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

["H.J. Lu" <hjl.tools@gmail.com>]

[-- 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