From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Daniel Borkmann <daniel@iogearbox.net>,
john fastabend <john.fastabend@gmail.com>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 2/3] bpf: Track spill/fill of bounded scalars.
Date: Tue, 6 Oct 2020 20:35:20 -0700 [thread overview]
Message-ID: <CAEf4BzZ-jWrWQPvd7CNOwxhi9s7d6QJq4P+ZoKGa0Pr-0yQ_Vw@mail.gmail.com> (raw)
In-Reply-To: <20201006200955.12350-3-alexei.starovoitov@gmail.com>
On Tue, Oct 6, 2020 at 1:10 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> From: Yonghong Song <yhs@fb.com>
>
> Under register pressure the llvm may spill registers with bounds into the stack.
> The verifier has to track them through spill/fill otherwise many kinds of bound
> errors will be seen. The spill/fill of induction variables was already
> happening. This patch extends this logic from tracking spill/fill of a constant
> into any bounded register. There is no need to track spill/fill of unbounded,
> since no new information will be retrieved from the stack during register fill.
>
> Though extra stack difference could cause state pruning to be less effective, no
> adverse affects were seen from this patch on selftests and on cilium programs.
>
> Signed-off-by: Yonghong Song <yhs@fb.com>
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
> ---
Acked-by: Andrii Nakryiko <andrii@kernel.org>
> kernel/bpf/verifier.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
[...]
next prev parent reply other threads:[~2020-10-07 3:35 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-06 20:09 [PATCH bpf-next 0/3] bpf: Make the verifier recognize llvm register allocation patterns Alexei Starovoitov
2020-10-06 20:09 ` [PATCH bpf-next 1/3] bpf: Propagate scalar ranges through register assignments Alexei Starovoitov
2020-10-07 1:56 ` Andrii Nakryiko
2020-10-07 2:18 ` Alexei Starovoitov
2020-10-07 3:31 ` Andrii Nakryiko
2020-10-07 4:15 ` Alexei Starovoitov
2020-10-07 4:42 ` Andrii Nakryiko
2020-10-07 5:13 ` Alexei Starovoitov
2020-10-07 23:44 ` John Fastabend
2020-10-07 23:55 ` John Fastabend
2020-10-08 1:45 ` Alexei Starovoitov
2020-10-08 15:18 ` John Fastabend
2020-10-08 15:53 ` Alexei Starovoitov
2020-10-06 20:09 ` [PATCH bpf-next 2/3] bpf: Track spill/fill of bounded scalars Alexei Starovoitov
2020-10-07 3:35 ` Andrii Nakryiko [this message]
2020-10-06 20:09 ` [PATCH bpf-next 3/3] selftests/bpf: Add profiler test Alexei Starovoitov
2020-10-07 1:22 ` Jakub Kicinski
2020-10-07 1:35 ` Alexei Starovoitov
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