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.
The __kcrctab* sections store 32-bit entities, so use ALIGN(4) for those.
Testing with the kallsyms selftest on x86_64 we see a savings of about
1,958,153 ns in the worst case which may or not be within noise. Testing
on parisc would be useful and welcomed.
On x86_64 before:
Performance counter stats for '/sbin/modprobe test_kallsyms_b':
86,430,119 ns duration_time
84,407,000 ns system_time
213 page-faults
0.086430119 seconds time elapsed
0.000000000 seconds user
0.084407000 seconds sys
Performance counter stats for '/sbin/modprobe test_kallsyms_b':
85,777,474 ns duration_time
82,581,000 ns system_time
212 page-faults
0.085777474 seconds time elapsed
0.000000000 seconds user
0.082581000 seconds sys
Performance counter stats for '/sbin/modprobe test_kallsyms_b':
87,906,053 ns duration_time
87,939,000 ns system_time
212 page-faults
0.087906053 seconds time elapsed
0.000000000 seconds user
0.087939000 seconds sys
After:
Performance counter stats for '/sbin/modprobe test_kallsyms_b':
82,925,631 ns duration_time
83,000,000 ns system_time
212 page-faults
0.082925631 seconds time elapsed
0.000000000 seconds user
0.083000000 seconds sys
Performance counter stats for '/sbin/modprobe test_kallsyms_b':
87,776,380 ns duration_time
86,678,000 ns system_time
213 page-faults
0.087776380 seconds time elapsed
0.000000000 seconds user
0.086678000 seconds sys
Performance counter stats for '/sbin/modprobe test_kallsyms_b':
85,947,900 ns duration_time
82,006,000 ns system_time
212 page-faults
0.085947900 seconds time elapsed
0.000000000 seconds user
0.082006000 seconds sys
Signed-off-by: Helge Deller <deller@gmx.de>
[mcgrof: ran kallsyms selftests on x86_64]
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
1 file changed
