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Make obsolete syscall wrappers into compat symbols (bug 18472).

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Various Linux kernel syscalls have become obsolete over time.
Specifically, the following are obsolete in all kernel versions
supported by glibc, are not present for architectures more recently
added to the kernel, and as such, the wrapper functions for them
should be compat symbols, not in static libc and not available for new
links with shared libc.

* bdflush: in Linux 2.6, does nothing if present.

* create_module get_kernel_syms query_module: Linux 2.4 module
  interface, syscalls not present in Linux 2.6.

* uselib: part of the mechanism for loading a.out shared libraries,
  irrelevant with ELF.

This patch adds support for syscalls.list to list syscall aliases of
the form NAME@VERSION:OBSOLETED, with SHLIB_COMPAT conditionals being
generated for such aliases.  Those five syscalls are then made into
compat symbols (obsoleted in glibc 2.23, so future ports won't have
these symbols at all), with the header <sys/kdaemon.h> declaring
bdflush being removed.  When we move to 3.2 as minimum kernel version,
the same can be done for nfsservctl (removed in Linux 3.1) as well.

Tested for x86_64 and x86 (testsuite, as well as checking that the
symbols in question indeed become compat symbols, that they are indeed
omitted from static libc, and that the generated SHLIB_COMPAT
conditionals look right).

	[BZ #18472]
	* sysdeps/unix/Makefile ($(objpfx)stub-syscalls.c): Handle entries
	for the form NAME@VERSION:OBSOLETED and generate SHLIB_COMPAT
	conditionals for them.
	* sysdeps/unix/make-syscalls.sh (emit_weak_aliases): Likewise.
	* sysdeps/unix/sysv/linux/sys/kdaemon.h: Remove file.
	* sysdeps/unix/sysv/linux/Makefile (sysdep_headers): Remove
	sys/kdaemon.h.
	* sysdeps/unix/sysv/linux/syscalls.list (bdflush): Make into
	compat-only syscall, obsoleted in glibc 2.23.
	(create_module): Likewise.
	(get_kernel_syms): Likewise.
	(query_module): Likewise.
	(uselib): Likewise.
	* manual/sysinfo.texi (System Parameters): Do not mention bdflush.
This commit is contained in:
Joseph Myers 2015-12-14 22:52:15 +00:00
parent 5db0877750
commit eed3e1eb79
8 changed files with 58 additions and 48 deletions
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18
ChangeLog
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@ -1,3 +1,21 @@
2015-12-14 Joseph Myers <joseph@codesourcery.com>
[BZ #18472]
* sysdeps/unix/Makefile ($(objpfx)stub-syscalls.c): Handle entries
for the form NAME@VERSION:OBSOLETED and generate SHLIB_COMPAT
conditionals for them.
* sysdeps/unix/make-syscalls.sh (emit_weak_aliases): Likewise.
* sysdeps/unix/sysv/linux/sys/kdaemon.h: Remove file.
* sysdeps/unix/sysv/linux/Makefile (sysdep_headers): Remove
sys/kdaemon.h.
* sysdeps/unix/sysv/linux/syscalls.list (bdflush): Make into
compat-only syscall, obsoleted in glibc 2.23.
(create_module): Likewise.
(get_kernel_syms): Likewise.
(query_module): Likewise.
(uselib): Likewise.
* manual/sysinfo.texi (System Parameters): Do not mention bdflush.
2015-12-11 Aurelien Jarno <aurelien@aurel32.net>
* sysdeps/unix/sysv/linux/arm/ioperm.c: Do not include

7
NEWS
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@ -53,6 +53,13 @@ Version 2.23
* The obsolete header <regexp.h> has been removed. Programs that require
this header must be updated to use <regex.h> instead.
* The obsolete functions bdflush, create_module, get_kernel_syms,
query_module and uselib are no longer available to newly linked binaries;
the header <sys/kdaemon.h> has been removed. These functions and header
were specific to systems using the Linux kernel and could not usefully be
used with the GNU C Library on systems with version 2.6 or later of the
Linux kernel.
* Optimized string, wcsmbs and memory functions for IBM z13.
Implemented by Stefan Liebler.

2
manual/sysinfo.texi
View File

@ -1286,6 +1286,4 @@ parameters are:
@code{gethostname}, @code{sethostname} (@xref{Host Identification}.)
@item
@code{uname} (@xref{Platform Type}.)
@item
@code{bdflush}
@end itemize

14
sysdeps/unix/Makefile
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@ -59,8 +59,20 @@ $(objpfx)stub-syscalls.c: $(common-objpfx)sysd-syscalls \
*@*) \
ver=$${call##*@}; call=$${call%%@*}; \
ver=`echo "$$ver" | sed 's/\./_/g'`; \
case $$ver in \
*:*) \
compat_ver=$${ver#*:}; \
ver=$${ver%%:*}; \
compat_cond="SHLIB_COMPAT (libc, $$ver, $$compat_ver)"; \
;; \
*) \
compat_cond=""; \
;; \
esac; \
if [ -n "$$compat_cond" ]; then echo "#if $$compat_cond"; fi; \
echo "strong_alias (_no_syscall, __$${call}_$${ver})"; \
echo "compat_symbol (libc, __$${call}_$${ver}, $$call, $$ver);" \
echo "compat_symbol (libc, __$${call}_$${ver}, $$call, $$ver);"; \
if [ -n "$$compat_cond" ]; then echo "#endif"; fi; \
;; \
*) echo "weak_alias (_no_syscall, $$call)"; \
echo "stub_warning ($$call)"; \

21
sysdeps/unix/make-syscalls.sh
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@ -81,12 +81,9 @@ emit_weak_aliases()
# We use the <shlib-compat.h> macros to generate the versioned aliases
# so that the version sets can be mapped to the configuration's
# minimum version set as per shlib-versions DEFAULT lines. But note
# we don't generate any "#if SHLIB_COMPAT (...)" conditionals. To do
# that we'd need to change the syscalls.list format so that it can
# list the "obsoleted" version set too. If it ever arises that we
# have a syscall entry point that is obsoleted by a newer version set,
# we'll have to revamp all this.
# minimum version set as per shlib-versions DEFAULT lines. If an
# entry point is specified in the form NAME@VERSION:OBSOLETED, a
# SHLIB_COMPAT conditional is generated.
if [ $any_versioned = t ]; then
echo " echo '#include <shlib-compat.h>'; \\"
fi
@ -113,7 +110,17 @@ emit_weak_aliases()
*@*)
base=`echo $name | sed 's/@.*//'`
ver=`echo $name | sed 's/.*@//;s/\./_/g'`
echo " echo '#if defined SHARED && IS_IN (libc)'; \\"
case $ver in
*:*)
compat_ver=${ver#*:}
ver=${ver%%:*}
compat_cond=" && SHLIB_COMPAT (libc, $ver, $compat_ver)"
;;
*)
compat_cond=
;;
esac
echo " echo '#if defined SHARED && IS_IN (libc)$compat_cond'; \\"
if test -z "$vcount" ; then
source=$strong
vcount=1

2
sysdeps/unix/sysv/linux/Makefile
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@ -29,7 +29,7 @@ CFLAGS-tst-writev.c += "-DARTIFICIAL_LIMIT=0x80000000-__getpagesize()"
# here and in any non-Linux configuration that uses it; other
# configurations will not install the file.
sysdep_headers += sys/mount.h sys/acct.h sys/sysctl.h \
sys/klog.h sys/kdaemon.h \
sys/klog.h \
sys/user.h sys/prctl.h \
sys/kd.h sys/soundcard.h sys/vt.h \
sys/quota.h sys/fsuid.h \

32
sysdeps/unix/sysv/linux/sys/kdaemon.h
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@ -1,32 +0,0 @@
/* Copyright (C) 1996-2015 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/>. */
/* Interfaces to control the various kernel daemons. */
#ifndef _SYS_KDAEMON_H
#define _SYS_KDAEMON_H 1
#include <features.h>
__BEGIN_DECLS
/* Start, flush, or tune the kernel's buffer flushing daemon. */
extern int bdflush (int __func, long int __data) __THROW;
__END_DECLS
#endif /* _SYS_KDAEMON_H */

10
sysdeps/unix/sysv/linux/syscalls.list
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@ -2,12 +2,12 @@
adjtimex adjtime adjtimex i:p __adjtimex adjtimex ntp_adjtime
alarm - alarm i:i alarm
bdflush EXTRA bdflush i:ii bdflush
bdflush EXTRA bdflush i:ii __compat_bdflush bdflush@GLIBC_2.0:GLIBC_2.23
capget EXTRA capget i:pp capget
capset EXTRA capset i:pp capset
clock_adjtime EXTRA clock_adjtime i:ip clock_adjtime
creat - creat Ci:si creat
create_module EXTRA create_module 3 create_module
create_module EXTRA create_module 3 __compat_create_module create_module@GLIBC_2.0:GLIBC_2.23
delete_module EXTRA delete_module 3 delete_module
epoll_create EXTRA epoll_create i:i epoll_create
epoll_create1 EXTRA epoll_create1 i:i epoll_create1
@ -16,7 +16,7 @@ epoll_wait EXTRA epoll_wait Ci:ipii epoll_wait
execve - execve i:spp __execve execve
fdatasync - fdatasync Ci:i fdatasync
flock - flock i:ii __flock flock
get_kernel_syms EXTRA get_kernel_syms i:p get_kernel_syms
get_kernel_syms EXTRA get_kernel_syms i:p __compat_get_kernel_syms get_kernel_syms@GLIBC_2.0:GLIBC_2.23
getegid - getegid Ei: __getegid getegid
geteuid - geteuid Ei: __geteuid geteuid
getpgid - getpgid i:i __getpgid getpgid
@ -53,7 +53,7 @@ pivot_root EXTRA pivot_root i:ss pivot_root
poll - poll Ci:pii __libc_poll __poll poll
prctl EXTRA prctl i:iiiii __prctl prctl
putpmsg - putpmsg i:ippii putpmsg
query_module EXTRA query_module i:sipip query_module
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:piiii __remap_file_pages remap_file_pages
sched_getp - sched_getparam i:ip __sched_getparam sched_getparam
@ -78,7 +78,7 @@ swapon - swapon i:si __swapon swapon
swapoff - swapoff i:s __swapoff swapoff
tee EXTRA tee Ci:iiii tee
unshare EXTRA unshare i:i unshare
uselib EXTRA uselib i:s uselib
uselib EXTRA uselib i:s __compat_uselib uselib@GLIBC_2.0:GLIBC_2.23
utime - utime i:sP utime
vmsplice EXTRA vmsplice Ci:iPii vmsplice
wait4 - wait4 i:iWiP __wait4 wait4