linux-kernel - Re: [RFC perf/core 05/11] uprobes: Add mapping for optimized uprobe trampolines

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAADnVQJJ0WS=Y1EudjiFD8fn4zHCz6x1auaEEHaYHsP15Vks2Q@mail.gmail.com>
Date: Thu, 21 Nov 2024 08:02:12 -0800
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>, Jiri Olsa <olsajiri@...il.com>, 
	Oleg Nesterov <oleg@...hat.com>, Andrii Nakryiko <andrii@...nel.org>, bpf <bpf@...r.kernel.org>, 
	Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>, 
	John Fastabend <john.fastabend@...il.com>, Hao Luo <haoluo@...gle.com>, 
	Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, 
	Alan Maguire <alan.maguire@...cle.com>, LKML <linux-kernel@...r.kernel.org>, 
	linux-trace-kernel <linux-trace-kernel@...r.kernel.org>, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [RFC perf/core 05/11] uprobes: Add mapping for optimized uprobe trampolines

On Thu, Nov 21, 2024 at 4:17 AM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Wed, Nov 20, 2024 at 04:07:38PM -0800, Andrii Nakryiko wrote:
>
> > USDTs are meant to be "transparent" to the surrounding code and they
> > don't mark any clobbered registers. Technically it could be added, but
> > I'm not a fan of this.
>
> Sure. Anyway, another thing to consider is FRED, will all of this still
> matter once that lands? If FRED gets us INT3 performance close to what
> SYSCALL has, then all this work will go unused.

afaik not a single cpu in the datacenter supports FRED while
uprobe overhead is real.
imo it's worth improving performance today for existing cpus.
I suspect arm64 might benefit too. Even if arm hw does the same
amount of work for trap vs syscall the sw overhead of handling
trap is different.
I suspect that equation will apply to future FRED cpus too.