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authorMatthias Maennich <maennich@google.com>2019-09-06 11:32:26 +0100
committerJessica Yu <jeyu@kernel.org>2019-09-10 10:30:09 +0200
commited13fc33f763035a7c290f11c7111877c3a5daab (patch)
tree40cc79e8871ff027f7063ba38dd9f25790feace0 /arch/m68k
parentc5e4a062fe661806ab291a7576dc4a41613adb86 (diff)
downloadlinux-ed13fc33f763035a7c290f11c7111877c3a5daab.tar.bz2
export: explicitly align struct kernel_symbol
This change allows growing struct kernel_symbol without wasting bytes to alignment. It also concretized the alignment of ksymtab entries if relative references are used for ksymtab entries. struct kernel_symbol was already implicitly being aligned to the word size, except on x86_64 and m68k, where it is aligned to 16 and 2 bytes, respectively. As far as I can tell there is no requirement for aligning struct kernel_symbol to 16 bytes on x86_64, but gcc aligns structs to their size, and the linker aligns the custom __ksymtab sections to the largest data type contained within, so setting KSYM_ALIGN to 16 was necessary to stay consistent with the code generated for non-ASM EXPORT_SYMBOL(). Now that non-ASM EXPORT_SYMBOL() explicitly aligns to word size (8), KSYM_ALIGN is no longer necessary. In case of relative references, the alignment has been changed accordingly to not waste space when adding new struct members. As for m68k, struct kernel_symbol is aligned to 2 bytes even though the structure itself is 8 bytes; using a 4-byte alignment shouldn't hurt. I manually verified the output of the __ksymtab sections didn't change on x86, x86_64, arm, arm64 and m68k. As expected, the section contents didn't change, and the ELF section alignment only changed on x86_64 and m68k. Feedback from other archs more than welcome. Co-developed-by: Martijn Coenen <maco@android.com> Signed-off-by: Martijn Coenen <maco@android.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Matthias Maennich <maennich@google.com> Signed-off-by: Jessica Yu <jeyu@kernel.org>
Diffstat (limited to 'arch/m68k')
-rw-r--r--arch/m68k/include/asm/export.h1
1 files changed, 0 insertions, 1 deletions
diff --git a/arch/m68k/include/asm/export.h b/arch/m68k/include/asm/export.h
index 0af20f48bd07..b53008b67ce1 100644
--- a/arch/m68k/include/asm/export.h
+++ b/arch/m68k/include/asm/export.h
@@ -1,3 +1,2 @@
-#define KSYM_ALIGN 2
#define KCRC_ALIGN 2
#include <asm-generic/export.h>