diff options
| author | Andrew Turner <andrew@FreeBSD.org> | 2026-02-03 14:01:32 +0000 |
|---|---|---|
| committer | Andrew Turner <andrew@FreeBSD.org> | 2026-02-03 17:11:51 +0000 |
| commit | 32d1f18865abe94d351a6f178a93b7195595ec69 (patch) | |
| tree | 6a2920e59bee6bc5c4595be80bd45fd83090953c | |
| parent | f0516ed4652cfb7435f8c5a16b46dc067779a1a8 (diff) | |
libc/aarch64: Add memset for a 64 byte dc zva
On arm64 we can use the "dc zva" instruction to zero memory. The CPU
tells software if the instruction is implemented, and if so the size
and alignment it will use.
When the size is 64-bytes the Arm Optimized Routines implementation of
memset can use dc zva to zero memory, and has a build flag to skip
checking.
Use this flag to build a version of memset that will be used when this
assumption is true.
Sponsored by: Arm Ltd
Differential Revision: https://reviews.freebsd.org/D54776
| -rw-r--r-- | lib/libc/aarch64/string/Makefile.inc | 4 | ||||
| -rw-r--r-- | lib/libc/aarch64/string/memset_resolver.c | 13 | ||||
| -rw-r--r-- | lib/libc/aarch64/string/memset_zva64.S | 4 |
3 files changed, 20 insertions, 1 deletions
diff --git a/lib/libc/aarch64/string/Makefile.inc b/lib/libc/aarch64/string/Makefile.inc index 20a844f80e17..bc05e849aa20 100644 --- a/lib/libc/aarch64/string/Makefile.inc +++ b/lib/libc/aarch64/string/Makefile.inc @@ -42,7 +42,8 @@ MDSRCS+= \ memcpy_resolver.c \ memmove_resolver.c \ memset.S \ - memset_resolver.c + memset_resolver.c \ + memset_zva64.S # # Add the above functions. Generate an asm file that includes the needed @@ -77,3 +78,4 @@ CFLAGS.${FILE}+=-I${SRCTOP}/contrib/arm-optimized-routines/string CFLAGS.memchr.S+=-I${SRCTOP}/contrib/arm-optimized-routines/string CFLAGS.memcpy.S+=-I${SRCTOP}/contrib/arm-optimized-routines/string CFLAGS.memset.S+=-I${SRCTOP}/contrib/arm-optimized-routines/string +CFLAGS.memset_zva64.S+=-I${SRCTOP}/contrib/arm-optimized-routines/string diff --git a/lib/libc/aarch64/string/memset_resolver.c b/lib/libc/aarch64/string/memset_resolver.c index 34ca98aa1d34..277e8c177de9 100644 --- a/lib/libc/aarch64/string/memset_resolver.c +++ b/lib/libc/aarch64/string/memset_resolver.c @@ -25,18 +25,31 @@ * SUCH DAMAGE. */ #include <sys/types.h> + +#include <machine/armreg.h> #include <machine/ifunc.h> #include <elf.h> void *__memset_aarch64(void *, int, size_t); +void *__memset_aarch64_zva64(void *, int, size_t); void *__memset_aarch64_mops(void *, int, size_t); DEFINE_UIFUNC(, void *, memset, (void *, int, size_t)) { + uint64_t dczid; + if (ifunc_arg->_hwcap2 & HWCAP2_MOPS) return (__memset_aarch64_mops); + /* + * Check for the DC ZVA instruction, and it will + * zero 64 bytes (4 * 4byte words). + */ + dczid = READ_SPECIALREG(dczid_el0); + if ((dczid & DCZID_DZP) == 0 && DCZID_BS_SIZE(dczid) == 4) + return (__memset_aarch64_zva64); + return (__memset_aarch64); } diff --git a/lib/libc/aarch64/string/memset_zva64.S b/lib/libc/aarch64/string/memset_zva64.S new file mode 100644 index 000000000000..7f1cf6ba577a --- /dev/null +++ b/lib/libc/aarch64/string/memset_zva64.S @@ -0,0 +1,4 @@ +/* Used when we know we have a 64-byte dc zva instruction */ +#define __memset_aarch64 __memset_aarch64_zva64 +#define SKIP_ZVA_CHECK +#include "aarch64/memset.S" |