Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 8 Sep 2022 12:08:19 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Josh Poimboeuf <jpoimboe@kernel.org>
Cc:     "Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@kernel.org>,
        Suleiman Souhlal <suleiman@google.com>,
        bpf <bpf@vger.kernel.org>, linux-kernel@vger.kernel.org,
        Borislav Petkov <bp@suse.de>, x86@kernel.org
Subject: Re: [PATCH v2 1/2] x86/kprobes: Fix kprobes instruction boudary
 check with CONFIG_RETHUNK
Message-ID: <Yxm/EyW1upzPUZuH@hirez.programming.kicks-ass.net>
References: <166260087224.759381.4170102827490658262.stgit@devnote2>
 <166260088298.759381.11727280480035568118.stgit@devnote2>
 <20220908050855.w77mimzznrlp6pwe@treble>
 <Yxm2QU1NJIkIyrrU@hirez.programming.kicks-ass.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <Yxm2QU1NJIkIyrrU@hirez.programming.kicks-ass.net>
Precedence: bulk

On Thu, Sep 08, 2022 at 11:30:41AM +0200, Peter Zijlstra wrote:
> Once that lands the rules are:
> 
>  0-5 INT3 after RET, !CONFIG_RETHUNK && !CONFIG_SLS: 0
>                      CONFIG_SLS: 1
> 		     CONFIG_RETHUNK: 4-5 depending on compiler version
> 
>  0-1 INT3 after RET: !CONFIG_SLS: 0
> 		     CONFIG_SLS: 0-1 depending on compiler version
> 
> Now, given we know the compiler version at build time, this could be
> determined and used in kprobes, but meh.

Oh also, for giggles, we have a number of sites that have ret;int3
independent of CONFIG_SLS because that was easier than figuring out what
all should be done.