[PATCH v2 bpf-next 11/11] tools/bpftool: add bpftool support for split BTF

[Andrii Nakryiko]

Add ability to work with split BTF by providing extra -B flag, which allows to
specify the path to the base BTF file.

Acked-by: Song Liu <songliubrav...@fb.com>
Signed-off-by: Andrii Nakryiko <and...@kernel.org>
---
 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