bpf: Merge printk and seq_printf VARARG max macros

MAX_SNPRINTF_VARARGS and MAX_SEQ_PRINTF_VARARGS are used by bpf helpers
bpf_snprintf and bpf_seq_printf to limit their varargs. Both call into
bpf_bprintf_prepare for print formatting logic and have convenience
macros in libbpf (BPF_SNPRINTF, BPF_SEQ_PRINTF) which use the same
helper macros to convert varargs to a byte array.

Changing shared functionality to support more varargs for either bpf
helper would affect the other as well, so let's combine the _VARARGS
macros to make this more obvious.

Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210917182911.2426606-2-davemarchevsky@fb.com

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index f4c16f1..be8d57e 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2216,6 +2216,8 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
 struct btf_id_set;
 bool btf_id_set_contains(const struct btf_id_set *set, u32 id);
 
+#define MAX_BPRINTF_VARARGS            12
+
 int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
                        u32 **bin_buf, u32 num_args);
 void bpf_bprintf_cleanup(void);

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 9aabf84..8f9f392 100644 (file)
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -979,15 +979,13 @@ out:
        return err;
 }
 
-#define MAX_SNPRINTF_VARARGS           12
-
 BPF_CALL_5(bpf_snprintf, char *, str, u32, str_size, char *, fmt,
           const void *, data, u32, data_len)
 {
        int err, num_args;
        u32 *bin_args;
 
-       if (data_len % 8 || data_len > MAX_SNPRINTF_VARARGS * 8 ||
+       if (data_len % 8 || data_len > MAX_BPRINTF_VARARGS * 8 ||
            (data_len && !data))
                return -EINVAL;
        num_args = data_len / 8;

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 067e88c..4ec779f 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -414,15 +414,13 @@ const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
        return &bpf_trace_printk_proto;
 }
 
-#define MAX_SEQ_PRINTF_VARARGS         12
-
 BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size,
           const void *, data, u32, data_len)
 {
        int err, num_args;
        u32 *bin_args;
 
-       if (data_len & 7 || data_len > MAX_SEQ_PRINTF_VARARGS * 8 ||
+       if (data_len & 7 || data_len > MAX_BPRINTF_VARARGS * 8 ||
            (data_len && !data))
                return -EINVAL;
        num_args = data_len / 8;