Hide internal __sysinfo function to allow direct access within libc.so and
libc.a without using GOT nor PLT.
[BZ #18822]
* sysdeps/unix/sysv/linux/include/sys/sysinfo.h (__sysinfo): Add
attribute_hidden.
On Linux-based configurations, bits/syscall.h is a generated file.
To avoid build-ordering problems, the Linux sys/syscall.h only includes
bits/syscall.h if _LIBC is not defined. After the _ISOMAC-testsuite
changes, this means any test case that includes sys/syscall.h tries to
pull in bits/syscall.h. This would be fine, because it'll definitely
have been generated by the time we start compiling tests, except that
the generated <builddir>/misc/bits/syscall.h is not visible in the
include path, because nothing needed it till now. So we either get
the bits/syscall.h from the host system, or the build fails.
The fix is simple: add a shim header for bits/syscall.h. I put it in
sysdeps/unix/sysv/linux/include instead of the top-level include/
because bits/syscall.h doesn't exist at all on other configurations as
far as I can tell.
This is known to affect nptl/tst-cond2[45]. Thanks to John David
Anglin for noticing the problem.
[BZ #21514]
* sysdeps/unix/sysv/linux/include/bits/syscall.h: New shim header
pointing to the generated file in <builddir>/misc/bits/syscall.h.
This adds a test to ensure that the problems fixed in the last several
patches do not recur. Each directory checks the headers that it
installs for two properties: first, each header must be compilable in
isolation, as both C and C++, under a representative combination of
language and library conformance levels; second, there is a blacklist
of identifiers that may not appear in any installed header, currently
consisting of the legacy BSD typedefs. (There is an exemption for the
headers that define those typedefs, and for the RPC headers. It may be
necessary to make this more sophisticated if we add more stuff to the
blacklist in the future.)
In order for this test to work correctly, every wrapper header
that actually defines something must guard those definitions with
#ifndef _ISOMAC. This is the existing mechanism used by the conform/
tests to tell wrapper headers not to define anything that the public
header wouldn't, and not to use anything from libc-symbols.h. conform/
only cares for headers that we need to check for standards conformance,
whereas this test applies to *every* header. (Headers in include/ that
are either installed directly, or are internal-use-only and do *not*
correspond to any installed header, are not affected.)
* scripts/check-installed-headers.sh: New script.
* Rules: In each directory that defines header files to be installed,
run check-installed-headers.sh on them as a special test.
* Makefile: Likewise for the headers installed at top level.
* include/aliases.h, include/alloca.h, include/argz.h
* include/arpa/nameser.h, include/arpa/nameser_compat.h
* include/elf.h, include/envz.h, include/err.h
* include/execinfo.h, include/fpu_control.h, include/getopt.h
* include/gshadow.h, include/ifaddrs.h, include/libintl.h
* include/link.h, include/malloc.h, include/mcheck.h
* include/mntent.h, include/netinet/ether.h
* include/nss.h, include/obstack.h, include/printf.h
* include/pty.h, include/resolv.h, include/rpc/auth.h
* include/rpc/auth_des.h, include/rpc/auth_unix.h
* include/rpc/clnt.h, include/rpc/des_crypt.h
* include/rpc/key_prot.h, include/rpc/netdb.h
* include/rpc/pmap_clnt.h, include/rpc/pmap_prot.h
* include/rpc/pmap_rmt.h, include/rpc/rpc.h
* include/rpc/rpc_msg.h, include/rpc/svc.h
* include/rpc/svc_auth.h, include/rpc/xdr.h
* include/rpcsvc/nis_callback.h, include/rpcsvc/nislib.h
* include/rpcsvc/yp.h, include/rpcsvc/ypclnt.h
* include/rpcsvc/ypupd.h, include/shadow.h
* include/stdio_ext.h, include/sys/epoll.h
* include/sys/file.h, include/sys/gmon.h, include/sys/ioctl.h
* include/sys/prctl.h, include/sys/profil.h
* include/sys/statfs.h, include/sys/sysctl.h
* include/sys/sysinfo.h, include/ttyent.h, include/utmp.h
* sysdeps/arm/nacl/include/bits/setjmp.h
* sysdeps/mips/include/sys/asm.h
* sysdeps/unix/sysv/linux/include/sys/sysinfo.h
* sysdeps/unix/sysv/linux/include/sys/timex.h
* sysdeps/x86/fpu/include/bits/fenv.h:
Add #ifndef _ISOMAC guard around internal declarations.
Add multiple-inclusion guard if not already present.
Profiling git's test suite, Linus noted [1] that a disproportionately
large amount of time was spent reading /proc/meminfo. This is done by
the glibc functions get_phys_pages and get_avphys_pages, but they only
need the MemTotal and MemFree fields, respectively. That same
information can be obtained with a single syscall, sysinfo, instead of
six: open, fstat, mmap, read, close, munmap. While sysinfo also
provides more than necessary, it does a lot less work than what the
kernel needs to do to provide the entire /proc/meminfo. Both strace -T
and in-app microbenchmarks shows that the sysinfo() approach is
roughly an order of magnitude faster.
sysinfo() is much older than what glibc currently requires, so I don't
think there's any reason to keep the old parsing code. Moreover, this
makes get_[av]phys_pages work even in the absence of /proc.
Linus noted that something as simple as 'bash -c "echo"' would trigger
the reading of /proc/meminfo, but gdb says that many more applications
than just bash are affected:
Starting program: /bin/bash "-c" "echo"
Breakpoint 1, __get_phys_pages () at ../sysdeps/unix/sysv/linux/getsysstats.c:283
283 ../sysdeps/unix/sysv/linux/getsysstats.c: No such file or directory.
(gdb) bt
So it seems that any application that uses qsort on a moderately sized
array will incur this cost (once), which is obviously proportionately
more expensive for lots of short-lived processes (such as the git test
suite).
[1] http://thread.gmane.org/gmane.linux.kernel/2019285
Signed-off-by: Rasmus Villemoes <rv@rasmusvillemoes.dk>
* sysdeps/unix/sysv/linux/getsysstats.c (__get_phys_pages):
Use sysinfo system call instead of parsing /proc/meminfo.
* sysdeps/unix/sysv/linux/getsysstats.c (__get_avphys_pages):
Likewise.
Bug 14132 is removal of the old INTDEF/INTUSE system of *_internal
aliases as obsoleted by the hidden_proto / hidden_def system. Various
cases were cleaned up in 2012, but some remain. This patch removes
the use of this mechanism for __adjtimex.
Tested for x86_64 that stripped installed shared libraries are
unchanged by the patch.
[BZ #14132]
* sysdeps/unix/sysv/linux/include/sys/timex.h: New file.
* sysdeps/unix/sysv/linux/adjtime.c [!ADJTIMEX] (ADJTIMEX): Do not
use INTUSE.
[!ADJTIMEX] (INTUSE(__adjtimex)): Remove declaration.
* sysdeps/unix/sysv/linux/alpha/adjtime.c (__adjtimex_internal):
Remove alias.
(__adjtimex): Define using libc_hidden_ver.
* sysdeps/unix/sysv/linux/ntp_gettime.c (INTUSE(__adjtimex)):
Remove declaration.
(ntp_gettime): Call __adjtimex directly.
* sysdeps/unix/sysv/linux/ntp_gettimex.c (INTUSE(__adjtimex)):
Remove declaration.
(ntp_gettimex): Call __adjtimex directly.
* sysdeps/unix/sysv/linux/syscalls.list (adjtimex): Remove
__adjtimex_internal alias.
