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[bpf-next,v3,5/6] libbpf: Introduce a BPF_SNPRINTF helper macro

Message ID 20210412153754.235500-6-revest@chromium.org (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series Add a snprintf eBPF helper | expand

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Commit Message

Florent Revest April 12, 2021, 3:37 p.m. UTC
Similarly to BPF_SEQ_PRINTF, this macro turns variadic arguments into an
array of u64, making it more natural to call the bpf_snprintf helper.

Signed-off-by: Florent Revest <revest@chromium.org>
---
 tools/lib/bpf/bpf_tracing.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

Comments

Andrii Nakryiko April 13, 2021, 11:18 p.m. UTC | #1
On Mon, Apr 12, 2021 at 8:38 AM Florent Revest <revest@chromium.org> wrote:
>
> Similarly to BPF_SEQ_PRINTF, this macro turns variadic arguments into an
> array of u64, making it more natural to call the bpf_snprintf helper.
>
> Signed-off-by: Florent Revest <revest@chromium.org>
> ---

Nice!

Acked-by: Andrii Nakryiko <andrii@kernel.org>

>  tools/lib/bpf/bpf_tracing.h | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>
> diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h
> index 1c2e91ee041d..8c954ebc0c7c 100644
> --- a/tools/lib/bpf/bpf_tracing.h
> +++ b/tools/lib/bpf/bpf_tracing.h
> @@ -447,4 +447,22 @@ static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args)
>                        ___param, sizeof(___param));             \
>  })
>
> +/*
> + * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of
> + * an array of u64.
> + */
> +#define BPF_SNPRINTF(out, out_size, fmt, args...)              \
> +({                                                             \
> +       static const char ___fmt[] = fmt;                       \
> +       unsigned long long ___param[___bpf_narg(args)];         \
> +                                                               \
> +       _Pragma("GCC diagnostic push")                          \
> +       _Pragma("GCC diagnostic ignored \"-Wint-conversion\"")  \
> +       ___bpf_fill(___param, args);                            \
> +       _Pragma("GCC diagnostic pop")                           \
> +                                                               \
> +       bpf_snprintf(out, out_size, ___fmt,                     \
> +                    ___param, sizeof(___param));               \
> +})
> +
>  #endif
> --
> 2.31.1.295.g9ea45b61b8-goog
>
diff mbox series

Patch

diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h
index 1c2e91ee041d..8c954ebc0c7c 100644
--- a/tools/lib/bpf/bpf_tracing.h
+++ b/tools/lib/bpf/bpf_tracing.h
@@ -447,4 +447,22 @@  static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args)
 		       ___param, sizeof(___param));		\
 })
 
+/*
+ * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of
+ * an array of u64.
+ */
+#define BPF_SNPRINTF(out, out_size, fmt, args...)		\
+({								\
+	static const char ___fmt[] = fmt;			\
+	unsigned long long ___param[___bpf_narg(args)];		\
+								\
+	_Pragma("GCC diagnostic push")				\
+	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")	\
+	___bpf_fill(___param, args);				\
+	_Pragma("GCC diagnostic pop")				\
+								\
+	bpf_snprintf(out, out_size, ___fmt,			\
+		     ___param, sizeof(___param));		\
+})
+
 #endif