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=-9.8 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_GIT 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 83EE1C47E49 for ; Tue, 29 Oct 2019 16:59:15 +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 4A47F20679 for ; Tue, 29 Oct 2019 16:59:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="h6GnS44u" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4A47F20679 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com 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:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=Ex8Hlkv/X5EiB2TqTRMjN+1QXw2dx1Vem/QjtWHYksc=; b=h6GnS44u0UuLcA7p7JR589RM+K 0EWDrmQlRj27R4R+z/p3vmMmeyoQJ8MvgPB40I1Fk2hcS7pXLDDoWApng7vganUsdiKDmzDtSpSlO ga93tNObgVvJ5YwpRESmngwZ5WWlhzcGNMkLmt6OvOWGDNKMV5Akk3BuyXhYdXmVWYwmxWJ2LBiWZ zapXZ7ehWE2BTMt5LVJnb/0IvXpGYlanUV2z4BicOMqR63u+WhlHgWvgaUmG/ATepxh6u3kfgOLLI dF0h11wIZlFJfzRRaZ46USKeXkcCPim5Z/b/yNJW5TJayt8suStvO2uhHZ3nOsHM4VxxZbwIG7l2R jEp1RNYw==; 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 1iPUpj-0005R8-No; Tue, 29 Oct 2019 16:59:03 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iPUpU-0005BK-71 for linux-arm-kernel@lists.infradead.org; Tue, 29 Oct 2019 16:58:50 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1F44C337; Tue, 29 Oct 2019 09:58:45 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C11D13F71F; Tue, 29 Oct 2019 09:58:42 -0700 (PDT) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org, Steven Rostedt Subject: [PATCHv2 1/8] ftrace: add ftrace_init_nop() Date: Tue, 29 Oct 2019 16:58:25 +0000 Message-Id: <20191029165832.33606-2-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20191029165832.33606-1-mark.rutland@arm.com> References: <20191029165832.33606-1-mark.rutland@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191029_095848_392496_319E0549 X-CRM114-Status: GOOD ( 19.92 ) 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: mark.rutland@arm.com, 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 MIME-Version: 1.0 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 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 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++; -- 2.11.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel