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This fixes the mutex pretty printer so that, if the owner ID isn't recorded
(such as in the current lock elision implementation), "Owner ID" will be shown
as "Unknown" instead of 0. It also changes the mutex printer output so that it
says "Acquired" instead of "Locked". The mutex tests are updated accordingly.
In addition, this adds a paragraph to the "Known issues" section of the
printers README explaining that the printer output isn't guaranteed to cover
every detail.
2017-01-14 Martin Galvan <martingalvan@sourceware.org>
* README.pretty-printers (Known issues): Warn about printers not
always covering everything.
* nptl/nptl-printers.py (MutexPrinter): Change output.
* nptl/test-mutex-printers.py: Fix test and adapt to changed output.
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Any changes to the per-thread list of robust mutexes currently acquired as
well as the pending-operations entry are not simply sequential code but
basically concurrent with any actions taken by the kernel when it tries
to clean up after a crash. This is not quite like multi-thread concurrency
but more like signal-handler concurrency.
This patch fixes latent bugs by adding compiler barriers where necessary so
that it is ensured that the kernel crash handling sees consistent data.
This is meant to be easy to backport, so we do not use C11-style signal
fences yet.
* nptl/descr.h (ENQUEUE_MUTEX_BOTH, DEQUEUE_MUTEX): Add compiler
barriers and comments.
* nptl/pthread_mutex_lock.c (__pthread_mutex_lock_full): Likewise.
* nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Likewise.
* nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise.
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lll_robust_unlock on i386 and x86_64 first sets the futex word to
FUTEX_WAITERS|0 before calling __lll_unlock_wake, which will set the
futex word to 0. If the thread is killed between these steps, then the
futex word will be FUTEX_WAITERS|0, and the kernel (at least current
upstream) will not set it to FUTEX_OWNER_DIED|FUTEX_WAITERS because 0 is
not equal to the TID of the crashed thread.
The lll_robust_lock assembly code on i386 and x86_64 is not prepared to
deal with this case because the fastpath tries to only CAS 0 to TID and
not FUTEX_WAITERS|0 to TID; the slowpath simply waits until it can CAS 0
to TID or the futex_word has the FUTEX_OWNER_DIED bit set.
This issue is fixed by removing the custom x86 assembly code and using
the generic C code instead. However, instead of adding more duplicate
code to the custom x86 lowlevellock.h, the code of the lll_robust* functions
is inlined into the single call sites that exist for each of these functions
in the pthread_mutex_* functions. The robust mutex paths in the latter
have been slightly reorganized to make them simpler.
This patch is meant to be easy to backport, so C11-style atomics are not
used.
[BZ #20985]
* nptl/Makefile: Adapt.
* nptl/pthread_mutex_cond_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove.
(LLL_ROBUST_MUTEX_LOCK_MODIFIER): New.
* nptl/pthread_mutex_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove.
(LLL_ROBUST_MUTEX_LOCK_MODIFIER): New.
(__pthread_mutex_lock_full): Inline lll_robust* functions and adapt.
* nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Inline
lll_robust* functions and adapt.
* nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise.
* sysdeps/nptl/lowlevellock.h (__lll_robust_lock_wait,
__lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait,
__lll_robust_timedlock, __lll_robust_unlock): Remove.
* sysdeps/unix/sysv/linux/i386/lowlevellock.h (lll_robust_lock,
lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove.
* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h (lll_robust_lock,
lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove.
* sysdeps/unix/sysv/linux/sparc/lowlevellock.h (__lll_robust_lock_wait,
__lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait,
__lll_robust_timedlock, __lll_robust_unlock): Remove.
* nptl/lowlevelrobustlock.c: Remove file.
* nptl/lowlevelrobustlock.sym: Likewise.
* sysdeps/unix/sysv/linux/i386/lowlevelrobustlock.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/lowlevelrobustlock.S: Likewise.
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This replaces the pthread rwlock with a new implementation that uses a
more scalable algorithm (primarily through not using a critical section
anymore to make state changes). The fast path for rdlock acquisition and
release is now basically a single atomic read-modify write or CAS and a few
branches. See nptl/pthread_rwlock_common.c for details.
* nptl/DESIGN-rwlock.txt: Remove.
* nptl/lowlevelrwlock.sym: Remove.
* nptl/Makefile: Add new tests.
* nptl/pthread_rwlock_common.c: New file. Contains the new rwlock.
* nptl/pthreadP.h (PTHREAD_RWLOCK_PREFER_READER_P): Remove.
(PTHREAD_RWLOCK_WRPHASE, PTHREAD_RWLOCK_WRLOCKED,
PTHREAD_RWLOCK_RWAITING, PTHREAD_RWLOCK_READER_SHIFT,
PTHREAD_RWLOCK_READER_OVERFLOW, PTHREAD_RWLOCK_WRHANDOVER,
PTHREAD_RWLOCK_FUTEX_USED): New.
* nptl/pthread_rwlock_init.c (__pthread_rwlock_init): Adapt to new
implementation.
* nptl/pthread_rwlock_rdlock.c (__pthread_rwlock_rdlock_slow): Remove.
(__pthread_rwlock_rdlock): Adapt.
* nptl/pthread_rwlock_timedrdlock.c
(pthread_rwlock_timedrdlock): Adapt.
* nptl/pthread_rwlock_timedwrlock.c
(pthread_rwlock_timedwrlock): Adapt.
* nptl/pthread_rwlock_trywrlock.c (pthread_rwlock_trywrlock): Adapt.
* nptl/pthread_rwlock_tryrdlock.c (pthread_rwlock_tryrdlock): Adapt.
* nptl/pthread_rwlock_unlock.c (pthread_rwlock_unlock): Adapt.
* nptl/pthread_rwlock_wrlock.c (__pthread_rwlock_wrlock_slow): Remove.
(__pthread_rwlock_wrlock): Adapt.
* nptl/tst-rwlock10.c: Adapt.
* nptl/tst-rwlock11.c: Adapt.
* nptl/tst-rwlock17.c: New file.
* nptl/tst-rwlock18.c: New file.
* nptl/tst-rwlock19.c: New file.
* nptl/tst-rwlock2b.c: New file.
* nptl/tst-rwlock8.c: Adapt.
* nptl/tst-rwlock9.c: Adapt.
* sysdeps/aarch64/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* sysdeps/arm/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* sysdeps/hppa/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* sysdeps/ia64/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* sysdeps/m68k/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* sysdeps/microblaze/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* sysdeps/mips/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* sysdeps/nios2/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* sysdeps/s390/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* sysdeps/sh/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* sysdeps/sparc/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* sysdeps/tile/nptl/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* sysdeps/unix/sysv/linux/alpha/bits/pthreadtypes.h
(pthread_rwlock_t): Adapt.
* sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h
(pthread_rwlock_t): Adapt.
* sysdeps/x86/bits/pthreadtypes.h (pthread_rwlock_t): Adapt.
* nptl/nptl-printers.py (): Adapt.
* nptl/nptl_lock_constants.pysym: Adapt.
* nptl/test-rwlock-printers.py: Adapt.
* nptl/test-rwlockattr-printers.c: Adapt.
* nptl/test-rwlockattr-printers.py: Adapt.
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Mixing them up breaks the gdb pretty printer tests.
ChangeLog:
2017-01-02 Martin Galvan <martingalvan@sourceware.org>
* nptl/nptl-printers.py: Fix tabs/spaces mismatches.
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I've updated copyright dates in glibc for 2017. This is the patch for
the changes not generated by scripts/update-copyrights and subsequent
build / regeneration of generated files.
Please remember to include 2017 in the dates for any new files added
in future (which means updating any existing uncommitted patches you
have that add new files to use the new copyright dates in them).
* NEWS: Update copyright dates.
* catgets/gencat.c (print_version): Likewise.
* csu/version.c (banner): Likewise.
* debug/catchsegv.sh: Likewise.
* debug/pcprofiledump.c (print_version): Likewise.
* debug/xtrace.sh (do_version): Likewise.
* elf/ldconfig.c (print_version): Likewise.
* elf/ldd.bash.in: Likewise.
* elf/pldd.c (print_version): Likewise.
* elf/sotruss.sh: Likewise.
* elf/sprof.c (print_version): Likewise.
* iconv/iconv_prog.c (print_version): Likewise.
* iconv/iconvconfig.c (print_version): Likewise.
* locale/programs/locale.c (print_version): Likewise.
* locale/programs/localedef.c (print_version): Likewise.
* login/programs/pt_chown.c (print_version): Likewise.
* malloc/memusage.sh (do_version): Likewise.
* malloc/memusagestat.c (print_version): Likewise.
* malloc/mtrace.pl: Likewise.
* manual/libc.texinfo: Likewise.
* nptl/version.c (banner): Likewise.
* nscd/nscd.c (print_version): Likewise.
* nss/getent.c (print_version): Likewise.
* nss/makedb.c (print_version): Likewise.
* posix/getconf.c (main): Likewise.
* scripts/test-installation.pl: Likewise.
* sysdeps/unix/sysv/linux/lddlibc4.c (main): Likewise.
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This is a new implementation for condition variables, required
after http://austingroupbugs.net/view.php?id=609 to fix bug 13165. In
essence, we need to be stricter in which waiters a signal or broadcast
is required to wake up; this couldn't be solved using the old algorithm.
ISO C++ made a similar clarification, so this also fixes a bug in
current libstdc++, for example.
We can't use the old algorithm anymore because futexes do not guarantee
to wake in FIFO order. Thus, when we wake, we can't simply let any
waiter grab a signal, but we need to ensure that one of the waiters
happening before the signal is woken up. This is something the previous
algorithm violated (see bug 13165).
There's another issue specific to condvars: ABA issues on the underlying
futexes. Unlike mutexes that have just three states, or semaphores that
have no tokens or a limited number of them, the state of a condvar is
the *order* of the waiters. A waiter on a semaphore can grab a token
whenever one is available; a condvar waiter must only consume a signal
if it is eligible to do so as determined by the relative order of the
waiter and the signal.
Therefore, this new algorithm maintains two groups of waiters: Those
eligible to consume signals (G1), and those that have to wait until
previous waiters have consumed signals (G2). Once G1 is empty, G2
becomes the new G1. 64b counters are used to avoid ABA issues.
This condvar doesn't yet use a requeue optimization (ie, on a broadcast,
waking just one thread and requeueing all others on the futex of the
mutex supplied by the program). I don't think doing the requeue is
necessarily the right approach (but I haven't done real measurements
yet):
* If a program expects to wake many threads at the same time and make
that scalable, a condvar isn't great anyway because of how it requires
waiters to operate mutually exclusive (due to the mutex usage). Thus, a
thundering herd problem is a scalability problem with or without the
optimization. Using something like a semaphore might be more
appropriate in such a case.
* The scalability problem is actually at the mutex side; the condvar
could help (and it tries to with the requeue optimization), but it
should be the mutex who decides how that is done, and whether it is done
at all.
* Forcing all but one waiter into the kernel-side wait queue of the
mutex prevents/avoids the use of lock elision on the mutex. Thus, it
prevents the only cure against the underlying scalability problem
inherent to condvars.
* If condvars use short critical sections (ie, hold the mutex just to
check a binary flag or such), which they should do ideally, then forcing
all those waiter to proceed serially with kernel-based hand-off (ie,
futex ops in the mutex' contended state, via the futex wait queues) will
be less efficient than just letting a scalable mutex implementation take
care of it. Our current mutex impl doesn't employ spinning at all, but
if critical sections are short, spinning can be much better.
* Doing the requeue stuff requires all waiters to always drive the mutex
into the contended state. This leads to each waiter having to call
futex_wake after lock release, even if this wouldn't be necessary.
[BZ #13165]
* nptl/pthread_cond_broadcast.c (__pthread_cond_broadcast): Rewrite to
use new algorithm.
* nptl/pthread_cond_destroy.c (__pthread_cond_destroy): Likewise.
* nptl/pthread_cond_init.c (__pthread_cond_init): Likewise.
* nptl/pthread_cond_signal.c (__pthread_cond_signal): Likewise.
* nptl/pthread_cond_wait.c (__pthread_cond_wait): Likewise.
(__pthread_cond_timedwait): Move here from pthread_cond_timedwait.c.
(__condvar_confirm_wakeup, __condvar_cancel_waiting,
__condvar_cleanup_waiting, __condvar_dec_grefs,
__pthread_cond_wait_common): New.
(__condvar_cleanup): Remove.
* npt/pthread_condattr_getclock.c (pthread_condattr_getclock): Adapt.
* npt/pthread_condattr_setclock.c (pthread_condattr_setclock):
Likewise.
* npt/pthread_condattr_getpshared.c (pthread_condattr_getpshared):
Likewise.
* npt/pthread_condattr_init.c (pthread_condattr_init): Likewise.
* nptl/tst-cond1.c: Add comment.
* nptl/tst-cond20.c (do_test): Adapt.
* nptl/tst-cond22.c (do_test): Likewise.
* sysdeps/aarch64/nptl/bits/pthreadtypes.h (pthread_cond_t): Adapt
structure.
* sysdeps/arm/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/ia64/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/m68k/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/microblaze/nptl/bits/pthreadtypes.h (pthread_cond_t):
Likewise.
* sysdeps/mips/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/nios2/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/s390/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/sh/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/tile/nptl/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/unix/sysv/linux/alpha/bits/pthreadtypes.h (pthread_cond_t):
Likewise.
* sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h (pthread_cond_t):
Likewise.
* sysdeps/x86/bits/pthreadtypes.h (pthread_cond_t): Likewise.
* sysdeps/nptl/internaltypes.h (COND_NWAITERS_SHIFT): Remove.
(COND_CLOCK_BITS): Adapt.
* sysdeps/nptl/pthread.h (PTHREAD_COND_INITIALIZER): Adapt.
* nptl/pthreadP.h (__PTHREAD_COND_CLOCK_MONOTONIC_MASK,
__PTHREAD_COND_SHARED_MASK): New.
* nptl/nptl-printers.py (CLOCK_IDS): Remove.
(ConditionVariablePrinter, ConditionVariableAttributesPrinter): Adapt.
* nptl/nptl_lock_constants.pysym: Adapt.
* nptl/test-cond-printers.py: Adapt.
* sysdeps/unix/sysv/linux/hppa/internaltypes.h (cond_compat_clear,
cond_compat_check_and_clear): Adapt.
* sysdeps/unix/sysv/linux/hppa/pthread_cond_timedwait.c: Remove file ...
* sysdeps/unix/sysv/linux/hppa/pthread_cond_wait.c
(__pthread_cond_timedwait): ... and move here.
* nptl/DESIGN-condvar.txt: Remove file.
* nptl/lowlevelcond.sym: Likewise.
* nptl/pthread_cond_timedwait.c: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i486/pthread_cond_wait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i586/pthread_cond_wait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/i386/i686/pthread_cond_wait.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_broadcast.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_signal.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S: Likewise.
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The address of the stack canary is stored in a per-thread variable,
which means that we must ensure that the TLS area is intialized before
calling any -fstack-protector'ed functions. For dynamically linked
applications, we ensure this (in a later patch) by disabling
-fstack-protector for the whole dynamic linker, but for static
applications, the AT_ENTRY address is called directly by the kernel, so
we must deal with the problem differently.
In static appliations, __libc_setup_tls performs the TCB setup and TLS
initialization, so this commit arranges for it to be called early and
unconditionally. The call (and the stack guard initialization) is
before the DL_SYSDEP_OSCHECK hook, which if set will probably call
functions which are stack-protected (it does on Linux and NaCL too). We
also move apply_irel up, so that we can still safely call functions that
require ifuncs while in __libc_setup_tls (though if stack-protection is
enabled we still have to avoid calling functions that are not
stack-protected at this stage).
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The value of CPPFLAGS provided by the environment may have optimizations
that interfere with the pretty printer test requirements. To override
such optimizations the pretty printer tests must also specify CPPFLAGS.
The existing pretty printer tests are fixed and the
README.pretty-printers is updated with the new requirement.
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Assume that Thread 1 waits to acquire a robust mutex using futexes to
block (and thus sets the FUTEX_WAITERS flag), and is unblocked when this
mutex is released. If Thread 2 concurrently acquires the lock and is
killed, Thread 1 can recover from the died owner but fail to restore the
FUTEX_WAITERS flag. This can lead to a Thread 3 that also blocked using
futexes at the same time as Thread 1 to not get woken up because
FUTEX_WAITERS is not set anymore.
The fix for this is to ensure that we continue to preserve the
FUTEX_WAITERS flag whenever we may have set it or shared it with another
thread. This is the same requirement as in the algorithm for normal
mutexes, only that the robust mutexes need additional handling for died
owners and thus preserving the FUTEX_WAITERS flag cannot be done just in
the futex slowpath code.
[BZ #20973]
* nptl/pthread_mutex_lock.c (__pthread_mutex_lock_full): Fix lost
wake-up in robust mutexes.
* nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Likewise.
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The label was lost during the conversion to the new test framework
in commit c23de0aacbeaa7a091609b35764bed931475a16d, and the --command
option is currently unused.
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The new test driver in <support/test-driver.c> has feature parity with
the old one. The main difference is that its hooking mechanism is
based on functions and function pointers instead of macros. This
commit also implements a new environment variable, TEST_COREDUMPS,
which disables the code which disables coredumps (that is, it enables
them if the invocation environment has not disabled them).
<test-skeleton.c> defines wrapper functions so that it is possible to
use existing macros with the new-style hook functionality.
This commit changes only a few test cases to the new test driver, to
make sure that it works as expected.
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This patch adds pretty printers for the following NPTL types:
- pthread_mutex_t
- pthread_mutexattr_t
- pthread_cond_t
- pthread_condattr_t
- pthread_rwlock_t
- pthread_rwlockattr_t
To load the pretty printers into your gdb session, do the following:
python
import sys
sys.path.insert(0, '/path/to/glibc/build/nptl/pretty-printers')
end
source /path/to/glibc/source/pretty-printers/nptl-printers.py
You can check which printers are registered and enabled by issuing the
'info pretty-printer' gdb command. Printers should trigger automatically when
trying to print a variable of one of the types mentioned above.
The printers are architecture-independent, and were tested on an AMD64 running
Ubuntu 14.04 and an x86 VM running Fedora 24.
In order to work, the printers need to know the values of various flags that
are scattered throughout pthread.h and pthreadP.h as enums and #defines. Since
replicating these constants in the printers file itself would create a
maintenance burden, I wrote a script called gen-py-const.awk that Makerules uses
to extract the constants. This script is pretty much the same as gen-as-const.awk,
except it doesn't cast the constant values to 'long' and is thorougly documented.
The constants need only to be enumerated in a .pysym file, which is then referenced
by a Make variable called gen-py-const-headers.
As for the install directory, I discussed this with Mike Frysinger and Siddhesh
Poyarekar, and we agreed that it can be handled in a separate patch, and shouldn't
block merging of this one.
In addition, I've written a series of test cases for the pretty printers.
Each lock type (mutex, condvar and rwlock) has two test programs, one for itself
and other for its related 'attributes' object. Each test program in turn has a
PExpect-based Python script that drives gdb and compares its output to the
expected printer's. The tests run on the glibc host, which is assumed to have
both gdb and PExpect; if either is absent the tests will fail with code 77
(UNSUPPORTED). For cross-testing you should use cross-test-ssh.sh as test-wrapper.
I've tested the printers on both native builds and a cross build using a Beaglebone
Black running Debian, with the build system's filesystem shared with the board
through NFS.
Finally, I've written a README that explains all this and more.
* INSTALL: Regenerated.
* Makeconfig: Add comments and whitespace to make the control flow
clearer.
(+link-printers-tests, +link-pie-printers-tests, CFLAGS-printers-tests,
installed-rtld-LDFLAGS, built-rtld-LDFLAGS, link-libc-rpath,
link-libc-tests-after-rpath-link, link-libc-printers-tests): New.
(rtld-LDFLAGS, rtld-tests-LDFLAGS, link-libc-tests-rpath-link,
link-libc-tests): Use the new variables as required.
* Makerules ($(py-const)): New rule.
generated: Add $(py-const).
* README.pretty-printers: New file.
* Rules (tests-printers-programs, tests-printers-out, py-env): New.
(others): Depend on $(py-const).
(tests): Depend on $(tests-printers-programs) or $(tests-printers-out),
as required. Pass $(tests-printers) to merge-test-results.sh.
* manual/install.texi: Add requirements for testing the pretty printers.
* nptl/Makefile (gen-py-const-headers, pretty-printers, tests-printers,
CFLAGS-test-mutexattr-printers.c CFLAGS-test-mutex-printers.c,
CFLAGS-test-condattr-printers.c, CFLAGS-test-cond-printers.c,
CFLAGS-test-rwlockattr-printers.c CFLAGS-test-rwlock-printers.c,
tests-printers-libs): Define.
* nptl/nptl-printers.py: New file.
* nptl/nptl_lock_constants.pysym: Likewise.
* nptl/test-cond-printers.c: Likewise.
* nptl/test-cond-printers.py: Likewise.
* nptl/test-condattr-printers.c: Likewise.
* nptl/test-condattr-printers.py: Likewise.
* nptl/test-mutex-printers.c: Likewise.
* nptl/test-mutex-printers.py: Likewise.
* nptl/test-mutexattr-printers.c: Likewise.
* nptl/test-mutexattr-printers.py: Likewise.
* nptl/test-rwlock-printers.c: Likewise.
* nptl/test-rwlock-printers.py: Likewise.
* nptl/test-rwlockattr-printers.c: Likewise.
* nptl/test-rwlockattr-printers.py: Likewise.
* scripts/gen-py-const.awk: Likewise.
* scripts/test_printers_common.py: Likewise.
* scripts/test_printers_exceptions.py: Likewise.
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This change moves the main implementation of _dl_catch_error,
_dl_signal_error to libc.so, where TLS variables can be used
directly. This removes a writable function pointer from the
rtld_global variable.
For use during initial relocation, minimal implementations of these
functions are provided in ld.so. These are eventually interposed
by the libc.so implementations. This is implemented by compiling
elf/dl-error-skeleton.c twice, via elf/dl-error.c and
elf/dl-error-minimal.c.
As a side effect of this change, the static version of dl-error.c
no longer includes support for the
_dl_signal_cerror/_dl_receive_error mechanism because it is only
used in ld.so.
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This patch remove the PID cache and usage in current GLIBC code. Current
usage is mainly used a performance optimization to avoid the syscall,
however it adds some issues:
- The exposed clone syscall will try to set pid/tid to make the new
thread somewhat compatible with current GLIBC assumptions. This cause
a set of issue with new workloads and usecases (such as BZ#17214 and
[1]) as well for new internal usage of clone to optimize other algorithms
(such as clone plus CLONE_VM for posix_spawn, BZ#19957).
- The caching complexity also added some bugs in the past [2] [3] and
requires more effort of each port to handle such requirements (for
both clone and vfork implementation).
- Caching performance gain in mainly on getpid and some specific
code paths. The getpid performance leverage is questionable [4],
either by the idea of getpid being a hotspot as for the getpid
implementation itself (if it is indeed a justifiable hotspot a
vDSO symbol could let to a much more simpler solution).
Other usage is mainly for non usual code paths, such as pthread
cancellation signal and handling.
For thread creation (on stack allocation) the code simplification in fact
adds some performance gain due the no need of transverse the stack cache
and invalidate each element pid.
Other thread usages will require a direct getpid syscall, such as
cancellation/setxid signal, thread cancellation, thread fail path (at
create_thread), and thread signal (pthread_kill and pthread_sigqueue).
However these are hardly usual hotspots and I think adding a syscall is
justifiable.
It also simplifies both the clone and vfork arch-specific implementation.
And by review each fork implementation there are some discrepancies that
this patch also solves:
- microblaze clone/vfork does not set/reset the pid/tid field
- hppa uses the default vfork implementation that fallback to fork.
Since vfork is deprecated I do not think we should bother with it.
The patch also removes the TID caching in clone. My understanding for
such semantic is try provide some pthread usage after a user program
issue clone directly (as done by thread creation with CLONE_PARENT_SETTID
and pthread tid member). However, as stated before in multiple discussions
threads, GLIBC provides clone syscalls without further supporting all this
semantics.
I ran a full make check on x86_64, x32, i686, armhf, aarch64, and powerpc64le.
For sparc32, sparc64, and mips I ran the basic fork and vfork tests from
posix/ folder (on a qemu system). So it would require further testing
on alpha, hppa, ia64, m68k, nios2, s390, sh, and tile (I excluded microblaze
because it is already implementing the patch semantic regarding clone/vfork).
[1] https://codereview.chromium.org/800183004/
[2] https://sourceware.org/ml/libc-alpha/2006-07/msg00123.html
[3] https://sourceware.org/bugzilla/show_bug.cgi?id=15368
[4] http://yarchive.net/comp/linux/getpid_caching.html
* sysdeps/nptl/fork.c (__libc_fork): Remove pid cache setting.
* nptl/allocatestack.c (allocate_stack): Likewise.
(__reclaim_stacks): Likewise.
(setxid_signal_thread): Obtain pid through syscall.
* nptl/nptl-init.c (sigcancel_handler): Likewise.
(sighandle_setxid): Likewise.
* nptl/pthread_cancel.c (pthread_cancel): Likewise.
* sysdeps/unix/sysv/linux/pthread_kill.c (__pthread_kill): Likewise.
* sysdeps/unix/sysv/linux/pthread_sigqueue.c (pthread_sigqueue):
Likewise.
* sysdeps/unix/sysv/linux/createthread.c (create_thread): Likewise.
* sysdeps/unix/sysv/linux/getpid.c: Remove file.
* nptl/descr.h (struct pthread): Change comment about pid value.
* nptl/pthread_getattr_np.c (pthread_getattr_np): Remove thread
pid assert.
* sysdeps/unix/sysv/linux/pthread-pids.h (__pthread_initialize_pids):
Do not set pid value.
* nptl_db/td_ta_thr_iter.c (iterate_thread_list): Remove thread
pid cache check.
* nptl_db/td_thr_validate.c (td_thr_validate): Likewise.
* sysdeps/aarch64/nptl/tcb-offsets.sym: Remove pid offset.
* sysdeps/alpha/nptl/tcb-offsets.sym: Likewise.
* sysdeps/arm/nptl/tcb-offsets.sym: Likewise.
* sysdeps/hppa/nptl/tcb-offsets.sym: Likewise.
* sysdeps/i386/nptl/tcb-offsets.sym: Likewise.
* sysdeps/ia64/nptl/tcb-offsets.sym: Likewise.
* sysdeps/m68k/nptl/tcb-offsets.sym: Likewise.
* sysdeps/microblaze/nptl/tcb-offsets.sym: Likewise.
* sysdeps/mips/nptl/tcb-offsets.sym: Likewise.
* sysdeps/nios2/nptl/tcb-offsets.sym: Likewise.
* sysdeps/powerpc/nptl/tcb-offsets.sym: Likewise.
* sysdeps/s390/nptl/tcb-offsets.sym: Likewise.
* sysdeps/sh/nptl/tcb-offsets.sym: Likewise.
* sysdeps/sparc/nptl/tcb-offsets.sym: Likewise.
* sysdeps/tile/nptl/tcb-offsets.sym: Likewise.
* sysdeps/x86_64/nptl/tcb-offsets.sym: Likewise.
* sysdeps/unix/sysv/linux/aarch64/clone.S: Remove pid and tid caching.
* sysdeps/unix/sysv/linux/alpha/clone.S: Likewise.
* sysdeps/unix/sysv/linux/arm/clone.S: Likewise.
* sysdeps/unix/sysv/linux/hppa/clone.S: Likewise.
* sysdeps/unix/sysv/linux/i386/clone.S: Likewise.
* sysdeps/unix/sysv/linux/ia64/clone2.S: Likewise.
* sysdeps/unix/sysv/linux/mips/clone.S: Likewise.
* sysdeps/unix/sysv/linux/nios2/clone.S: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/clone.S: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/clone.S: Likewise.
* sysdeps/unix/sysv/linux/sh/clone.S: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/clone.S: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/clone.S: Likewise.
* sysdeps/unix/sysv/linux/tile/clone.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/clone.S: Likewise.
* sysdeps/unix/sysv/linux/aarch64/vfork.S: Remove pid set and reset.
* sysdeps/unix/sysv/linux/alpha/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/arm/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/i386/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/ia64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/m68k/clone.S: Likewise.
* sysdeps/unix/sysv/linux/m68k/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/mips/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/nios2/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/sh/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/tile/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/tst-clone2.c (f): Remove direct pthread
struct access.
(clone_test): Remove function.
(do_test): Rewrite to take in consideration pid is not cached anymore.
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This patch consolidates all Linux lseek/lseek64/llseek implementation
in on on sysdeps/unix/sysv/linux/lseek{64}.c. It also removes the llseek
file and instead consolidate the LFS lseek implementation on lseek64.c
as for other LFS symbols implementations.
The general idea is:
- lseek: ABIs that not define __OFF_T_MATCHES_OFF64_T will preferable
use __NR__llseek if kernel supports it, otherwise they will use __NR_lseek.
ABIs that defines __OFF_T_MATCHES_OFF64_T won't produce any symbol.
- lseek64: ABIs with __OFF_T_MATCHES_OFF64_T will preferable use __NR_lseek
(since it will use 64-bit arguments without low/high splitting) and
__NR__llseek if __NR_lseek is not defined (for some ILP32 ports).
- llseek: files will be removed and symbols will be aliased ot lseek64.
ABI without __OFF_T_MATCHES_OFF64_T and without __NR_llseek (basically MIPS64n32
so far) are covered by building lseek with off_t as expected and lseek64
using __NR_lseek (as expected for off64_t being passed using 64-bit registers).
For this consolidation I mantained the x32 assembly specific implementation
because to correctly fix this it would required both the x32 fix for
{INLINE,INTERNAL}_SYSCALL [1] and a wrapper to correctly subscribe it to
return 64 bits instead of default 32 bits (as for times). It could a future
cleanup.
It is based on my previous {INTERNAL,INLINE}_SYSCALL_CALL macro [2],
although it is mainly for simplification.
Tested on x86_64, i686, aarch64, armhf, and powerpc64le.
* nptl/Makefile (libpthread-routines): Remove ptw-llseek and add
ptw-lseek64.
* sysdeps/unix/sysv/linux/Makefile (sysdeps_routines): Remove llseek.
* sysdeps/unix/sysv/linux/alpha/Makefile (sysdeps_routines):
Likewise.
* sysdeps/unix/sysv/linux/generic/wordsize-32/llseek.c: Remove file.
* sysdeps/unix/sysv/linux/generic/wordsize-32/lseek.c: Remove file.
* sysdeps/unix/sysv/linux/mips/mips64/llseek.c: Likewise.
* sysdeps/unix/sysv/linux/llseek.c: Remove file.
* sysdeps/unix/sysv/linux/lseek.c: New file.
* sysdeps/unix/sysv/linux/lseek64.c: Add default Linux implementation.
* sysdeps/unix/sysv/linux/mips/mips64/syscalls.list: Remove lseek and
__libc_lseek64 from auto-generation.
* sysdeps/unix/sysv/linux/wordsize-64/syscalls.list: Likewise.
* sysdeps/unix/sysv/linux/x86_64/x32/lseek64.S: New file.
[1] https://sourceware.org/ml/libc-alpha/2016-08/msg00443.html
[2] https://sourceware.org/ml/libc-alpha/2016-08/msg00646.html
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Replaces calls to write on file descriptor 2 with calls to write_message,
which writes to STDOUT_FILENO (1) and properly deals with the return of
write.
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In the test cases, there are writes to stdout which do not check the result
value. This patch replaces such occurrences with calls to write_message,
which properly deals with the unused result.
Tested for powerpc64le.
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