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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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modules: Ensure 64-bit alignment on __ksymtab_* sections

On 64-bit architectures without CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
(e.g. ppc64, ppc64le, parisc, s390x,...) the __KSYM_REF() macro stores
64-bit pointers into the __ksymtab* sections.
Make sure that those sections will be correctly aligned at module link time,
otherwise unaligned memory accesses may happen at runtime.

As per unaligned-memory-access [0] "unaligned memory accesses [...]
will not work correctly on certain platforms and will cause performance
problems on others", so fix this.

The __kcrctab* sections store 32-bit entities, so use ALIGN(4) for those.

Signed-off-by: Helge Deller <deller@gmx.de>
[mcgrof: added unaligned-memory-access justification]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/core-api/unaligned-memory-access.rst # [0]
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

authored by

Helge Deller and committed by
Luis Chamberlain 335de24e 8e929cb5

+4 -4
+4 -4
scripts/module.lds.S
··· 18 18 *(.export_symbol) 19 19 } 20 20 21 - __ksymtab 0 : { *(SORT(___ksymtab+*)) } 22 - __ksymtab_gpl 0 : { *(SORT(___ksymtab_gpl+*)) } 23 - __kcrctab 0 : { *(SORT(___kcrctab+*)) } 24 - __kcrctab_gpl 0 : { *(SORT(___kcrctab_gpl+*)) } 21 + __ksymtab 0 : ALIGN(8) { *(SORT(___ksymtab+*)) } 22 + __ksymtab_gpl 0 : ALIGN(8) { *(SORT(___ksymtab_gpl+*)) } 23 + __kcrctab 0 : ALIGN(4) { *(SORT(___kcrctab+*)) } 24 + __kcrctab_gpl 0 : ALIGN(4) { *(SORT(___kcrctab_gpl+*)) } 25 25 26 26 .ctors 0 : ALIGN(8) { *(SORT(.ctors.*)) *(.ctors) } 27 27 .init_array 0 : ALIGN(8) { *(SORT(.init_array.*)) *(.init_array) }