[PATCH v14 03/92] dyndbg.lds.S: fix lost dyndbg sections in modules

Jim Cromie
2026-04-23T20:54:18Z

In an (unused) experimental variation of this series, I had trouble
with __dyndbg* sections getting lost in drm drivers. While it didn't
happen in this series, it exposed a non-obvious weakness. So fix it,
by following the model demonstrated in codetag.lds.h.

Introduce include/asm-generic/dyndbg.lds.h, with 2 macros:

DYNDBG_SECTIONS() gets the 2 BOUNDED_SECTION_BY(__yndbg*) calls from
vmlinux.lds.h DATA_DATA, which now includes the new file and calls the
new macro.

MOD_DYNDBG_SECTIONS also has the 2 BOUNDED_SECTION_BY calls, but wraps
them with output section syntax to keep them as known and separate ELF
sections in the module.ko.

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 <arnd@arndb.de>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
MAINTAINERS | 1 +
include/asm-generic/dyndbg.lds.h | 19 +++++++++++++++++++
include/asm-generic/vmlinux.lds.h | 6 ++----
scripts/module.lds.S | 2 ++
4 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 5fcb7b991776..5c75109d2ee3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9069,6 +9069,7 @@ DYNAMIC DEBUG
M: Jason Baron <jbaron@akamai.com>
M: Jim Cromie <jim.cromie@gmail.com>
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..f95683aa16b6
--- /dev/null
+++ b/include/asm-generic/dyndbg.lds.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ASM_GENERIC_DYNDBG_LDS_H
+#define __ASM_GENERIC_DYNDBG_LDS_H
+
+#include <asm-generic/bounded_sections.lds.h>
+#define DYNDBG_SECTIONS() \
+ . = ALIGN(8); \
+ BOUNDED_SECTION_BY(__dyndbg, ___dyndbg) \
+ BOUNDED_SECTION_BY(__dyndbg_classes, ___dyndbg_classes)
+
+#define MOD_DYNDBG_SECTIONS() \
+ __dyndbg : { \
+ BOUNDED_SECTION_BY(__dyndbg, ___dyndbg) \
+ } \
+ __dyndbg_classes : { \
+ BOUNDED_SECTION_BY(__dyndbg_classes, ___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 acb4aadd74da..9324066aab51 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -340,6 +340,7 @@
/*
* .data section
*/
+#include <asm-generic/dyndbg.lds.h>
#define DATA_DATA \
*(.xiptext) \
*(DATA_MAIN) \
@@ -353,10 +354,7 @@
*(.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 2dc4c8c3e667..027c5c286ea0 100644
--- a/scripts/module.lds.S
+++ b/scripts/module.lds.S
@@ -10,6 +10,7 @@
#endif

#include <asm-generic/codetag.lds.h>
+#include <asm-generic/dyndbg.lds.h>

SECTIONS {
/DISCARD/ : {
@@ -59,6 +60,7 @@ SECTIONS {
*(.rodata..L*)
}

+ MOD_DYNDBG_SECTIONS()
MOD_SEPARATE_CODETAG_SECTIONS()
}

--
2.53.0