bpf: Add bpf_seq_printf_btf helper

A helper is added to allow seq file writing of kernel data
structures using vmlinux BTF.  Its signature is

long bpf_seq_printf_btf(struct seq_file *m, struct btf_ptr *ptr,
                        u32 btf_ptr_size, u64 flags);

Flags and struct btf_ptr definitions/use are identical to the
bpf_snprintf_btf helper, and the helper returns 0 on success
or a negative error value.

Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1601292670-1616-8-git-send-email-alan.maguire@oracle.com
This commit is contained in:
Alan Maguire 2020-09-28 12:31:09 +01:00 committed by Alexei Starovoitov
parent eb58bbf2e5
commit eb411377ae
6 changed files with 56 additions and 2 deletions

View File

@ -68,6 +68,8 @@ const struct btf_type *btf_type_id_size(const struct btf *btf,
void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
struct seq_file *m);
int btf_type_seq_show_flags(const struct btf *btf, u32 type_id, void *obj,
struct seq_file *m, u64 flags);
/*
* Copy len bytes of string representation of obj of BTF type_id into buf.

View File

@ -3630,6 +3630,14 @@ union bpf_attr {
* The number of bytes that were written (or would have been
* written if output had to be truncated due to string size),
* or a negative error in cases of failure.
*
* long bpf_seq_printf_btf(struct seq_file *m, struct btf_ptr *ptr, u32 ptr_size, u64 flags)
* Description
* Use BTF to write to seq_write a string representation of
* *ptr*->ptr, using *ptr*->type_id as per bpf_snprintf_btf().
* *flags* are identical to those used for bpf_snprintf_btf.
* Return
* 0 on success or a negative error in case of failure.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@ -3782,6 +3790,7 @@ union bpf_attr {
FN(d_path), \
FN(copy_from_user), \
FN(snprintf_btf), \
FN(seq_printf_btf), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper

View File

@ -5346,8 +5346,8 @@ static void btf_seq_show(struct btf_show *show, const char *fmt,
seq_vprintf((struct seq_file *)show->target, fmt, args);
}
static int btf_type_seq_show_flags(const struct btf *btf, u32 type_id,
void *obj, struct seq_file *m, u64 flags)
int btf_type_seq_show_flags(const struct btf *btf, u32 type_id,
void *obj, struct seq_file *m, u64 flags)
{
struct btf_show sseq;

View File

@ -2217,6 +2217,7 @@ const struct bpf_func_proto bpf_get_current_ancestor_cgroup_id_proto __weak;
const struct bpf_func_proto bpf_get_local_storage_proto __weak;
const struct bpf_func_proto bpf_get_ns_current_pid_tgid_proto __weak;
const struct bpf_func_proto bpf_snprintf_btf_proto __weak;
const struct bpf_func_proto bpf_seq_printf_btf_proto __weak;
const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void)
{

View File

@ -71,6 +71,10 @@ static struct bpf_raw_event_map *bpf_get_raw_tracepoint_module(const char *name)
u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
u64 bpf_get_stack(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
static int bpf_btf_printf_prepare(struct btf_ptr *ptr, u32 btf_ptr_size,
u64 flags, const struct btf **btf,
s32 *btf_id);
/**
* trace_call_bpf - invoke BPF program
* @call: tracepoint event
@ -776,6 +780,31 @@ static const struct bpf_func_proto bpf_seq_write_proto = {
.arg3_type = ARG_CONST_SIZE_OR_ZERO,
};
BPF_CALL_4(bpf_seq_printf_btf, struct seq_file *, m, struct btf_ptr *, ptr,
u32, btf_ptr_size, u64, flags)
{
const struct btf *btf;
s32 btf_id;
int ret;
ret = bpf_btf_printf_prepare(ptr, btf_ptr_size, flags, &btf, &btf_id);
if (ret)
return ret;
return btf_type_seq_show_flags(btf, btf_id, ptr->ptr, m, flags);
}
static const struct bpf_func_proto bpf_seq_printf_btf_proto = {
.func = bpf_seq_printf_btf,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_BTF_ID,
.arg1_btf_id = &btf_seq_file_ids[0],
.arg2_type = ARG_PTR_TO_MEM,
.arg3_type = ARG_CONST_SIZE_OR_ZERO,
.arg4_type = ARG_ANYTHING,
};
static __always_inline int
get_map_perf_counter(struct bpf_map *map, u64 flags,
u64 *value, u64 *enabled, u64 *running)
@ -1695,6 +1724,10 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return prog->expected_attach_type == BPF_TRACE_ITER ?
&bpf_seq_write_proto :
NULL;
case BPF_FUNC_seq_printf_btf:
return prog->expected_attach_type == BPF_TRACE_ITER ?
&bpf_seq_printf_btf_proto :
NULL;
case BPF_FUNC_d_path:
return &bpf_d_path_proto;
default:

View File

@ -3630,6 +3630,14 @@ union bpf_attr {
* The number of bytes that were written (or would have been
* written if output had to be truncated due to string size),
* or a negative error in cases of failure.
*
* long bpf_seq_printf_btf(struct seq_file *m, struct btf_ptr *ptr, u32 ptr_size, u64 flags)
* Description
* Use BTF to write to seq_write a string representation of
* *ptr*->ptr, using *ptr*->type_id as per bpf_snprintf_btf().
* *flags* are identical to those used for bpf_snprintf_btf.
* Return
* 0 on success or a negative error in case of failure.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@ -3782,6 +3790,7 @@ union bpf_attr {
FN(d_path), \
FN(copy_from_user), \
FN(snprintf_btf), \
FN(seq_printf_btf), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper