Re: [PATCH bpf-next 11/11] tools/bpftool: add bpftool support for split BTF

[Song Liu <songliubraving@fb.com>]

> On Oct 28, 2020, at 5:59 PM, Andrii Nakryiko <andrii@kernel.org> wrote:
> 
> Add ability to work with split BTF by providing extra -B flag, which allows to
> specify the path to the base BTF file.
> 
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

Acked-by: Song Liu <songliubraving@fb.com>

> ---
> tools/bpf/bpftool/btf.c  |  9 ++++++---
> tools/bpf/bpftool/main.c | 15 ++++++++++++++-
> tools/bpf/bpftool/main.h |  1 +
> 3 files changed, 21 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
> index 8ab142ff5eac..c96b56e8e3a4 100644
> --- a/tools/bpf/bpftool/btf.c
> +++ b/tools/bpf/bpftool/btf.c
> @@ -358,8 +358,12 @@ static int dump_btf_raw(const struct btf *btf,
> 		}
> 	} else {
> 		int cnt = btf__get_nr_types(btf);
> +		int start_id = 1;
> 
> -		for (i = 1; i <= cnt; i++) {
> +		if (base_btf)
> +			start_id = btf__get_nr_types(base_btf) + 1;
> +
> +		for (i = start_id; i <= cnt; i++) {
> 			t = btf__type_by_id(btf, i);
> 			dump_btf_type(btf, i, t);
> 		}
> @@ -438,7 +442,6 @@ static int do_dump(int argc, char **argv)
> 		return -1;
> 	}
> 	src = GET_ARG();
> -
> 	if (is_prefix(src, "map")) {
> 		struct bpf_map_info info = {};
> 		__u32 len = sizeof(info);
> @@ -499,7 +502,7 @@ static int do_dump(int argc, char **argv)
> 		}
> 		NEXT_ARG();
> 	} else if (is_prefix(src, "file")) {
> -		btf = btf__parse(*argv, NULL);
> +		btf = btf__parse_split(*argv, base_btf);
> 		if (IS_ERR(btf)) {
> 			err = -PTR_ERR(btf);
> 			btf = NULL;
> diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
> index 682daaa49e6a..b86f450e6fce 100644
> --- a/tools/bpf/bpftool/main.c
> +++ b/tools/bpf/bpftool/main.c
> @@ -11,6 +11,7 @@
> 
> #include <bpf/bpf.h>
> #include <bpf/libbpf.h>
> +#include <bpf/btf.h>
> 
> #include "main.h"
> 
> @@ -28,6 +29,7 @@ bool show_pinned;
> bool block_mount;
> bool verifier_logs;
> bool relaxed_maps;
> +struct btf *base_btf;
> struct pinned_obj_table prog_table;
> struct pinned_obj_table map_table;
> struct pinned_obj_table link_table;
> @@ -391,6 +393,7 @@ int main(int argc, char **argv)
> 		{ "mapcompat",	no_argument,	NULL,	'm' },
> 		{ "nomount",	no_argument,	NULL,	'n' },
> 		{ "debug",	no_argument,	NULL,	'd' },
> +		{ "base-btf",	required_argument, NULL, 'B' },
> 		{ 0 }
> 	};
> 	int opt, ret;
> @@ -407,7 +410,7 @@ int main(int argc, char **argv)
> 	hash_init(link_table.table);
> 
> 	opterr = 0;
> -	while ((opt = getopt_long(argc, argv, "Vhpjfmnd",
> +	while ((opt = getopt_long(argc, argv, "VhpjfmndB:",
> 				  options, NULL)) >= 0) {
> 		switch (opt) {
> 		case 'V':
> @@ -441,6 +444,15 @@ int main(int argc, char **argv)
> 			libbpf_set_print(print_all_levels);
> 			verifier_logs = true;
> 			break;
> +		case 'B':
> +			base_btf = btf__parse(optarg, NULL);
> +			if (libbpf_get_error(base_btf)) {
> +				p_err("failed to parse base BTF at '%s': %ld\n",
> +				      optarg, libbpf_get_error(base_btf));
> +				base_btf = NULL;
> +				return -1;
> +			}
> +			break;
> 		default:
> 			p_err("unrecognized option '%s'", argv[optind - 1]);
> 			if (json_output)
> @@ -465,6 +477,7 @@ int main(int argc, char **argv)
> 		delete_pinned_obj_table(&map_table);
> 		delete_pinned_obj_table(&link_table);
> 	}
> +	btf__free(base_btf);
> 
> 	return ret;
> }
> diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
> index c46e52137b87..76e91641262b 100644
> --- a/tools/bpf/bpftool/main.h
> +++ b/tools/bpf/bpftool/main.h
> @@ -90,6 +90,7 @@ extern bool show_pids;
> extern bool block_mount;
> extern bool verifier_logs;
> extern bool relaxed_maps;
> +extern struct btf *base_btf;
> extern struct pinned_obj_table prog_table;
> extern struct pinned_obj_table map_table;
> extern struct pinned_obj_table link_table;
> -- 
> 2.24.1
>