riscv: Add RVV memcpy for both multiarch and non-multiarch builds

This patch adds an RVV-optimized implementation of memcpy for RISC-V and
enables it for both multiarch (IFUNC) and non-multiarch builds.

The implementation integrates Hau Hsu's 2023 RVV work under a unified
ifunc-based framework. A vectorized version (__memcpy_vector) is added
alongside the generic fallback (__memcpy_generic). The runtime resolver
selects the RVV variant when RISCV_HWPROBE_KEY_IMA_EXT_0 reports vector
support (RVV).

Currently, the resolver still selects the RVV variant even when the RVV
extension is disabled via prctl(). As a consequence, any process that
has RVV disabled via prctl() will receive SIGILL when calling memcpy().

Co-authored-by: Hau Hsu <hau.hsu@sifive.com>
Co-authored-by: Jerry Shih <jerry.shih@sifive.com>
Signed-off-by: Yao Zihong <zihong.plct@isrc.iscas.ac.cn>
Reviewed-by: Peter Bergner <bergner@tenstorrent.com>

diff --git a/sysdeps/riscv/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/riscv/multiarch/dl-symbol-redir-ifunc.h
index 69a0790838900023cb7e4aed99c9ba0f07a0e78b..a4ff47107b5e5be2d225e3449224d86871a75501 100644 (file)
--- a/sysdeps/riscv/multiarch/dl-symbol-redir-ifunc.h
+++ b/sysdeps/riscv/multiarch/dl-symbol-redir-ifunc.h
@@ -20,6 +20,7 @@
 #define _DL_IFUNC_GENERIC_H
 
 #ifndef SHARED
+asm ("memcpy = __memcpy_generic");
 asm ("memset = __memset_generic");
 asm ("memcpy = __memcpy_generic");
 #endif

diff --git a/sysdeps/riscv/multiarch/memcpy-vector.S b/sysdeps/riscv/multiarch/memcpy-vector.S
new file mode 100644 (file)
index 0000000..97b80b8
--- /dev/null
+++ b/sysdeps/riscv/multiarch/memcpy-vector.S
@@ -0,0 +1,24 @@
+/* Re-include the RISC-V RVV based memcpy implementation.
+   Copyright (C) 2026 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#if IS_IN(libc)
+# define MEMCPY __memcpy_vector
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(name)
+# include <sysdeps/riscv/rvv/memcpy.S>
+#endif

diff --git a/sysdeps/riscv/rvv/memcpy.S b/sysdeps/riscv/rvv/memcpy.S
new file mode 100644 (file)
index 0000000..b4d600c
--- /dev/null
+++ b/sysdeps/riscv/rvv/memcpy.S
@@ -0,0 +1,54 @@
+/* RISC-V RVV based memcpy.
+   Copyright (C) 2026 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+#include <sys/asm.h>
+
+#ifndef MEMCPY
+# define MEMCPY memcpy
+#endif
+
+#define dst a0
+#define src a1
+#define num a2
+
+#define ivl a3
+#define dst_ptr a4
+
+#define ELEM_LMUL_SETTING m8
+#define vdata v0
+
+ENTRY (MEMCPY)
+.option push
+.option arch, +v
+    mv dst_ptr, dst
+L(loop):
+    vsetvli ivl, num, e8, ELEM_LMUL_SETTING, ta, ma
+
+    vle8.v vdata, (src)
+    sub num, num, ivl
+    add src, src, ivl
+    vse8.v vdata, (dst_ptr)
+    add dst_ptr, dst_ptr, ivl
+
+    bnez num, L(loop)
+
+    ret
+.option pop
+END (MEMCPY)
+libc_hidden_builtin_def (memcpy)

diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
index c82693251a0e4abf52e357622d7892c103e83319..32be517d21475460ca52aaa1d4d0d6b6b80e7134 100644 (file)
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
@@ -2,6 +2,7 @@ ifeq ($(subdir),string)
 sysdep_routines += \
   memcpy \
   memcpy-generic \
+  memcpy-vector \
   memcpy_noalignment \
   memset \
   memset-generic \

diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c b/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
index f4154bb8f787a849f604dc6e074fbbe25589f283..0eb55a5ad8242066148c8b8c89d32e8f7f3d2eb6 100644 (file)
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
@@ -44,6 +44,8 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   }
 
   IFUNC_IMPL (i, name, memcpy,
+             IFUNC_IMPL_ADD (array, i, memcpy, rvv_enabled,
+                             __memcpy_vector)
              IFUNC_IMPL_ADD (array, i, memcpy, fast_unaligned,
                              __memcpy_noalignment)
              IFUNC_IMPL_ADD (array, i, memcpy, 1, __memcpy_generic))

diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/memcpy.c b/sysdeps/unix/sysv/linux/riscv/multiarch/memcpy.c
index f0966934313ebd6df5c7a2923530cc24efe6b0da..11919d815aca40d09250ce3505dfecb118a62f68 100644 (file)
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/memcpy.c
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/memcpy.c
@@ -32,11 +32,16 @@ extern __typeof (__redirect_memcpy) __libc_memcpy;
 
 extern __typeof (__redirect_memcpy) __memcpy_generic attribute_hidden;
 extern __typeof (__redirect_memcpy) __memcpy_noalignment attribute_hidden;
+extern __typeof (__redirect_memcpy) __memcpy_vector attribute_hidden;
 
 static inline __typeof (__redirect_memcpy) *
 select_memcpy_ifunc (uint64_t dl_hwcap, __riscv_hwprobe_t hwprobe_func)
 {
   unsigned long long int v;
+  if (__riscv_hwprobe_one (hwprobe_func, RISCV_HWPROBE_KEY_IMA_EXT_0, &v) == 0
+      && (v & RISCV_HWPROBE_IMA_V) == RISCV_HWPROBE_IMA_V)
+    return __memcpy_vector;
+
   if (__riscv_hwprobe_one (hwprobe_func, RISCV_HWPROBE_KEY_CPUPERF_0, &v) == 0
       && (v & RISCV_HWPROBE_MISALIGNED_MASK) == RISCV_HWPROBE_MISALIGNED_FAST)
     return __memcpy_noalignment;