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Date: Wed, 15 May 2024 21:19:47 -0700
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Subject: [PATCH v1 2/3] perf bpf filter: Add uid and gid terms
From: Ian Rogers <irogers@google.com>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, 
	Arnaldo Carvalho de Melo <acme@kernel.org>, Namhyung Kim <namhyung@kernel.org>, 
	Mark Rutland <mark.rutland@arm.com>, 
	Alexander Shishkin <alexander.shishkin@linux.intel.com>, Jiri Olsa <jolsa@kernel.org>, 
	Ian Rogers <irogers@google.com>, Adrian Hunter <adrian.hunter@intel.com>, 
	Kan Liang <kan.liang@linux.intel.com>, Changbin Du <changbin.du@huawei.com>, 
	John Fastabend <john.fastabend@gmail.com>, Andrii Nakryiko <andrii@kernel.org>, 
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, 
	bpf@vger.kernel.org
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Allow the BPF filter to use the uid and gid terms determined by the
bpf_get_current_uid_gid BPF helper. For example, the following will
record the cpu-clock event system wide discarding samples that don't
belong to the current user.

$ perf record -e cpu-clock --filter "uid == $(id -u)" -a sleep 0.1

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/Documentation/perf-record.txt     | 2 +-
 tools/perf/util/bpf-filter.c                 | 4 ++++
 tools/perf/util/bpf-filter.l                 | 2 ++
 tools/perf/util/bpf_skel/sample-filter.h     | 3 +++
 tools/perf/util/bpf_skel/sample_filter.bpf.c | 4 ++++
 5 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 6015fdd08fb6..059bc40c5ee1 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -200,7 +200,7 @@ OPTIONS
 	  ip, id, tid, pid, cpu, time, addr, period, txn, weight, phys_addr,
 	  code_pgsz, data_pgsz, weight1, weight2, weight3, ins_lat, retire_lat,
 	  p_stage_cyc, mem_op, mem_lvl, mem_snoop, mem_remote, mem_lock,
-	  mem_dtlb, mem_blk, mem_hops
+	  mem_dtlb, mem_blk, mem_hops, uid, gid
 
 	The <operator> can be one of:
 	  ==, !=, >, >=, <, <=, &
diff --git a/tools/perf/util/bpf-filter.c b/tools/perf/util/bpf-filter.c
index 7e8d179f03dc..c5d6c192d33a 100644
--- a/tools/perf/util/bpf-filter.c
+++ b/tools/perf/util/bpf-filter.c
@@ -80,6 +80,10 @@ static int check_sample_flags(struct evsel *evsel, struct perf_bpf_filter_expr *
 		CHECK_TERM(DATA_PAGE_SIZE);
 		CHECK_TERM(WEIGHT_STRUCT);
 		CHECK_TERM(DATA_SRC);
+	case PBF_TERM_UID:
+	case PBF_TERM_GID:
+		/* Not dependent on the sample_type as computed from a BPF helper. */
+		return 0;
 	case PBF_TERM_NONE:
 	default:
 		break;
diff --git a/tools/perf/util/bpf-filter.l b/tools/perf/util/bpf-filter.l
index 62c959813466..2a7c839f3fae 100644
--- a/tools/perf/util/bpf-filter.l
+++ b/tools/perf/util/bpf-filter.l
@@ -95,6 +95,8 @@ mem_lock	{ return sample_part(PBF_TERM_DATA_SRC, 5); }
 mem_dtlb	{ return sample_part(PBF_TERM_DATA_SRC, 6); }
 mem_blk		{ return sample_part(PBF_TERM_DATA_SRC, 7); }
 mem_hops	{ return sample_part(PBF_TERM_DATA_SRC, 8); }
+uid		{ return sample(PBF_TERM_UID); }
+gid		{ return sample(PBF_TERM_GID); }
 
 "=="		{ return operator(PBF_OP_EQ); }
 "!="		{ return operator(PBF_OP_NEQ); }
diff --git a/tools/perf/util/bpf_skel/sample-filter.h b/tools/perf/util/bpf_skel/sample-filter.h
index 161d5ff49cb6..3e64ccacc5e5 100644
--- a/tools/perf/util/bpf_skel/sample-filter.h
+++ b/tools/perf/util/bpf_skel/sample-filter.h
@@ -34,6 +34,9 @@ enum perf_bpf_filter_term {
 	PBF_TERM_DATA_PAGE_SIZE,
 	PBF_TERM_WEIGHT_STRUCT,
 	PBF_TERM_DATA_SRC,
+	/* Terms computed from BPF helpers. */
+	PBF_TERM_UID,
+	PBF_TERM_GID,
 };
 
 /* BPF map entry for filtering */
diff --git a/tools/perf/util/bpf_skel/sample_filter.bpf.c b/tools/perf/util/bpf_skel/sample_filter.bpf.c
index 8666c85e9333..da4b5eb7cce3 100644
--- a/tools/perf/util/bpf_skel/sample_filter.bpf.c
+++ b/tools/perf/util/bpf_skel/sample_filter.bpf.c
@@ -146,6 +146,10 @@ static inline __u64 perf_get_sample(struct bpf_perf_event_data_kern *kctx,
 		}
 		/* return the whole word */
 		return kctx->data->data_src.val;
+	case PBF_TERM_UID:
+		return bpf_get_current_uid_gid() & 0xFFFFFFFF;
+	case PBF_TERM_GID:
+		return bpf_get_current_uid_gid() >> 32;
 	default:
 		break;
 	}
-- 
2.45.0.rc1.225.g2a3ae87e7f-goog