From: Jakub Kicinski <jakub.kicinski@netronome.com>
To: Andrii Nakryiko <andriin@fb.com>
Cc: Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
Yonghong Song <yhs@fb.com>, Martin Lau <kafai@fb.com>,
"andrii.nakryiko@gmail.com" <andrii.nakryiko@gmail.com>
Subject: Re: [PATCHv2] bpftool: Try to read btf as raw data if elf read fails
Date: Fri, 25 Oct 2019 09:31:16 -0700 [thread overview]
Message-ID: <20191025093116.67756660@cakuba.hsd1.ca.comcast.net> (raw)
In-Reply-To: <aeb566cd-42a7-9b3a-d495-c71cdca08b86@fb.com>
On Fri, 25 Oct 2019 05:01:17 +0000, Andrii Nakryiko wrote:
> >> +static bool is_btf_raw(const char *file)
> >> +{
> >> + __u16 magic = 0;
> >> + int fd;
> >> +
> >> + fd = open(file, O_RDONLY);
> >> + if (fd < 0)
> >> + return false;
> >> +
> >> + read(fd, &magic, sizeof(magic));
> >> + close(fd);
> >> + return magic == BTF_MAGIC;
> >
> > Isn't it suspicious to read() 2 bytes into an u16 and compare to a
> > constant like endianness doesn't matter? Quick grep doesn't reveal
> > BTF_MAGIC being endian-aware..
>
> Right now we support only loading BTF in native endianness, so I think
> this should do. If we ever add ability to load non-native endianness,
> then we'll have to adjust this.
This doesn't do native endianness, this does LE-only. It will not work
on BE machines.
next prev parent reply other threads:[~2019-10-25 16:31 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-24 13:23 [PATCHv2] bpftool: Try to read btf as raw data if elf read fails Jiri Olsa
2019-10-24 13:31 ` Jiri Olsa
2019-10-24 17:54 ` Jakub Kicinski
2019-10-25 5:01 ` Andrii Nakryiko
2019-10-25 16:31 ` Jakub Kicinski [this message]
2019-10-25 16:32 ` Jiri Olsa
2019-10-25 16:53 ` Andrii Nakryiko
2019-10-25 17:32 ` Jakub Kicinski
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