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* fix stale locks left behind when pthread_create failsRich Felker2013-02-011-3/+6
| | | | this bug seems to have been around a long time.
* if pthread_create fails, it must not attempt mmap if there is no mappingRich Felker2013-02-011-1/+1
| | | | | this bug was introduced when support for application-provided stacks was originally added.
* pthread stack treatment overhaul for application-provided stacks, etc.Rich Felker2013-02-013-23/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | the main goal of these changes is to address the case where an application provides a stack of size N, but TLS has size M that's a significant portion of the size N (or even larger than N), thus giving the application less stack space than it expected or no stack at all! the new strategy pthread_create now uses is to only put TLS on the application-provided stack if TLS is smaller than 1/8 of the stack size or 2k, whichever is smaller. this ensures that the application always has "close enough" to what it requested, and the threshold is chosen heuristically to make sure "sane" amounts of TLS still end up in the application-provided stack. if TLS does not fit the above criteria, pthread_create uses mmap to obtain space for TLS, but still uses the application-provided stack for actual call frame stack. this is to avoid wasting memory, and for the sake of supporting ugly hacks like garbage collection based on assumptions that the implementation will use the provided stack range. in order for the above heuristics to ever succeed, the amount of TLS space wasted on POSIX TSD (pthread_key_create based) needed to be reduced. otherwise, these changes would preclude any use of pthread_create without mmap, which would have serious memory usage and performance costs for applications trying to create huge numbers of threads using pre-allocated stack space. the new value of PTHREAD_KEYS_MAX is the minimum allowed by POSIX, 128. this should still be plenty more than real-world applications need, especially now that C11/gcc-style TLS is now supported in musl, and most apps and libraries choose to use that instead of POSIX TSD when available. at the same time, PTHREAD_STACK_MIN has been decreased. it was originally set to PAGE_SIZE back when there was no support for TLS or application-provided stacks, and requests smaller than a whole page did not make sense. now, there are two good reasons to support requests smaller than a page: (1) applications could provide pre-allocated stacks smaller than a page, and (2) with smaller stack sizes, stack+TLS+TSD can all fit in one page, making it possible for applications which need huge numbers of threads with minimal stack needs to allocate exactly one page per thread. the new value of PTHREAD_STACK_MIN, 2k, is aligned with the minimum size for sigaltstack.
* replace __wake function with macro that performs direct syscallRich Felker2013-02-011-9/+0
| | | | | | | | | | | this should generate faster and smaller code, especially with inline syscalls. the conditional with cnt is ugly, but thankfully cnt is always a constant anyway so it gets evaluated at compile time. it may be preferable to make separate __wake and __wakeall macros without a count argument. priv flag is not used yet; private futex support still needs to be done at some point in the future.
* fix some restrict-qualifier mismatches in newly added interfacesRich Felker2012-11-271-2/+2
| | | | | these should have little/no practical impact but they're needed for strict conformance.
* powerpc: handle syscall error in clone.rofl0r2012-11-191-25/+9
| | | | sigsetjmp: store temporaries in jmp_buf rather than on stack.
* fix powerpc asm not to store data in volatile space below stack pointerRich Felker2012-11-181-4/+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.
* add stub versions of some missing optional pthread interfacesRich Felker2012-11-175-0/+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.
* fix indention with spaces in powerpc asmRich Felker2012-11-141-8/+8
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* Merge remote-tracking branch 'ppc-port/ppc-squashed'Rich Felker2012-11-144-0/+154
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| * PPC port cleaned up, static linking works well now.rofl0r2012-11-134-4/+147
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| * import preliminary ppc work by rdp.Richard Pennington2012-11-131-0/+11
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* | debloat src/thread tree but putting lots of junk in one fileRich Felker2012-11-1116-108/+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.
* | add support for thread scheduling (POSIX TPS option)Rich Felker2012-11-1112-4/+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.
* | clean up sloppy nested inclusion from pthread_impl.hRich Felker2012-11-0812-8/+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).
* fix order of syscall args for microblaze clone syscallRich Felker2012-10-191-3/+2
| | | | | with this commit, based on testing with patches to qemu which are not yet upstream,
* ensure microblaze __set_thread_area returns successRich Felker2012-10-181-1/+2
| | | | | since it did not set the return-value register, the caller could wrongly interpret this as failure.
* fix microblaze asm relocations for shared libcRich Felker2012-10-171-1/+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.
* add support for TLS variant I, presently needed for arm and mipsRich Felker2012-10-153-2/+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.
* fix overlap of thread stacks with thread tls segmentsRich Felker2012-10-141-2/+1
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* clean up and refactor program initializationRich Felker2012-10-071-1/+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.
* support for TLS in dynamic-loaded (dlopen) modulesRich Felker2012-10-053-23/+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.
* beginnings of full TLS support in shared librariesRich Felker2012-10-042-0/+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).
* TLS (GNU/C11 thread-local storage) support for static-linked programsRich Felker2012-10-042-14/+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.
* protect sem_open against cancellationRich Felker2012-09-301-13/+19
| | | | | also fix one minor bug: failure to free the early-reserved slot when the semaphore later found to already be mapped.
* overhaul sem_openRich Felker2012-09-301-105/+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.
* sem_open should make process-shared semaphoresRich Felker2012-09-291-1/+1
| | | | | this did not matter because we don't yet treat process-shared special. when private futex support is added, however, it will matter.
* use O_CLOEXEC to open semaphore files in sem_openRich Felker2012-09-291-2/+2
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* fix some indention-with-spaces that crept inRich Felker2012-09-291-4/+4
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* microblaze portRich Felker2012-09-294-0/+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.
* fix arm clone syscall bug (no effect unless app uses clone)Rich Felker2012-09-271-2/+1
| | | | | the code to exit the new thread/process after the start function returns was mixed up in its syscall convention.
* update mips cancellation-point syscall asm with 7-arg and r25 fixesRich Felker2012-09-151-2/+5
| | | | | these fixes were already made to the normal syscall asm but not the cancellation point version.
* fix mips syscall_cp_asm code (saved register usage)Rich Felker2012-09-091-2/+2
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* further use of _Noreturn, for non-plain-C functionsRich Felker2012-09-061-2/+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.
* use restrict everywhere it's required by c99 and/or posix 2008Rich Felker2012-09-0626-26/+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.
* fix extremely rare but dangerous race condition in robust mutexesRich Felker2012-08-173-20/+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.
* fix (hopefully) all hard-coded 8's for kernel sigset_t sizeRich Felker2012-08-094-7/+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.
* retry on cas failures in sem_trywaitRich Felker2012-07-241-2/+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.
* avoid blx instruction which does not exist on armv4t or armv4Rich Felker2012-07-141-1/+2
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* fix several locks that weren't updated right for new futex-based __lockRich Felker2012-07-123-7/+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.
* fix pthread_kill unlockingRich Felker2012-07-121-1/+1
| | | | it had not been updated for the futex-based locks
* fix potential race condition in detached threadsRich Felker2012-07-112-4/+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.
* mips clone: don't free stack space used to copy argRich Felker2012-07-111-1/+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...
* fix mips clone() on real linux kernelRich Felker2012-07-111-4/+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.
* fix clone() on mips (args were in wrong order)Rich Felker2012-07-111-3/+2
| | | | with this change, threads on mips seem to be working
* first attempt at making threads work on mipsRich Felker2012-07-113-0/+67
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* generic c version of __set_thread_area for archs where it worksRich Felker2012-07-111-1/+5
| | | | on other archs, like x86[_64], asm version is required
* add pthread_attr_setstack interface (and get)Rich Felker2012-06-093-9/+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.
* remove implementation-reserved bits when saving signal maskRich Felker2012-06-021-1/+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.
* remove no-longer-needed unblocking of signals in pthread_createRich Felker2012-06-021-1/+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.
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