From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BD554476CF1; Tue, 13 Oct 2026 02:36:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791858998; cv=none; b=dZH/A+6z4C+fdz4gZkYrV1fdrMg4jtZzcEUnJPbvybc1jD7qJ33JvtV6yeTq2BH9Kl2GRiTUb0iLnxhtiDxOsctD7eUkKzq0ZhS/V7vhHipaxHYzBwFePPFteFKopOimhwqzqF4h1AoRPHNWX0G56BiLvaQRvUVJCTZAAtg5SNY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791858998; c=relaxed/simple; bh=/ENcQ9rKYlJBY78ObfNLhqdgC7PShzthxe+0hsOPRWU=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=ZRtOOMwOEFHv1tf44JzQDNx+kjYMkj4+to3rk0R3VFcsdVkydGWFD4zhDKe8rqVp+N1J4u3AJedl8AfirwMDgQIwXzQmcABa+S66Fd2+N87PoKmw5Fyp6WZNf/vCfKjvDzcFL3EmWHSGggd4SJTmXQsWqTJI4gRVvfCMHwEnHtI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dX4NQ0Nd; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dX4NQ0Nd" Received: by smtp.kernel.org (Postfix) with ESMTPS id 31635C4DDEA; Tue, 13 Oct 2026 02:36:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1791858998; bh=/ENcQ9rKYlJBY78ObfNLhqdgC7PShzthxe+0hsOPRWU=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=dX4NQ0NdD2QPj4Fo6Mh+ob3qziuArGSxOgum1YkfZtYJr1miiFu3rDYoS1FqY58Mp BpLtsK9UgvDHIGJ2NkuH/vDfcEYZY5++cJ2lczfURLLo1nD57nvbpAzTInYZogDRat eliNRos+atZKYBwbGNaIG8PUB+gmVXskXg9joO+sy38yH5xW2LjAVBalhz2PEzGsL5 zxH6RUwuF2A7UF/X2BwRAjnkaubLN3v0fYTL6z9TC4srbUqF6vpAgGllNFWA1v5nCn X/MLvaXo/5txS79KdFYmYcdIBOJywlmcnzi4dIF6hDxt0G8q7Fr5i8fvkqS+v6E8n1 0t+mcAO3IFFvQ== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A564CC6B03; Tue, 13 Oct 2026 02:36:38 +0000 (UTC) From: Jim Cromie via B4 Relay Date: Mon, 12 Oct 2026 20:36:37 -0600 Subject: [PATCH v12 06/40] dyndbg.lds.S: fix lost dyndbg sections in modules Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261012-dd-cmap-part2-clean-v12-6-3c8cc5725def@gmail.com> References: <20261012-dd-cmap-part2-clean-v12-0-3c8cc5725def@gmail.com> In-Reply-To: <20261012-dd-cmap-part2-clean-v12-0-3c8cc5725def@gmail.com> To: Jason Baron , Shuah Khan , Andrew Morton , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Arnd Bergmann , Luis Chamberlain , Petr Pavlu , Daniel Gomez , Sami Tolvanen , Aaron Tomlin , Jonathan Corbet , Greg Kroah-Hartman , Nathan Chancellor , Nicolas Schier , Shuah Khan , Randy Dunlap , "Rafael J. Wysocki" , Pavel Machek , Len Brown , Jonathan Corbet , Petr Mladek , Steven Rostedt , John Ogness , Sergey Senozhatsky , =?utf-8?q?Thomas_Wei=C3=9Fschuh?= Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-arch@vger.kernel.org, linux-modules@vger.kernel.org, linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-pm@vger.kernel.org, Jim Cromie X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1791858995; l=5098; i=jim.cromie@gmail.com; s=20260203; h=from:subject:message-id; bh=GVa+JISyaOIBbonPye2T/V/PFEj55G7uS2nqxUBKA2c=; b=lvK71rInhJzOsSUMIY69lnxBlpkdKYd1Z8x0DN3TOZQ+5ANofNPAhZK/LA+VAkw/J9uk6yxW6 VoFPvhkBrD5DWjmYFBL68iFI58YufNBGdvxGMpCV2FjaCXPe0YauJG8 X-Developer-Key: i=jim.cromie@gmail.com; a=ed25519; pk=C6E5ODlPQo7ZBynATXH9wg7K6HxP0pIXyf4s38Qw0XE= X-Endpoint-Received: by B4 Relay for jim.cromie@gmail.com/20260203 with auth_id=958 X-Original-From: Jim Cromie Reply-To: jim.cromie@gmail.com From: Jim Cromie With CONFIG_DRM_USE_DYNAMIC_DEBUG=y, several build configs had problems with __dyndbg* sections getting lost in drm drivers. Fix this by following the model demonstrated in codetag.lds.h. Introduce include/asm-generic/dyndbg.lds.h, to bundle dynamic-debug's multiple sections together, into 2 macros: vmlinux.lds.h DATA_DATA: move the 2 BOUNDED_SECTION_BY(__dyndbg*) calls into dyndbg.lds.h DYNDBG_SECTIONS(). vmlinux.lds.h now includes the new file and calls the new macro. MOD_DYNDBG_SECTIONS keeps the 2 sections by name, aligns them and sets the output address to 0 when the sections are empty. dyndbg.lds.h includes (reuses) bounded-section.lds.h scripts/module.lds.S: now calls MOD_DYNDBG_SECTIONS right before the CODETAG macro (consistent with their placements in vmlinux.lds.h), and also includes dyndbg.lds.h This isolates vmlinux.lds.h from further __dyndbg section additions. CC: Arnd Bergmann Signed-off-by: Jim Cromie Reviewed-by: Petr Pavlu --- v3: move #includes to top, drop extra ALIGN(8) in DYNDBG_SECTIONS, add RvBy v2: Address linker script review feedback for relocatable modules. MOD_DYNDBG_SECTIONS() used the BOUNDED_SECTION_BY() macro, which proved problematic for kernel modules for two reasons: 1. Unwanted Empty Sections: BOUNDED_SECTION_BY() automatically generates `__start` and `__stop` symbols. When applied to `MOD_DYNDBG_SECTIONS()`, the linker assumes the sections are populated due to the symbol definitions, forcing an empty `__dyndbg` and `__dyndbg_classes` output section in every compiled module, even those without dynamic debug configuration. Since the module loader uses `section_objs()` to locate data via ELF headers instead of relying on `__start`/`__stop` symbols, these assignments are completely unnecessary. 2. Non-zero Output Addresses: During relocatable linking (e.g., `ld.bfd -r`), omitting an explicit base address causes the section to inherit the current location counter. This results in non-zero sh_addr values in `.ko` files, which is confusing, degrades compressibility, and can cause issues with external tools parsing the ELF. Fix both issues by dropping `BOUNDED_SECTION_BY()` in favor of a simple `KEEP(*(...))` constraint and explicitly defining the sections with a `0` base address: `__dyndbg 0 : ALIGN(8) { ... }`. fixup-inc-vml --- MAINTAINERS | 1 + include/asm-generic/dyndbg.lds.h | 18 ++++++++++++++++++ include/asm-generic/vmlinux.lds.h | 6 ++---- scripts/module.lds.S | 2 ++ 4 files changed, 23 insertions(+), 4 deletions(-) diff --git a/MAINTAINERS b/MAINTAINERS index 98954b1746f6..af888d6c660c 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9259,6 +9259,7 @@ DYNAMIC DEBUG M: Jason Baron M: Jim Cromie S: Maintained +F: include/asm-generic/dyndbg.lds.h F: include/linux/dynamic_debug.h F: lib/dynamic_debug.c F: lib/test_dynamic_debug.c diff --git a/include/asm-generic/dyndbg.lds.h b/include/asm-generic/dyndbg.lds.h new file mode 100644 index 000000000000..9d8951bef688 --- /dev/null +++ b/include/asm-generic/dyndbg.lds.h @@ -0,0 +1,18 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ASM_GENERIC_DYNDBG_LDS_H +#define __ASM_GENERIC_DYNDBG_LDS_H + +#include +#define DYNDBG_SECTIONS() \ + BOUNDED_SECTION_BY(__dyndbg, ___dyndbg) \ + BOUNDED_SECTION_BY(__dyndbg_classes, ___dyndbg_classes) + +#define MOD_DYNDBG_SECTIONS() \ + __dyndbg 0 : ALIGN(8) { \ + KEEP(*(__dyndbg)) \ + } \ + __dyndbg_classes 0 : ALIGN(8) { \ + KEEP(*(__dyndbg_classes)) \ + } + +#endif /* __ASM_GENERIC_DYNDBG_LDS_H */ diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index c3376665d027..48f00c5e8762 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -52,6 +52,7 @@ #include #include +#include #ifndef LOAD_OFFSET #define LOAD_OFFSET 0 @@ -344,10 +345,7 @@ *(.data..do_once) \ STRUCT_ALIGN(); \ *(__tracepoints) \ - /* implement dynamic printk debug */ \ - . = ALIGN(8); \ - BOUNDED_SECTION_BY(__dyndbg_classes, ___dyndbg_classes) \ - BOUNDED_SECTION_BY(__dyndbg, ___dyndbg) \ + DYNDBG_SECTIONS() \ CODETAG_SECTIONS() \ LIKELY_PROFILE() \ BRANCH_PROFILE() \ diff --git a/scripts/module.lds.S b/scripts/module.lds.S index d0f200428957..5950ff8edc31 100644 --- a/scripts/module.lds.S +++ b/scripts/module.lds.S @@ -5,6 +5,7 @@ */ #include +#include SECTIONS { /DISCARD/ : { @@ -56,6 +57,7 @@ SECTIONS { *(.rodata..L*) } + MOD_DYNDBG_SECTIONS() MOD_SEPARATE_CODETAG_SECTIONS() } -- 2.56.0