From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00027CA9EB5 for ; Mon, 4 Nov 2019 13:16:40 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B4D9C21D7D for ; Mon, 4 Nov 2019 13:16:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="PkubWQj9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B4D9C21D7D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=lsIJqkS+1wngPS8F5VALte2jQBv16IBbkj1zMTbv1OE=; b=PkubWQj9SQU72Y K6JQG8WSJWawwZ3Qzk+hJyaUmVG7ZlfTyl8zXivNfM34eojS3+lrY9V3fo6xfPj6CwZuyCVjoeVkL MiUwX/olergMSdyJiqnUJg9OXp4GkYeUoMpl9ESslD7MhBl8oGbUg8/j17s18CBiSz+gZDhK0RcUH FG2qXDXC1vlnWWxv5QQ7S/qrtj0TXXzE7kRj0Q4niSTN2S18n1sW4Yx+ONNar9wBN8VzeD/xkM/Gu owHQEKsfKIixhrBChHJRGoVvQ7L/ZGb8spoIqWnfgqg8GZhv7yWC2TZG3KrIKRkjDSwbAg5SlJ3hP SG6zOPLIWf1Vkh8UmfVg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iRcDo-0000Am-6Q; Mon, 04 Nov 2019 13:16:40 +0000 Received: from smtprelay0223.hostedemail.com ([216.40.44.223] helo=smtprelay.hostedemail.com) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iRcDi-00009k-R2 for linux-arm-kernel@lists.infradead.org; Mon, 04 Nov 2019 13:16:38 +0000 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay06.hostedemail.com (Postfix) with ESMTP id 3E06C18223820; Mon, 4 Nov 2019 13:16:29 +0000 (UTC) X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-HE-Tag: bun95_37f61587f310e X-Filterd-Recvd-Size: 6513 Received: from grimm.local.home (unknown [146.247.46.6]) (Authenticated sender: rostedt@goodmis.org) by omf13.hostedemail.com (Postfix) with ESMTPA; Mon, 4 Nov 2019 13:16:24 +0000 (UTC) Date: Mon, 4 Nov 2019 08:16:20 -0500 From: Steven Rostedt To: Mark Rutland Subject: Re: [PATCHv2 1/8] ftrace: add ftrace_init_nop() Message-ID: <20191104081620.732320a8@grimm.local.home> In-Reply-To: <20191029165832.33606-2-mark.rutland@arm.com> References: <20191029165832.33606-1-mark.rutland@arm.com> <20191029165832.33606-2-mark.rutland@arm.com> X-Mailer: Claws Mail 3.17.4git49 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191104_051636_920023_717DA346 X-CRM114-Status: GOOD ( 26.55 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jthierry@redhat.com, linux-parisc@vger.kernel.org, peterz@infradead.org, catalin.marinas@arm.com, deller@gmx.de, jpoimboe@redhat.com, linux-kernel@vger.kernel.org, James.Bottomley@HansenPartnership.com, takahiro.akashi@linaro.org, will@kernel.org, mingo@redhat.com, james.morse@arm.com, jeyu@kernel.org, amit.kachhap@arm.com, svens@stackframe.org, duwe@suse.de, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 29 Oct 2019 16:58:25 +0000 Mark Rutland wrote: > Architectures may need to perform special initialization of ftrace > callsites, and today they do so by special-casing ftrace_make_nop() when > the expected branch address is MCOUNT_ADDR. In some cases (e.g. for > patchable-function-entry), we don't have an mcount-like symbol and don't > want a synthetic MCOUNT_ADDR, but we may need to perform some > initialization of callsites. > > To make it possible to separate initialization from runtime > modification, and to handle cases without an mcount-like symbol, this > patch adds an optional ftrace_init_nop() function that architectures can > implement, which does not pass a branch address. > > Where an architecture does not provide ftrace_init_nop(), we will fall > back to the existing behaviour of calling ftrace_make_nop() with > MCOUNT_ADDR. > > At the same time, ftrace_code_disable() is renamed to > ftrace_nop_initialize() to make it clearer that it is intended to > intialize a callsite into a disabled state, and is not for disabling a > callsite that has been runtime enabled. The kerneldoc description of rec > arguments is updated to cover non-mcount callsites. > > Signed-off-by: Mark Rutland > Reviewed-by: Ard Biesheuvel > Cc: Ingo Molnar > Cc: Steven Rostedt Reviewed-by: Steven Rostedt (VMware) -- Steve > Cc: Torsten Duwe > --- > include/linux/ftrace.h | 35 ++++++++++++++++++++++++++++++++--- > kernel/trace/ftrace.c | 6 +++--- > 2 files changed, 35 insertions(+), 6 deletions(-) > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index 8a8cb3c401b2..9867d90d635e 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -499,7 +499,7 @@ static inline int ftrace_disable_ftrace_graph_caller(void) { return 0; } > /** > * ftrace_make_nop - convert code into nop > * @mod: module structure if called by module load initialization > - * @rec: the mcount call site record > + * @rec: the call site record (e.g. mcount/fentry) > * @addr: the address that the call site should be calling > * > * This is a very sensitive operation and great care needs > @@ -520,9 +520,38 @@ static inline int ftrace_disable_ftrace_graph_caller(void) { return 0; } > extern int ftrace_make_nop(struct module *mod, > struct dyn_ftrace *rec, unsigned long addr); > > + > +/** > + * ftrace_init_nop - initialize a nop call site > + * @mod: module structure if called by module load initialization > + * @rec: the call site record (e.g. mcount/fentry) > + * > + * This is a very sensitive operation and great care needs > + * to be taken by the arch. The operation should carefully > + * read the location, check to see if what is read is indeed > + * what we expect it to be, and then on success of the compare, > + * it should write to the location. > + * > + * The code segment at @rec->ip should contain the contents created by > + * the compiler > + * > + * Return must be: > + * 0 on success > + * -EFAULT on error reading the location > + * -EINVAL on a failed compare of the contents > + * -EPERM on error writing to the location > + * Any other value will be considered a failure. > + */ > +#ifndef ftrace_init_nop > +static inline int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) > +{ > + return ftrace_make_nop(mod, rec, MCOUNT_ADDR); > +} > +#endif > + > /** > * ftrace_make_call - convert a nop call site into a call to addr > - * @rec: the mcount call site record > + * @rec: the call site record (e.g. mcount/fentry) > * @addr: the address that the call site should call > * > * This is a very sensitive operation and great care needs > @@ -545,7 +574,7 @@ extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr); > #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > /** > * ftrace_modify_call - convert from one addr to another (no nop) > - * @rec: the mcount call site record > + * @rec: the call site record (e.g. mcount/fentry) > * @old_addr: the address expected to be currently called to > * @addr: the address to change to > * > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index f296d89be757..5259d4dea675 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -2494,14 +2494,14 @@ struct dyn_ftrace *ftrace_rec_iter_record(struct ftrace_rec_iter *iter) > } > > static int > -ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec) > +ftrace_nop_initialize(struct module *mod, struct dyn_ftrace *rec) > { > int ret; > > if (unlikely(ftrace_disabled)) > return 0; > > - ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR); > + ret = ftrace_init_nop(mod, rec); > if (ret) { > ftrace_bug_type = FTRACE_BUG_INIT; > ftrace_bug(ret, rec); > @@ -2943,7 +2943,7 @@ static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs) > * to the NOP instructions. > */ > if (!__is_defined(CC_USING_NOP_MCOUNT) && > - !ftrace_code_disable(mod, p)) > + !ftrace_nop_initialize(mod, p)) > break; > > update_cnt++; _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel