From: Eduard Zingerman <eddyz87@gmail.com>
To: Leon Hwang <hffilwlqm@gmail.com>, bpf@vger.kernel.org
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev,
john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com,
haoluo@google.com, jolsa@kernel.org, x86@kernel.org,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, hpa@zytor.com, mykolal@fb.com,
shuah@kernel.org, davem@davemloft.net, dsahern@kernel.org,
tangyeechou@gmail.com, kernel-patches-bot@fb.com,
maciej.fijalkowski@intel.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [RFC PATCH bpf-next 1/2] bpf, x64: Fix tailcall infinite loop bug
Date: Tue, 15 Aug 2023 17:35:50 +0300 [thread overview]
Message-ID: <841306f0691a7d56be72be0bb3c7472eadcc3367.camel@gmail.com> (raw)
In-Reply-To: <43201fd2-dca7-9294-1dea-8460a9e99296@gmail.com>
On Tue, 2023-08-15 at 11:01 +0800, Leon Hwang wrote:
[...]
> a) Initial value of RAX is in emit_prologue().
> if (!ebpf_from_cbpf) {
> if (tail_call_reachable && !is_subprog)
> /* When it's the entry of the whole
> * tailcall context, zeroing the RAX
> * means init tail_call_cnt.
> */
> EMIT2(0x31, 0xC0); /* xor eax, eax */
> else
> // Keep the same asm layout.
> EMIT2(0x66, 0x90); /* nop2 */
> }
> I'd like to add this comment to emit_prologue().
Got it, thank you.
[...]
next prev parent reply other threads:[~2023-08-15 14:35 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-14 13:41 [RFC PATCH bpf-next 0/2] bpf, x64: Fix tailcall infinite loop bug Leon Hwang
2023-08-14 13:41 ` [RFC PATCH bpf-next 1/2] " Leon Hwang
2023-08-15 0:52 ` Eduard Zingerman
2023-08-15 3:01 ` Leon Hwang
2023-08-15 14:35 ` Eduard Zingerman [this message]
2023-08-17 22:31 ` Alexei Starovoitov
2023-08-18 2:10 ` Leon Hwang
2023-08-18 19:59 ` Alexei Starovoitov
2023-08-19 3:38 ` Leon Hwang
2023-08-14 13:41 ` [RFC PATCH bpf-next 2/2] selftests/bpf: Add testcases for tailcall infinite loop bug fixing Leon Hwang
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