From: Jiri Olsa <jolsa@redhat.com>
To: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
Andrii Nakryiko <andriin@fb.com>, Yonghong Song <yhs@fb.com>,
Martin KaFai Lau <kafai@fb.com>
Subject: Re: [PATCH] bpftool: Try to read btf as raw data if elf read fails
Date: Mon, 21 Oct 2019 16:02:27 +0200 [thread overview]
Message-ID: <20191021140227.GD32718@krava> (raw)
In-Reply-To: <20191018153905.600d7c8a@cakuba.netronome.com>
On Fri, Oct 18, 2019 at 03:39:05PM -0700, Jakub Kicinski wrote:
> On Fri, 18 Oct 2019 12:34:04 +0200, Jiri Olsa wrote:
> > 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_
>
> > + free(buf);
> > + fclose(f);
> > + return btf;
> > +}
> > +
ok for all above
> > 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.
I'm getting confusing warnings from gcc about this,
but there is a code path where do_dump would return
untouched err:
do_dump
int err;
} else if (is_prefix(src, "file")) {
btf = btf__parse_elf(*argv, NULL); // succeeds
}
while (argc) {
if (is_prefix(*argv, "format")) {
else { // in here
goto done;
}
done:
return err;
thanks,
jirka
next prev parent reply other threads:[~2019-10-21 14:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-18 10:34 [PATCH] bpftool: Try to read btf as raw data if elf read fails Jiri Olsa
2019-10-18 16:48 ` Andrii Nakryiko
2019-10-18 20:04 ` Yonghong Song
2019-10-21 13:55 ` Jiri Olsa
2019-10-21 13:54 ` Jiri Olsa
2019-10-18 22:39 ` Jakub Kicinski
2019-10-21 14:02 ` Jiri Olsa [this message]
2019-10-21 23:16 ` Jakub Kicinski
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