tetragon: Add TAIL_CALL_* enums for generic tail calls

Adding TAIL_CALL_* enum values to identify tail calls for generic probes and make it more human friendly. Suggested-by: Djalal Harouni <[email protected]> Signed-off-by: Jiri Olsa <[email protected]>
cilium · Nov 27, 2023 · 92e4c99 · 92e4c99
1 parent beaf407
commit 92e4c99
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Showing 5 changed files with 24 additions and 25 deletions.
diff --git a/bpf/process/bpf_generic_kprobe.c b/bpf/process/bpf_generic_kprobe.c
@@ -113,7 +113,7 @@ generic_kprobe_start_process_filter(void *ctx)
 #endif
 
 	/* Tail call into filters. */
-	tail_call(ctx, &kprobe_calls, 2);
+	tail_call(ctx, &kprobe_calls, TAIL_CALL_FILTER);
 	return 0;
 }
 
@@ -187,7 +187,7 @@ generic_kprobe_process_filter(void *ctx)
 	ret = generic_process_filter(&msg->sel, &msg->current, &msg->ns,
 				     &msg->caps, &filter_map, msg->idx);
 	if (ret == PFILTER_CONTINUE)
-		tail_call(ctx, &kprobe_calls, 2);
+		tail_call(ctx, &kprobe_calls, TAIL_CALL_FILTER);
 	else if (ret == PFILTER_ACCEPT)
 		tail_call(ctx, &kprobe_calls, 0);
 	/* If filter does not accept drop it. Ideally we would
@@ -196,9 +196,6 @@ generic_kprobe_process_filter(void *ctx)
 	return PFILTER_REJECT;
 }
 
-// Filter tailcalls: kprobe/6...kprobe/10
-// see also: MIN_FILTER_TAILCALL, MAX_FILTER_TAILCALL
-
 __attribute__((section("kprobe/3"), used)) int
 generic_kprobe_filter_arg(void *ctx)
 {

diff --git a/bpf/process/bpf_generic_tracepoint.c b/bpf/process/bpf_generic_tracepoint.c
@@ -196,7 +196,7 @@ generic_tracepoint_event(struct generic_tracepoint_event_arg *ctx)
 #ifdef __CAP_CHANGES_FILTER
 	msg->sel.match_cap = 0;
 #endif
-	tail_call(ctx, &tp_calls, 2);
+	tail_call(ctx, &tp_calls, TAIL_CALL_FILTER);
 	return 0;
 }
 
@@ -221,18 +221,15 @@ generic_tracepoint_filter(void *ctx)
 	ret = generic_process_filter(&msg->sel, &msg->current, &msg->ns,
 				     &msg->caps, &filter_map, msg->idx);
 	if (ret == PFILTER_CONTINUE)
-		tail_call(ctx, &tp_calls, 2);
+		tail_call(ctx, &tp_calls, TAIL_CALL_FILTER);
 	else if (ret == PFILTER_ACCEPT)
-		tail_call(ctx, &tp_calls, 1);
+		tail_call(ctx, &tp_calls, TAIL_CALL_PROCESS);
 	/* If filter does not accept drop it. Ideally we would
 	 * log error codes for later review, TBD.
 	 */
 	return PFILTER_REJECT;
 }
 
-// Filter tailcalls: tracepoint/6...tracepoint/10
-// see also: MIN_FILTER_TAILCALL, MAX_FILTER_TAILCALL
-
 __attribute__((section("tracepoint/3"), used)) int
 generic_tracepoint_arg(void *ctx)
 {

diff --git a/bpf/process/bpf_generic_uprobe.c b/bpf/process/bpf_generic_uprobe.c
@@ -89,7 +89,7 @@ generic_uprobe_start_process_filter(void *ctx)
 	if (!generic_process_filter_binary(config))
 		return 0;
 	/* Tail call into filters. */
-	tail_call(ctx, &uprobe_calls, 2);
+	tail_call(ctx, &uprobe_calls, TAIL_CALL_FILTER);
 	return 0;
 }
 
@@ -130,7 +130,7 @@ generic_uprobe_process_filter(void *ctx)
 	ret = generic_process_filter(&msg->sel, &msg->current, &msg->ns,
 				     &msg->caps, &filter_map, msg->idx);
 	if (ret == PFILTER_CONTINUE)
-		tail_call(ctx, &uprobe_calls, 2);
+		tail_call(ctx, &uprobe_calls, TAIL_CALL_FILTER);
 	else if (ret == PFILTER_ACCEPT)
 		tail_call(ctx, &uprobe_calls, 0);
 	/* If filter does not accept drop it. Ideally we would

diff --git a/bpf/process/generic_calls.h b/bpf/process/generic_calls.h
@@ -61,12 +61,12 @@ generic_process_event(void *ctx, struct bpf_map_def *heap_map,
 	/* Continue to process other arguments. */
 	if (index < 4) {
 		e->filter_tailcall_index = index + 1;
-		tail_call(ctx, tailcals, 1);
+		tail_call(ctx, tailcals, TAIL_CALL_PROCESS);
 	}
 
 	/* Last argument, go send.. */
 	e->filter_tailcall_index = 0;
-	tail_call(ctx, tailcals, 3);
+	tail_call(ctx, tailcals, TAIL_CALL_ARGS);
 	return 0;
 }
 

diff --git a/bpf/process/types/basic.h b/bpf/process/types/basic.h
@@ -95,6 +95,14 @@ enum {
 	FGS_SIGKILL = 9,
 };
 
+enum {
+	TAIL_CALL_PROCESS = 1,
+	TAIL_CALL_FILTER = 2,
+	TAIL_CALL_ARGS = 3,
+	TAIL_CALL_ACTIONS = 4,
+	TAIL_CALL_SEND = 5,
+};
+
 struct selector_action {
 	__u32 actionlen;
 	__u32 act[];
@@ -183,12 +191,9 @@ static inline __attribute__((always_inline)) __u32 get_index(void *ctx)
 #define get_index(ctx) 0
 #endif
 
-// Filter tailcalls are {kprobe,tracepoint}/{6,7,8,9,10}
-// We do one tail-call per selector, so we can have up to 5 selectors.
-#define MIN_FILTER_TAILCALL 6
-#define MAX_FILTER_TAILCALL 10
-#define MAX_SELECTORS	    (MAX_FILTER_TAILCALL - MIN_FILTER_TAILCALL + 1)
-#define MAX_SELECTORS_MASK  7
+// We do one tail-call per selector, we can have up to 5 selectors.
+#define MAX_SELECTORS	   5
+#define MAX_SELECTORS_MASK 7
 
 static inline __attribute__((always_inline)) long
 filter_32ty_map(struct selector_arg_filter *filter, char *args);
@@ -2182,7 +2187,7 @@ filter_read_arg(void *ctx, struct bpf_map_def *heap,
 		index++;
 		if (index <= MAX_SELECTORS && e->sel.active[index & MAX_SELECTORS_MASK]) {
 			e->filter_tailcall_index = index;
-			tail_call(ctx, tailcalls, 3);
+			tail_call(ctx, tailcalls, TAIL_CALL_ARGS);
 		}
 		// reject if we did not attempt to tailcall, or if tailcall failed.
 		return filter_args_reject(e->func_id);
@@ -2192,10 +2197,10 @@ filter_read_arg(void *ctx, struct bpf_map_def *heap,
 	// otherwise pass==1 indicates using default action.
 	if (pass > 1) {
 		e->pass = pass;
-		tail_call(ctx, tailcalls, 4);
+		tail_call(ctx, tailcalls, TAIL_CALL_ACTIONS);
 	}
 
-	tail_call(ctx, tailcalls, 5);
+	tail_call(ctx, tailcalls, TAIL_CALL_SEND);
 	return 1;
 }
 
@@ -2237,7 +2242,7 @@ generic_actions(void *ctx, struct bpf_map_def *heap,
 
 	postit = do_actions(ctx, e, actions, override_tasks);
 	if (postit)
-		tail_call(ctx, tailcalls, 5);
+		tail_call(ctx, tailcalls, TAIL_CALL_SEND);
 	return 1;
 }