[PATCH v12 03/69] dyndbg.lds.S: fix lost dyndbg sections in modules

[Jim Cromie]

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 moves the 2 BOUNDED_SECTION_BY calls from DATA_DATA in
vmlinux.lds.h, which now includes the 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.

Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
---
 include/asm-generic/dyndbg.lds.h  | 19 +++++++++++++++++++
 include/asm-generic/vmlinux.lds.h |  6 ++----
 scripts/module.lds.S              |  2 ++
 3 files changed, 23 insertions(+), 4 deletions(-)
 create mode 100644 include/asm-generic/dyndbg.lds.h

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 462f124ad457..b59f343818b0 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 054ef99e8288..8a7b0741bf8d 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/ : {
@@ -60,6 +61,7 @@ SECTIONS {
 		*(.rodata..L*)
 	}
 
+	MOD_DYNDBG_SECTIONS()
 	MOD_SEPARATE_CODETAG_SECTIONS()
 }
 
-- 
2.53.0