[PATCH] Add a C wrapper for prctl [BZ #25896]

[PATCH] Add a C wrapper for prctl [BZ #25896]

[H.J. Lu]

Add a C wrapper to pass arguments in

/* Control process execution.  */
extern int prctl (int __option, ...) __THROW;

to prctl syscall:

extern int prctl (int, unsigned long int, unsigned long int,
		  unsigned long int, unsigned long int);
---
 include/sys/prctl.h                   |  2 ++
 sysdeps/unix/sysv/linux/Makefile      |  2 +-
 sysdeps/unix/sysv/linux/prctl.c       | 38 +++++++++++++++++++++++++++
 sysdeps/unix/sysv/linux/syscalls.list |  1 -
 4 files changed, 41 insertions(+), 2 deletions(-)
 create mode 100644 sysdeps/unix/sysv/linux/prctl.c

diff --git a/include/sys/prctl.h b/include/sys/prctl.h
index 0920ed642b..1a74d83879 100644
--- a/include/sys/prctl.h
+++ b/include/sys/prctl.h
@@ -4,6 +4,8 @@
 # ifndef _ISOMAC
 
 extern int __prctl (int __option, ...);
+libc_hidden_proto (__prctl)
+libc_hidden_proto (prctl)
 
 # endif /* !_ISOMAC */
 #endif
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index db78eeadd1..0326f92c40 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -59,7 +59,7 @@ sysdep_routines += adjtimex clone umount umount2 readahead sysctl \
 		   eventfd eventfd_read eventfd_write prlimit \
 		   personality epoll_wait tee vmsplice splice \
 		   open_by_handle_at mlock2 pkey_mprotect pkey_set pkey_get \
-		   timerfd_gettime timerfd_settime \
+		   timerfd_gettime timerfd_settime prctl \
 		   process_vm_readv process_vm_writev
 
 CFLAGS-gethostid.c = -fexceptions
diff --git a/sysdeps/unix/sysv/linux/prctl.c b/sysdeps/unix/sysv/linux/prctl.c
new file mode 100644
index 0000000000..b3fc12ccf5
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/prctl.c
@@ -0,0 +1,38 @@
+/* prctl - Linux specific syscall.
+   Copyright (C) 2020 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 <stdarg.h>
+#include <sys/prctl.h>
+
+int
+__prctl (int option, ...)
+{
+  va_list arg;
+  va_start (arg, option);
+  unsigned long int arg2 = va_arg (arg, unsigned long int);
+  unsigned long int arg3 = va_arg (arg, unsigned long int);
+  unsigned long int arg4 = va_arg (arg, unsigned long int);
+  unsigned long int arg5 = va_arg (arg, unsigned long int);
+  va_end (arg);
+  return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
+}
+
+libc_hidden_def (__prctl)
+weak_alias (__prctl, prctl)
+hidden_weak (prctl)
diff --git a/sysdeps/unix/sysv/linux/syscalls.list b/sysdeps/unix/sysv/linux/syscalls.list
index ced77d49fa..1d8893d1b8 100644
--- a/sysdeps/unix/sysv/linux/syscalls.list
+++ b/sysdeps/unix/sysv/linux/syscalls.list
@@ -43,7 +43,6 @@ nfsservctl	EXTRA	nfsservctl	i:ipp	__compat_nfsservctl	nfsservctl@GLIBC_2.0:GLIBC
 pipe		-	pipe		i:f	__pipe		pipe
 pipe2		-	pipe2		i:fi	__pipe2		pipe2
 pivot_root	EXTRA	pivot_root	i:ss	pivot_root
-prctl		EXTRA	prctl		i:iiiii	__prctl		prctl
 query_module	EXTRA	query_module	i:sipip	__compat_query_module	query_module@GLIBC_2.0:GLIBC_2.23
 quotactl	EXTRA	quotactl	i:isip	quotactl
 remap_file_pages -	remap_file_pages i:pUiUi	__remap_file_pages remap_file_pages
-- 
2.25.4

Re: [PATCH] Add a C wrapper for prctl [BZ #25896]

[Florian Weimer]

* H. J. Lu via Libc-alpha:

> Add a C wrapper to pass arguments in
>
> /* Control process execution.  */
> extern int prctl (int __option, ...) __THROW;
>
> to prctl syscall:
>
> extern int prctl (int, unsigned long int, unsigned long int,
> 		  unsigned long int, unsigned long int);
> ---
>  include/sys/prctl.h                   |  2 ++
>  sysdeps/unix/sysv/linux/Makefile      |  2 +-
>  sysdeps/unix/sysv/linux/prctl.c       | 38 +++++++++++++++++++++++++++
>  sysdeps/unix/sysv/linux/syscalls.list |  1 -
>  4 files changed, 41 insertions(+), 2 deletions(-)
>  create mode 100644 sysdeps/unix/sysv/linux/prctl.c
>
> diff --git a/include/sys/prctl.h b/include/sys/prctl.h
> index 0920ed642b..1a74d83879 100644
> --- a/include/sys/prctl.h
> +++ b/include/sys/prctl.h
> @@ -4,6 +4,8 @@
>  # ifndef _ISOMAC
>  
>  extern int __prctl (int __option, ...);
> +libc_hidden_proto (__prctl)
> +libc_hidden_proto (prctl)

I see we have some internal callers of prctl.  I will clean this up
later.

> diff --git a/sysdeps/unix/sysv/linux/prctl.c b/sysdeps/unix/sysv/linux/prctl.c
> new file mode 100644
> index 0000000000..b3fc12ccf5
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/prctl.c
> @@ -0,0 +1,38 @@
> +/* prctl - Linux specific syscall.
> +   Copyright (C) 2020 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 <stdarg.h>
> +#include <sys/prctl.h>
> +
> +int
> +__prctl (int option, ...)
> +{
> +  va_list arg;
> +  va_start (arg, option);
> +  unsigned long int arg2 = va_arg (arg, unsigned long int);
> +  unsigned long int arg3 = va_arg (arg, unsigned long int);
> +  unsigned long int arg4 = va_arg (arg, unsigned long int);
> +  unsigned long int arg5 = va_arg (arg, unsigned long int);
> +  va_end (arg);
> +  return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
> +}

Please add a comment that this over-reads arguments for some option
values, something like:

/* Unconditionally read all potential arguments.  This may pass
   garbage values to the kernel, but avoids the need for teaching
   glibc the argument counts of individual options (including ones
   that are added to the kernel in the future).  */

Rest looks fine.  Generated code is quite a bit worse, but I don't
think this matter here.

V2 [PATCH] Add a C wrapper for prctl [BZ #25896]

[H.J. Lu]

On Thu, Apr 30, 2020 at 09:26:18AM +0200, Florian Weimer wrote:
> * H. J. Lu via Libc-alpha:
> 
> > Add a C wrapper to pass arguments in
> >
> > /* Control process execution.  */
> > extern int prctl (int __option, ...) __THROW;
> >
> > to prctl syscall:
> >
> > extern int prctl (int, unsigned long int, unsigned long int,
> > 		  unsigned long int, unsigned long int);
> > ---
> >  include/sys/prctl.h                   |  2 ++
> >  sysdeps/unix/sysv/linux/Makefile      |  2 +-
> >  sysdeps/unix/sysv/linux/prctl.c       | 38 +++++++++++++++++++++++++++
> >  sysdeps/unix/sysv/linux/syscalls.list |  1 -
> >  4 files changed, 41 insertions(+), 2 deletions(-)
> >  create mode 100644 sysdeps/unix/sysv/linux/prctl.c
> >
> > diff --git a/include/sys/prctl.h b/include/sys/prctl.h
> > index 0920ed642b..1a74d83879 100644
> > --- a/include/sys/prctl.h
> > +++ b/include/sys/prctl.h
> > @@ -4,6 +4,8 @@
> >  # ifndef _ISOMAC
> >  
> >  extern int __prctl (int __option, ...);
> > +libc_hidden_proto (__prctl)
> > +libc_hidden_proto (prctl)
> 
> I see we have some internal callers of prctl.  I will clean this up
> later.
> 
> 
> Please add a comment that this over-reads arguments for some option
> values, something like:
> 
> /* Unconditionally read all potential arguments.  This may pass
>    garbage values to the kernel, but avoids the need for teaching
>    glibc the argument counts of individual options (including ones
>    that are added to the kernel in the future).  */
> 
> Rest looks fine.  Generated code is quite a bit worse, but I don't
> think this matter here.

Here is the updated patch.  I added the assembly version for x86.  Other
arches can do

#include <sysdeps/unix/sysv/linux/x86/prctl.S>

if they are similar.

OK for master?

Thanks.

H.J.
---
Add a C wrapper to pass arguments in

/* Control process execution.  */
extern int prctl (int __option, ...) __THROW;

to prctl syscall:

extern int prctl (int, unsigned long int, unsigned long int,
		  unsigned long int, unsigned long int);

On Linux/x86, since the prctl syscall interface:

extern int prctl (int, unsigned long int, unsigned long int,
		  unsigned long int, unsigned long int);

and the glibc prctl interface:

extern int prctl (int option, ...);

pass the arguments identically, the assembly verion:

PSEUDO (__prctl, prctl, 5)
	ret
PSEUDO_END (__prctl)

is used.
---
 include/sys/prctl.h                        |  2 +
 sysdeps/unix/sysv/linux/Makefile           |  2 +-
 sysdeps/unix/sysv/linux/prctl.c            | 43 ++++++++++++++++++++++
 sysdeps/unix/sysv/linux/syscalls.list      |  1 -
 sysdeps/unix/sysv/linux/x86/prctl.S        | 38 +++++++++++++++++++
 sysdeps/unix/sysv/linux/x86_64/x32/prctl.S | 28 ++++++++++++++
 6 files changed, 112 insertions(+), 2 deletions(-)
 create mode 100644 sysdeps/unix/sysv/linux/prctl.c
 create mode 100644 sysdeps/unix/sysv/linux/x86/prctl.S
 create mode 100644 sysdeps/unix/sysv/linux/x86_64/x32/prctl.S

diff --git a/include/sys/prctl.h b/include/sys/prctl.h
index 0920ed642b..1a74d83879 100644
--- a/include/sys/prctl.h
+++ b/include/sys/prctl.h
@@ -4,6 +4,8 @@
 # ifndef _ISOMAC
 
 extern int __prctl (int __option, ...);
+libc_hidden_proto (__prctl)
+libc_hidden_proto (prctl)
 
 # endif /* !_ISOMAC */
 #endif
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index db78eeadd1..0326f92c40 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -59,7 +59,7 @@ sysdep_routines += adjtimex clone umount umount2 readahead sysctl \
 		   eventfd eventfd_read eventfd_write prlimit \
 		   personality epoll_wait tee vmsplice splice \
 		   open_by_handle_at mlock2 pkey_mprotect pkey_set pkey_get \
-		   timerfd_gettime timerfd_settime \
+		   timerfd_gettime timerfd_settime prctl \
 		   process_vm_readv process_vm_writev
 
 CFLAGS-gethostid.c = -fexceptions
diff --git a/sysdeps/unix/sysv/linux/prctl.c b/sysdeps/unix/sysv/linux/prctl.c
new file mode 100644
index 0000000000..49049fd85f
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/prctl.c
@@ -0,0 +1,43 @@
+/* prctl - Linux specific syscall.
+   Copyright (C) 2020 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 <stdarg.h>
+#include <sys/prctl.h>
+
+/* Unconditionally read all potential arguments.  This may pass
+   garbage values to the kernel, but avoids the need for teaching
+   glibc the argument counts of individual options (including ones
+   that are added to the kernel in the future).  */
+
+int
+__prctl (int option, ...)
+{
+  va_list arg;
+  va_start (arg, option);
+  unsigned long int arg2 = va_arg (arg, unsigned long int);
+  unsigned long int arg3 = va_arg (arg, unsigned long int);
+  unsigned long int arg4 = va_arg (arg, unsigned long int);
+  unsigned long int arg5 = va_arg (arg, unsigned long int);
+  va_end (arg);
+  return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
+}
+
+libc_hidden_def (__prctl)
+weak_alias (__prctl, prctl)
+hidden_weak (prctl)
diff --git a/sysdeps/unix/sysv/linux/syscalls.list b/sysdeps/unix/sysv/linux/syscalls.list
index ced77d49fa..1d8893d1b8 100644
--- a/sysdeps/unix/sysv/linux/syscalls.list
+++ b/sysdeps/unix/sysv/linux/syscalls.list
@@ -43,7 +43,6 @@ nfsservctl	EXTRA	nfsservctl	i:ipp	__compat_nfsservctl	nfsservctl@GLIBC_2.0:GLIBC
 pipe		-	pipe		i:f	__pipe		pipe
 pipe2		-	pipe2		i:fi	__pipe2		pipe2
 pivot_root	EXTRA	pivot_root	i:ss	pivot_root
-prctl		EXTRA	prctl		i:iiiii	__prctl		prctl
 query_module	EXTRA	query_module	i:sipip	__compat_query_module	query_module@GLIBC_2.0:GLIBC_2.23
 quotactl	EXTRA	quotactl	i:isip	quotactl
 remap_file_pages -	remap_file_pages i:pUiUi	__remap_file_pages remap_file_pages
diff --git a/sysdeps/unix/sysv/linux/x86/prctl.S b/sysdeps/unix/sysv/linux/x86/prctl.S
new file mode 100644
index 0000000000..99bb62ad39
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/prctl.S
@@ -0,0 +1,38 @@
+/* prctl - Linux specific syscall.  Linux/x86 version.
+   Copyright (C) 2020 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>
+
+/* On Linux/x86, the prctl syscall interface:
+
+   extern int prctl (int, unsigned long int, unsigned long int,
+		     unsigned long int, unsigned long int);
+
+   and the glibc prctl interface:
+
+   extern int prctl (int option, ...);
+
+   pass the arguments identically.  */
+
+PSEUDO (__prctl, prctl, 5)
+	ret
+PSEUDO_END (__prctl)
+
+hidden_def (__prctl)
+weak_alias (__prctl, prctl)
+hidden_weak (prctl)
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/prctl.S b/sysdeps/unix/sysv/linux/x86_64/x32/prctl.S
new file mode 100644
index 0000000000..5acf5406a8
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/prctl.S
@@ -0,0 +1,28 @@
+/* prctl - Linux specific syscall.  Linux/x32 version.
+   Copyright (C) 2020 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>
+
+/* On Linux/x32, we need to zero-extend from 32 bits to 64 bits for the
+   last 4 arguments.  */
+
+#undef DOARGS_5
+#define DOARGS_5 \
+  movl %esi, %esi; movl %edx, %edx; movl %ecx, %r10d; movl %r8d, %r8d;
+
+#include <sysdeps/unix/sysv/linux/x86/prctl.S>
-- 
2.26.2

Re: V2 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Andreas Schwab]

On Apr 30 2020, H.J. Lu via Libc-alpha wrote:

> diff --git a/include/sys/prctl.h b/include/sys/prctl.h
> index 0920ed642b..1a74d83879 100644
> --- a/include/sys/prctl.h
> +++ b/include/sys/prctl.h
> @@ -4,6 +4,8 @@
>  # ifndef _ISOMAC
>  
>  extern int __prctl (int __option, ...);
> +libc_hidden_proto (__prctl)
> +libc_hidden_proto (prctl)

Why do you need the hidden alias for prctl?  All references inside
libc.so should use __prctl.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

Re: V2 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Florian Weimer]

* Andreas Schwab:

> On Apr 30 2020, H.J. Lu via Libc-alpha wrote:
>
>> diff --git a/include/sys/prctl.h b/include/sys/prctl.h
>> index 0920ed642b..1a74d83879 100644
>> --- a/include/sys/prctl.h
>> +++ b/include/sys/prctl.h
>> @@ -4,6 +4,8 @@
>>  # ifndef _ISOMAC
>>  
>>  extern int __prctl (int __option, ...);
>> +libc_hidden_proto (__prctl)
>> +libc_hidden_proto (prctl)
>
> Why do you need the hidden alias for prctl?  All references inside
> libc.so should use __prctl.

Right.  I want to clean this up in a separate patch.

Re: V2 [PATCH] Add a C wrapper for prctl [BZ #25896]

[H.J. Lu]

On Thu, Apr 30, 2020 at 6:43 AM Florian Weimer <fw@deneb.enyo.de> wrote:
>
> * Andreas Schwab:
>
> > On Apr 30 2020, H.J. Lu via Libc-alpha wrote:
> >
> >> diff --git a/include/sys/prctl.h b/include/sys/prctl.h
> >> index 0920ed642b..1a74d83879 100644
> >> --- a/include/sys/prctl.h
> >> +++ b/include/sys/prctl.h
> >> @@ -4,6 +4,8 @@
> >>  # ifndef _ISOMAC
> >>
> >>  extern int __prctl (int __option, ...);
> >> +libc_hidden_proto (__prctl)
> >> +libc_hidden_proto (prctl)
> >
> > Why do you need the hidden alias for prctl?  All references inside
> > libc.so should use __prctl.
>
> Right.  I want to clean this up in a separate patch.

I will wait for your cleanup patch and remove the hidden alias for prctl.

-- 
H.J.

Re: V2 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Andreas Schwab]

On Apr 30 2020, Florian Weimer wrote:

> * Andreas Schwab:
>
>> On Apr 30 2020, H.J. Lu via Libc-alpha wrote:
>>
>>> diff --git a/include/sys/prctl.h b/include/sys/prctl.h
>>> index 0920ed642b..1a74d83879 100644
>>> --- a/include/sys/prctl.h
>>> +++ b/include/sys/prctl.h
>>> @@ -4,6 +4,8 @@
>>>  # ifndef _ISOMAC
>>>  
>>>  extern int __prctl (int __option, ...);
>>> +libc_hidden_proto (__prctl)
>>> +libc_hidden_proto (prctl)
>>
>> Why do you need the hidden alias for prctl?  All references inside
>> libc.so should use __prctl.
>
> Right.  I want to clean this up in a separate patch.

??? Why adding it in the first place?

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

Re: V2 [PATCH] Add a C wrapper for prctl [BZ #25896]

[H.J. Lu]

On Thu, Apr 30, 2020 at 6:51 AM Andreas Schwab <schwab@linux-m68k.org> wrote:
>
> On Apr 30 2020, Florian Weimer wrote:
>
> > * Andreas Schwab:
> >
> >> On Apr 30 2020, H.J. Lu via Libc-alpha wrote:
> >>
> >>> diff --git a/include/sys/prctl.h b/include/sys/prctl.h
> >>> index 0920ed642b..1a74d83879 100644
> >>> --- a/include/sys/prctl.h
> >>> +++ b/include/sys/prctl.h
> >>> @@ -4,6 +4,8 @@
> >>>  # ifndef _ISOMAC
> >>>
> >>>  extern int __prctl (int __option, ...);
> >>> +libc_hidden_proto (__prctl)
> >>> +libc_hidden_proto (prctl)
> >>
> >> Why do you need the hidden alias for prctl?  All references inside
> >> libc.so should use __prctl.
> >
> > Right.  I want to clean this up in a separate patch.
>
> ??? Why adding it in the first place?
>
> Andreas.
>

It was there before my patch:

0000000000000000 T __GI___prctl
0000000000000000 T __GI_prctl
                 U _GLOBAL_OFFSET_TABLE_
                 U __libc_errno
0000000000000000 T __prctl
0000000000000000 W prctl

-- 
H.J.

Re: V2 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Florian Weimer]

* Andreas Schwab:

> On Apr 30 2020, Florian Weimer wrote:
>
>> * Andreas Schwab:
>>
>>> On Apr 30 2020, H.J. Lu via Libc-alpha wrote:
>>>
>>>> diff --git a/include/sys/prctl.h b/include/sys/prctl.h
>>>> index 0920ed642b..1a74d83879 100644
>>>> --- a/include/sys/prctl.h
>>>> +++ b/include/sys/prctl.h
>>>> @@ -4,6 +4,8 @@
>>>>  # ifndef _ISOMAC
>>>>  
>>>>  extern int __prctl (int __option, ...);
>>>> +libc_hidden_proto (__prctl)
>>>> +libc_hidden_proto (prctl)
>>>
>>> Why do you need the hidden alias for prctl?  All references inside
>>> libc.so should use __prctl.
>>
>> Right.  I want to clean this up in a separate patch.
>
> ??? Why adding it in the first place?

I thought pthread_getname was linked into libc, but looks like it's in
libpthread, so its use of prctl (not __prctl) should be fine.

H.J., what happens if you drop the hidden alias for prctl?

Re: V2 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Andreas Schwab]

On Apr 30 2020, H.J. Lu wrote:

> On Thu, Apr 30, 2020 at 6:51 AM Andreas Schwab <schwab@linux-m68k.org> wrote:
>>
>> On Apr 30 2020, Florian Weimer wrote:
>>
>> > * Andreas Schwab:
>> >
>> >> On Apr 30 2020, H.J. Lu via Libc-alpha wrote:
>> >>
>> >>> diff --git a/include/sys/prctl.h b/include/sys/prctl.h
>> >>> index 0920ed642b..1a74d83879 100644
>> >>> --- a/include/sys/prctl.h
>> >>> +++ b/include/sys/prctl.h
>> >>> @@ -4,6 +4,8 @@
>> >>>  # ifndef _ISOMAC
>> >>>
>> >>>  extern int __prctl (int __option, ...);
>> >>> +libc_hidden_proto (__prctl)
>> >>> +libc_hidden_proto (prctl)
>> >>
>> >> Why do you need the hidden alias for prctl?  All references inside
>> >> libc.so should use __prctl.
>> >
>> > Right.  I want to clean this up in a separate patch.
>>
>> ??? Why adding it in the first place?
>>
>> Andreas.
>>
>
> It was there before my patch:

That doesn't matter, the syscall template adds it blindly to all names.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

Re: V2 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Adhemerval Zanella]

On 30/04/2020 10:03, H.J. Lu via Libc-alpha wrote:

> Here is the updated patch.  I added the assembly version for x86.  Other
> arches can do
> 
> #include <sysdeps/unix/sysv/linux/x86/prctl.S>

Do we really an assembly optimization for this? I hardly think this
a hotstop symbol.

V3 [PATCH] Add a C wrapper for prctl [BZ #25896]

[H.J. Lu]

[-- Attachment #1: Type: text/plain, Size: 1192 bytes --]

On Thu, Apr 30, 2020 at 7:04 AM Andreas Schwab <schwab@linux-m68k.org> wrote:
>
> On Apr 30 2020, H.J. Lu wrote:
>
> > On Thu, Apr 30, 2020 at 6:51 AM Andreas Schwab <schwab@linux-m68k.org> wrote:
> >>
> >> On Apr 30 2020, Florian Weimer wrote:
> >>
> >> > * Andreas Schwab:
> >> >
> >> >> On Apr 30 2020, H.J. Lu via Libc-alpha wrote:
> >> >>
> >> >>> diff --git a/include/sys/prctl.h b/include/sys/prctl.h
> >> >>> index 0920ed642b..1a74d83879 100644
> >> >>> --- a/include/sys/prctl.h
> >> >>> +++ b/include/sys/prctl.h
> >> >>> @@ -4,6 +4,8 @@
> >> >>>  # ifndef _ISOMAC
> >> >>>
> >> >>>  extern int __prctl (int __option, ...);
> >> >>> +libc_hidden_proto (__prctl)
> >> >>> +libc_hidden_proto (prctl)
> >> >>
> >> >> Why do you need the hidden alias for prctl?  All references inside
> >> >> libc.so should use __prctl.
> >> >
> >> > Right.  I want to clean this up in a separate patch.
> >>
> >> ??? Why adding it in the first place?
> >>
> >> Andreas.
> >>
> >
> > It was there before my patch:
>
> That doesn't matter, the syscall template adds it blindly to all names.
>
> Andreas.
>

Here is the updated patch without

libc_hidden_proto (prctl)

OK for master?

Thanks.

-- 
H.J.

[-- Attachment #2: 0001-Add-a-C-wrapper-for-prctl-BZ-25896.patch --]
[-- Type: text/x-patch, Size: 7659 bytes --]

From ee8672af3ef5f3db438c0abb39b2673944181292 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 29 Apr 2020 07:38:49 -0700
Subject: [PATCH] Add a C wrapper for prctl [BZ #25896]

Add a C wrapper to pass arguments in

/* Control process execution.  */
extern int prctl (int __option, ...) __THROW;

to prctl syscall:

extern int prctl (int, unsigned long int, unsigned long int,
		  unsigned long int, unsigned long int);

On Linux/x86, since the prctl syscall interface:

extern int prctl (int, unsigned long int, unsigned long int,
		  unsigned long int, unsigned long int);

and the glibc prctl interface:

extern int prctl (int option, ...);

pass the arguments identically, the assembly verion:

PSEUDO (__prctl, prctl, 5)
	ret
PSEUDO_END (__prctl)

is used.
---
 include/sys/prctl.h                        |  1 +
 sysdeps/unix/sysv/linux/Makefile           |  2 +-
 sysdeps/unix/sysv/linux/prctl.c            | 42 ++++++++++++++++++++++
 sysdeps/unix/sysv/linux/syscalls.list      |  1 -
 sysdeps/unix/sysv/linux/x86/prctl.S        | 37 +++++++++++++++++++
 sysdeps/unix/sysv/linux/x86_64/x32/prctl.S | 28 +++++++++++++++
 6 files changed, 109 insertions(+), 2 deletions(-)
 create mode 100644 sysdeps/unix/sysv/linux/prctl.c
 create mode 100644 sysdeps/unix/sysv/linux/x86/prctl.S
 create mode 100644 sysdeps/unix/sysv/linux/x86_64/x32/prctl.S

diff --git a/include/sys/prctl.h b/include/sys/prctl.h
index 0920ed642b..d33f3a290e 100644
--- a/include/sys/prctl.h
+++ b/include/sys/prctl.h
@@ -4,6 +4,7 @@
 # ifndef _ISOMAC
 
 extern int __prctl (int __option, ...);
+libc_hidden_proto (__prctl)
 
 # endif /* !_ISOMAC */
 #endif
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index db78eeadd1..0326f92c40 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -59,7 +59,7 @@ sysdep_routines += adjtimex clone umount umount2 readahead sysctl \
 		   eventfd eventfd_read eventfd_write prlimit \
 		   personality epoll_wait tee vmsplice splice \
 		   open_by_handle_at mlock2 pkey_mprotect pkey_set pkey_get \
-		   timerfd_gettime timerfd_settime \
+		   timerfd_gettime timerfd_settime prctl \
 		   process_vm_readv process_vm_writev
 
 CFLAGS-gethostid.c = -fexceptions
diff --git a/sysdeps/unix/sysv/linux/prctl.c b/sysdeps/unix/sysv/linux/prctl.c
new file mode 100644
index 0000000000..d5725f14cf
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/prctl.c
@@ -0,0 +1,42 @@
+/* prctl - Linux specific syscall.
+   Copyright (C) 2020 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 <stdarg.h>
+#include <sys/prctl.h>
+
+/* Unconditionally read all potential arguments.  This may pass
+   garbage values to the kernel, but avoids the need for teaching
+   glibc the argument counts of individual options (including ones
+   that are added to the kernel in the future).  */
+
+int
+__prctl (int option, ...)
+{
+  va_list arg;
+  va_start (arg, option);
+  unsigned long int arg2 = va_arg (arg, unsigned long int);
+  unsigned long int arg3 = va_arg (arg, unsigned long int);
+  unsigned long int arg4 = va_arg (arg, unsigned long int);
+  unsigned long int arg5 = va_arg (arg, unsigned long int);
+  va_end (arg);
+  return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
+}
+
+libc_hidden_def (__prctl)
+weak_alias (__prctl, prctl)
diff --git a/sysdeps/unix/sysv/linux/syscalls.list b/sysdeps/unix/sysv/linux/syscalls.list
index ced77d49fa..1d8893d1b8 100644
--- a/sysdeps/unix/sysv/linux/syscalls.list
+++ b/sysdeps/unix/sysv/linux/syscalls.list
@@ -43,7 +43,6 @@ nfsservctl	EXTRA	nfsservctl	i:ipp	__compat_nfsservctl	nfsservctl@GLIBC_2.0:GLIBC
 pipe		-	pipe		i:f	__pipe		pipe
 pipe2		-	pipe2		i:fi	__pipe2		pipe2
 pivot_root	EXTRA	pivot_root	i:ss	pivot_root
-prctl		EXTRA	prctl		i:iiiii	__prctl		prctl
 query_module	EXTRA	query_module	i:sipip	__compat_query_module	query_module@GLIBC_2.0:GLIBC_2.23
 quotactl	EXTRA	quotactl	i:isip	quotactl
 remap_file_pages -	remap_file_pages i:pUiUi	__remap_file_pages remap_file_pages
diff --git a/sysdeps/unix/sysv/linux/x86/prctl.S b/sysdeps/unix/sysv/linux/x86/prctl.S
new file mode 100644
index 0000000000..ce9903ab15
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/prctl.S
@@ -0,0 +1,37 @@
+/* prctl - Linux specific syscall.  Linux/x86 version.
+   Copyright (C) 2020 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>
+
+/* On Linux/x86, the prctl syscall interface:
+
+   extern int prctl (int, unsigned long int, unsigned long int,
+		     unsigned long int, unsigned long int);
+
+   and the glibc prctl interface:
+
+   extern int prctl (int option, ...);
+
+   pass the arguments identically.  */
+
+PSEUDO (__prctl, prctl, 5)
+	ret
+PSEUDO_END (__prctl)
+
+hidden_def (__prctl)
+weak_alias (__prctl, prctl)
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/prctl.S b/sysdeps/unix/sysv/linux/x86_64/x32/prctl.S
new file mode 100644
index 0000000000..5acf5406a8
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/prctl.S
@@ -0,0 +1,28 @@
+/* prctl - Linux specific syscall.  Linux/x32 version.
+   Copyright (C) 2020 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>
+
+/* On Linux/x32, we need to zero-extend from 32 bits to 64 bits for the
+   last 4 arguments.  */
+
+#undef DOARGS_5
+#define DOARGS_5 \
+  movl %esi, %esi; movl %edx, %edx; movl %ecx, %r10d; movl %r8d, %r8d;
+
+#include <sysdeps/unix/sysv/linux/x86/prctl.S>
-- 
2.26.2

Re: V2 [PATCH] Add a C wrapper for prctl [BZ #25896]

[H.J. Lu]

On Thu, Apr 30, 2020 at 9:06 AM Adhemerval Zanella via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
>
>
> On 30/04/2020 10:03, H.J. Lu via Libc-alpha wrote:
>
> > Here is the updated patch.  I added the assembly version for x86.  Other
> > arches can do
> >
> > #include <sysdeps/unix/sysv/linux/x86/prctl.S>
>
> Do we really an assembly optimization for this? I hardly think this
> a hotstop symbol.

I have no strong opinion on this.

-- 
H.J.

Re: V2 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Florian Weimer]

* H. J. Lu via Libc-alpha:

> On Thu, Apr 30, 2020 at 9:06 AM Adhemerval Zanella via Libc-alpha
> <libc-alpha@sourceware.org> wrote:
>>
>>
>>
>> On 30/04/2020 10:03, H.J. Lu via Libc-alpha wrote:
>>
>> > Here is the updated patch.  I added the assembly version for x86.  Other
>> > arches can do
>> >
>> > #include <sysdeps/unix/sysv/linux/x86/prctl.S>
>>
>> Do we really an assembly optimization for this? I hardly think this
>> a hotstop symbol.
>
> I have no strong opinion on this.

Me neither.

Re: V3 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Florian Weimer]

* H. J. Lu via Libc-alpha:

> From ee8672af3ef5f3db438c0abb39b2673944181292 Mon Sep 17 00:00:00 2001
> From: "H.J. Lu" <hjl.tools@gmail.com>
> Date: Wed, 29 Apr 2020 07:38:49 -0700
> Subject: [PATCH] Add a C wrapper for prctl [BZ #25896]
>
> Add a C wrapper to pass arguments in

The commit message is only correct if you drop the .S files.

> /* Control process execution.  */
> extern int prctl (int __option, ...) __THROW;
>
> to prctl syscall:
>
> extern int prctl (int, unsigned long int, unsigned long int,
> 		  unsigned long int, unsigned long int);
>
> On Linux/x86, since the prctl syscall interface:
>
> extern int prctl (int, unsigned long int, unsigned long int,
> 		  unsigned long int, unsigned long int);
>
> and the glibc prctl interface:
>
> extern int prctl (int option, ...);
>
> pass the arguments identically, the assembly verion:
>
> PSEUDO (__prctl, prctl, 5)
> 	ret
> PSEUDO_END (__prctl)
>
> is used.

Doesn't x86 include x32?

Apart from these nits, the patch looks good.  Please settle the matter
of the .S files with Adhemerval. 8-)

[PATCH] Add a wrapper for prctl [BZ #25896]

[H.J. Lu]

[-- Attachment #1: Type: text/plain, Size: 1424 bytes --]

On Thu, Apr 30, 2020 at 9:53 AM Florian Weimer <fw@deneb.enyo.de> wrote:
>
> * H. J. Lu via Libc-alpha:
>
> > From ee8672af3ef5f3db438c0abb39b2673944181292 Mon Sep 17 00:00:00 2001
> > From: "H.J. Lu" <hjl.tools@gmail.com>
> > Date: Wed, 29 Apr 2020 07:38:49 -0700
> > Subject: [PATCH] Add a C wrapper for prctl [BZ #25896]
> >
> > Add a C wrapper to pass arguments in
>
> The commit message is only correct if you drop the .S files.
>
> > /* Control process execution.  */
> > extern int prctl (int __option, ...) __THROW;
> >
> > to prctl syscall:
> >
> > extern int prctl (int, unsigned long int, unsigned long int,
> >                 unsigned long int, unsigned long int);
> >
> > On Linux/x86, since the prctl syscall interface:
> >
> > extern int prctl (int, unsigned long int, unsigned long int,
> >                 unsigned long int, unsigned long int);
> >
> > and the glibc prctl interface:
> >
> > extern int prctl (int option, ...);
> >
> > pass the arguments identically, the assembly verion:
> >
> > PSEUDO (__prctl, prctl, 5)
> >       ret
> > PSEUDO_END (__prctl)
> >
> > is used.
>
> Doesn't x86 include x32?

Yes.

> Apart from these nits, the patch looks good.  Please settle the matter
> of the .S files with Adhemerval. 8-)

Since the C version is so much worse than the assembler version,
I prefer to include the assembler wrapper.  But I won't insist.

Adhemerval, please comment.

Thanks.

-- 
H.J.

[-- Attachment #2: 0001-Add-a-wrapper-for-prctl-BZ-25896.patch --]
[-- Type: application/x-patch, Size: 9212 bytes --]

Re: V2 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Adhemerval Zanella]

On 30/04/2020 13:51, Florian Weimer wrote:
> * H. J. Lu via Libc-alpha:
> 
>> On Thu, Apr 30, 2020 at 9:06 AM Adhemerval Zanella via Libc-alpha
>> <libc-alpha@sourceware.org> wrote:
>>>
>>>
>>>
>>> On 30/04/2020 10:03, H.J. Lu via Libc-alpha wrote:
>>>
>>>> Here is the updated patch.  I added the assembly version for x86.  Other
>>>> arches can do
>>>>
>>>> #include <sysdeps/unix/sysv/linux/x86/prctl.S>
>>>
>>> Do we really an assembly optimization for this? I hardly think this
>>> a hotstop symbol.
>>
>> I have no strong opinion on this.
> 
> Me neither.
> 
I would prefer to push for an assembly optimization for symbol that
performance is paramount and usually might appear as a hotspot. 
My understanding is usually prctl is used scarcely and I think
it would be better to use the C generic.

V4 [PATCH] Add a C wrapper for prctl [BZ #25896]

[H.J. Lu]

[-- Attachment #1: Type: text/plain, Size: 994 bytes --]

On Thu, Apr 30, 2020 at 10:24 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 30/04/2020 13:51, Florian Weimer wrote:
> > * H. J. Lu via Libc-alpha:
> >
> >> On Thu, Apr 30, 2020 at 9:06 AM Adhemerval Zanella via Libc-alpha
> >> <libc-alpha@sourceware.org> wrote:
> >>>
> >>>
> >>>
> >>> On 30/04/2020 10:03, H.J. Lu via Libc-alpha wrote:
> >>>
> >>>> Here is the updated patch.  I added the assembly version for x86.  Other
> >>>> arches can do
> >>>>
> >>>> #include <sysdeps/unix/sysv/linux/x86/prctl.S>
> >>>
> >>> Do we really an assembly optimization for this? I hardly think this
> >>> a hotstop symbol.
> >>
> >> I have no strong opinion on this.
> >
> > Me neither.
> >
> I would prefer to push for an assembly optimization for symbol that
> performance is paramount and usually might appear as a hotspot.
> My understanding is usually prctl is used scarcely and I think
> it would be better to use the C generic.

This is the patch I am checking in.

-- 
H.J.

[-- Attachment #2: 0001-Add-a-C-wrapper-for-prctl-BZ-25896.patch --]
[-- Type: text/x-patch, Size: 4192 bytes --]

From bd66a4111db106249d6f16fba7c55bd6cec1d779 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 29 Apr 2020 07:38:49 -0700
Subject: [PATCH] Add a C wrapper for prctl [BZ #25896]

Add a C wrapper to pass arguments in

/* Control process execution.  */
extern int prctl (int __option, ...) __THROW;

to prctl syscall:

extern int prctl (int, unsigned long int, unsigned long int,
		  unsigned long int, unsigned long int);
---
 include/sys/prctl.h                   |  1 +
 sysdeps/unix/sysv/linux/Makefile      |  2 +-
 sysdeps/unix/sysv/linux/prctl.c       | 42 +++++++++++++++++++++++++++
 sysdeps/unix/sysv/linux/syscalls.list |  1 -
 4 files changed, 44 insertions(+), 2 deletions(-)
 create mode 100644 sysdeps/unix/sysv/linux/prctl.c

diff --git a/include/sys/prctl.h b/include/sys/prctl.h
index 0920ed642b..d33f3a290e 100644
--- a/include/sys/prctl.h
+++ b/include/sys/prctl.h
@@ -4,6 +4,7 @@
 # ifndef _ISOMAC
 
 extern int __prctl (int __option, ...);
+libc_hidden_proto (__prctl)
 
 # endif /* !_ISOMAC */
 #endif
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index db78eeadd1..0326f92c40 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -59,7 +59,7 @@ sysdep_routines += adjtimex clone umount umount2 readahead sysctl \
 		   eventfd eventfd_read eventfd_write prlimit \
 		   personality epoll_wait tee vmsplice splice \
 		   open_by_handle_at mlock2 pkey_mprotect pkey_set pkey_get \
-		   timerfd_gettime timerfd_settime \
+		   timerfd_gettime timerfd_settime prctl \
 		   process_vm_readv process_vm_writev
 
 CFLAGS-gethostid.c = -fexceptions
diff --git a/sysdeps/unix/sysv/linux/prctl.c b/sysdeps/unix/sysv/linux/prctl.c
new file mode 100644
index 0000000000..d5725f14cf
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/prctl.c
@@ -0,0 +1,42 @@
+/* prctl - Linux specific syscall.
+   Copyright (C) 2020 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 <stdarg.h>
+#include <sys/prctl.h>
+
+/* Unconditionally read all potential arguments.  This may pass
+   garbage values to the kernel, but avoids the need for teaching
+   glibc the argument counts of individual options (including ones
+   that are added to the kernel in the future).  */
+
+int
+__prctl (int option, ...)
+{
+  va_list arg;
+  va_start (arg, option);
+  unsigned long int arg2 = va_arg (arg, unsigned long int);
+  unsigned long int arg3 = va_arg (arg, unsigned long int);
+  unsigned long int arg4 = va_arg (arg, unsigned long int);
+  unsigned long int arg5 = va_arg (arg, unsigned long int);
+  va_end (arg);
+  return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
+}
+
+libc_hidden_def (__prctl)
+weak_alias (__prctl, prctl)
diff --git a/sysdeps/unix/sysv/linux/syscalls.list b/sysdeps/unix/sysv/linux/syscalls.list
index ced77d49fa..1d8893d1b8 100644
--- a/sysdeps/unix/sysv/linux/syscalls.list
+++ b/sysdeps/unix/sysv/linux/syscalls.list
@@ -43,7 +43,6 @@ nfsservctl	EXTRA	nfsservctl	i:ipp	__compat_nfsservctl	nfsservctl@GLIBC_2.0:GLIBC
 pipe		-	pipe		i:f	__pipe		pipe
 pipe2		-	pipe2		i:fi	__pipe2		pipe2
 pivot_root	EXTRA	pivot_root	i:ss	pivot_root
-prctl		EXTRA	prctl		i:iiiii	__prctl		prctl
 query_module	EXTRA	query_module	i:sipip	__compat_query_module	query_module@GLIBC_2.0:GLIBC_2.23
 quotactl	EXTRA	quotactl	i:isip	quotactl
 remap_file_pages -	remap_file_pages i:pUiUi	__remap_file_pages remap_file_pages
-- 
2.26.2

Re: V3 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Florian Weimer]

* H. J. Lu:

> Here is the updated patch without
>
> libc_hidden_proto (prctl)
>
> OK for master?

Looks good to me.

Bad LOADARGS_N on PPC

[H.J. Lu]

On Thu, Apr 30, 2020 at 2:07 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Thu, Apr 30, 2020 at 1:29 PM Matheus Castanho <msc@linux.ibm.com> wrote:
> >
> > I see failures on all builds for all ppc* targets after this commit:
> >
> > ../sysdeps/unix/sysv/linux/prctl.c: In function ‘__prctl’:
> > ../sysdeps/unix/sysv/linux/prctl.c:36:21: error: unused variable ‘arg5’
> > [-Werror=unused-variable]
> >    36 |   unsigned long int arg5 = va_arg (arg, unsigned long int);
> >       |                     ^~~~
> > ../sysdeps/unix/sysv/linux/prctl.c:35:21: error: unused variable ‘arg4’
> > [-Werror=unused-variable]
> >    35 |   unsigned long int arg4 = va_arg (arg, unsigned long int);
> >       |                     ^~~~
> > ../sysdeps/unix/sysv/linux/prctl.c:34:21: error: unused variable ‘arg3’
> > [-Werror=unused-variable]
> >    34 |   unsigned long int arg3 = va_arg (arg, unsigned long int);
> >       |                     ^~~~
> > ../sysdeps/unix/sysv/linux/prctl.c:33:21: error: unused variable ‘arg2’
> > [-Werror=unused-variable]
> >    33 |   unsigned long int arg2 = va_arg (arg, unsigned long int);
> >       |
>
> II am not familiar with ppc. There are:
>
> return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
>
> Why are arg2, arg3, arg4, arg5 unused?  What are passed to kernel
> on ppc?
>

See:

https://sourceware.org/bugzilla/show_bug.cgi?id=25902

with a patch.   But I can't test it natively.

-- 
H.J.

Re: Bad LOADARGS_N on PPC

[Tulio Magno Quites Machado Filho]

"H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org> writes:

> See:
>
> https://sourceware.org/bugzilla/show_bug.cgi?id=25902
>
> with a patch.   But I can't test it natively.

Tested.  LGTM.

Could you push it, please?

-- 
Tulio Magno

[PATCH] powerpc: Rename argN to _argN in LOADARGS_N [BZ #25902]

[H.J. Lu]

[-- Attachment #1: Type: text/plain, Size: 598 bytes --]

On Thu, Apr 30, 2020 at 7:03 PM Tulio Magno Quites Machado Filho
<tuliom@ascii.art.br> wrote:
>
> "H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org> writes:
>
> > See:
> >
> > https://sourceware.org/bugzilla/show_bug.cgi?id=25902
> >
> > with a patch.   But I can't test it natively.
>
> Tested.  LGTM.
>
> Could you push it, please?

This is I am checking in.  I will backport it to 2.30/2.31 branches
together with

commit ff026950e280bc3e9487b41b460fb31bc5b57721
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Apr 30 10:42:43 2020 -0700

    Add a C wrapper for prctl [BZ #25896]

-- 
H.J.

[-- Attachment #2: 0001-powerpc-Rename-argN-to-_argN-in-LOADARGS_N-BZ-25902.patch --]
[-- Type: text/x-patch, Size: 3257 bytes --]

From 14f43dd34dcf1ba29386c01cd0b286dffb37412d Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Thu, 30 Apr 2020 15:49:47 -0700
Subject: [PATCH] powerpc: Rename argN to _argN in LOADARGS_N [BZ #25902]

LOADARGS_N in powerpc/sysdep.h uses argN as local variables.  It breaks
when argN is also a function argument.  Rename argN to _argN to avoid
conflict.
---
 sysdeps/unix/sysv/linux/powerpc/sysdep.h | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/powerpc/sysdep.h b/sysdeps/unix/sysv/linux/powerpc/sysdep.h
index fd79bbcf3c..b2bca598b9 100644
--- a/sysdeps/unix/sysv/linux/powerpc/sysdep.h
+++ b/sysdeps/unix/sysv/linux/powerpc/sysdep.h
@@ -100,53 +100,53 @@
 #define LOADARGS_0(name, dummy) \
 	r0 = name
 #define LOADARGS_1(name, __arg1) \
-	long int arg1 = (long int) (__arg1); \
+	long int _arg1 = (long int) (__arg1); \
 	LOADARGS_0(name, 0); \
 	extern void __illegally_sized_syscall_arg1 (void); \
 	if (__builtin_classify_type (__arg1) != 5 \
 	    && sizeof (__arg1) > SYSCALL_ARG_SIZE) \
 	  __illegally_sized_syscall_arg1 (); \
-	r3 = arg1
+	r3 = _arg1
 #define LOADARGS_2(name, __arg1, __arg2) \
-	long int arg2 = (long int) (__arg2); \
+	long int _arg2 = (long int) (__arg2); \
 	LOADARGS_1(name, __arg1); \
 	extern void __illegally_sized_syscall_arg2 (void); \
 	if (__builtin_classify_type (__arg2) != 5 \
 	    && sizeof (__arg2) > SYSCALL_ARG_SIZE) \
 	  __illegally_sized_syscall_arg2 (); \
-	r4 = arg2
+	r4 = _arg2
 #define LOADARGS_3(name, __arg1, __arg2, __arg3) \
-	long int arg3 = (long int) (__arg3); \
+	long int _arg3 = (long int) (__arg3); \
 	LOADARGS_2(name, __arg1, __arg2); \
 	extern void __illegally_sized_syscall_arg3 (void); \
 	if (__builtin_classify_type (__arg3) != 5 \
 	    && sizeof (__arg3) > SYSCALL_ARG_SIZE) \
 	  __illegally_sized_syscall_arg3 (); \
-	r5 = arg3
+	r5 = _arg3
 #define LOADARGS_4(name, __arg1, __arg2, __arg3, __arg4) \
-	long int arg4 = (long int) (__arg4); \
+	long int _arg4 = (long int) (__arg4); \
 	LOADARGS_3(name, __arg1, __arg2, __arg3); \
 	extern void __illegally_sized_syscall_arg4 (void); \
 	if (__builtin_classify_type (__arg4) != 5 \
 	    && sizeof (__arg4) > SYSCALL_ARG_SIZE) \
 	  __illegally_sized_syscall_arg4 (); \
-	r6 = arg4
+	r6 = _arg4
 #define LOADARGS_5(name, __arg1, __arg2, __arg3, __arg4, __arg5) \
-	long int arg5 = (long int) (__arg5); \
+	long int _arg5 = (long int) (__arg5); \
 	LOADARGS_4(name, __arg1, __arg2, __arg3, __arg4); \
 	extern void __illegally_sized_syscall_arg5 (void); \
 	if (__builtin_classify_type (__arg5) != 5 \
 	    && sizeof (__arg5) > SYSCALL_ARG_SIZE) \
 	  __illegally_sized_syscall_arg5 (); \
-	r7 = arg5
+	r7 = _arg5
 #define LOADARGS_6(name, __arg1, __arg2, __arg3, __arg4, __arg5, __arg6) \
-	long int arg6 = (long int) (__arg6); \
+	long int _arg6 = (long int) (__arg6); \
 	LOADARGS_5(name, __arg1, __arg2, __arg3, __arg4, __arg5); \
 	extern void __illegally_sized_syscall_arg6 (void); \
 	if (__builtin_classify_type (__arg6) != 5 \
 	    && sizeof (__arg6) > SYSCALL_ARG_SIZE) \
 	  __illegally_sized_syscall_arg6 (); \
-	r8 = arg6
+	r8 = _arg6
 
 #define ASM_INPUT_0 "0" (r0)
 #define ASM_INPUT_1 ASM_INPUT_0, "1" (r3)
-- 
2.26.2

Please test: [2.31/2.30] [PATCH] powerpc: Rename argN to _argN in LOADARGS_N [BZ #25902]

[H.J. Lu]

[-- Attachment #1: Type: text/plain, Size: 921 bytes --]

On Thu, Apr 30, 2020 at 7:18 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Thu, Apr 30, 2020 at 7:03 PM Tulio Magno Quites Machado Filho
> <tuliom@ascii.art.br> wrote:
> >
> > "H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org> writes:
> >
> > > See:
> > >
> > > https://sourceware.org/bugzilla/show_bug.cgi?id=25902
> > >
> > > with a patch.   But I can't test it natively.
> >
> > Tested.  LGTM.
> >
> > Could you push it, please?
>
> This is I am checking in.  I will backport it to 2.30/2.31 branches
> together with
>
> commit ff026950e280bc3e9487b41b460fb31bc5b57721
> Author: H.J. Lu <hjl.tools@gmail.com>
> Date:   Thu Apr 30 10:42:43 2020 -0700
>
>     Add a C wrapper for prctl [BZ #25896]
>

I need to update both  powerpc32/sysdep.h and powerpc64/sysdep.h
on 2.30 and 2.31 branches, instead of just powerpc/sysdep.h.   Can
someone please test this patch on 2.30 and 2.31 branches on PPC?

Thanks.

-- 
H.J.

[-- Attachment #2: 0001-powerpc-Rename-argN-to-_argN-in-LOADARGS_N-BZ-25902.patch --]
[-- Type: application/x-patch, Size: 5975 bytes --]

Re: Please test: [2.31/2.30] [PATCH] powerpc: Rename argN to _argN in LOADARGS_N [BZ #25902]

[Matheus Castanho]

On 5/1/20 8:11 PM, H.J. Lu wrote:
> On Thu, Apr 30, 2020 at 7:18 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>>
>> On Thu, Apr 30, 2020 at 7:03 PM Tulio Magno Quites Machado Filho
>> <tuliom@ascii.art.br> wrote:
>>>
>>> "H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org> writes:
>>>
>>>> See:
>>>>
>>>> https://sourceware.org/bugzilla/show_bug.cgi?id=25902
>>>>
>>>> with a patch.   But I can't test it natively.
>>>
>>> Tested.  LGTM.
>>>
>>> Could you push it, please?
>>
>> This is I am checking in.  I will backport it to 2.30/2.31 branches
>> together with
>>
>> commit ff026950e280bc3e9487b41b460fb31bc5b57721
>> Author: H.J. Lu <hjl.tools@gmail.com>
>> Date:   Thu Apr 30 10:42:43 2020 -0700
>>
>>     Add a C wrapper for prctl [BZ #25896]
>>
> 
> I need to update both  powerpc32/sysdep.h and powerpc64/sysdep.h
> on 2.30 and 2.31 branches, instead of just powerpc/sysdep.h.   Can
> someone please test this patch on 2.30 and 2.31 branches on PPC?
> 

- Cherry-picked "ff026950e2 Add a C wrapper for prctl [BZ #25896]" on
top of current release/2.30/master and release/2.31/master
- Fixed minor merge conflicts
- Applied the patch you sent

Tested on ppc, ppc64 and ppc64le. Both branches built fine and all tests
passed on all arch variants.

Thanks.

> Thanks.
> 

Re: Please test: [2.31/2.30] [PATCH] powerpc: Rename argN to _argN in LOADARGS_N [BZ #25902]

[H.J. Lu]

On Mon, May 4, 2020 at 9:00 AM Matheus Castanho <msc@linux.ibm.com> wrote:
>
> On 5/1/20 8:11 PM, H.J. Lu wrote:
> > On Thu, Apr 30, 2020 at 7:18 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >>
> >> On Thu, Apr 30, 2020 at 7:03 PM Tulio Magno Quites Machado Filho
> >> <tuliom@ascii.art.br> wrote:
> >>>
> >>> "H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org> writes:
> >>>
> >>>> See:
> >>>>
> >>>> https://sourceware.org/bugzilla/show_bug.cgi?id=25902
> >>>>
> >>>> with a patch.   But I can't test it natively.
> >>>
> >>> Tested.  LGTM.
> >>>
> >>> Could you push it, please?
> >>
> >> This is I am checking in.  I will backport it to 2.30/2.31 branches
> >> together with
> >>
> >> commit ff026950e280bc3e9487b41b460fb31bc5b57721
> >> Author: H.J. Lu <hjl.tools@gmail.com>
> >> Date:   Thu Apr 30 10:42:43 2020 -0700
> >>
> >>     Add a C wrapper for prctl [BZ #25896]
> >>
> >
> > I need to update both  powerpc32/sysdep.h and powerpc64/sysdep.h
> > on 2.30 and 2.31 branches, instead of just powerpc/sysdep.h.   Can
> > someone please test this patch on 2.30 and 2.31 branches on PPC?
> >
>
> - Cherry-picked "ff026950e2 Add a C wrapper for prctl [BZ #25896]" on
> top of current release/2.30/master and release/2.31/master
> - Fixed minor merge conflicts
> - Applied the patch you sent
>
> Tested on ppc, ppc64 and ppc64le. Both branches built fine and all tests
> passed on all arch variants.

Thanks.

> Thanks.
>
> > Thanks.
> >



-- 
H.J.

Re: V3 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Florian Weimer]

* H. J. Lu via Libc-alpha:

> From ee8672af3ef5f3db438c0abb39b2673944181292 Mon Sep 17 00:00:00 2001
> From: "H.J. Lu" <hjl.tools@gmail.com>
> Date: Wed, 29 Apr 2020 07:38:49 -0700
> Subject: [PATCH] Add a C wrapper for prctl [BZ #25896]
>
> Add a C wrapper to pass arguments in
>
> /* Control process execution.  */
> extern int prctl (int __option, ...) __THROW;
>
> to prctl syscall:
>
> extern int prctl (int, unsigned long int, unsigned long int,
> 		  unsigned long int, unsigned long int);
>
> On Linux/x86, since the prctl syscall interface:
>
> extern int prctl (int, unsigned long int, unsigned long int,
> 		  unsigned long int, unsigned long int);
>
> and the glibc prctl interface:
>
> extern int prctl (int option, ...);
>
> pass the arguments identically, the assembly verion:
>
> PSEUDO (__prctl, prctl, 5)
> 	ret
> PSEUDO_END (__prctl)
>
> is used.

This broke ABI on powerpc64le-linux-gnu because the calling convention
is not identical.  The manual page specifies the second prototype.

I filed a GCC RFE so that we can deal with this in a more elegant
manner:

  rs6000: Option not to use parameter save area in variadic function
  implementations
  <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107606>

I don't know whether we should restrict the C prctl wrapper to x86 x32,
or if we should add an assembler wrapper on powerpc64le-linux-gnu.

Thanks,
Florian

Re: V3 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Adhemerval Zanella Netto]

On 10/11/22 05:33, Florian Weimer via Libc-alpha wrote:
> * H. J. Lu via Libc-alpha:
> 
>> From ee8672af3ef5f3db438c0abb39b2673944181292 Mon Sep 17 00:00:00 2001
>> From: "H.J. Lu" <hjl.tools@gmail.com>
>> Date: Wed, 29 Apr 2020 07:38:49 -0700
>> Subject: [PATCH] Add a C wrapper for prctl [BZ #25896]
>>
>> Add a C wrapper to pass arguments in
>>
>> /* Control process execution.  */
>> extern int prctl (int __option, ...) __THROW;
>>
>> to prctl syscall:
>>
>> extern int prctl (int, unsigned long int, unsigned long int,
>> 		  unsigned long int, unsigned long int);
>>
>> On Linux/x86, since the prctl syscall interface:
>>
>> extern int prctl (int, unsigned long int, unsigned long int,
>> 		  unsigned long int, unsigned long int);
>>
>> and the glibc prctl interface:
>>
>> extern int prctl (int option, ...);
>>
>> pass the arguments identically, the assembly verion:
>>
>> PSEUDO (__prctl, prctl, 5)
>> 	ret
>> PSEUDO_END (__prctl)
>>
>> is used.
> 
> This broke ABI on powerpc64le-linux-gnu because the calling convention
> is not identical.  The manual page specifies the second prototype.
> 
> I filed a GCC RFE so that we can deal with this in a more elegant
> manner:
> 
>   rs6000: Option not to use parameter save area in variadic function
>   implementations
>   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107606>
> 
> I don't know whether we should restrict the C prctl wrapper to x86 x32,
> or if we should add an assembler wrapper on powerpc64le-linux-gnu.
> 
> Thanks,
> Florian
> 

The previous syscalls.list entry marked the function as 5 argument one
instead of variadic, so I think it would be better to add a way each
ABI to use this instead of the variadic one. Something like:

  #if PRCTL_VARIADIC_OK
  int
  __prctl (int option, ...)
  {
    va_list arg;
    va_start (arg, option);
    unsigned long int arg2 = va_arg (arg, unsigned long int);
    unsigned long int arg3 = va_arg (arg, unsigned long int);
    unsigned long int arg4 = va_arg (arg, unsigned long int);
    unsigned long int arg5 = va_arg (arg, unsigned long int);
    va_end (arg);
    return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
  }
  #else
  int
  __prctl (int option, int arg1, int arg2, int arg3, int arg4, int arg5)
  {
    return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
  }
  #endif

Or if powerpc64le is the only affected add a specific C implementation for
it.  I think we should really move away from assembler wrappers.

Re: V3 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Florian Weimer]

* Adhemerval Zanella Netto:

> The previous syscalls.list entry marked the function as 5 argument one
> instead of variadic, so I think it would be better to add a way each
> ABI to use this instead of the variadic one. Something like:
>
>   #if PRCTL_VARIADIC_OK
>   int
>   __prctl (int option, ...)
>   {
>     va_list arg;
>     va_start (arg, option);
>     unsigned long int arg2 = va_arg (arg, unsigned long int);
>     unsigned long int arg3 = va_arg (arg, unsigned long int);
>     unsigned long int arg4 = va_arg (arg, unsigned long int);
>     unsigned long int arg5 = va_arg (arg, unsigned long int);
>     va_end (arg);
>     return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
>   }
>   #else
>   int
>   __prctl (int option, int arg1, int arg2, int arg3, int arg4, int arg5)
>   {
>     return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
>   }
>   #endif

(The arguments need to be unsigned long int.)

This is not easy to do in C because the GCC aliasing machinery performs
type checking (as it should).

We can probably use

#define prctl prctl_XXX
#define __prctl __prctl_XXX

before including <sys/prctl.h>, but that's quite ugly.  Do you still
want me to proceed with the C version?

Thanks,
Florian

Re: V3 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Adhemerval Zanella Netto]

On 10/11/22 09:03, Florian Weimer wrote:
> * Adhemerval Zanella Netto:
> 
>> The previous syscalls.list entry marked the function as 5 argument one
>> instead of variadic, so I think it would be better to add a way each
>> ABI to use this instead of the variadic one. Something like:
>>
>>   #if PRCTL_VARIADIC_OK
>>   int
>>   __prctl (int option, ...)
>>   {
>>     va_list arg;
>>     va_start (arg, option);
>>     unsigned long int arg2 = va_arg (arg, unsigned long int);
>>     unsigned long int arg3 = va_arg (arg, unsigned long int);
>>     unsigned long int arg4 = va_arg (arg, unsigned long int);
>>     unsigned long int arg5 = va_arg (arg, unsigned long int);
>>     va_end (arg);
>>     return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
>>   }
>>   #else
>>   int
>>   __prctl (int option, int arg1, int arg2, int arg3, int arg4, int arg5)
>>   {
>>     return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
>>   }
>>   #endif
> 
> (The arguments need to be unsigned long int.)
> 
> This is not easy to do in C because the GCC aliasing machinery performs
> type checking (as it should).
> 
> We can probably use
> 
> #define prctl prctl_XXX
> #define __prctl __prctl_XXX

Yes, I did not include it but we already do it for non-LFS to LFS alias.

> 
> before including <sys/prctl.h>, but that's quite ugly.  Do you still
> want me to proceed with the C version?

I would, although it is not the simplest solution.

Re: V3 [PATCH] Add a C wrapper for prctl [BZ #25896]

[Florian Weimer]

* Adhemerval Zanella Netto:

> On 10/11/22 09:03, Florian Weimer wrote:
>> * Adhemerval Zanella Netto:
>> 
>>> The previous syscalls.list entry marked the function as 5 argument one
>>> instead of variadic, so I think it would be better to add a way each
>>> ABI to use this instead of the variadic one. Something like:
>>>
>>>   #if PRCTL_VARIADIC_OK
>>>   int
>>>   __prctl (int option, ...)
>>>   {
>>>     va_list arg;
>>>     va_start (arg, option);
>>>     unsigned long int arg2 = va_arg (arg, unsigned long int);
>>>     unsigned long int arg3 = va_arg (arg, unsigned long int);
>>>     unsigned long int arg4 = va_arg (arg, unsigned long int);
>>>     unsigned long int arg5 = va_arg (arg, unsigned long int);
>>>     va_end (arg);
>>>     return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
>>>   }
>>>   #else
>>>   int
>>>   __prctl (int option, int arg1, int arg2, int arg3, int arg4, int arg5)
>>>   {
>>>     return INLINE_SYSCALL_CALL (prctl, option, arg2, arg3, arg4, arg5);
>>>   }
>>>   #endif
>> 
>> (The arguments need to be unsigned long int.)
>> 
>> This is not easy to do in C because the GCC aliasing machinery performs
>> type checking (as it should).
>> 
>> We can probably use
>> 
>> #define prctl prctl_XXX
>> #define __prctl __prctl_XXX
>
> Yes, I did not include it but we already do it for non-LFS to LFS alias.
>
>> 
>> before including <sys/prctl.h>, but that's quite ugly.  Do you still
>> want me to proceed with the C version?
>
> I would, although it is not the simplest solution.

It's not too bad.  I'm going to make the internal __prctl prototype
non-variadic.

Thanks,
Florian