diff mbox

Add ifunc memcpy and memmove for aarch64

Message ID 1486509609.2866.59.camel@caviumnetworks.com
State New, archived
Headers show

Commit Message

Steve Ellcey Feb. 7, 2017, 11:20 p.m. UTC
OK, here is the basic IFUNC enablement for aarch64 without the
memcpy/memmove changes that use it.  I verified that it builds and
causes no regressions on aarch64.  As mentioned in the original email
this code depends on the mrs instruction which is privileged, but the
4.11 kernel will have emulation for it (https://lkml.org/lkml/2017/1/10
/816).

OK to checkin this part?

Steve Ellcey
sellcey@cavium.com


2017-02-07  Steve Ellcey  <sellcey@caviumnetworks.com>
	    Adhemerval Zanella  <adhemerval.zanella@linaro.org>

	* sysdeps/aarch64/dl-machine.h: Include cpu-features.c.
	(DL_PLATFORM_INIT): New define.
	(dl_platform_init): New function.
	* sysdeps/aarch64/ldsodefs.h: Include cpu-features.h.
	* sysdeps/unix/sysv/linux/aarch64/cpu-features.c: New file.
	* sysdeps/unix/sysv/linux/aarch64/cpu-features.h: Ditto.
	* sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c: Ditto.
	* sysdeps/unix/sysv/linux/aarch64/libc-start.c: Ditto.

Comments

Siddhesh Poyarekar Feb. 8, 2017, 5:45 a.m. UTC | #1
On Wednesday 08 February 2017 04:50 AM, Steve Ellcey wrote:
> OK, here is the basic IFUNC enablement for aarch64 without the
> memcpy/memmove changes that use it.  I verified that it builds and
> causes no regressions on aarch64.  As mentioned in the original email
> this code depends on the mrs instruction which is privileged, but the
> 4.11 kernel will have emulation for it (https://lkml.org/lkml/2017/1/10
> /816).
> 
> OK to checkin this part?

Looks OK with a couple of nits below.

> 
> Steve Ellcey
> sellcey@cavium.com
> 
> 
> 2017-02-07  Steve Ellcey  <sellcey@caviumnetworks.com>
> 	    Adhemerval Zanella  <adhemerval.zanella@linaro.org>
> 
> 	* sysdeps/aarch64/dl-machine.h: Include cpu-features.c.
> 	(DL_PLATFORM_INIT): New define.
> 	(dl_platform_init): New function.
> 	* sysdeps/aarch64/ldsodefs.h: Include cpu-features.h.
> 	* sysdeps/unix/sysv/linux/aarch64/cpu-features.c: New file.
> 	* sysdeps/unix/sysv/linux/aarch64/cpu-features.h: Ditto.
> 	* sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c: Ditto.
> 	* sysdeps/unix/sysv/linux/aarch64/libc-start.c: Ditto.

I was told years ago that we prefer 'Likewise' to 'Ditto' :)

> 
> 
> ifunc.patch
> 
> 
> diff --git a/sysdeps/aarch64/dl-machine.h b/sysdeps/aarch64/dl-machine.h
> index 84b8aec..15d79a6 100644
> --- a/sysdeps/aarch64/dl-machine.h
> +++ b/sysdeps/aarch64/dl-machine.h
> @@ -25,6 +25,7 @@
>  #include <tls.h>
>  #include <dl-tlsdesc.h>
>  #include <dl-irel.h>
> +#include <cpu-features.c>
>  
>  /* Return nonzero iff ELF header is compatible with the running host.  */
>  static inline int __attribute__ ((unused))
> @@ -225,6 +226,23 @@ _dl_start_user:								\n\
>  #define ELF_MACHINE_NO_REL 1
>  #define ELF_MACHINE_NO_RELA 0
>  
> +#define DL_PLATFORM_INIT dl_platform_init ()
> +
> +static inline void __attribute__ ((unused))
> +dl_platform_init (void)
> +{
> +  if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
> +    /* Avoid an empty string which would disturb us.  */
> +    GLRO(dl_platform) = NULL;
> +
> +#ifdef SHARED
> +  /* init_cpu_features has been called early from __libc_start_main in
> +     static executable.  */
> +  init_cpu_features (&GLRO(dl_aarch64_cpu_features));
> +#endif
> +}
> +
> +
>  static inline ElfW(Addr)
>  elf_machine_fixup_plt (struct link_map *map, lookup_t t,
>  		       const ElfW(Rela) *reloc,
> diff --git a/sysdeps/aarch64/ldsodefs.h b/sysdeps/aarch64/ldsodefs.h
> index f277074..ba4ada3 100644
> --- a/sysdeps/aarch64/ldsodefs.h
> +++ b/sysdeps/aarch64/ldsodefs.h
> @@ -20,6 +20,7 @@
>  #define _AARCH64_LDSODEFS_H 1
>  
>  #include <elf.h>
> +#include <cpu-features.h>
>  
>  struct La_aarch64_regs;
>  struct La_aarch64_retval;
> diff --git a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
> index e69de29..8e4b514 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
> +++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
> @@ -0,0 +1,38 @@
> +/* Initialize CPU feature data.  AArch64 version.
> +   This file is part of the GNU C Library.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +
> +   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
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <cpu-features.h>
> +
> +#ifndef HWCAP_CPUID
> +# define HWCAP_CPUID		(1 << 11)
> +#endif
> +
> +static inline void
> +init_cpu_features (struct cpu_features *cpu_features)
> +{
> +  if (GLRO(dl_hwcap) & HWCAP_CPUID)
> +    {
> +      register uint64_t id = 0;
> +      asm volatile ("mrs %0, midr_el1" : "=r"(id));
> +      cpu_features->midr_el1 = id;
> +    }
> +  else
> +    {
> +      cpu_features->midr_el1 = 0;
> +    }
> +}
> diff --git a/sysdeps/unix/sysv/linux/aarch64/cpu-features.h b/sysdeps/unix/sysv/linux/aarch64/cpu-features.h
> index e69de29..c92b650 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.h
> +++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.h
> @@ -0,0 +1,49 @@
> +/* Initialize CPU feature data.  AArch64 version.
> +   This file is part of the GNU C Library.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +
> +   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
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef _CPU_FEATURES_AARCH64_H
> +#define _CPU_FEATURES_AARCH64_H
> +
> +#include <stdint.h>
> +
> +#define MIDR_PARTNUM_SHIFT	4
> +#define MIDR_PARTNUM_MASK	(0xfff << MIDR_PARTNUM_SHIFT)
> +#define MIDR_PARTNUM(midr)	\
> +	(((midr) & MIDR_PARTNUM_MASK) >> MIDR_PARTNUM_SHIFT)
> +#define MIDR_ARCHITECTURE_SHIFT	16
> +#define MIDR_ARCHITECTURE_MASK	(0xf << MIDR_ARCHITECTURE_SHIFT)
> +#define MIDR_ARCHITECTURE(midr)	\
> +	(((midr) & MIDR_ARCHITECTURE_MASK) >> MIDR_ARCHITECTURE_SHIFT)
> +#define MIDR_VARIANT_SHIFT	20
> +#define MIDR_VARIANT_MASK	(0xf << MIDR_VARIANT_SHIFT)
> +#define MIDR_VARIANT(midr)	\
> +	(((midr) & MIDR_VARIANT_MASK) >> MIDR_VARIANT_SHIFT)
> +#define MIDR_IMPLEMENTOR_SHIFT	24
> +#define MIDR_IMPLEMENTOR_MASK	(0xff << MIDR_IMPLEMENTOR_SHIFT)
> +#define MIDR_IMPLEMENTOR(midr)	\
> +	(((midr) & MIDR_IMPLEMENTOR_MASK) >> MIDR_IMPLEMENTOR_SHIFT)
> +
> +#define IS_THUNDERX(midr) (MIDR_IMPLEMENTOR(midr) == 'C'	\
> +			   && MIDR_PARTNUM(midr) == 0x0a1)
> +
> +struct cpu_features
> +{
> +  uint64_t midr_el1;
> +};
> +
> +#endif /* _CPU_FEATURES_AARCH64_H  */
> diff --git a/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c b/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c
> index e69de29..438046a 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c
> +++ b/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c
> @@ -0,0 +1,60 @@
> +/* Data for AArch64 version of processor capability information.
> +   Linux version.
> +   Copyright (C) 2017 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
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* If anything should be added here check whether the size of each string
> +   is still ok with the given array size.
> +
> +   All the #ifdefs in the definitions are quite irritating but
> +   necessary if we want to avoid duplicating the information.  There
> +   are three different modes:
> +
> +   - PROCINFO_DECL is defined.  This means we are only interested in
> +     declarations.
> +
> +   - PROCINFO_DECL is not defined:
> +
> +     + if SHARED is defined the file is included in an array
> +       initializer.  The .element = { ... } syntax is needed.
> +
> +     + if SHARED is not defined a normal array initialization is
> +       needed.
> +  */
> +
> +#ifndef PROCINFO_CLASS
> +# define PROCINFO_CLASS
> +#endif
> +
> +#if !IS_IN (ldconfig)
> +# if !defined PROCINFO_DECL && defined SHARED
> +  ._dl_aarch64_cpu_features
> +# else
> +PROCINFO_CLASS struct cpu_features _dl_aarch64_cpu_features
> +# endif
> +# ifndef PROCINFO_DECL
> += { }
> +# endif
> +# if !defined SHARED || defined PROCINFO_DECL
> +;
> +# else
> +,
> +# endif
> +#endif
> +
> +#undef PROCINFO_DECL
> +#undef PROCINFO_CLASS
> diff --git a/sysdeps/unix/sysv/linux/aarch64/libc-start.c b/sysdeps/unix/sysv/linux/aarch64/libc-start.c
> index e69de29..c98aff1 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/libc-start.c
> +++ b/sysdeps/unix/sysv/linux/aarch64/libc-start.c
> @@ -0,0 +1,40 @@

You've forgotten to add a one line description for this file.

> +/* Copyright (C) 2017 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
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifdef SHARED
> +# include <csu/libc-start.c>
> +# else
> +/* The main work is done in the generic function.  */
> +# define LIBC_START_DISABLE_INLINE
> +# define LIBC_START_MAIN generic_start_main
> +# include <csu/libc-start.c>
> +# include <cpu-features.c>
> +
> +extern struct cpu_features _dl_aarch64_cpu_features;
> +
> +int
> +__libc_start_main (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
> +		   int argc, char **argv,
> +		   __typeof (main) init,
> +		   void (*fini) (void),
> +		   void (*rtld_fini) (void), void *stack_end)
> +{
> +  init_cpu_features (&_dl_aarch64_cpu_features);
> +  return generic_start_main (main, argc, argv, init, fini, rtld_fini,
> +			     stack_end);
> +}
> +#endif
>
Siddhesh Poyarekar Feb. 8, 2017, 5:46 a.m. UTC | #2
On Wednesday 08 February 2017 11:15 AM, Siddhesh Poyarekar wrote:
> Looks OK with a couple of nits below.

Oh and I suppose you need an ack from the ARM maintainers as well before
you push.

Siddhesh
Szabolcs Nagy Feb. 8, 2017, 12:03 p.m. UTC | #3
On 08/02/17 05:46, Siddhesh Poyarekar wrote:
> On Wednesday 08 February 2017 11:15 AM, Siddhesh Poyarekar wrote:
>> Looks OK with a couple of nits below.
> 
> Oh and I suppose you need an ack from the ARM maintainers as well before
> you push.
> 

arm maintainer != aarch64 maintainer.
diff mbox

Patch

diff --git a/sysdeps/aarch64/dl-machine.h b/sysdeps/aarch64/dl-machine.h
index 84b8aec..15d79a6 100644
--- a/sysdeps/aarch64/dl-machine.h
+++ b/sysdeps/aarch64/dl-machine.h
@@ -25,6 +25,7 @@ 
 #include <tls.h>
 #include <dl-tlsdesc.h>
 #include <dl-irel.h>
+#include <cpu-features.c>
 
 /* Return nonzero iff ELF header is compatible with the running host.  */
 static inline int __attribute__ ((unused))
@@ -225,6 +226,23 @@  _dl_start_user:								\n\
 #define ELF_MACHINE_NO_REL 1
 #define ELF_MACHINE_NO_RELA 0
 
+#define DL_PLATFORM_INIT dl_platform_init ()
+
+static inline void __attribute__ ((unused))
+dl_platform_init (void)
+{
+  if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
+    /* Avoid an empty string which would disturb us.  */
+    GLRO(dl_platform) = NULL;
+
+#ifdef SHARED
+  /* init_cpu_features has been called early from __libc_start_main in
+     static executable.  */
+  init_cpu_features (&GLRO(dl_aarch64_cpu_features));
+#endif
+}
+
+
 static inline ElfW(Addr)
 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 		       const ElfW(Rela) *reloc,
diff --git a/sysdeps/aarch64/ldsodefs.h b/sysdeps/aarch64/ldsodefs.h
index f277074..ba4ada3 100644
--- a/sysdeps/aarch64/ldsodefs.h
+++ b/sysdeps/aarch64/ldsodefs.h
@@ -20,6 +20,7 @@ 
 #define _AARCH64_LDSODEFS_H 1
 
 #include <elf.h>
+#include <cpu-features.h>
 
 struct La_aarch64_regs;
 struct La_aarch64_retval;
diff --git a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
index e69de29..8e4b514 100644
--- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
+++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
@@ -0,0 +1,38 @@ 
+/* Initialize CPU feature data.  AArch64 version.
+   This file is part of the GNU C Library.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+
+   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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <cpu-features.h>
+
+#ifndef HWCAP_CPUID
+# define HWCAP_CPUID		(1 << 11)
+#endif
+
+static inline void
+init_cpu_features (struct cpu_features *cpu_features)
+{
+  if (GLRO(dl_hwcap) & HWCAP_CPUID)
+    {
+      register uint64_t id = 0;
+      asm volatile ("mrs %0, midr_el1" : "=r"(id));
+      cpu_features->midr_el1 = id;
+    }
+  else
+    {
+      cpu_features->midr_el1 = 0;
+    }
+}
diff --git a/sysdeps/unix/sysv/linux/aarch64/cpu-features.h b/sysdeps/unix/sysv/linux/aarch64/cpu-features.h
index e69de29..c92b650 100644
--- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.h
+++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.h
@@ -0,0 +1,49 @@ 
+/* Initialize CPU feature data.  AArch64 version.
+   This file is part of the GNU C Library.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+
+   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
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _CPU_FEATURES_AARCH64_H
+#define _CPU_FEATURES_AARCH64_H
+
+#include <stdint.h>
+
+#define MIDR_PARTNUM_SHIFT	4
+#define MIDR_PARTNUM_MASK	(0xfff << MIDR_PARTNUM_SHIFT)
+#define MIDR_PARTNUM(midr)	\
+	(((midr) & MIDR_PARTNUM_MASK) >> MIDR_PARTNUM_SHIFT)
+#define MIDR_ARCHITECTURE_SHIFT	16
+#define MIDR_ARCHITECTURE_MASK	(0xf << MIDR_ARCHITECTURE_SHIFT)
+#define MIDR_ARCHITECTURE(midr)	\
+	(((midr) & MIDR_ARCHITECTURE_MASK) >> MIDR_ARCHITECTURE_SHIFT)
+#define MIDR_VARIANT_SHIFT	20
+#define MIDR_VARIANT_MASK	(0xf << MIDR_VARIANT_SHIFT)
+#define MIDR_VARIANT(midr)	\
+	(((midr) & MIDR_VARIANT_MASK) >> MIDR_VARIANT_SHIFT)
+#define MIDR_IMPLEMENTOR_SHIFT	24
+#define MIDR_IMPLEMENTOR_MASK	(0xff << MIDR_IMPLEMENTOR_SHIFT)
+#define MIDR_IMPLEMENTOR(midr)	\
+	(((midr) & MIDR_IMPLEMENTOR_MASK) >> MIDR_IMPLEMENTOR_SHIFT)
+
+#define IS_THUNDERX(midr) (MIDR_IMPLEMENTOR(midr) == 'C'	\
+			   && MIDR_PARTNUM(midr) == 0x0a1)
+
+struct cpu_features
+{
+  uint64_t midr_el1;
+};
+
+#endif /* _CPU_FEATURES_AARCH64_H  */
diff --git a/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c b/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c
index e69de29..438046a 100644
--- a/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c
+++ b/sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c
@@ -0,0 +1,60 @@ 
+/* Data for AArch64 version of processor capability information.
+   Linux version.
+   Copyright (C) 2017 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
+   <http://www.gnu.org/licenses/>.  */
+
+/* If anything should be added here check whether the size of each string
+   is still ok with the given array size.
+
+   All the #ifdefs in the definitions are quite irritating but
+   necessary if we want to avoid duplicating the information.  There
+   are three different modes:
+
+   - PROCINFO_DECL is defined.  This means we are only interested in
+     declarations.
+
+   - PROCINFO_DECL is not defined:
+
+     + if SHARED is defined the file is included in an array
+       initializer.  The .element = { ... } syntax is needed.
+
+     + if SHARED is not defined a normal array initialization is
+       needed.
+  */
+
+#ifndef PROCINFO_CLASS
+# define PROCINFO_CLASS
+#endif
+
+#if !IS_IN (ldconfig)
+# if !defined PROCINFO_DECL && defined SHARED
+  ._dl_aarch64_cpu_features
+# else
+PROCINFO_CLASS struct cpu_features _dl_aarch64_cpu_features
+# endif
+# ifndef PROCINFO_DECL
+= { }
+# endif
+# if !defined SHARED || defined PROCINFO_DECL
+;
+# else
+,
+# endif
+#endif
+
+#undef PROCINFO_DECL
+#undef PROCINFO_CLASS
diff --git a/sysdeps/unix/sysv/linux/aarch64/libc-start.c b/sysdeps/unix/sysv/linux/aarch64/libc-start.c
index e69de29..c98aff1 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libc-start.c
+++ b/sysdeps/unix/sysv/linux/aarch64/libc-start.c
@@ -0,0 +1,40 @@ 
+/* Copyright (C) 2017 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
+   <http://www.gnu.org/licenses/>.  */
+
+#ifdef SHARED
+# include <csu/libc-start.c>
+# else
+/* The main work is done in the generic function.  */
+# define LIBC_START_DISABLE_INLINE
+# define LIBC_START_MAIN generic_start_main
+# include <csu/libc-start.c>
+# include <cpu-features.c>
+
+extern struct cpu_features _dl_aarch64_cpu_features;
+
+int
+__libc_start_main (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
+		   int argc, char **argv,
+		   __typeof (main) init,
+		   void (*fini) (void),
+		   void (*rtld_fini) (void), void *stack_end)
+{
+  init_cpu_features (&_dl_aarch64_cpu_features);
+  return generic_start_main (main, argc, argv, init, fini, rtld_fini,
+			     stack_end);
+}
+#endif