* [PATCH bpf-next] libbpf: fix BTF-defined map's __type macro handling of arrays
@ 2019-10-04 4:02 Andrii Nakryiko
2019-10-06 1:05 ` Alexei Starovoitov
0 siblings, 1 reply; 2+ messages in thread
From: Andrii Nakryiko @ 2019-10-04 4:02 UTC (permalink / raw)
To: bpf, netdev, ast, daniel; +Cc: andrii.nakryiko, kernel-team, Andrii Nakryiko
Due to a quirky C syntax of declaring pointers to array or function
prototype, existing __type() macro doesn't work with map key/value types
that are array or function prototype. One has to create a typedef first
and use it to specify key/value type for a BPF map. By using typeof(),
pointer to type is now handled uniformly for all kinds of types. Convert
one of self-tests as a demonstration.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
N.B. This patch depends on patch set that moves bpf_helpers.h into libbpf to
avoid conflicts.
tools/lib/bpf/bpf_helpers.h | 2 +-
tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c | 3 +--
2 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index 2d3d1f51cdd0..6f68e4d3aff7 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -3,7 +3,7 @@
#define __BPF_HELPERS__
#define __uint(name, val) int (*name)[val]
-#define __type(name, val) val *name
+#define __type(name, val) typeof(val) *name
/* Helper macro to print out debug messages */
#define bpf_printk(fmt, ...) \
diff --git a/tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c b/tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c
index f8ffa3f3d44b..6cc4479ac9df 100644
--- a/tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c
+++ b/tools/testing/selftests/bpf/progs/test_get_stack_rawtp.c
@@ -47,12 +47,11 @@ struct {
* issue and avoid complicated C programming massaging.
* This is an acceptable workaround since there is one entry here.
*/
-typedef __u64 raw_stack_trace_t[2 * MAX_STACK_RAWTP];
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__uint(max_entries, 1);
__type(key, __u32);
- __type(value, raw_stack_trace_t);
+ __type(value, __u64[2 * MAX_STACK_RAWTP]);
} rawdata_map SEC(".maps");
SEC("raw_tracepoint/sys_enter")
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH bpf-next] libbpf: fix BTF-defined map's __type macro handling of arrays
2019-10-04 4:02 [PATCH bpf-next] libbpf: fix BTF-defined map's __type macro handling of arrays Andrii Nakryiko
@ 2019-10-06 1:05 ` Alexei Starovoitov
0 siblings, 0 replies; 2+ messages in thread
From: Alexei Starovoitov @ 2019-10-06 1:05 UTC (permalink / raw)
To: Andrii Nakryiko
Cc: bpf, Network Development, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Kernel Team
On Fri, Oct 4, 2019 at 1:10 AM Andrii Nakryiko <andriin@fb.com> wrote:
>
> Due to a quirky C syntax of declaring pointers to array or function
> prototype, existing __type() macro doesn't work with map key/value types
> that are array or function prototype. One has to create a typedef first
> and use it to specify key/value type for a BPF map. By using typeof(),
> pointer to type is now handled uniformly for all kinds of types. Convert
> one of self-tests as a demonstration.
>
> Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Applied. Thanks
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