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2012-11-19powerpc: handle syscall error in clone.rofl0r-25/+9
sigsetjmp: store temporaries in jmp_buf rather than on stack.
2012-11-18fix powerpc asm not to store data in volatile space below stack pointerRich Felker-4/+4
it's essential to decrement the stack pointer before writing to new stack space, rather than afterwards. otherwise there is a race condition during which asynchronous code (signals) could clobber the data being stored. it may be possible to optimize the code further using stwu, but I wanted to avoid making any changes to the actual stack layout in this commit. further improvements can be made separately if desired.
2012-11-17add stub versions of some missing optional pthread interfacesRich Felker-0/+30
priority inheritance is not yet supported, and priority protection probably will not be supported ever unless there's serious demand for it (it's a fairly heavy-weight feature). per-thread cpu clocks would be nice to have, but to my knowledge linux is still not capable of supporting them. glibc fakes them by using the _process_ cpu-time clock and subtracting the thread creation time, which gives seriously incorrect semantics (worse than not supporting the feature at all), so until there's a way to do it right, it will remain as a stub that always fails.
2012-11-14fix indention with spaces in powerpc asmRich Felker-8/+8
2012-11-14Merge remote-tracking branch 'ppc-port/ppc-squashed'Rich Felker-0/+154
2012-11-13PPC port cleaned up, static linking works well now.rofl0r-4/+147
2012-11-13import preliminary ppc work by rdp.Richard Pennington-0/+11
2012-11-11debloat src/thread tree but putting lots of junk in one fileRich Felker-108/+93
POSIX includes mostly-useless attribute-get functions for each attribute-set function, presumably out of some object-oriented dogmatism. the get functions are not useful with the simple idiomatic usage of attributes. there are of course possible valid uses of them (like writing wrappers for pthread init functions that perform special actions on the presence of certain attributes), but considering how tiny these functions are anyway, little is lost by putting them all in one file, and some build-time cost and archive-file-size benefits are achieved.
2012-11-11add support for thread scheduling (POSIX TPS option)Rich Felker-4/+106
linux's sched_* syscalls actually implement the TPS (thread scheduling) functionality, not the PS (process scheduling) functionality which the sched_* functions are supposed to have. omitting support for the PS option (and having the sched_* interfaces fail with ENOSYS rather than omitting them, since some broken software assumes they exist) seems to be the only conforming way to do this on linux.
2012-11-08clean up sloppy nested inclusion from pthread_impl.hRich Felker-8/+13
this mirrors the stdio_impl.h cleanup. one header which is not strictly needed, errno.h, is left in pthread_impl.h, because since pthread functions return their error codes rather than using errno, nearly every single pthread function needs the errno constants. in a few places, rather than bringing in string.h to use memset, the memset was replaced by direct assignment. this seems to generate much better code anyway, and makes many functions which were previously non-leaf functions into leaf functions (possibly eliminating a great deal of bloat on some platforms where non-leaf functions require ugly prologue and/or epilogue).
2012-10-19fix order of syscall args for microblaze clone syscallRich Felker-3/+2
with this commit, based on testing with patches to qemu which are not yet upstream,
2012-10-18ensure microblaze __set_thread_area returns successRich Felker-1/+2
since it did not set the return-value register, the caller could wrongly interpret this as failure.
2012-10-17fix microblaze asm relocations for shared libcRich Felker-1/+1
only @PLT relocations are considered functions for purposes of -Bsymbolic-functions, so always use @PLT. it should not hurt in the static-linked case.
2012-10-15add support for TLS variant I, presently needed for arm and mipsRich Felker-2/+6
despite documentation that makes it sound a lot different, the only ABI-constraint difference between TLS variants II and I seems to be that variant II stores the initial TLS segment immediately below the thread pointer (i.e. the thread pointer points to the end of it) and variant I stores the initial TLS segment above the thread pointer, requiring the thread descriptor to be stored below. the actual value stored in the thread pointer register also tends to have per-arch random offsets applied to it for silly micro-optimization purposes. with these changes applied, TLS should be basically working on all supported archs except microblaze. I'm still working on getting the necessary information and a working toolchain that can build TLS binaries for microblaze, but in theory, static-linked programs with TLS and dynamic-linked programs where only the main executable uses TLS should already work on microblaze. alignment constraints have not yet been heavily tested, so it's possible that this code does not always align TLS segments correctly on archs that need TLS variant I.
2012-10-14fix overlap of thread stacks with thread tls segmentsRich Felker-2/+1
2012-10-07clean up and refactor program initializationRich Felker-1/+1
the code in __libc_start_main is now responsible for parsing auxv, rather than duplicating the parsing all over the place. this should shave off a few cycles and some code size. __init_libc is left as an external-linkage function despite the fact that it could be static, to prevent it from being inlined and permanently wasting stack space when main is called. a few other minor changes are included, like eliminating per-thread ssp canaries (they were likely broken when combined with certain dlopen usages, and completely unnecessary) and some other unnecessary checks. since this code gets linked into every program, it should be as small and simple as possible.
2012-10-05support for TLS in dynamic-loaded (dlopen) modulesRich Felker-23/+28
unlike other implementations, this one reserves memory for new TLS in all pre-existing threads at dlopen-time, and dlopen will fail with no resources consumed and no new libraries loaded if memory is not available. memory is not immediately distributed to running threads; that would be too complex and too costly. instead, assurances are made that threads needing the new TLS can obtain it in an async-signal-safe way from a buffer belonging to the dynamic linker/new module (via atomic fetch-and-add based allocator). I've re-appropriated the lock that was previously used for __synccall (synchronizing set*id() syscalls between threads) as a general pthread_create lock. it's a "backwards" rwlock where the "read" operation is safe atomic modification of the live thread count, which multiple threads can perform at the same time, and the "write" operation is making sure the count does not increase during an operation that depends on it remaining bounded (__synccall or dlopen). in static-linked programs that don't use __synccall, this lock is a no-op and has no cost.
2012-10-04beginnings of full TLS support in shared librariesRich Felker-0/+8
this code will not work yet because the necessary relocations are not supported, and cannot be supported without some internal changes to how relocation processing works (coming soon).
2012-10-04TLS (GNU/C11 thread-local storage) support for static-linked programsRich Felker-14/+33
the design for TLS in dynamic-linked programs is mostly complete too, but I have not yet implemented it. cost is nonzero but still low for programs which do not use TLS and/or do not use threads (a few hundred bytes of new code, plus dependency on memcpy). i believe it can be made smaller at some point by merging __init_tls and __init_security into __libc_start_main and avoiding duplicate auxv-parsing code. at the same time, I've also slightly changed the logic pthread_create uses to allocate guard pages to ensure that guard pages are not counted towards commit charge.
2012-09-30protect sem_open against cancellationRich Felker-13/+19
also fix one minor bug: failure to free the early-reserved slot when the semaphore later found to already be mapped.
2012-09-30overhaul sem_openRich Felker-105/+96
this function was overly complicated and not even obviously correct. avoid using openat/linkat just like in shm_open, and instead expand pathname using code shared with shm_open. remove bogus (and dangerous, with priorities) use of spinlocks. this commit also heavily streamlines the code and ensures there are no failure cases that can happen after a new semaphore has been created in the filesystem, since that case is unreportable.
2012-09-29sem_open should make process-shared semaphoresRich Felker-1/+1
this did not matter because we don't yet treat process-shared special. when private futex support is added, however, it will matter.
2012-09-29use O_CLOEXEC to open semaphore files in sem_openRich Felker-2/+2
2012-09-29fix some indention-with-spaces that crept inRich Felker-4/+4
2012-09-29microblaze portRich Felker-0/+65
based on initial work by rdp, with heavy modifications. some features including threads are untested because qemu app-level emulation seems to be broken and I do not have a proper system image for testing.
2012-09-27fix arm clone syscall bug (no effect unless app uses clone)Rich Felker-2/+1
the code to exit the new thread/process after the start function returns was mixed up in its syscall convention.
2012-09-15update mips cancellation-point syscall asm with 7-arg and r25 fixesRich Felker-2/+5
these fixes were already made to the normal syscall asm but not the cancellation point version.
2012-09-09fix mips syscall_cp_asm code (saved register usage)Rich Felker-2/+2
2012-09-06further use of _Noreturn, for non-plain-C functionsRich Felker-2/+2
note that POSIX does not specify these functions as _Noreturn, because POSIX is aligned with C99, not the new C11 standard. when POSIX is eventually updated to C11, it will almost surely give these functions the _Noreturn attribute. for now, the actual _Noreturn keyword is not used anyway when compiling with a c99 compiler, which is what POSIX requires; the GCC __attribute__ is used instead if it's available, however. in a few places, I've added infinite for loops at the end of _Noreturn functions to silence compiler warnings. presumably __buildin_unreachable could achieve the same thing, but it would only work on newer GCCs and would not be portable. the loops should have near-zero code size cost anyway. like the previous _Noreturn commit, this one is based on patches contributed by philomath.
2012-09-06use restrict everywhere it's required by c99 and/or posix 2008Rich Felker-26/+26
to deal with the fact that the public headers may be used with pre-c99 compilers, __restrict is used in place of restrict, and defined appropriately for any supported compiler. we also avoid the form [restrict] since older versions of gcc rejected it due to a bug in the original c99 standard, and instead use the form *restrict.
2012-08-17fix extremely rare but dangerous race condition in robust mutexesRich Felker-20/+33
if new shared mappings of files/devices/shared memory can be made between the time a robust mutex is unlocked and its subsequent removal from the pending slot in the robustlist header, the kernel can inadvertently corrupt data in the newly-mapped pages when the process terminates. i am fixing the bug by using the same global vm lock mechanism that was used to fix the race condition with unmapping barriers after pthread_barrier_wait returns.
2012-08-09fix (hopefully) all hard-coded 8's for kernel sigset_t sizeRich Felker-7/+12
some minor changes to how hard-coded sets for thread-related purposes are handled were also needed, since the old object sizes were not necessarily sufficient. things have gotten a bit ugly in this area, and i think a cleanup is in order at some point, but for now the goal is just to get the code working on all supported archs including mips, which was badly broken by linux rejecting syscalls with the wrong sigset_t size.
2012-07-24retry on cas failures in sem_trywaitRich Felker-2/+2
this seems counter-intuitive since sem_trywait is supposed to just try once, not wait for the semaphore. however, the retry loop is not a wait. instead, it's to handle the case where the value changes due to a simultaneous post or wait from another thread while the semaphore value remains positive. in such a case, it's absolutely wrong for sem_trywait to fail with EAGAIN because the semaphore is not busy.
2012-07-14avoid blx instruction which does not exist on armv4t or armv4Rich Felker-1/+2
2012-07-12fix several locks that weren't updated right for new futex-based __lockRich Felker-7/+7
these could have caused memory corruption due to invalid accesses to the next field. all should be fixed now; I found the errors with fgrep -r '__lock(&', which is bogus since the argument should be an array.
2012-07-12fix pthread_kill unlockingRich Felker-1/+1
it had not been updated for the futex-based locks
2012-07-11fix potential race condition in detached threadsRich Felker-4/+10
after the thread unmaps its own stack/thread structure, the kernel, performing child tid clear and futex wake, could clobber a new mapping made at the same location as the just-removed thread's tid field. disable kernel clearing of child tid to prevent this.
2012-07-11mips clone: don't free stack space used to copy argRich Felker-1/+0
the mips abi reserves stack space equal to the size of the in-register args for the callee to save the args, if desired. this would cause the beginning of the thread structure to be clobbered...
2012-07-11fix mips clone() on real linux kernelRich Felker-4/+7
the old code worked in qemu app-level emulation, but not on real kernels where the clone syscall does not copy the register values to the new thread. save arguments on the new thread stack instead.
2012-07-11fix clone() on mips (args were in wrong order)Rich Felker-3/+2
with this change, threads on mips seem to be working
2012-07-11first attempt at making threads work on mipsRich Felker-0/+67
2012-07-11generic c version of __set_thread_area for archs where it worksRich Felker-1/+5
on other archs, like x86[_64], asm version is required
2012-06-09add pthread_attr_setstack interface (and get)Rich Felker-9/+37
i originally omitted these (optional, per POSIX) interfaces because i considered them backwards implementation details. however, someone later brought to my attention a fairly legitimate use case: allocating thread stacks in memory that's setup for sharing and/or fast transfer between CPU and GPU so that the thread can move data to a GPU directly from automatic-storage buffers without having to go through additional buffer copies. perhaps there are other situations in which these interfaces are useful too.
2012-06-02remove implementation-reserved bits when saving signal maskRich Felker-1/+11
this fix is necessary because a program could be started with some of the implementation-reserved signals masked (e.g. due to exec having been called from a signal handler, or from a non-musl program) and then could obtain an invalid-to-use-later sigset_t as the old/saved signal mask.
2012-06-02remove no-longer-needed unblocking of signals in pthread_createRich Felker-1/+0
this action is now performed in pthread_self initialization; it must be performed there in case the first call to pthread_create is from a signal handler, in which case the old signal mask could be restored on return from the signal.
2012-05-25ensure pthread-internal signals are unblocked before threads are usedRich Felker-0/+1
if the process started with these signals blocked, cancellation could fail or setxid could deadlock. there is no way to globally unblock them after threads have been created. by unblocking them in the pthread_self initialization for the main thread, we ensure that they're unblocked before any other threads are created and also outside of any signal handler context (sigaction initialized pthread_self), which is important so that return from a signal handler won't re-block them.
2012-05-25remove leftover cp_sp cruft from cancellation code, fix small bugRich Felker-3/+1
the bug was that cancellation requests which arrived while a cancellation point was interrupted by a signal handler would not be acted upon when the signal handler returns. this was because cp_sp was never set; it's no longer needed or used. instead, just always re-raise the signal when cancellation was not acted upon. this wastes a tiny amount of time in the rare case where it even matters, but it ensures correctness and simplifies the code.
2012-05-23fix bad opcode in arm syscall_cp_asmRich Felker-1/+1
2012-05-23fix issue with longjmp out of signal handlers and cancellationRich Felker-52/+35
stale state information indicating that a thread was possibly blocked at a cancellation point could get left behind if longjmp was used to exit a signal handler that interrupted a cancellation point. to fix the issue, we throw away the state information entirely and simply compare the saved instruction pointer to a range of code addresses in the __syscall_cp_asm function. all the ugly PIC work (which becomes minimal anyway with this approach) is defered to cancellation time instead of happening at every syscall, which should improve performance too. this commit also fixes cancellation on arm, which was mildly broken (race condition, not checking cancellation flag once inside the cancellation point zone). apparently i forgot to implement that. the new arm code is untested, but appears correct; i'll test and fix it later if there are problems.
2012-05-23simplify cancellation push/pop slightlyRich Felker-12/+9
no need to pass unnecessary extra arguments on to the core code in pthread_create.c. this just wastes cycles and code bloat.