From: Daniel Borkmann <daniel@iogearbox.net>
To: Alexei Starovoitov <ast@plumgrid.com>
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: Re: [PATCH net] ebpf, x86: fix general protection fault when tail call is invoked
Date: Tue, 28 Jul 2015 19:17:11 +0200 [thread overview]
Message-ID: <55B7B917.4090102@iogearbox.net> (raw)
In-Reply-To: <55B7B590.8030600@plumgrid.com>
On 07/28/2015 07:02 PM, Alexei Starovoitov wrote:
> On 7/28/15 6:26 AM, Daniel Borkmann wrote:
>> After patch, disassembly:
>>
>> [...]
>> 9e: lea 0x80(%rsi,%rdx,8),%rax <--- CONFIG_LOCKDEP/CONFIG_LOCK_STAT
>> 48 8d 84 d6 80 00 00 00
>> a6: mov (%rax),%rax
>> 48 8b 00
>> [...]
>>
>> [...]
>> 9e: lea 0x50(%rsi,%rdx,8),%rax <--- No CONFIG_LOCKDEP
>> 48 8d 84 d6 50 00 00 00
>> a6: mov (%rax),%rax
>> 48 8b 00
>> [...]
>>
>> Fixes: b52f00e6a715 ("x86: bpf_jit: implement bpf_tail_call() helper")
>> Signed-off-by: Daniel Borkmann<daniel@iogearbox.net>
>
> Thanks for fixing it.
No problem!
> Most of my development is actually with LOCKDEP on, but I don't ever
> turn LOCK_STAT on, so sadly missed this 48 byte increase of 80 byte
> structure :(
I feel that at some point we might have hit this anyway, e.g. Huawei
guys with their perf work further extending bpf_maps, etc, etc.
Thanks,
Daniel
next prev parent reply other threads:[~2015-07-28 17:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-28 13:26 [PATCH net] ebpf, x86: fix general protection fault when tail call is invoked Daniel Borkmann
2015-07-28 17:02 ` Alexei Starovoitov
2015-07-28 17:17 ` Daniel Borkmann [this message]
2015-07-30 0:04 ` David Miller
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