Commit eb411377 authored by Alan Maguire's avatar Alan Maguire Committed by Alexei Starovoitov
Browse files

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: default avatarAlexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: default avatarAlan Maguire <alan.maguire@oracle.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1601292670-1616-8-git-send-email-alan.maguire@oracle.com
parent eb58bbf2

include/linux/btf.h

+2 −0
Original line number Diff line number Diff line
@@ -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.

include/uapi/linux/bpf.h

+9 −0
Original line number Diff line number Diff line
@@ -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

kernel/bpf/btf.c

+2 −2
Original line number Diff line number Diff line
@@ -5346,7 +5346,7 @@ 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,

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;

kernel/bpf/core.c

+1 −0
Original line number Diff line number Diff line
@@ -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)

{

kernel/trace/bpf_trace.c

+33 −0
Original line number Diff line number Diff line
@@ -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:

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