[PATCH 1/8] perf bpf filter: Introduce basic BPF filter expression

Namhyung Kim
2023-02-19T06:13:38Z

This implements a tiny parser for the filter expressions used for BPF.
Each expression will be converted to struct perf_bpf_filter_expr and
be passed to a BPF map.

For now, I'd like to start with the very basic comparisons like EQ or
GT. The LHS should be a term for sample data and the RHS is a number.
The expressions are connected by a comma. For example,

period > 10000
ip < 0x1000000000000, cpu == 3

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/util/Build | 16 +++++++++
tools/perf/util/bpf-filter.c | 37 +++++++++++++++++++
tools/perf/util/bpf-filter.h | 36 +++++++++++++++++++
tools/perf/util/bpf-filter.l | 70 ++++++++++++++++++++++++++++++++++++
tools/perf/util/bpf-filter.y | 53 +++++++++++++++++++++++++++
5 files changed, 212 insertions(+)
create mode 100644 tools/perf/util/bpf-filter.c
create mode 100644 tools/perf/util/bpf-filter.h
create mode 100644 tools/perf/util/bpf-filter.l
create mode 100644 tools/perf/util/bpf-filter.y

diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 918b501f9bd8..6af73fb5c797 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -154,6 +154,9 @@ perf-$(CONFIG_PERF_BPF_SKEL) += bpf_counter.o
perf-$(CONFIG_PERF_BPF_SKEL) += bpf_counter_cgroup.o
perf-$(CONFIG_PERF_BPF_SKEL) += bpf_ftrace.o
perf-$(CONFIG_PERF_BPF_SKEL) += bpf_off_cpu.o
+perf-$(CONFIG_PERF_BPF_SKEL) += bpf-filter.o
+perf-$(CONFIG_PERF_BPF_SKEL) += bpf-filter-flex.o
+perf-$(CONFIG_PERF_BPF_SKEL) += bpf-filter-bison.o

ifeq ($(CONFIG_LIBTRACEEVENT),y)
perf-$(CONFIG_PERF_BPF_SKEL) += bpf_lock_contention.o
@@ -266,6 +269,16 @@ $(OUTPUT)util/pmu-bison.c $(OUTPUT)util/pmu-bison.h: util/pmu.y
$(Q)$(call echo-cmd,bison)$(BISON) -v $< -d $(PARSER_DEBUG_BISON) $(BISON_FILE_PREFIX_MAP) \
-o $(OUTPUT)util/pmu-bison.c -p perf_pmu_

+$(OUTPUT)util/bpf-filter-flex.c $(OUTPUT)util/bpf-filter-flex.h: util/bpf-filter.l $(OUTPUT)util/bpf-filter-bison.c
+ $(call rule_mkdir)
+ $(Q)$(call echo-cmd,flex)$(FLEX) -o $(OUTPUT)util/bpf-filter-flex.c \
+ --header-file=$(OUTPUT)util/bpf-filter-flex.h $(PARSER_DEBUG_FLEX) $<
+
+$(OUTPUT)util/bpf-filter-bison.c $(OUTPUT)util/bpf-filter-bison.h: util/bpf-filter.y
+ $(call rule_mkdir)
+ $(Q)$(call echo-cmd,bison)$(BISON) -v $< -d $(PARSER_DEBUG_BISON) $(BISON_FILE_PREFIX_MAP) \
+ -o $(OUTPUT)util/bpf-filter-bison.c -p perf_bpf_filter_
+
FLEX_GE_26 := $(shell expr $(shell $(FLEX) --version | sed -e 's/flex \([0-9]\+\).\([0-9]\+\)/\1\2/g') \>\= 26)
ifeq ($(FLEX_GE_26),1)
flex_flags := -Wno-switch-enum -Wno-switch-default -Wno-unused-function -Wno-redundant-decls -Wno-sign-compare -Wno-unused-parameter -Wno-missing-prototypes -Wno-missing-declarations
@@ -279,6 +292,7 @@ endif
CFLAGS_parse-events-flex.o += $(flex_flags)
CFLAGS_pmu-flex.o += $(flex_flags)
CFLAGS_expr-flex.o += $(flex_flags)
+CFLAGS_bpf-filter-flex.o += $(flex_flags)

bison_flags := -DYYENABLE_NLS=0
BISON_GE_35 := $(shell expr $(shell $(BISON) --version | grep bison | sed -e 's/.\+ \([0-9]\+\).\([0-9]\+\)/\1\2/g') \>\= 35)
@@ -290,10 +304,12 @@ endif
CFLAGS_parse-events-bison.o += $(bison_flags)
CFLAGS_pmu-bison.o += -DYYLTYPE_IS_TRIVIAL=0 $(bison_flags)
CFLAGS_expr-bison.o += -DYYLTYPE_IS_TRIVIAL=0 $(bison_flags)
+CFLAGS_bpf-filter-bison.o += -DYYLTYPE_IS_TRIVIAL=0 $(bison_flags)

$(OUTPUT)util/parse-events.o: $(OUTPUT)util/parse-events-flex.c $(OUTPUT)util/parse-events-bison.c
$(OUTPUT)util/pmu.o: $(OUTPUT)util/pmu-flex.c $(OUTPUT)util/pmu-bison.c
$(OUTPUT)util/expr.o: $(OUTPUT)util/expr-flex.c $(OUTPUT)util/expr-bison.c
+$(OUTPUT)util/bpf-filter.o: $(OUTPUT)util/bpf-filter-flex.c $(OUTPUT)util/bpf-filter-bison.c

CFLAGS_bitmap.o += -Wno-unused-parameter -DETC_PERFCONFIG="BUILD_STR($(ETC_PERFCONFIG_SQ))"
CFLAGS_find_bit.o += -Wno-unused-parameter -DETC_PERFCONFIG="BUILD_STR($(ETC_PERFCONFIG_SQ))"
diff --git a/tools/perf/util/bpf-filter.c b/tools/perf/util/bpf-filter.c
new file mode 100644
index 000000000000..6b1148fcfb0e
--- /dev/null
+++ b/tools/perf/util/bpf-filter.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdlib.h>
+
+#include "util/bpf-filter.h"
+#include "util/bpf-filter-flex.h"
+#include "util/bpf-filter-bison.h"
+
+struct perf_bpf_filter_expr *perf_bpf_filter_expr__new(unsigned long sample_flags,
+ enum perf_bpf_filter_op op,
+ unsigned long val)
+{
+ struct perf_bpf_filter_expr *expr;
+
+ expr = malloc(sizeof(*expr));
+ if (expr != NULL) {
+ expr->sample_flags = sample_flags;
+ expr->op = op;
+ expr->val = val;
+ }
+ return expr;
+}
+
+int perf_bpf_filter__parse(struct list_head *expr_head, const char *str)
+{
+ YY_BUFFER_STATE buffer;
+ int ret;
+
+ buffer = perf_bpf_filter__scan_string(str);
+
+ ret = perf_bpf_filter_parse(expr_head);
+
+ perf_bpf_filter__flush_buffer(buffer);
+ perf_bpf_filter__delete_buffer(buffer);
+ perf_bpf_filter_lex_destroy();
+
+ return ret;
+}
\ No newline at end of file
diff --git a/tools/perf/util/bpf-filter.h b/tools/perf/util/bpf-filter.h
new file mode 100644
index 000000000000..fd5b1164a322
--- /dev/null
+++ b/tools/perf/util/bpf-filter.h
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef PERF_UTIL_BPF_FILTER_H
+#define PERF_UTIL_BPF_FILTER_H
+
+#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,
+};
+
+struct perf_bpf_filter_expr {
+ struct list_head list;
+ enum perf_bpf_filter_op op;
+ unsigned long sample_flags;
+ unsigned long val;
+};
+
+#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);
+#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;
+}
+#endif /* HAVE_BPF_SKEL*/
+#endif /* PERF_UTIL_BPF_FILTER_H */
\ No newline at end of file
diff --git a/tools/perf/util/bpf-filter.l b/tools/perf/util/bpf-filter.l
new file mode 100644
index 000000000000..34c6a9fd4fa4
--- /dev/null
+++ b/tools/perf/util/bpf-filter.l
@@ -0,0 +1,70 @@
+%option prefix="perf_bpf_filter_"
+%option noyywrap
+
+%{
+#include <stdlib.h>
+#include <linux/perf_event.h>
+
+#include "bpf-filter.h"
+#include "bpf-filter-bison.h"
+
+static int sample(unsigned long sample_flag)
+{
+ perf_bpf_filter_lval.sample = sample_flag;
+ return BFT_SAMPLE;
+}
+
+static int operator(enum perf_bpf_filter_op op)
+{
+ perf_bpf_filter_lval.op = op;
+ return BFT_OP;
+}
+
+static int value(int base)
+{
+ long num;
+
+ errno = 0;
+ num = strtoul(perf_bpf_filter_text, NULL, base);
+ if (errno)
+ return BFT_ERROR;
+
+ perf_bpf_filter_lval.num = num;
+ return BFT_NUM;
+}
+
+%}
+
+num_dec [0-9]+
+num_hex 0[Xx][0-9a-fA-F]+
+
+%%
+
+{num_dec} { return value(10); }
+{num_hex} { return value(16); }
+
+ip { return sample(PERF_SAMPLE_IP); }
+id { return sample(PERF_SAMPLE_ID); }
+tid { return sample(PERF_SAMPLE_TID); }
+cpu { return sample(PERF_SAMPLE_CPU); }
+time { return sample(PERF_SAMPLE_TIME); }
+addr { return sample(PERF_SAMPLE_ADDR); }
+period { return sample(PERF_SAMPLE_PERIOD); }
+txn { return sample(PERF_SAMPLE_TRANSACTION); }
+weight { return sample(PERF_SAMPLE_WEIGHT); }
+phys_addr { return sample(PERF_SAMPLE_PHYS_ADDR); }
+code_pgsz { return sample(PERF_SAMPLE_CODE_PAGE_SIZE); }
+data_pgsz { return sample(PERF_SAMPLE_DATA_PAGE_SIZE); }
+
+"==" { return operator(PBF_OP_EQ); }
+"!=" { return operator(PBF_OP_NEQ); }
+">" { return operator(PBF_OP_GT); }
+"<" { return operator(PBF_OP_LT); }
+">=" { return operator(PBF_OP_GE); }
+"<=" { return operator(PBF_OP_LE); }
+"&" { return operator(PBF_OP_AND); }
+
+"," { return ','; }
+. { }
+
+%%
diff --git a/tools/perf/util/bpf-filter.y b/tools/perf/util/bpf-filter.y
new file mode 100644
index 000000000000..510e944a6fa2
--- /dev/null
+++ b/tools/perf/util/bpf-filter.y
@@ -0,0 +1,53 @@
+%parse-param {struct list_head *expr_head}
+
+%{
+
+#include <stdio.h>
+#include <string.h>
+#include <linux/compiler.h>
+#include <linux/list.h>
+#include "bpf-filter.h"
+
+static void perf_bpf_filter_error(struct list_head *expr __maybe_unused,
+ char const *msg)
+{
+ printf("perf_bpf_filter: %s\n", msg);
+}
+
+%}
+
+%union
+{
+ unsigned long num;
+ unsigned long sample;
+ enum perf_bpf_filter_op op;
+ struct perf_bpf_filter_expr *expr;
+}
+
+%token BFT_SAMPLE BFT_OP BFT_ERROR BFT_NUM
+%type <expr> filter_term
+%destructor { free ($$); } <expr>
+%type <sample> BFT_SAMPLE
+%type <op> BFT_OP
+%type <num> BFT_NUM
+
+%%
+
+filter:
+filter ',' filter_term
+{
+ list_add_tail(&$3->list, expr_head);
+}
+|
+filter_term
+{
+ list_add_tail(&$1->list, expr_head);
+}
+
+filter_term:
+BFT_SAMPLE BFT_OP BFT_NUM
+{
+ $$ = perf_bpf_filter_expr__new($1, $2, $3);
+}
+
+%%
--
2.39.2.637.g21b0678d19-goog