[PATCH v3 2/2] malloc: aarch64: Add ifuncs for malloc functions
Yury Khrustalev
yury.khrustalev@arm.com
Fri Aug 14 09:23:24 GMT 2026
Introduce ifuncs and resolvers for functions pertinent to the
malloc interface on the AArch64 target: malloc, calloc, free,
realloc, memalign, valloc, pvalloc, posix_memalign, aligned_alloc,
free_sized, free_aligned_sized, malloc_usable_size.
A target can define the USE_MULTIARCH_MALLOC macro. In this case
it must provide alternative aliases for the malloc functions that
point to the ifuncs.
This implementation respects the --disable-multi-arch configure
flag. If multi-arch support is disabled, the generic aliases
are used on aarch64.
This patch contains aarch64-specific resolvers. At this point they
return core implementations but in the future they can be changed
to support for features, e.g. to handle memory tagging.
---
malloc/malloc-internal.h | 1 +
malloc/malloc.c | 11 ++-
sysdeps/aarch64/multiarch/Makefile | 6 ++
sysdeps/aarch64/multiarch/malloc-ifuncs.c | 82 +++++++++++++++++++++++
sysdeps/aarch64/multiarch/malloc-ifuncs.h | 25 +++++++
sysdeps/generic/malloc-ifuncs.h | 36 ++++++++++
6 files changed, 159 insertions(+), 2 deletions(-)
create mode 100644 sysdeps/aarch64/multiarch/malloc-ifuncs.c
create mode 100644 sysdeps/aarch64/multiarch/malloc-ifuncs.h
create mode 100644 sysdeps/generic/malloc-ifuncs.h
diff --git a/malloc/malloc-internal.h b/malloc/malloc-internal.h
index 4b36a76cf8..29bc3734c6 100644
--- a/malloc/malloc-internal.h
+++ b/malloc/malloc-internal.h
@@ -25,6 +25,7 @@
#include <hugepages.h>
#include <calloc-clear-memory.h>
#include <malloc-api.h>
+#include <malloc-ifuncs.h>
/* Called in the parent process before a fork. */
void __malloc_fork_lock_parent (void) attribute_hidden;
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 4866c59e65..5fc35a14f4 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -5168,6 +5168,9 @@ __malloc_info (int options, FILE *fp)
}
#if IS_IN (libc)
+
+/* See sysdeps/generic/malloc-ifuncs.h for details. */
+# if !USE_MULTIARCH_MALLOC
strong_alias (__libc_malloc, malloc)
strong_alias (__libc_realloc, realloc)
strong_alias (__libc_free, free)
@@ -5180,6 +5183,7 @@ weak_alias (__malloc_usable_size, malloc_usable_size)
weak_alias (__aligned_alloc, aligned_alloc)
weak_alias (__free_sized, free_sized)
weak_alias (__free_aligned_sized, free_aligned_sized)
+#endif /* !USE_MULTIARCH_MALLOC */
weak_alias (__malloc_info, malloc_info)
weak_alias (__libc_mallinfo, mallinfo)
@@ -5187,11 +5191,14 @@ weak_alias (__libc_mallinfo2, mallinfo2)
weak_alias (__libc_mallopt, mallopt)
weak_alias (__malloc_stats, malloc_stats)
weak_alias (__malloc_trim, malloc_trim)
+
#endif /* IS_IN (libc) */
-#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_26)
+#if !USE_MULTIARCH_MALLOC
+# if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_26)
compat_symbol (libc, __libc_free, cfree, GLIBC_2_0);
-#endif
+# endif
+#endif /* !USE_MULTIARCH_MALLOC */
/* ------------------------------------------------------------
History:
diff --git a/sysdeps/aarch64/multiarch/Makefile b/sysdeps/aarch64/multiarch/Makefile
index 6294a70c25..a8a03a0491 100644
--- a/sysdeps/aarch64/multiarch/Makefile
+++ b/sysdeps/aarch64/multiarch/Makefile
@@ -20,3 +20,9 @@ sysdep_routines += \
strlen_generic \
# sysdep_routines
endif # ifeq ($(subdir),string)
+
+ifeq ($(subdir),malloc)
+sysdep_routines += \
+ malloc-ifuncs \
+ # sysdep_routines
+endif # ifeq ($(subdir),malloc)
diff --git a/sysdeps/aarch64/multiarch/malloc-ifuncs.c b/sysdeps/aarch64/multiarch/malloc-ifuncs.c
new file mode 100644
index 0000000000..4b5db036ff
--- /dev/null
+++ b/sysdeps/aarch64/multiarch/malloc-ifuncs.c
@@ -0,0 +1,82 @@
+/* Code for ifunc resolvers for malloc: aarch64 version.
+ 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 "malloc-ifuncs.h"
+
+#if USE_MULTIARCH_MALLOC
+# if IS_IN (libc)
+
+#include <init-arch.h>
+#include <malloc-api.h>
+#include <shlib-compat.h>
+
+libc_ifunc_hidden (__libc_malloc, __libc_malloc_redirect,
+ __libc_malloc)
+strong_alias (__libc_malloc_redirect, malloc)
+
+libc_ifunc_hidden (__libc_calloc, __libc_calloc_redirect,
+ __libc_calloc)
+weak_alias (__libc_calloc_redirect, calloc)
+
+libc_ifunc_hidden (__libc_memalign, __libc_memalign_redirect,
+ __libc_memalign)
+weak_alias (__libc_memalign_redirect, memalign)
+
+libc_ifunc_hidden (__libc_valloc, __libc_valloc_redirect,
+ __libc_valloc)
+weak_alias (__libc_valloc_redirect, valloc)
+
+libc_ifunc_hidden (__libc_pvalloc, __libc_pvalloc_redirect,
+ __libc_pvalloc)
+weak_alias (__libc_pvalloc_redirect, pvalloc)
+
+libc_ifunc_hidden (__libc_realloc, __libc_realloc_redirect,
+ __libc_realloc)
+strong_alias (__libc_realloc_redirect, realloc)
+
+libc_ifunc_hidden (__libc_free, __libc_free_redirect,
+ __libc_free)
+strong_alias (__libc_free_redirect, free)
+
+libc_ifunc_hidden (__malloc_usable_size, __malloc_usable_size_redirect,
+ __malloc_usable_size)
+weak_alias (__malloc_usable_size_redirect, malloc_usable_size)
+
+libc_ifunc_hidden (__posix_memalign, __posix_memalign_redirect,
+ __posix_memalign)
+weak_alias (__posix_memalign_redirect, posix_memalign)
+
+libc_ifunc_hidden (__aligned_alloc, __aligned_alloc_redirect,
+ __aligned_alloc)
+weak_alias (__aligned_alloc_redirect, aligned_alloc)
+
+libc_ifunc_hidden (__free_sized, __free_sized_redirect,
+ __free_sized)
+weak_alias (__free_sized_redirect, free_sized)
+
+libc_ifunc_hidden (__free_aligned_sized, __free_aligned_sized_redirect,
+ __free_aligned_sized)
+weak_alias (__free_aligned_sized_redirect, free_aligned_sized)
+
+# endif /* IS_IN (libc) */
+
+# if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_26)
+compat_symbol (libc, __libc_free_redirect, cfree, GLIBC_2_0);
+# endif
+
+#endif /* #if USE_MULTIARCH_MALLOC */
diff --git a/sysdeps/aarch64/multiarch/malloc-ifuncs.h b/sysdeps/aarch64/multiarch/malloc-ifuncs.h
new file mode 100644
index 0000000000..abd5d3ef19
--- /dev/null
+++ b/sysdeps/aarch64/multiarch/malloc-ifuncs.h
@@ -0,0 +1,25 @@
+/* Definitions for ifunc resolvers for malloc: aarch64 version.
+ 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/>. */
+
+#ifndef _AARCH64_MALLOC_IFUNCS_H
+#define _AARCH64_MALLOC_IFUNCS_H
+
+/* AArch64 target provides ifuncs for malloc functions. */
+#define USE_MULTIARCH_MALLOC 1
+
+#endif /* _AARCH64_MALLOC_IFUNCS_H */
diff --git a/sysdeps/generic/malloc-ifuncs.h b/sysdeps/generic/malloc-ifuncs.h
new file mode 100644
index 0000000000..8fe88af95e
--- /dev/null
+++ b/sysdeps/generic/malloc-ifuncs.h
@@ -0,0 +1,36 @@
+/* Definitions for ifunc resolvers for malloc: generic version.
+ 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/>. */
+
+#ifndef _GENERIC_MALLOC_IFUNCS_H
+#define _GENERIC_MALLOC_IFUNCS_H
+
+/* Targets that support GNU ifuncs should define this macro
+ if they provide ifuncs for malloc functions.
+
+ When USE_MULTIARCH_MALLOC is defined as 1, the following
+ functions should be implemented via ifuncs:
+
+ malloc, calloc, free, realloc
+ memalign, valloc, pvalloc
+ posix_memalign
+ malloc_usable_size
+ aligned_alloc, free_sized, free_aligned_sized
+*/
+#define USE_MULTIARCH_MALLOC 0
+
+#endif /* _GENERIC_MALLOC_IFUNCS_H */
--
2.47.3
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