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Merge branch 'bpftool: fix feature output when helper probes fail'

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Milan Landaverde says:

====================

Currently in bpftool's feature probe, we incorrectly tell the user that
all of the helper functions are supported for program types where helper
probing fails or is explicitly unsupported[1]:

$ bpftool feature probe
...
eBPF helpers supported for program type tracing:
	- bpf_map_lookup_elem
	- bpf_map_update_elem
	- bpf_map_delete_elem
	...
	- bpf_redirect_neigh
	- bpf_check_mtu
	- bpf_sys_bpf
	- bpf_sys_close

This patch adjusts bpftool to relay to the user when helper support
can't be determined:

$ bpftool feature probe
...
eBPF helpers supported for program type lirc_mode2:
    Program type not supported
eBPF helpers supported for program type tracing:
    Could not determine which helpers are available
eBPF helpers supported for program type struct_opts:
    Could not determine which helpers are available
eBPF helpers supported for program type ext:
    Could not determine which helpers are available

Rather than imply that no helpers are available for the program type, we
let the user know that helper function probing failed entirely.

[1] https://lore.kernel.org/bpf/20211217171202.3352835-2-andrii@kernel.org/
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
This commit is contained in:
Andrii Nakryiko
2022-05-09 17:16:05 -07:00
parent 7b3a063824 b06a92a18d
commit bfa92e0bdc
1 changed files with 17 additions and 5 deletions
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22
tools/bpf/bpftool/feature.c
View File

@@ -638,7 +638,7 @@ probe_map_type(enum bpf_map_type map_type, const char *define_prefix,
res = probe_map_type_ifindex(map_type, ifindex);
} else {
res = libbpf_probe_bpf_map_type(map_type, NULL);
res = libbpf_probe_bpf_map_type(map_type, NULL) > 0;
}
/* Probe result depends on the success of map creation, no additional
@@ -690,7 +690,7 @@ probe_helper_ifindex(enum bpf_func_id id, enum bpf_prog_type prog_type,
return res;
}
static void
static bool
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)
@@ -701,7 +701,7 @@ probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
if (ifindex)
res = probe_helper_ifindex(id, prog_type, ifindex);
else
res = libbpf_probe_bpf_helper(prog_type, id, NULL);
res = libbpf_probe_bpf_helper(prog_type, id, NULL) > 0;
#ifdef USE_LIBCAP
/* Probe may succeed even if program load fails, for
* unprivileged users check that we did not fail because of
@@ -723,6 +723,8 @@ probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
if (res)
printf("\n\t- %s", helper_name[id]);
}
return res;
}
static void
@@ -732,6 +734,7 @@ probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
const char *ptype_name = prog_type_name[prog_type];
char feat_name[128];
unsigned int id;
bool probe_res = false;
if (ifindex)
/* Only test helpers for offload-able program types */
@@ -764,7 +767,7 @@ probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
continue;
/* fallthrough */
default:
probe_helper_for_progtype(prog_type, supported_type,
probe_res |= probe_helper_for_progtype(prog_type, supported_type,
define_prefix, id, ptype_name,
ifindex);
}
@@ -772,8 +775,17 @@ probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
if (json_output)
jsonw_end_array(json_wtr);
else if (!define_prefix)
else if (!define_prefix) {
printf("\n");
if (!probe_res) {
if (!supported_type)
printf("\tProgram type not supported\n");
else
printf("\tCould not determine which helpers are available\n");
}
}
}
static void