diff mbox series

[v2,bpf-next,3/4] libbpf: Introduce bpf_ksym_exists() macro.

Message ID 20230317201920.62030-4-alexei.starovoitov@gmail.com (mailing list archive)
State Accepted
Commit 5cbd3fe3a91df46ea201cc5d8ab4e390332ec26e
Delegated to: BPF
Headers show
Series bpf: Add detection of kfuncs. | expand

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netdev/checkpatch warning CHECK: Macro argument 'sym' may be better as '(sym)' to avoid precedence issues WARNING: line length of 102 exceeds 80 columns
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Commit Message

Alexei Starovoitov March 17, 2023, 8:19 p.m. UTC 
From: Alexei Starovoitov <ast@kernel.org>

Introduce bpf_ksym_exists() macro that can be used by BPF programs
to detect at load time whether particular ksym (either variable or kfunc)
is present in the kernel.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 tools/lib/bpf/bpf_helpers.h | 3 +++
 1 file changed, 3 insertions(+)

Comments

Andrii Nakryiko March 17, 2023, 10:53 p.m. UTC | #1 
On Fri, Mar 17, 2023 at 1:19 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> From: Alexei Starovoitov <ast@kernel.org>
>
> Introduce bpf_ksym_exists() macro that can be used by BPF programs
> to detect at load time whether particular ksym (either variable or kfunc)
> is present in the kernel.
>
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
> ---
>  tools/lib/bpf/bpf_helpers.h | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
> index 7d12d3e620cc..b49823117dae 100644
> --- a/tools/lib/bpf/bpf_helpers.h
> +++ b/tools/lib/bpf/bpf_helpers.h
> @@ -177,6 +177,9 @@ enum libbpf_tristate {
>  #define __kptr_untrusted __attribute__((btf_type_tag("kptr_untrusted")))
>  #define __kptr __attribute__((btf_type_tag("kptr")))
>
> +#define bpf_ksym_exists(sym) \
> +       ({ _Static_assert(!__builtin_constant_p(!!sym), #sym " should be marked as __weak"); !!sym; })
> +

I reformatted this to fit under 100 characters.

-#define bpf_ksym_exists(sym) \
-       ({ _Static_assert(!__builtin_constant_p(!!sym), #sym " should
be marked as __weak"); !!sym; })
+#define bpf_ksym_exists(sym) ({
                                 \
+       _Static_assert(!__builtin_constant_p(!!sym), #sym " should be
marked as __weak");       \
+       !!sym;
                         \
+})


Other than that, it looks great! Applied to bpf-next, thanks.



>  #ifndef ___bpf_concat
>  #define ___bpf_concat(a, b) a ## b
>  #endif
> --
> 2.34.1
>
diff mbox series

Patch

diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index 7d12d3e620cc..b49823117dae 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -177,6 +177,9 @@  enum libbpf_tristate {
 #define __kptr_untrusted __attribute__((btf_type_tag("kptr_untrusted")))
 #define __kptr __attribute__((btf_type_tag("kptr")))
 
+#define bpf_ksym_exists(sym) \
+	({ _Static_assert(!__builtin_constant_p(!!sym), #sym " should be marked as __weak"); !!sym; })
+
 #ifndef ___bpf_concat
 #define ___bpf_concat(a, b) a ## b
 #endif