default exported asm symbols to zero

With binutils-2.26 and before, a weak missing symbol was kept during the
final link, and a missing CRC for an export would lead to that CRC being
treated as zero implicitly.  With binutils-2.27, the crc symbol gets
dropped, and any module trying to use it will fail to load.

This sets the weak CRC symbol to zero explicitly, making it defined in
vmlinux, which in turn lets us load the modules referring to that CRC.

The comment above the __CRC_SYMBOL macro suggests that this was always
the intention, although it also seems that all symbols defined in C have
a correct CRC these days, and only the exports that are now done in
assembly need this.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Adam Borowski <kilobyte@angband.pl>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h
index 63554e9f6e0c68595943e27d2734ad4fa8271007..59a3b2f58c2282a8a7b81dfc0baecab0864e510a 100644 (file)
--- a/include/asm-generic/export.h
+++ b/include/asm-generic/export.h
@@ -54,6 +54,7 @@ KSYM(__kstrtab_\name):
 KSYM(__kcrctab_\name):
        __put KSYM(__crc_\name)
        .weak KSYM(__crc_\name)
+       .set KSYM(__crc_\name), 0
        .previous
 #endif
 #endif