = expr->op, + .flags = expr->sample_flags, + .value = expr->val, + }; + bpf_map_update_elem(fd, &i, &entry, BPF_ANY); + i++; + } + + prog = skel->progs.perf_sample_filter; + for (x = 0; x < xyarray__max_x(evsel->core.fd); x++) { + for (y = 0; y < xyarray__max_y(evsel->core.fd); y++) { + link = bpf_program__attach_perf_event(prog, FD(evsel, x, y)); + if (IS_ERR(link)) { + pr_err("Failed to attach perf sample-filter program\n"); + return PTR_ERR(link); + } + } + } + evsel->bpf_skel = skel; + return 0; +} + +int perf_bpf_filter__destroy(struct evsel *evsel) +{ + struct perf_bpf_filter_expr *expr, *tmp; + + list_for_each_entry_safe(expr, tmp, &evsel->bpf_filters, list) { + list_del(&expr->list); + free(expr); + } + sample_filter_bpf__destroy(evsel->bpf_skel); + return 0; +} + struct perf_bpf_filter_expr *perf_bpf_filter_expr__new(unsigned long sample_flags, enum perf_bpf_filter_op op, unsigned long val) diff --git a/tools/perf/util/bpf-filter.h b/tools/perf/util/bpf-filter.h index fd5b1164a322..6077930073f9 100644 --- a/tools/perf/util/bpf-filter.h +++ b/tools/perf/util/bpf-filter.h @@ -4,15 +4,7 @@ #include <linux/list.h> -enum perf_bpf_filter_op { - PBF_OP_EQ, - PBF_OP_NEQ, - PBF_OP_GT, - PBF_OP_GE, - PBF_OP_LT, - PBF_OP_LE, - PBF_OP_AND, -}; +#include "bpf_skel/sample-filter.h" struct perf_bpf_filter_expr { struct list_head list; @@ -21,16 +13,30 @@ struct perf_bpf_filter_expr { unsigned long val; }; +struct evsel; + #ifdef HAVE_BPF_SKEL struct perf_bpf_filter_expr *perf_bpf_filter_expr__new(unsigned long sample_flags, enum perf_bpf_filter_op op, unsigned long val); int perf_bpf_filter__parse(struct list_head *expr_head, const char *str); +int perf_bpf_filter__prepare(struct evsel *evsel); +int perf_bpf_filter__destroy(struct evsel *evsel); + #else /* !HAVE_BPF_SKEL */ + static inline int perf_bpf_filter__parse(struct list_head *expr_head __maybe_unused, const char *str __maybe_unused) { return -ENOSYS; } +static inline int perf_bpf_filter__prepare(struct evsel *evsel) +{ + return -ENOSYS; +} +static inline int perf_bpf_filter__destroy(struct evsel *evsel) +{ + return -ENOSYS; +} #endif /* HAVE_BPF_SKEL*/ #endif /* PERF_UTIL_BPF_FILTER_H */ \ No newline at end of file diff --git a/tools/perf/util/bpf_skel/sample-filter.h b/tools/perf/util/bpf_skel/sample-filter.h new file mode 100644 index 000000000000..862060bfda14 --- /dev/null +++ b/tools/perf/util/bpf_skel/sample-filter.h @@ -0,0 +1,24 @@ +#ifndef PERF_UTIL_BPF_SKEL_SAMPLE_FILTER_H +#define PERF_UTIL_BPF_SKEL_SAMPLE_FILTER_H + +#define MAX_FILTERS 32 + +/* supported filter operations */ +enum perf_bpf_filter_op { + PBF_OP_EQ, + PBF_OP_NEQ, + PBF_OP_GT, + PBF_OP_GE, + PBF_OP_LT, + PBF_OP_LE, + PBF_OP_AND +}; + +/* BPF map entry for filtering */ +struct perf_bpf_filter_entry { + enum perf_bpf_filter_op op; + __u64 flags; + __u64 value; +}; + +#endif /* PERF_UTIL_BPF_SKEL_SAMPLE_FILTER_H */ \ No newline at end of file diff --git a/tools/perf/util/bpf_skel/sample_filter.bpf.c b/tools/perf/util/bpf_skel/sample_filter.bpf.c new file mode 100644 index 000000000000..c07256279c3e --- /dev/null +++ b/tools/perf/util/bpf_skel/sample_filter.bpf.c @@ -0,0 +1,126 @@ +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +// Copyright (c) 2023 Google +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> +#include <bpf/bpf_core_read.h> + +#include "sample-filter.h" + +/* BPF map that will be filled by user space */ +struct filters { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, int); + __type(value, struct perf_bpf_filter_entry); + __uint(max_entries, MAX_FILTERS); +} filters SEC(".maps"); + +int dropped; + +void *bpf_cast_to_kern_ctx(void *) __ksym; + +/* new kernel perf_sample_data definition */ +struct perf_sample_data___new { + __u64 sample_flags; +} __attribute__((preserve_access_index)); + +/* helper function to return the given perf sample data */ +static inline __u64 perf_get_sample(struct bpf_perf_event_data_kern *kctx, + struct perf_bpf_filter_entry *entry) +{ + struct perf_sample_data___new *data = (void *)kctx->data; + + if (!bpf_core_field_exists(data->sample_flags) || + (data->sample_flags & entry->flags) == 0) + return 0; + + switch (entry->flags) { + case PERF_SAMPLE_IP: + return kctx->data->ip; + case PERF_SAMPLE_ID: + return kctx->data->id; + case PERF_SAMPLE_TID: + return kctx->data->tid_entry.tid; + case PERF_SAMPLE_CPU: + return kctx->data->cpu_entry.cpu; + case PERF_SAMPLE_TIME: + return kctx->data->time; + case PERF_SAMPLE_ADDR: + return kctx->data->addr; + case PERF_SAMPLE_PERIOD: + return kctx->data->period; + case PERF_SAMPLE_TRANSACTION: + return kctx->data->txn; + case PERF_SAMPLE_WEIGHT: + return kctx->data->weight.full; + case PERF_SAMPLE_PHYS_ADDR: + return kctx->data->phys_addr; + case PERF_SAMPLE_CODE_PAGE_SIZE: + return kctx->data->code_page_size; + case PERF_SAMPLE_DATA_PAGE_SIZE: + return kctx->data->data_page_size; + default: + break; + } + return 0; +} + +/* BPF program to be called from perf event overflow handler */ +SEC("perf_event") +int perf_sample_filter(void *ctx) +{ + struct bpf_perf_event_data_kern *kctx; + struct perf_bpf_filter_entry *entry; + __u64 sample_data; + int i; + + kctx = bpf_cast_to_kern_ctx(ctx); + + for (i = 0; i < MAX_FILTERS; i++) { + int key = i; /* needed for verifier :( */ + + entry = bpf_map_lookup_elem(&filters, &key); + if (entry == NULL) + break; + sample_data = perf_get_sample(kctx, entry); + + switch (entry->op) { + case PBF_OP_EQ: + if (!(sample_data == entry->value)) + goto drop; + break; + case PBF_OP_NEQ: + if (!(sample_data != entry->value)) + goto drop; + break; + case PBF_OP_GT: + if (!(sample_data > entry->value)) + goto drop; + break; + case PBF_OP_GE: + if (!(sample_data >= entry->value)) + goto drop; + break; + case PBF_OP_LT: + if (!(sample_data < entry->value)) + goto drop; + break; + case PBF_OP_LE: + if (!(sample_data <= entry->value)) + goto drop; + break; + case PBF_OP_AND: + if (!(sample_data & entry->value)) + goto drop; + break; + } + } + /* generate sample data */ + return 1; + +drop: + __sync_fetch_and_add(&dropped, 1); + return 0; +} + +char LICENSE[] SEC("license") = "Dual BSD/GPL"; diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h index 24cb807ef6ce..6845642485ec 100644 --- a/tools/perf/util/evsel.h +++ b/tools/perf/util/evsel.h @@ -151,8 +151,10 @@ struct evsel { */ struct bpf_counter_ops *bpf_counter_ops; - /* for perf-stat -b */ - struct list_head bpf_counter_list; + union { + struct list_head bpf_counter_list; /* for perf-stat -b */ + struct list_head bpf_filters; /* for perf-record --filter */ + }; /* for perf-stat --use-bpf */ int bperf_leader_prog_fd; @@ -160,6 +162,7 @@ struct evsel { union { struct bperf_leader_bpf *leader_skel; struct bperf_follower_bpf *follower_skel; + void *bpf_skel; }; unsigned long open_flags; int precise_ip_original;
The BPF program will be attached to a perf_event and be triggered when it overflows. It'd iterate the filters map and compare the sample value according to the expression. If any of them fails, the sample would be dropped. Also it needs to have the corresponding sample data for the expression so it compares data->sample_flags with the given value. To access the sample data, it uses the bpf_cast_to_kern_ctx() kfunc which was added in v6.2 kernel. Signed-off-by: Namhyung Kim <namhyung@kernel.org> --- tools/perf/Makefile.perf | 2 +- tools/perf/util/bpf-filter.c | 64 ++++++++++ tools/perf/util/bpf-filter.h | 24 ++-- tools/perf/util/bpf_skel/sample-filter.h | 24 ++++ tools/perf/util/bpf_skel/sample_filter.bpf.c | 126 +++++++++++++++++++ tools/perf/util/evsel.h | 7 +- 6 files changed, 235 insertions(+), 12 deletions(-) create mode 100644 tools/perf/util/bpf_skel/sample-filter.h create mode 100644 tools/perf/util/bpf_skel/sample_filter.bpf.c