[PATCH 5.15 1/4] bpf: Merge printk and seq_printf VARARG max macros

Thadeu Lima de Souza Cascardo
2024-02-17T12:13:42Z

From: Dave Marchevsky <davemarchevsky@fb.com>

commit 335ff4990cf3bfa42d8846f9b3d8c09456f51801 upstream.

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
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
---
include/linux/bpf.h | 2 ++
kernel/bpf/helpers.c | 4 +---
kernel/trace/bpf_trace.c | 4 +---
3 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 00c615fc8ec3..175d623a16a1 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2286,6 +2286,8 @@ void bpf_arch_poke_desc_update(struct bpf_jit_poke_descriptor *poke,
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 11e406ad16ae..4eb3b929504d 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -979,15 +979,13 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
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 85a36b19c2b8..34455856c035 100644
--- 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;
--
2.34.1