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| author | Heiko Carstens <hca@linux.ibm.com> | 2023-04-25 13:42:11 +0200 |
|---|---|---|
| committer | Alexander Gordeev <agordeev@linux.ibm.com> | 2023-05-15 14:12:14 +0200 |
| commit | fbac266f095de92b93e7c91c71cdca432c2c9275 (patch) | |
| tree | 75c1f682e65031c03532b880eab1cab559afba82 /arch/s390/Kconfig | |
| parent | 1f2597cd3686955a4d64e01909dbfe625a2a35a1 (diff) | |
| download | linux-stable-fbac266f095de92b93e7c91c71cdca432c2c9275.tar.gz linux-stable-fbac266f095de92b93e7c91c71cdca432c2c9275.tar.bz2 linux-stable-fbac266f095de92b93e7c91c71cdca432c2c9275.zip | |
s390: select ARCH_SUPPORTS_INT128
s390 has instructions to support 128 bit arithmetics, e.g. a 64 bit
multiply instruction with a 128 bit result. Also 128 bit integer
artithmetics are already used in s390 specific architecture code (see
e.g. read_persistent_clock64()).
Therefore select ARCH_SUPPORTS_INT128.
However limit this to clang for now, since gcc generates inefficient code,
which may lead to stack overflows, when compiling
lib/crypto/curve25519-hacl64.c which depends on ARCH_SUPPORTS_INT128. The
gcc generated functions have 6kb stack frames, compared to only 1kb of the
code generated with clang.
If the kernel is compiled with -Os library calls for __ashlti3(),
__ashrti3(), and __lshrti3() may be generated. Similar to arm64
and riscv provide assembler implementations for these functions.
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Diffstat (limited to 'arch/s390/Kconfig')
| -rw-r--r-- | arch/s390/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index db20c1589a98..0c1bfac08e05 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -117,6 +117,7 @@ config S390 select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_DEBUG_PAGEALLOC select ARCH_SUPPORTS_HUGETLBFS + select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 && CC_IS_CLANG select ARCH_SUPPORTS_NUMA_BALANCING select ARCH_SUPPORTS_PER_VMA_LOCK select ARCH_USE_BUILTIN_BSWAP |