From patchwork Tue Oct 29 16:58:25 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 178046 Delivered-To: patch@linaro.org Received: by 2002:a92:409a:0:0:0:0:0 with SMTP id d26csp67218ill; Tue, 29 Oct 2019 09:58:50 -0700 (PDT) X-Google-Smtp-Source: APXvYqwlsKCipRKQp135du2supmxofPO03eDd+MOgFDyMofpyMhDJuLA0TFbfXBege67C1YrFRpx X-Received: by 2002:a50:ab50:: with SMTP id t16mr27012858edc.171.1572368330617; Tue, 29 Oct 2019 09:58:50 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1572368330; cv=none; d=google.com; s=arc-20160816; b=zBUdu0ss/FhJ/wA9KJbs4HKgIttnhGyPD/Kh8SG2Ek7Zx7ExYtXduchm8wFzRisLyK 3XS+4JhyLwvwrLdQnSIWQLD/EAjIgkZ400z987opcRxhaVlwyC6kJKCFNVt7I0DLNwTE UpVFh1QLcW7PAEhaD7Re1WeXrYO1JaX0k7UFQQeTrLUynAtes+oarYXIddooik09LunJ zfAzem/ggJ/Yd1/F0ngPnDU7qAIq/WaPOL76KNCRtrfO4jO59sL8aVatvjAqdvKzguDn IISB3bBd43yL3DyiUAsHJPBQp4AbshOGXF77LOspT9JooPNglrgjw+sPk9VOdu6Wy+CV p65w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from; bh=QdkSYnKrCuYhJ3tUiAND7/60PlI0VedHoAaUzR1hZaU=; b=pRU1bbg6hhivVuttKJ1WqZGhLK+TOV7u1GI1xPtOh/gOsbFo2HxERzyMARy2VeHtnb BGEPDgVdSVYXAHVoW6He9/3eFXKgiRgf6ygrclkCd87NtsAGppBWDkZvEmInLG5O2tM9 X2kTl9QTy1O3a1L6eXDqK583FhB5kzAm1LqQaK90u3Xoroht36fcfDdYC2LrZkdpzP90 gou/hWFfDP2FJ8XmJNenB0vB9cdVmMkbFnlX78k2Tnui9c5U/gYjLJBvUe3V/zeETXLN 95Ck1JJOD0mlY7uJmyBmLhCirwd1sI81fg+Qvv5Q6XaW0kz+PDxI9ObMq2TtpAab4cxK g/eQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id l12si6020128edk.60.2019.10.29.09.58.50; Tue, 29 Oct 2019 09:58:50 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390637AbfJ2Q6q (ORCPT + 26 others); Tue, 29 Oct 2019 12:58:46 -0400 Received: from foss.arm.com ([217.140.110.172]:54558 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727279AbfJ2Q6p (ORCPT ); Tue, 29 Oct 2019 12:58:45 -0400 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 Cc: linux-kernel@vger.kernel.org, amit.kachhap@arm.com, catalin.marinas@arm.com, deller@gmx.de, duwe@suse.de, James.Bottomley@HansenPartnership.com, james.morse@arm.com, jeyu@kernel.org, jpoimboe@redhat.com, jthierry@redhat.com, linux-parisc@vger.kernel.org, mark.rutland@arm.com, mingo@redhat.com, peterz@infradead.org, svens@stackframe.org, takahiro.akashi@linaro.org, will@kernel.org 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> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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(-) -- 2.11.0 Reviewed-by: Miroslav Benes Reviewed-by: Steven Rostedt (VMware) 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++;