linux-kernel - [PATCH 1/2] vmlinux.lds.h: fix BOUNDED_SECTION_(PRE|POST)

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Message-Id: <20221117002022.860237-2-jim.cromie@gmail.com>
Date:   Wed, 16 Nov 2022 17:20:21 -0700
From:   Jim Cromie <jim.cromie@...il.com>
To:     jbaron@...mai.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org
Cc:     Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH 1/2] vmlinux.lds.h: fix BOUNDED_SECTION_(PRE|POST)_LABEL macros

commit foo added BOUNDED_SECTION_(PRE|POST)_LABEL macros,
encapsulating the basic boilerplate to: KEEP/pack records into a
section, and to mark the begin and end of the section with
linker-symbols.

But it tried to do extra, adding KEEP(*(.gnu.linkonce.##_sec_)) to
optionally reserve a header record in front of the data.  It wrongly
placed the KEEP after the linker-symbol starting the section,
so if a header was added, it would wind up in the data.

Putting the KEEP in the "correct" place proved brittle, and too clever
by half.  The obvious safe fix is to remove the KEEP, and provide
separate macros to do the extra work.

While here, the macro var-names: _s_, _e_ are nearly invisible, change
them to more obvious names: _BEGIN_, _END_

Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
 include/asm-generic/vmlinux.lds.h | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 50851425b229..85d5d5b203dc 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -199,17 +199,15 @@
 # endif
 #endif
 
-#define BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, _s_, _e_)		\
-	_s_##_label_ = .;						\
-	KEEP(*(.gnu.linkonce.##_sec_))					\
+#define BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_)	\
+	_BEGIN_##_label_ = .;						\
 	KEEP(*(_sec_))							\
-	_e_##_label_ = .;
+	_END_##_label_ = .;
 
-#define BOUNDED_SECTION_POST_LABEL(_sec_, _label_, _s_, _e_)		\
-	_label_##_s_ = .;						\
-	KEEP(*(.gnu.linkonce.##_sec_))					\
+#define BOUNDED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_)	\
+	_label_##_BEGIN_ = .;						\
 	KEEP(*(_sec_))							\
-	_label_##_e_ = .;
+	_label_##_END_ = .;
 
 #define BOUNDED_SECTION_BY(_sec_, _label_)				\
 	BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, __start, __stop)
-- 
2.38.1