From patchwork Wed Jan 20 16:20:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johannes Berg X-Patchwork-Id: 1429315 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.infradead.org (client-ip=2001:8b0:10b:1231::1; helo=merlin.infradead.org; envelope-from=linux-um-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; secure) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=merlin.20170209 header.b=KA3Tk+SW; dkim-atps=neutral Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4DLW3l1W96z9sT6 for ; Thu, 21 Jan 2021 03:21:07 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.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: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=0OwhBe4bfWDP39SxGXJigRN4As0fl2SwyXZM1IrCPog=; b=KA3Tk+SWColyFB2P5C0xFSc7a e5soUMfw9B2kb5KyF2PhsnMZc+BhBaU1zoFzeM5Bj5JY3P8c5rPgdMBtkTqPR5p83Ie82CUtrAb5D keLWPH+ICm5ow8mP7lko7pVNGYsRsivUmd+tZaL+I/1GwoTqeD3tFGjWN2EK2olWO7+QyLVDIzt2n Q+0Tj4WoFL85gmmpCvCo26yZbx3WCrj1ylANwizI42gcEm/HZHWTDkYFOIjqhCw4sJjKL4o2gk1oW msMPcK+hOry6+CvDVLdhQ/R64dJ+IGMl9oJcaRuAw4oHrTK23MgFcqfmD0lyJ9/Z+l780ekh6kbyM lTjiD2TEA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l2GE1-0007fU-RZ; Wed, 20 Jan 2021 16:20:53 +0000 Received: from s3.sipsolutions.net ([2a01:4f8:191:4433::2] helo=sipsolutions.net) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l2GE0-0007eC-6F for linux-um@lists.infradead.org; Wed, 20 Jan 2021 16:20:52 +0000 Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.94) (envelope-from ) id 1l2GDw-009CUq-H0; Wed, 20 Jan 2021 17:20:48 +0100 From: Johannes Berg To: linux-um@lists.infradead.org Subject: [PATCH v2] init/gcov: allow CONFIG_CONSTRUCTORS on UML to fix module gcov Date: Wed, 20 Jan 2021 17:20:41 +0100 Message-Id: <20210120172041.c246a2cac2fb.I1358f584b76f1898373adfed77f4462c8705b736@changeid> X-Mailer: git-send-email 2.26.2 In-Reply-To: References: MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210120_112052_259820_01537F89 X-CRM114-Status: GOOD ( 15.27 ) X-Spam-Score: 0.4 (/) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (0.4 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_NONE SPF: sender does not publish an SPF Record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.4 KHOP_HELO_FCRDNS Relay HELO differs from its IP's reverse DNS X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Johannes Berg , Arnd Bergmann , Peter Oberparleiter , linux-kernel@vger.kernel.org, Jessica Yu , Andrew Morton Sender: "linux-um" Errors-To: linux-um-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org From: Johannes Berg On ARCH=um, loading a module doesn't result in its constructors getting called, which breaks module gcov since the debugfs files are never registered. On the other hand, in-kernel constructors have already been called by the dynamic linker, so we can't call them again. Get out of this conundrum by allowing CONFIG_CONSTRUCTORS to be selected, but avoiding the in-kernel constructor calls. Also remove the "if !UML" from GCOV selecting CONSTRUCTORS now, since we really do want CONSTRUCTORS, just not kernel binary ones. Signed-off-by: Johannes Berg Reviewed-by: Peter Oberparleiter --- Tested with a kernel configured with CONFIG_GCOV_KERNEL, without the patch nothing ever appears in /sys/kernel/debug/gcov/ (apart from the reset file), and with it we get the files and they work. v2: * special-case UML instead of splitting the CONSTRUCTORS config --- init/Kconfig | 1 - init/main.c | 8 +++++++- kernel/gcov/Kconfig | 2 +- 3 files changed, 8 insertions(+), 3 deletions(-) diff --git a/init/Kconfig b/init/Kconfig index b77c60f8b963..29ad68325028 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -76,7 +76,6 @@ config CC_HAS_ASM_INLINE config CONSTRUCTORS bool - depends on !UML config IRQ_WORK bool diff --git a/init/main.c b/init/main.c index c68d784376ca..a626e78dbf06 100644 --- a/init/main.c +++ b/init/main.c @@ -1066,7 +1066,13 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) /* Call all constructor functions linked into the kernel. */ static void __init do_ctors(void) { -#ifdef CONFIG_CONSTRUCTORS +/* + * For UML, the constructors have already been called by the + * normal setup code as it's just a normal ELF binary, so we + * cannot do it again - but we do need CONFIG_CONSTRUCTORS + * even on UML for modules. + */ +#if defined(CONFIG_CONSTRUCTORS) && !defined(CONFIG_UML) ctor_fn_t *fn = (ctor_fn_t *) __ctors_start; for (; fn < (ctor_fn_t *) __ctors_end; fn++) diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig index 3110c77230c7..f62de2dea8a3 100644 --- a/kernel/gcov/Kconfig +++ b/kernel/gcov/Kconfig @@ -4,7 +4,7 @@ menu "GCOV-based kernel profiling" config GCOV_KERNEL bool "Enable gcov-based kernel profiling" depends on DEBUG_FS - select CONSTRUCTORS if !UML + select CONSTRUCTORS default n help This option enables gcov-based code profiling (e.g. for code coverage