perf bpf filter: Add uid and gid terms

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 <[e-mail]>
Acked-by: Namhyung Kim <[e-mail]>
Cc: John Fastabend <[e-mail]>
Cc: Changbin Du <[e-mail]>
Cc: Yang Jihong <[e-mail]>
Cc: Andrii Nakryiko <[e-mail]>
Cc: [e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

tools/perf/Documentation/perf-record.txt

···
 	  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:
 	  ==, !=, >, >=, <, <=, &

tools/perf/util/bpf-filter.c

···
 	    (evsel->core.attr.sample_type & (1 << (expr->term - PBF_TERM_SAMPLE_START))))
 		return 0;
 
+	if (expr->term == PBF_TERM_UID || expr->term == PBF_TERM_GID) {
+		/* Not dependent on the sample_type as computed from a BPF helper. */
+		return 0;
+	}
+
 	if (expr->op == PBF_OP_GROUP_BEGIN) {
 		struct perf_bpf_filter_expr *group;
 

tools/perf/util/bpf-filter.l

···
 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); }

tools/perf/util/bpf_skel/sample-filter.h

···
 	PBF_TERM_CODE_PAGE_SIZE	= PBF_TERM_SAMPLE_START + 23, /* SAMPLE_CODE_PAGE_SIZE = 1U << 23 */
 	PBF_TERM_WEIGHT_STRUCT	= PBF_TERM_SAMPLE_START + 24, /* SAMPLE_WEIGHT_STRUCT = 1U << 24 */
 	PBF_TERM_SAMPLE_END	= PBF_TERM_WEIGHT_STRUCT,
+	/* Terms computed from BPF helpers. */
+	PBF_TERM_UID,
+	PBF_TERM_GID,
 };
 
 /* BPF map entry for filtering */

tools/perf/util/bpf_skel/sample_filter.bpf.c

···
 		}
 		/* 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;
 	case PBF_TERM_NONE:
 	case __PBF_UNUSED_TERM4:
 	case __PBF_UNUSED_TERM5: