From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org, x86@kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH] bpf: Tweak BPF jump table optimizations for objtool compatibility
Date: Tue, 5 May 2020 14:31:51 -0500 [thread overview]
Message-ID: <20200505193151.mkluubxvqz7zouf6@treble> (raw)
In-Reply-To: <20200505191405.v3xai47bxeaqsmyg@ast-mbp.dhcp.thefacebook.com>
On Tue, May 05, 2020 at 12:14:05PM -0700, Alexei Starovoitov wrote:
> >
> > Hi,
> >
> > I see the objtool warning:
> > kernel/bpf/core.o: warning: objtool: ___bpf_prog_run()+0x33: call without frame pointer save/setup
> >
> > when using:
> > gcc (SUSE Linux) 9.3.1 20200406 [revision 6db837a5288ee3ca5ec504fbd5a765817e556ac2]
> >
> > with the attached config file.
>
> Thanks Randy. I reproduced it.
This problem isn't a mystery, it's caused by __attribute__((optimize)).
The only real solution is to revert
3193c0836f20 ("bpf: Disable GCC -fgcse optimization for ___bpf_prog_run()")
Once you do that (and disable retpolines) then you should see the
problem described in my other email.
--
Josh
next prev parent reply other threads:[~2020-05-05 19:32 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-30 19:07 [PATCH] bpf: Tweak BPF jump table optimizations for objtool compatibility Josh Poimboeuf
2020-05-01 19:09 ` Alexei Starovoitov
2020-05-01 19:22 ` Josh Poimboeuf
2020-05-01 19:40 ` Alexei Starovoitov
2020-05-01 19:56 ` Josh Poimboeuf
2020-05-02 3:06 ` Alexei Starovoitov
2020-05-02 19:21 ` Josh Poimboeuf
2020-05-05 17:43 ` Alexei Starovoitov
2020-05-05 17:52 ` Randy Dunlap
2020-05-05 19:14 ` Alexei Starovoitov
2020-05-05 19:31 ` Josh Poimboeuf [this message]
2020-05-05 18:11 ` Josh Poimboeuf
2020-05-05 19:53 ` Alexei Starovoitov
2020-05-05 20:28 ` Josh Poimboeuf
2020-05-05 23:59 ` Alexei Starovoitov
2020-05-06 15:53 ` Josh Poimboeuf
2020-05-06 16:45 ` Alexei Starovoitov
2020-05-06 21:19 ` Josh Poimboeuf
2020-05-07 0:03 ` Alexei Starovoitov
2020-05-07 14:07 ` Josh Poimboeuf
2020-05-08 22:18 ` Alexei Starovoitov
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