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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
This commit is contained in:
Dave Marchevsky 2021-09-17 11:29:03 -07:00 committed by Alexei Starovoitov
parent af54faab84
commit 335ff4990c
3 changed files with 4 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/bpf.h
View File

@ -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);

4
kernel/bpf/helpers.c
View File

@ -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;

4
kernel/trace/bpf_trace.c
View File

@ -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;