[glibc] riscv: Add RVV strcpy for both multiarch and non-multiarch builds

Peter Bergner via Glibc-cvs <[email protected]>
Newsgroups gmane.comp.lib.glibc.cvs
Message-ID <[email protected]> 
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=40fb13ac3de0dbd792d9fe09230dc0d0d4cde444

commit 40fb13ac3de0dbd792d9fe09230dc0d0d4cde444
Author: Yao Zihong <[email protected]>
Date:   Mon Apr 20 16:19:08 2026 -0500

    riscv: Add RVV strcpy for both multiarch and non-multiarch builds
    
    This patch adds an RVV-optimized implementation of strcpy 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 (__strcpy_vector) is added
    alongside the generic fallback (__strcpy_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 strcpy().
    
    Co-authored-by: Hau Hsu <[email protected]>
    Co-authored-by: Jerry Shih <[email protected]>
    Signed-off-by: Yao Zihong <[email protected]>
    Reviewed-by: Peter Bergner <[email protected]>

Diff:
---
 sysdeps/riscv/multiarch/strcpy-generic.c           | 26 ++++++++++
 sysdeps/riscv/multiarch/strcpy-vector.S            | 24 +++++++++
 sysdeps/riscv/rvv/strcpy.S                         | 59 ++++++++++++++++++++++
 sysdeps/unix/sysv/linux/riscv/multiarch/Makefile   |  3 ++
 .../sysv/linux/riscv/multiarch/ifunc-impl-list.c   |  5 ++
 sysdeps/unix/sysv/linux/riscv/multiarch/strcpy.c   | 56 ++++++++++++++++++++
 6 files changed, 173 insertions(+)

diff --git a/sysdeps/riscv/multiarch/strcpy-generic.c b/sysdeps/riscv/multiarch/strcpy-generic.c
new file mode 100644
index 0000000000..8a29992570
--- /dev/null
+++ b/sysdeps/riscv/multiarch/strcpy-generic.c
@@ -0,0 +1,26 @@
+/* Re-include the default strcpy 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/>.  */
+
+#include <string.h>
+
+#if IS_IN(libc)
+# define STRCPY __strcpy_generic
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(x)
+# include <string/strcpy.c>
+#endif
diff --git a/sysdeps/riscv/multiarch/strcpy-vector.S b/sysdeps/riscv/multiarch/strcpy-vector.S
new file mode 100644
index 0000000000..f5381a98ce
--- /dev/null
+++ b/sysdeps/riscv/multiarch/strcpy-vector.S
@@ -0,0 +1,24 @@
+/* Re-include the RISC-V RVV based strcpy 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 STRCPY __strcpy_vector
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(name)
+# include <sysdeps/riscv/rvv/strcpy.S>
+#endif
diff --git a/sysdeps/riscv/rvv/strcpy.S b/sysdeps/riscv/rvv/strcpy.S
new file mode 100644
index 0000000000..e73558d812
--- /dev/null
+++ b/sysdeps/riscv/rvv/strcpy.S
@@ -0,0 +1,59 @@
+/* RISC-V RVV based strcpy.
+   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 STRCPY
+# define STRCPY strcpy
+#endif
+
+#define dst a0
+#define src a1
+#define dst_ptr a2
+
+#define ivl a3
+#define cur_vl a4
+#define active_elem_pos a5
+
+#define ELEM_LMUL_SETTING m1
+#define vmask1 v0
+#define vmask2 v1
+#define vstr1 v8
+#define vstr2 v16
+
+ENTRY (STRCPY)
+.option push
+.option arch, +v
+    mv dst_ptr, dst
+L(strcpy_loop):
+    vsetvli ivl, zero, e8, ELEM_LMUL_SETTING, ta, ma
+    vle8ff.v vstr1, (src)
+    vmseq.vx vmask2, vstr1, zero
+    csrr cur_vl, vl
+    vfirst.m active_elem_pos, vmask2
+    vmsif.m vmask1, vmask2
+    add src, src, cur_vl
+    vse8.v vstr1, (dst_ptr), vmask1.t
+    add dst_ptr, dst_ptr, cur_vl
+    bltz active_elem_pos, L(strcpy_loop)
+
+    ret
+.option pop
+END (STRCPY)
+libc_hidden_builtin_def (strcpy)
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
index 41ba27793d..c82693251a 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
@@ -9,6 +9,9 @@ sysdep_routines += \
   strcat \
   strcat-generic \
   strcat-vector \
+  strcpy \
+  strcpy-generic \
+  strcpy-vector \
   # sysdep_routines
 
 CFLAGS-memcpy_noalignment.c += -mno-strict-align
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 af64c04249..f4154bb8f7 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/ifunc-impl-list.c
@@ -58,5 +58,10 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 			      __strcat_vector)
 	      IFUNC_IMPL_ADD (array, i, strcat, 1, __strcat_generic))
 
+  IFUNC_IMPL (i, name, strcpy,
+	      IFUNC_IMPL_ADD (array, i, strcpy, rvv_enabled,
+			      __strcpy_vector)
+	      IFUNC_IMPL_ADD (array, i, strcpy, 1, __strcpy_generic))
+
   return 0;
 }
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/strcpy.c b/sysdeps/unix/sysv/linux/riscv/multiarch/strcpy.c
new file mode 100644
index 0000000000..ba47e8f89c
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/strcpy.c
@@ -0,0 +1,56 @@
+/* Multiple versions of strcpy.
+   All versions must be listed in ifunc-impl-list.c.
+   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)
+/* Redefine strcpy so that the compiler won't complain about the type
+   mismatch with the IFUNC selector in strong_alias, below.  */
+# undef strcpy
+# define strcpy __redirect_strcpy
+# include <stdint.h>
+# include <string.h>
+# include <ifunc-init.h>
+# include <riscv-ifunc.h>
+# include <sys/hwprobe.h>
+
+extern __typeof (__redirect_strcpy) __libc_strcpy;
+
+extern __typeof (__redirect_strcpy) __strcpy_generic attribute_hidden;
+extern __typeof (__redirect_strcpy) __strcpy_vector attribute_hidden;
+
+static inline __typeof (__redirect_strcpy) *
+select_strcpy_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 __strcpy_vector;
+  return __strcpy_generic;
+}
+
+riscv_libc_ifunc (__libc_strcpy, select_strcpy_ifunc);
+
+# undef strcpy
+strong_alias (__libc_strcpy, strcpy);
+# ifdef SHARED
+__hidden_ver1 (strcpy, __GI_strcpy, __redirect_strcpy)
+  __attribute__ ((visibility ("hidden"))) __attribute_copy__ (strcpy);
+# endif
+#else
+# include <string/strcpy.c>
+#endif
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