diff options
| 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/include/asm | |
| parent | 1f2597cd3686955a4d64e01909dbfe625a2a35a1 (diff) | |
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/include/asm')
| -rw-r--r-- | arch/s390/include/asm/asm-prototypes.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/s390/include/asm/asm-prototypes.h b/arch/s390/include/asm/asm-prototypes.h index c37eb921bfbf..a873e873e1ee 100644 --- a/arch/s390/include/asm/asm-prototypes.h +++ b/arch/s390/include/asm/asm-prototypes.h @@ -6,4 +6,8 @@ #include <asm/fpu/api.h> #include <asm-generic/asm-prototypes.h> +__int128_t __ashlti3(__int128_t a, int b); +__int128_t __ashrti3(__int128_t a, int b); +__int128_t __lshrti3(__int128_t a, int b); + #endif /* _ASM_S390_PROTOTYPES_H */ |