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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4CFB1C54EBC for ; Wed, 11 Jan 2023 23:09:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232626AbjAKXJu (ORCPT ); Wed, 11 Jan 2023 18:09:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56560 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233101AbjAKXJr (ORCPT ); Wed, 11 Jan 2023 18:09:47 -0500 Received: from mail-wm1-x330.google.com (mail-wm1-x330.google.com [IPv6:2a00:1450:4864:20::330]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3F8553224C for ; Wed, 11 Jan 2023 15:09:46 -0800 (PST) Received: by mail-wm1-x330.google.com with SMTP id p1-20020a05600c1d8100b003d8c9b191e0so13803734wms.4 for ; Wed, 11 Jan 2023 15:09:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=in-reply-to:content-disposition:mime-version:references :mail-followup-to:message-id:subject:cc:to:from:date:from:to:cc :subject:date:message-id:reply-to; bh=9UQScSJfyMGe4w+apoimOZM3ngB2dIeu4UVoAiWJO0g=; b=NivEwwX8J4L0H7sgLkPd37KpZrWb6uHyWcJAyn5yiWiPYvEvzOKcylhrA5kQOboSrD zKbsr6WJQsSAsM+7eK6SlNXlmPwo4nTUg6gue5TQ34pkOtynhnbTo1bj6r/ADYwEb5bf zJbRjF/r196NHPQQs24Z/3lOewFmqKT3CK8hg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references :mail-followup-to:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=9UQScSJfyMGe4w+apoimOZM3ngB2dIeu4UVoAiWJO0g=; b=McSRUtlwgfJpOy3U0kc/rn3MaKX1aRBtpNVtwK4I+N3HY9ZFVEkEQDytvFo4l/OppE FUTviE3yU0s9Ig5OjCYkFX+q6Hd9xFgNYAuFlfG0hPBpRqsV6QQDjsJLtQg9CtwrxuOw euVxHaqxKW2d/F5wD6u6rHCaq5qQiEWjEa5pZXD0+XafXrS8HY/lLOi7T+W5uM8I+CpC PLLGgMpxMAuHSb7ZZo/x3RkKAcjiP30xX2wfcEf0RjpLwAHaPUwndrlEK1grNkKsHzrZ RvS9+y/EK3SfFGS0/ny8Wf0bheNo/K9ITzokm9C8maTfDyd5rTgmILLQJZGNc/QMkCPp 4wOg== X-Gm-Message-State: AFqh2krAOaHVUuH3lvtC5OGbxeLHZzzWw37uY1igDQYD2chUs/u59xVy duTp9TKgyGePog3QB3gjpnqAeA== X-Google-Smtp-Source: AMrXdXsnDe3Ivq+JdQToTPbj4x7KGohtSYDeDDwMtFiMTv7llocWLZI46CtlGQeBOvjqpkl3kJYP/A== X-Received: by 2002:a05:600c:1c21:b0:3d2:2faf:e54b with SMTP id j33-20020a05600c1c2100b003d22fafe54bmr53489153wms.6.1673478584778; Wed, 11 Jan 2023 15:09:44 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id t9-20020a05600c198900b003d9e74dd9b2sm17037786wmq.9.2023.01.11.15.09.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Jan 2023 15:09:43 -0800 (PST) Date: Thu, 12 Jan 2023 00:09:41 +0100 From: Daniel Vetter To: Jim Cromie Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, jani.nikula@intel.com, ville.syrjala@linux.intel.com, daniel.vetter@ffwll.ch, seanpaul@chromium.org, robdclark@gmail.com, jbaron@akamai.com, gregkh@linuxfoundation.org Subject: Re: [RFC PATCH 00/17] DRM_USE_DYNAMIC_DEBUG regression Message-ID: Mail-Followup-To: Jim Cromie , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, jani.nikula@intel.com, ville.syrjala@linux.intel.com, seanpaul@chromium.org, robdclark@gmail.com, jbaron@akamai.com, gregkh@linuxfoundation.org References: <20221206003424.592078-1-jim.cromie@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221206003424.592078-1-jim.cromie@gmail.com> X-Operating-System: Linux phenom 5.19.0-2-amd64 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 05, 2022 at 05:34:07PM -0700, Jim Cromie wrote: > Hi everyone, > > DRM_USE_DYNAMIC_DEBUG=y has a regression on rc-* > > Regression is due to a chicken-egg problem loading modules; on > `modprobe i915`, drm is loaded 1st, and drm.debug is set. When > drm_debug_enabled() tested __drm_debug at runtime, that just worked. > > But with DRM_USE_DYNAMIC_DEBUG=y, the runtime test is replaced with a > post-load enablement of drm_dbg/dyndbg callsites (static-keys), via > dyndbg's callback on __drm_debug. Since all drm-drivers need drm.ko, > it is loaded 1st, then drm.debug=X is applied, then drivers load, but > too late for drm_dbgs to be enabled. > > STATUS > > For all-loadable drm,i915,amdgpu configs, it almost works, but > propagating drm.debug to dependent modules doesnt actually apply, > though the motions are there. This is not the problem I want to chase > here. > > The more basic trouble is: > > For builtin drm + helpers, things are broken pretty early; at the > beginning of dynamic_debug_init(). As the ddebug_sanity() commit-msg > describes in some detail, the records added by _USE fail to reference > the struct ddebug_class_map created and exported by _DEFINE, but get > separate addresses to "other" data that segv's when used as the > expected pointer. FWIW, the pointer val starts with "revi". So I honestly have no idea here, linker stuff is way beyond where I have clue. So what's the way forward here? The DEFINE/USE split does like the right thing to do at least from the "how it's used in drivers" pov. But if we're just running circles not quite getting there I dunno :-/ -Daniel > > OVERVIEW > > DECLARE_DYNDBG_CLASSMAP is broken: it is one-size-fits-all-poorly. > It muddles the distinction between a (single) definition, and multiple > references. Something exported should suffice. > > The core of this patchset splits it into: > > DYNDBG_CLASSMAP_DEFINE used once per subsystem to define each classmap > DYNDBG_CLASSMAP_USE declare dependence on a DEFINEd classmap > > This makes the weird coordinated-changes-by-identical-classmaps > "feature" unnecessary; the DEFINE can export the var, and USE refers > to the exported var. > > So this patchset adds another section: __dyndbg_class_refs. > > It is like __dyndbg_classes; it is scanned under ddebug_add_module(), > and attached to each module's ddebug_table. Once attached, it can be > used like classes to validate and apply class FOO >control queries. > > It also maps the class user -> definer explicitly, so that when the > module is loaded, the section scan can find the kernel-param that is > wired to dyndbg's kparam-callback, and apply its state-var, forex: > __drm_debug to the just loaded helper/driver module. > > Theres plenty to address Im sure. > > Jim Cromie (17): > test-dyndbg: fixup CLASSMAP usage error > test-dyndbg: show that DEBUG enables prdbgs at compiletime > dyndbg: fix readback value on LEVEL_NAMES interfaces > dyndbg: replace classmap list with a vector > dyndbg: make ddebug_apply_class_bitmap more selective > dyndbg: dynamic_debug_init - use pointer inequality, not strcmp > dyndbg: drop NUM_TYPE_ARRAY > dyndbg: reduce verbose/debug clutter > dyndbg-API: replace DECLARE_DYNDBG_CLASSMAP with > DYNDBG_CLASSMAP(_DEFINE|_USE) > dyndbg-API: specialize DYNDBG_CLASSMAP_(DEFINE|USE) > dyndbg-API: DYNDBG_CLASSMAP_USE drop extra args > dyndbg-API: DYNDBG_CLASSMAP_DEFINE() improvements > drm_print: fix stale macro-name in comment > dyndbg: unwrap __ddebug_add_module inner function NOTYET > dyndbg: ddebug_sanity() > dyndbg: mess-w-dep-class > dyndbg: miss-on HACK > > drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 14 +- > drivers/gpu/drm/display/drm_dp_helper.c | 14 +- > drivers/gpu/drm/drm_crtc_helper.c | 14 +- > drivers/gpu/drm/drm_print.c | 22 +-- > drivers/gpu/drm/i915/i915_params.c | 14 +- > drivers/gpu/drm/nouveau/nouveau_drm.c | 14 +- > include/asm-generic/vmlinux.lds.h | 3 + > include/drm/drm_print.h | 6 +- > include/linux/dynamic_debug.h | 57 ++++-- > include/linux/map.h | 54 ++++++ > kernel/module/main.c | 2 + > lib/dynamic_debug.c | 240 +++++++++++++++++++----- > lib/test_dynamic_debug.c | 47 ++--- > 13 files changed, 344 insertions(+), 157 deletions(-) > create mode 100644 include/linux/map.h > > -- > 2.38.1 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch