Re: [PATCH] bpftool: Try to read btf as raw data if elf read fails
From: Jakub Kicinski <hidden>
Date: 2019-10-18 22:39:16
Also in:
bpf
On Fri, 18 Oct 2019 12:34:04 +0200, Jiri Olsa wrote:
quoted hunk ↗ jump to hunk
The bpftool interface stays the same, but now it's possible to run it over BTF raw data, like: $ bpftool btf dump file /sys/kernel/btf/vmlinux libbpf: failed to get EHDR from /sys/kernel/btf/vmlinux [1] INT '(anon)' size=4 bits_offset=0 nr_bits=32 encoding=(none) [2] INT 'long unsigned int' size=8 bits_offset=0 nr_bits=64 encoding=(none) [3] CONST '(anon)' type_id=2 I'm also adding err init to 0 because I was getting uninitialized warnings from gcc. Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- tools/bpf/bpftool/btf.c | 47 ++++++++++++++++++++++++++++++++++++----- 1 file changed, 42 insertions(+), 5 deletions(-)diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c index 9a9376d1d3df..100fb7e02329 100644 --- a/tools/bpf/bpftool/btf.c +++ b/tools/bpf/bpftool/btf.c@@ -12,6 +12,9 @@ #include <libbpf.h> #include <linux/btf.h> #include <linux/hashtable.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <unistd.h> #include "btf.h" #include "json_writer.h"@@ -388,6 +391,35 @@ static int dump_btf_c(const struct btf *btf, return err; } +static struct btf *btf__parse_raw(const char *file) +{ + struct btf *btf = ERR_PTR(-EINVAL); + __u8 *buf = NULL;
Please drop the inits
+ struct stat st; + FILE *f; + + if (stat(file, &st)) + return btf;
And return constants here
+ f = fopen(file, "rb"); + if (!f) + return btf;
and here
+ buf = malloc(st.st_size); + if (!buf) + goto err;
and jump to the right place here.
+ if ((size_t) st.st_size != fread(buf, 1, st.st_size, f)) + goto err; + + btf = btf__new(buf, st.st_size); + +err:
The prefix for error labels which is shared with non-error path is exit_
quoted hunk ↗ jump to hunk
+ free(buf); + fclose(f); + return btf; +} + static int do_dump(int argc, char **argv) { struct btf *btf = NULL;@@ -397,7 +429,7 @@ static int do_dump(int argc, char **argv) __u32 btf_id = -1; const char *src; int fd = -1; - int err; + int err = 0;
This change looks unnecessary.
quoted hunk ↗ jump to hunk
if (!REQ_ARGS(2)) { usage();@@ -468,10 +500,15 @@ static int do_dump(int argc, char **argv) btf = btf__parse_elf(*argv, NULL); if (IS_ERR(btf)) { err = PTR_ERR(btf); - btf = NULL; - p_err("failed to load BTF from %s: %s", - *argv, strerror(err)); - goto done; + if (err == -LIBBPF_ERRNO__FORMAT) + btf = btf__parse_raw(*argv); + if (IS_ERR(btf)) { + btf = NULL; + /* Display the original error value. */ + p_err("failed to load BTF from %s: %s", + *argv, strerror(err)); + goto done; + } } NEXT_ARG(); } else {