From: Casey Chen <cachen@purestorage.com>
Date: Tue, 10 Jun 2025 16:22:58 +0000 (-0600)
Subject: alloc_tag: remove empty module tag section
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7e43195c609f0499e46c6bfa9472e39c76af445b;p=thirdparty%2Fkernel%2Flinux.git

alloc_tag: remove empty module tag section

The empty MOD_CODETAG_SECTIONS() macro added an incomplete .data section
in module linker script, which caused symbol lookup tools like gdb to
misinterpret symbol addresses e.g., __ib_process_cq incorrectly mapping to
unrelated functions like below.

  (gdb) disas __ib_process_cq
  Dump of assembler code for function trace_event_fields_cq_schedule:

Removing the empty section restores proper symbol resolution and layout,
ensuring .data placement behaves as expected.

Link: https://lkml.kernel.org/r/20250610162258.324645-1-cachen@purestorage.com
Fixes: 0db6f8d7820a ("alloc_tag: load module tags into separate contiguous memory")
       22d407b164ff ("lib: add allocation tagging support for memory allocation profiling")
Signed-off-by: Casey Chen <cachen@purestorage.com>
Reviewed-by: Yuanyuan Zhong <yzhong@purestorage.com>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/include/asm-generic/codetag.lds.h b/include/asm-generic/codetag.lds.h
index 372c320c50437..a45fe3d141a18 100644
--- a/include/asm-generic/codetag.lds.h
+++ b/include/asm-generic/codetag.lds.h
@@ -11,12 +11,6 @@
 #define CODETAG_SECTIONS()		\
 	SECTION_WITH_BOUNDARIES(alloc_tags)
 
-/*
- * Module codetags which aren't used after module unload, therefore have the
- * same lifespan as the module and can be safely unloaded with the module.
- */
-#define MOD_CODETAG_SECTIONS()
-
 #define MOD_SEPARATE_CODETAG_SECTION(_name)	\
 	.codetag.##_name : {			\
 		SECTION_WITH_BOUNDARIES(_name)	\
diff --git a/scripts/module.lds.S b/scripts/module.lds.S
index 450f1088d5fd3..ee79c41059f3d 100644
--- a/scripts/module.lds.S
+++ b/scripts/module.lds.S
@@ -52,17 +52,12 @@ SECTIONS {
 	.data : {
 		*(.data .data.[0-9a-zA-Z_]*)
 		*(.data..L*)
-		MOD_CODETAG_SECTIONS()
 	}
 
 	.rodata : {
 		*(.rodata .rodata.[0-9a-zA-Z_]*)
 		*(.rodata..L*)
 	}
-#else
-	.data : {
-		MOD_CODETAG_SECTIONS()
-	}
 #endif
 	MOD_SEPARATE_CODETAG_SECTIONS()
 }