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: <20241119091348.GE11903@noisy.programming.kicks-ass.net>
Date: Tue, 19 Nov 2024 10:13:48 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: Jiri Olsa <olsajiri@...il.com>, Oleg Nesterov <oleg@...hat.com>,
	Andrii Nakryiko <andrii@...nel.org>, 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>,
	linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [RFC perf/core 05/11] uprobes: Add mapping for optimized uprobe
 trampolines

On Mon, Nov 18, 2024 at 10:06:51PM -0800, Andrii Nakryiko wrote:

> > > Jiri, we could also have an option to support 64-bit call, right? We'd
> > > need nop9 for that, but it's an option as well to future-proofing this
> > > approach, no?
> >
> > hm, I don't think there's call with relative 64bit offset
> 
> why do you need a relative, when you have 64 bits? ;) there is a call
> to absolute address, no?

No, there is not :/ You get to use an indirect call, which means
multiple instructions and all the speculation joy.

IFF USDT thingies have AX clobbered (I couldn't find in a hurry) then
patching the multi instruction thing is relatively straight forward, if
they don't, its going to be a pain.