From: H.J. Lu <hjl.tools@gmail.com>
Date: Wed, 6 Apr 2022 13:06:37 +0000 (-0300)
Subject: Add declare_object_symbol_alias for assembly codes (BZ #28128)
X-Git-Tag: glibc-2.36~301
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=111254f3e1e1a7ae5c2eda7cebc98f93a61d417c;p=thirdparty%2Fglibc.git

Add declare_object_symbol_alias for assembly codes (BZ #28128)

There are 2 problems in:

 #define declare_symbol_alias(symbol, original, type, size) \
  declare_symbol_alias_1 (symbol, original, type, size)
 #ifdef __ASSEMBLER__
 # define declare_symbol_alias_1(symbol, original, type, size) \
   strong_alias (original, symbol); \
   .type C_SYMBOL_NAME (symbol), %##type; \
   .size C_SYMBOL_NAME (symbol), size

1. .type and .size are substituted by arguments.
2. %##type is expanded to "% type" due to the GCC bug:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101613

But assembler doesn't support "% type".

Workaround BZ #28128 by

1. Don't define declare_symbol_alias for assembly codes.
2. Define declare_object_symbol_alias for assembly codes.

Reviewed-by: Fangrui Song <maskray@google.com>
---

diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index 662bd118b13..4bb3d8c7ba5 100644
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -324,14 +324,16 @@ for linking")
    This is only necessary when defining something in assembly, or playing
    funny alias games where the size should be other than what the compiler
    thinks it is.  */
-#define declare_symbol_alias(symbol, original, type, size) \
-  declare_symbol_alias_1 (symbol, original, type, size)
 #ifdef __ASSEMBLER__
-# define declare_symbol_alias_1(symbol, original, type, size) \
-   strong_alias (original, symbol); \
-   .type C_SYMBOL_NAME (symbol), %##type; \
-   .size C_SYMBOL_NAME (symbol), size
+# define declare_object_symbol_alias(symbol, original, size) \
+  declare_object_symbol_alias_1 (symbol, original, size)
+# define declare_object_symbol_alias_1(symbol, original, s_size) \
+   strong_alias (original, symbol) ASM_LINE_SEP \
+   .type C_SYMBOL_NAME (symbol), %object ASM_LINE_SEP \
+   .size C_SYMBOL_NAME (symbol), s_size ASM_LINE_SEP
 #else /* Not __ASSEMBLER__.  */
+# define declare_symbol_alias(symbol, original, type, size) \
+  declare_symbol_alias_1 (symbol, original, type, size)
 # define declare_symbol_alias_1(symbol, original, type, size) \
    asm (".globl " __SYMBOL_PREFIX #symbol \
 	"\n\t" declare_symbol_alias_1_alias (symbol, original) \