[bpf-next,v3,2/5] bpftool: Make probes which emit dmesg warnings optional
diff mbox series

Message ID 20200225194446.20651-3-mrostecki@opensuse.org
State Changes Requested
Delegated to: BPF Maintainers
Headers show
Series
  • bpftool: Make probes which emit dmesg warnings optional
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Commit Message

Michal Rostecki Feb. 25, 2020, 7:44 p.m. UTC
Probes related to bpf_probe_write_user and bpf_trace_printk helpers emit
dmesg warnings which might be confusing for people running bpftool on
production environments. This change filters them out by default and
introduces the new positional argument "full" which enables all
available probes.

Signed-off-by: Michal Rostecki <mrostecki@opensuse.org>
---
 tools/bpf/bpftool/feature.c | 70 ++++++++++++++++++++++++++-----------
 1 file changed, 49 insertions(+), 21 deletions(-)

Comments

Daniel Borkmann Feb. 26, 2020, 3:35 p.m. UTC | #1
On 2/25/20 8:44 PM, Michal Rostecki wrote:
> Probes related to bpf_probe_write_user and bpf_trace_printk helpers emit
> dmesg warnings which might be confusing for people running bpftool on
> production environments. This change filters them out by default and
> introduces the new positional argument "full" which enables all
> available probes.
> 
> Signed-off-by: Michal Rostecki <mrostecki@opensuse.org>
[...]
> +		/* Skip helper functions which emit dmesg messages when not in
> +		 * the full mode.
> +		 */
> +		switch (id) {
> +		case 6: /* trace_printk */
> +		case 36: /* probe_write_user */

Please fix this into the actual enum above, then also the comment is not needed.

> +			if (!full_mode)
> +				continue;
> +			/* fallthrough */
> +		default:
> +			probe_helper_for_progtype(prog_type, supported_type,
> +						  define_prefix, id, ptype_name,
> +						  ifindex);
>   		}
>   	}

Patch
diff mbox series

diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
index 345e4a2b4f53..ada3e1502b45 100644
--- a/tools/bpf/bpftool/feature.c
+++ b/tools/bpf/bpftool/feature.c
@@ -513,14 +513,39 @@  probe_map_type(enum bpf_map_type map_type, const char *define_prefix,
 			   define_prefix);
 }
 
+static void
+probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
+			  const char *define_prefix, unsigned int id,
+			  const char *ptype_name, __u32 ifindex)
+{
+	bool res;
+
+	if (!supported_type)
+		res = false;
+	else
+		res = bpf_probe_helper(id, prog_type, ifindex);
+
+	if (json_output) {
+		if (res)
+			jsonw_string(json_wtr, helper_name[id]);
+	} else if (define_prefix) {
+		printf("#define %sBPF__PROG_TYPE_%s__HELPER_%s %s\n",
+		       define_prefix, ptype_name, helper_name[id],
+		       res ? "1" : "0");
+	} else {
+		if (res)
+			printf("\n\t- %s", helper_name[id]);
+	}
+}
+
 static void
 probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
-			   const char *define_prefix, __u32 ifindex)
+			   const char *define_prefix, bool full_mode,
+			   __u32 ifindex)
 {
 	const char *ptype_name = prog_type_name[prog_type];
 	char feat_name[128];
 	unsigned int id;
-	bool res;
 
 	if (ifindex)
 		/* Only test helpers for offload-able program types */
@@ -542,21 +567,19 @@  probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
 	}
 
 	for (id = 1; id < ARRAY_SIZE(helper_name); id++) {
-		if (!supported_type)
-			res = false;
-		else
-			res = bpf_probe_helper(id, prog_type, ifindex);
-
-		if (json_output) {
-			if (res)
-				jsonw_string(json_wtr, helper_name[id]);
-		} else if (define_prefix) {
-			printf("#define %sBPF__PROG_TYPE_%s__HELPER_%s %s\n",
-			       define_prefix, ptype_name, helper_name[id],
-			       res ? "1" : "0");
-		} else {
-			if (res)
-				printf("\n\t- %s", helper_name[id]);
+		/* Skip helper functions which emit dmesg messages when not in
+		 * the full mode.
+		 */
+		switch (id) {
+		case 6: /* trace_printk */
+		case 36: /* probe_write_user */
+			if (!full_mode)
+				continue;
+			/* fallthrough */
+		default:
+			probe_helper_for_progtype(prog_type, supported_type,
+						  define_prefix, id, ptype_name,
+						  ifindex);
 		}
 	}
 
@@ -655,7 +678,8 @@  static void section_map_types(const char *define_prefix, __u32 ifindex)
 }
 
 static void
-section_helpers(bool *supported_types, const char *define_prefix, __u32 ifindex)
+section_helpers(bool *supported_types, const char *define_prefix,
+		bool full_mode, __u32 ifindex)
 {
 	unsigned int i;
 
@@ -681,7 +705,7 @@  section_helpers(bool *supported_types, const char *define_prefix, __u32 ifindex)
 		       define_prefix);
 	for (i = BPF_PROG_TYPE_UNSPEC + 1; i < ARRAY_SIZE(prog_type_name); i++)
 		probe_helpers_for_progtype(i, supported_types[i],
-					   define_prefix, ifindex);
+					   define_prefix, full_mode, ifindex);
 
 	print_end_section();
 }
@@ -701,6 +725,7 @@  static int do_probe(int argc, char **argv)
 	enum probe_component target = COMPONENT_UNSPEC;
 	const char *define_prefix = NULL;
 	bool supported_types[128] = {};
+	bool full_mode = false;
 	__u32 ifindex = 0;
 	char *ifname;
 
@@ -740,6 +765,9 @@  static int do_probe(int argc, char **argv)
 				      strerror(errno));
 				return -1;
 			}
+		} else if (is_prefix(*argv, "full")) {
+			full_mode = true;
+			NEXT_ARG();
 		} else if (is_prefix(*argv, "macros") && !define_prefix) {
 			define_prefix = "";
 			NEXT_ARG();
@@ -775,7 +803,7 @@  static int do_probe(int argc, char **argv)
 		goto exit_close_json;
 	section_program_types(supported_types, define_prefix, ifindex);
 	section_map_types(define_prefix, ifindex);
-	section_helpers(supported_types, define_prefix, ifindex);
+	section_helpers(supported_types, define_prefix, full_mode, ifindex);
 	section_misc(define_prefix, ifindex);
 
 exit_close_json:
@@ -794,7 +822,7 @@  static int do_help(int argc, char **argv)
 	}
 
 	fprintf(stderr,
-		"Usage: %s %s probe [COMPONENT] [macros [prefix PREFIX]]\n"
+		"Usage: %s %s probe [COMPONENT] [full] [macros [prefix PREFIX]]\n"
 		"       %s %s help\n"
 		"\n"
 		"       COMPONENT := { kernel | dev NAME }\n"