From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117])
	(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
	(No client certificate requested)
	by smtp.lore.kernel.org (Postfix) with ESMTPS id D0592C433EF
	for <linuxppc-dev@archiver.kernel.org>; Wed, 22 Dec 2021 14:20:04 +0000 (UTC)
Received: from boromir.ozlabs.org (localhost [IPv6:::1])
	by lists.ozlabs.org (Postfix) with ESMTP id 4JJwSz0cbtz3c6B
	for <linuxppc-dev@archiver.kernel.org>; Thu, 23 Dec 2021 01:20:03 +1100 (AEDT)
Authentication-Results: lists.ozlabs.org;
	dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=suse.cz header.i=@suse.cz header.a=rsa-sha256 header.s=susede2_rsa header.b=xdk2jG0G;
	dkim=fail reason="signature verification failed" header.d=suse.cz header.i=@suse.cz header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=Ke6NY5LD;
	dkim-atps=neutral
Authentication-Results: lists.ozlabs.org;
 spf=pass (sender SPF authorized) smtp.mailfrom=suse.cz
 (client-ip=195.135.220.28; helo=smtp-out1.suse.de;
 envelope-from=mbenes@suse.cz; receiver=<UNKNOWN>)
Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key;
 unprotected) header.d=suse.cz header.i=@suse.cz header.a=rsa-sha256
 header.s=susede2_rsa header.b=xdk2jG0G; 
 dkim=pass header.d=suse.cz header.i=@suse.cz header.a=ed25519-sha256
 header.s=susede2_ed25519 header.b=Ke6NY5LD; 
 dkim-atps=neutral
Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28])
 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)
 key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256)
 (No client certificate requested)
 by lists.ozlabs.org (Postfix) with ESMTPS id 4JJwSD3R0dz2yPM
 for <linuxppc-dev@lists.ozlabs.org>; Thu, 23 Dec 2021 01:19:23 +1100 (AEDT)
Received: from relay2.suse.de (relay2.suse.de [149.44.160.134])
 by smtp-out1.suse.de (Postfix) with ESMTP id DE13B212B9;
 Wed, 22 Dec 2021 14:19:20 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa;
 t=1640182760; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc:
 mime-version:mime-version:content-type:content-type:
 in-reply-to:in-reply-to:references:references;
 bh=Zhr+Afm9qhm7LXnYhc731sR+IngmPtrNRK+NJVmgKNs=;
 b=xdk2jG0G0otlY+ZrBepZfL4FsYG+3amHldl6XT78E5OMXDCNt53VlsY/4KCA2iGJUbdyPb
 bKqXHEwQ1EMHkmMnofxOOyioayEurrupL+l/HHXnzXaTjI+TCZMo25//m8HN1si2ctz4fS
 anZS9KfAh5j3XE8d19HruXGvd6xixaw=
DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz;
 s=susede2_ed25519; t=1640182760;
 h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc:
 mime-version:mime-version:content-type:content-type:
 in-reply-to:in-reply-to:references:references;
 bh=Zhr+Afm9qhm7LXnYhc731sR+IngmPtrNRK+NJVmgKNs=;
 b=Ke6NY5LDOqwezFEELCgm1wBttjIxKixV5PSmi3L6yOjKJMWiWNgKI0WPgaKRDjitu9dis3
 DH3vhMXF23LHzxDw==
Received: from pobox.suse.cz (pobox.suse.cz [10.100.2.14])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (No client certificate requested)
 by relay2.suse.de (Postfix) with ESMTPS id 8B234A3B81;
 Wed, 22 Dec 2021 14:19:20 +0000 (UTC)
Date: Wed, 22 Dec 2021 15:19:20 +0100 (CET)
From: Miroslav Benes <mbenes@suse.cz>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Subject: Re: [PATCH v2 09/13] powerpc/ftrace: Implement
 CONFIG_DYNAMIC_FTRACE_WITH_ARGS
In-Reply-To: <5831f711a778fcd6eb51eb5898f1faae4378b35b.1640017960.git.christophe.leroy@csgroup.eu>
Message-ID: <alpine.LSU.2.21.2112221515020.18494@pobox.suse.cz>
References: <cover.1640017960.git.christophe.leroy@csgroup.eu>
 <5831f711a778fcd6eb51eb5898f1faae4378b35b.1640017960.git.christophe.leroy@csgroup.eu>
User-Agent: Alpine 2.21 (LSU 202 2017-01-01)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
X-BeenThere: linuxppc-dev@lists.ozlabs.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Linux on PowerPC Developers Mail List <linuxppc-dev.lists.ozlabs.org>
List-Unsubscribe: <https://lists.ozlabs.org/options/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe>
List-Archive: <http://lists.ozlabs.org/pipermail/linuxppc-dev/>
List-Post: <mailto:linuxppc-dev@lists.ozlabs.org>
List-Help: <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=help>
List-Subscribe: <https://lists.ozlabs.org/listinfo/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe>
Cc: mark.rutland@arm.com, Petr Mladek <pmladek@suse.com>,
 Joe Lawrence <joe.lawrence@redhat.com>, broonie@kernel.org,
 Jiri Kosina <jikos@kernel.org>,
 "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
 Steven Rostedt <rostedt@goodmis.org>, madvenka@linux.microsoft.com,
 Ingo Molnar <mingo@redhat.com>, Josh Poimboeuf <jpoimboe@redhat.com>,
 "live-patching@vger.kernel.org" <live-patching@vger.kernel.org>,
 "Naveen N . Rao" <naveen.n.rao@linux.vnet.ibm.com>,
 "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
 linux-arm-kernel@lists.infradead.org
Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Sender: "Linuxppc-dev"
 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

On Mon, 20 Dec 2021, Christophe Leroy wrote:

> Implement CONFIG_DYNAMIC_FTRACE_WITH_ARGS. It accelerates the call
> of livepatching.
> 
> Also note that powerpc being the last one to convert to
> CONFIG_DYNAMIC_FTRACE_WITH_ARGS, it will now be possible to remove
> klp_arch_set_pc() on all architectures.

Correct. We could replace it ftrace_instruction_pointer_set() and that is 
it. In fact, livepatch.h in both arch/x86/include/asm/ and 
arch/s390/include/asm/ could be removed with that.

On the other hand, there is arm64 live patching support being worked on 
and I am not sure what their plans about DYNAMIC_FTRACE_WITH_ARGS are. The 
above would make it a prerequisite.

Adding CCs... you can find the whole thread at 
https://lore.kernel.org/all/cover.1640017960.git.christophe.leroy@csgroup.eu/

Miroslav