perf bpf filter: Introduce basic BPF filter expression

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>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: James Clark <james.clark@arm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Song Liu <song@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230314234237.3008956-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 82 insertions, 0 deletions

diff --git a/tools/perf/util/bpf-filter.l b/tools/perf/util/bpf-filter.l
new file mode 100644
index 000000000000..f6c0b74ea285
--- /dev/null
+++ b/tools/perf/util/bpf-filter.l
@@ -0,0 +1,82 @@
+%option prefix="perf_bpf_filter_"
+%option noyywrap
+
+%{
+#include <stdio.h>
+#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;
+}
+
+static int error(const char *str)
+{
+	printf("perf_bpf_filter: Unexpected filter %s: %s\n", str, perf_bpf_filter_text);
+	return BFT_ERROR;
+}
+
+%}
+
+num_dec		[0-9]+
+num_hex		0[Xx][0-9a-fA-F]+
+space		[ \t]+
+ident		[_a-zA-Z][_a-zA-Z0-9]+
+
+%%
+
+{num_dec}	{ return value(10); }
+{num_hex}	{ return value(16); }
+{space}		{ }
+
+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 ','; }
+
+{ident}		{ return error("ident"); }
+.		{ return error("input"); }
+
+%%