Re: [PATCH bpf-next v1 1/3] bpf: Extract bpf_get_linfo_file_line

[Puranjay Mohan <puranjay@kernel.org>]

Kumar Kartikeya Dwivedi <memxor@gmail.com> writes:

> Extract bpf_get_linfo_file_line as its own function so that the logic to
> obtain the file, line, and line number for a given program can be shared
> in subsequent patches.
>
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> ---
>  include/linux/bpf.h |  2 ++
>  kernel/bpf/core.c   | 32 +++++++++++++++++++++++---------
>  2 files changed, 25 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 05b34a6355b0..2c4f92085d79 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -3946,6 +3946,8 @@ static inline bool bpf_is_subprog(const struct bpf_prog *prog)
>  	return prog->aux->func_idx != 0;
>  }
>  
> +int bpf_get_linfo_file_line(struct btf *btf, const struct bpf_line_info *linfo,
> +			    const char **filep, const char **linep, int *nump);
>  int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char **filep,
>  			   const char **linep, int *nump);
>  struct bpf_prog *bpf_prog_find_from_stack(void);
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index 1af5fb3f21d9..052dd78a2d81 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -3313,6 +3313,28 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(xdp_bulk_tx);
>  
>  #ifdef CONFIG_BPF_SYSCALL
>  
> +int bpf_get_linfo_file_line(struct btf *btf, const struct bpf_line_info *linfo,
> +			    const char **filep, const char **linep, int *nump)
> +{
> +	/* Get base component of the file path. */
> +	if (filep) {
> +		*filep = btf_name_by_offset(btf, linfo->file_name_off);
> +		*filep = kbasename(*filep);
> +	}
> +
> +	/* Obtain the source line, and strip whitespace in prefix. */
> +	if (linep) {
> +		*linep = btf_name_by_offset(btf, linfo->line_off);
> +		while (isspace(**linep))
> +			*linep += 1;
> +	}
> +
> +	if (nump)
> +		*nump = BPF_LINE_INFO_LINE_NUM(linfo->line_col);
> +
> +	return 0;

Nit: Just realized that this always returns 0, should be make this return void?

> +}
> +
>  int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char **filep,
>  			   const char **linep, int *nump)
>  {
> @@ -3347,15 +3369,7 @@ int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char *
>  	if (idx == -1)
>  		return -ENOENT;
>  
> -	/* Get base component of the file path. */
> -	*filep = btf_name_by_offset(btf, linfo[idx].file_name_off);
> -	*filep = kbasename(*filep);
> -	/* Obtain the source line, and strip whitespace in prefix. */
> -	*linep = btf_name_by_offset(btf, linfo[idx].line_off);
> -	while (isspace(**linep))
> -		*linep += 1;
> -	*nump = BPF_LINE_INFO_LINE_NUM(linfo[idx].line_col);
> -	return 0;
> +	return bpf_get_linfo_file_line(btf, &linfo[idx], filep, linep, nump);
>  }
>  
>  struct walk_stack_ctx {
> -- 
> 2.52.0