linux-kernel - [PATCH] linkage: Fix issue with missing symbol size

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Message-ID: <20220429091859.GS2731@worktop.programming.kicks-ass.net>
Date:   Fri, 29 Apr 2022 11:18:59 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     x86@...nel.org, jpoimboe@...hat.com, mark.rutland@....com
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        linux-toolchains@...r.kernel.org
Subject: [PATCH] linkage: Fix issue with missing symbol size


Occasionally, typically when a function doesn't end with 'ret', an
alias on that function will have 0 size.

The difference between what GCC generates and our linkage magic, is
that GCC doesn't appear to provide .size for the alias'ed symbol at
all. And indeed, removing this directive cures the issue.

Additionally, GCC also doesn't emit .type for alias symbols either, so
also omit that.

Fixes: e0891269a8c2 ("linkage: add SYM_FUNC_ALIAS{,_LOCAL,_WEAK}()")
Suggested-by: Mark Rutland <mark.rutland@....com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 include/linux/linkage.h |   15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

--- a/include/linux/linkage.h
+++ b/include/linux/linkage.h
@@ -171,12 +171,9 @@
 
 /* SYM_ALIAS -- use only if you have to */
 #ifndef SYM_ALIAS
-#define SYM_ALIAS(alias, name, sym_type, linkage)			\
-	linkage(alias) ASM_NL						\
-	.set alias, name ASM_NL						\
-	.type alias sym_type ASM_NL					\
-	.set .L__sym_size_##alias, .L__sym_size_##name ASM_NL		\
-	.size alias, .L__sym_size_##alias
+#define SYM_ALIAS(alias, name, linkage)			\
+	linkage(alias) ASM_NL				\
+	.set alias, name ASM_NL
 #endif
 
 /* === code annotations === */
@@ -261,7 +258,7 @@
  */
 #ifndef SYM_FUNC_ALIAS
 #define SYM_FUNC_ALIAS(alias, name)					\
-	SYM_ALIAS(alias, name, SYM_T_FUNC, SYM_L_GLOBAL)
+	SYM_ALIAS(alias, name, SYM_L_GLOBAL)
 #endif
 
 /*
@@ -269,7 +266,7 @@
  */
 #ifndef SYM_FUNC_ALIAS_LOCAL
 #define SYM_FUNC_ALIAS_LOCAL(alias, name)				\
-	SYM_ALIAS(alias, name, SYM_T_FUNC, SYM_L_LOCAL)
+	SYM_ALIAS(alias, name, SYM_L_LOCAL)
 #endif
 
 /*
@@ -277,7 +274,7 @@
  */
 #ifndef SYM_FUNC_ALIAS_WEAK
 #define SYM_FUNC_ALIAS_WEAK(alias, name)				\
-	SYM_ALIAS(alias, name, SYM_T_FUNC, SYM_L_WEAK)
+	SYM_ALIAS(alias, name, SYM_L_WEAK)
 #endif
 
 /* SYM_CODE_START -- use for non-C (special) functions */