From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f52.google.com (mail-wm1-f52.google.com [209.85.128.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9B6B8379979 for ; Mon, 1 Jun 2026 12:05:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.52 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780315520; cv=none; b=PpcCDWwvBD6hy1Mmx9Eq6dNSeMJ/pm7XfhSjub1+vmoKrkqQnwcpBks6j3o0uJVlPrUp4x8P+EgkpKhDlZ4QWVprVgbPO6tv9uQeik2qZUek4vWdeYQ+cHKhx/VXsoN6Nh60in1rk44rcpF4gqBxVdHXwUfr7o45bjk8kdmfMaY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780315520; c=relaxed/simple; bh=dHDLAmmZkSEwCrVjFAbC9GSDOGfjrhwtK5sTHYbJuoQ=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=ZLk/C2a8mOCjTWrUo6pTToAC4r3cdHNbsVSUPGJK7WRCth7LAMmtVnwVAMZFTLALg21SwfgqnIVJht/enBTUNKc2ZwF/NWS2EO6MUogzbNnGdx6gwt1rymCQlv7oLkWypERpQ2MTvp7qJProX+NI7M/WyxiktV28N3xWsmcYh2w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=TaEdvlZa; arc=none smtp.client-ip=209.85.128.52 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="TaEdvlZa" Received: by mail-wm1-f52.google.com with SMTP id 5b1f17b1804b1-4903d730b1fso90774125e9.2 for ; Mon, 01 Jun 2026 05:05:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1780315517; x=1780920317; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=Ks10Mou4dS+uM/gF5zD1xC7hoNz/3aUwUMnLMPkjLt0=; b=TaEdvlZaacjxn6igmxhyxUmq8lChVmItQcL2OA+lfuZjhA7KH+nDcTbdqgKGBvLu0I 3bNQZtu8xLTBENoTWNL+wl7lcsiKSh5XehyMyLo4QEzTrBDIXijDF6Jp0ZFWL2rH/rb4 7pPge7xcs2JRnKwhgRKw+/CiVIq2IC2mG+2Fvc/Zrw3n5odTSUd5EaAnqt9w4XdNersh xu8lJN3SaZQbhX+nYdlxBB4AyxavMF70TIr8OYFGGLCvMjwXyfykfwDzna8Rxogun2AL S/d+DL6Na8/PpSB0cv5YJb7rWFE8uU0/7yJy2Z2OSeYb1w7lLYD9qNBElJ9A4GERUQdv f6+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780315517; x=1780920317; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-gg:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=Ks10Mou4dS+uM/gF5zD1xC7hoNz/3aUwUMnLMPkjLt0=; b=pTv3DfIZTaxGHksssd9F8JTJSvv9L4Sc02bCD/iuVa9R19C0EkcH/EsCxAltwvXzn8 Ia+MZdMVukgTDje64u6Azs/oTSxguM1WH+ijlWIQ7NFS0odFQhJyj3vEIIVpAYz25OeU +6oNb+vVegeea4P2JPr4pS4w1nsgomgxicbK5WKAL0OR8eNs5iXQG8E7YbmEYThIySnU eAKi3OuB+571UPzWEvXZsrzslJKW6+GMp2QXDDI/AFZnesPCYQLH51+NDbiVdKGDY+Ou y1Pr4Ml/bperlZn8xWEaPobhcawDVzEYBFAxN1iPMw3wbjIA3WCmLL30Cy+niFP79mhy QHKQ== X-Gm-Message-State: AOJu0Yw2pPUrRxyZsrD7+kLRhV7wabFsrNQEEndvh7oomrkfp4c5xV7x ib1WOOsxYXDQX+wer4LDgDtx5UHCEtnVbSfLcHVNWqUJJl3MUu5xYfgd X-Gm-Gg: Acq92OE6VyMARQSYt/YQwwl0vv3kUhFgohb26rTxqtEWE0LAS2jUVrGMd+jrf4bDMtO 5smsBnnxTAjDm3iADGeqq08232yDZM1oXFqH9r8T09LZsiHJFbFlFSq76+u4qTlwhKmR2wbw/+J eml4pOw0T8iB/rDXekrbHkym2cr3Bxbm+SLP+BDAjeX5xVrZgRNWBjhtCTSOYuXLm0RUEu4U1X7 O5wxdj/NjcVRaaFCVpZLzHDNo5qi2RMcI9b4lgEHqWdwkXNy7tHH2DYU+uhbgwsrvFE5PhSrtS0 ULBdbc/FWAOtcGG5qNBIkx4pe0MhZSxE5IWfmMBwK2kPsl8580iKtyfMYld4eithxIF9aU6nTE1 41iVy4MirPQbA9nFFZow6C+DXgBizSnKjKDzUD4FiuqTWjmlUZJKMoipBUifw3dyIUrIAGrFgO2 4Jj7ZGIfzbdyDoGtjlxhLDQtFdHB8M0Fh4bSCvhgY/ww== X-Received: by 2002:a05:600c:c04b:20b0:490:3fdd:d353 with SMTP id 5b1f17b1804b1-490a29152demr143162745e9.8.1780315516822; Mon, 01 Jun 2026 05:05:16 -0700 (PDT) Received: from [172.16.188.153] ([213.181.114.83]) by smtp.googlemail.com with ESMTPSA id 5b1f17b1804b1-4909c152570sm103972805e9.9.2026.06.01.05.05.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Jun 2026 05:05:16 -0700 (PDT) From: Jim Cromie Date: Mon, 01 Jun 2026 12:04:53 +0000 Subject: [PATCH v3 07/24] dyndbg.lds.S: fix lost dyndbg sections in modules Precedence: bulk X-Mailing-List: linux-doc@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: <20260601-dd-maint-2-v3-7-4a15b241bd3c@gmail.com> References: <20260601-dd-maint-2-v3-0-4a15b241bd3c@gmail.com> In-Reply-To: <20260601-dd-maint-2-v3-0-4a15b241bd3c@gmail.com> To: Jonathan Corbet , Shuah Khan , Arnd Bergmann , Jason Baron , Luis Chamberlain , Petr Pavlu , Daniel Gomez , Sami Tolvanen , Aaron Tomlin , Andrew Morton , Shuah Khan , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-modules@vger.kernel.org, linux-kselftest@vger.kernel.org, dri-devel@lists.freedesktop.org, Jim Cromie X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1780315495; l=5103; i=jim.cromie@gmail.com; s=20260203; h=from:subject:message-id; bh=dHDLAmmZkSEwCrVjFAbC9GSDOGfjrhwtK5sTHYbJuoQ=; b=PQG/mC/MYN8ybEsRt1jpLWzZe9n+cpYR5hlwKDJxDHfZeAenGyn9KBu5ronOwgq41sw9dE2I3 sLG903nGuaVAHed+XjjBRzw1VXV8ccy6jMlqvG3zOfNGFRVad4AcGXP X-Developer-Key: i=jim.cromie@gmail.com; a=ed25519; pk=C6E5ODlPQo7ZBynATXH9wg7K6HxP0pIXyf4s38Qw0XE= 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 9ec290e38b44..6cf80e7ac039 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9083,6 +9083,7 @@ 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 2b1becd809be..0a1994bb8793 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 b62683061d79..2e62dc5bd5d4 100644 --- a/scripts/module.lds.S +++ b/scripts/module.lds.S @@ -10,6 +10,7 @@ #endif #include +#include SECTIONS { /DISCARD/ : { @@ -61,6 +62,7 @@ SECTIONS { *(.rodata..L*) } + MOD_DYNDBG_SECTIONS() MOD_SEPARATE_CODETAG_SECTIONS() } -- 2.54.0