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* fix deadlock race in pthread_onceRich Felker2014-04-151-2/+1
| | | | | | | | | | | | at the end of successful pthread_once, there was a race window during which another thread calling pthread_once would momentarily change the state back from 2 (finished) to 1 (in-progress). in this case, the status was immediately changed back, but with no wake call, meaning that waiters which arrived during this short window could block forever. there are two possible fixes. one would be adding the wake to the code path where it was missing. but it's better just to avoid reverting the status at all, by using compare-and-swap instead of swap.
* fix pointer type mismatch and misplacement of constRich Felker2014-03-241-2/+2
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* always initialize thread pointer at program startRich Felker2014-03-245-52/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | this is the first step in an overhaul aimed at greatly simplifying and optimizing everything dealing with thread-local state. previously, the thread pointer was initialized lazily on first access, or at program startup if stack protector was in use, or at certain random places where inconsistent state could be reached if it were not initialized early. while believed to be fully correct, the logic was fragile and non-obvious. in the first phase of the thread pointer overhaul, support is retained (and in some cases improved) for systems/situation where loading the thread pointer fails, e.g. old kernels. some notes on specific changes: - the confusing use of libc.main_thread as an indicator that the thread pointer is initialized is eliminated in favor of an explicit has_thread_pointer predicate. - sigaction no longer needs to ensure that the thread pointer is initialized before installing a signal handler (this was needed to prevent a situation where the signal handler caused the thread pointer to be initialized and the subsequent sigreturn cleared it again) but it still needs to ensure that implementation-internal thread-related signals are not blocked. - pthread tsd initialization for the main thread is deferred in a new manner to minimize bloat in the static-linked __init_tp code. - pthread_setcancelstate no longer needs special handling for the situation before the thread pointer is initialized. it simply fails on systems that cannot support a thread pointer, which are non-conforming anyway. - pthread_cleanup_push/pop now check for missing thread pointer and nop themselves out in this case, so stdio no longer needs to avoid the cancellable path when the thread pointer is not available. a number of cases remain where certain interfaces may crash if the system does not support a thread pointer. at this point, these should be limited to pthread interfaces, and the number of such cases should be fewer than before.
* rename superh port to "sh" for consistencyRich Felker2014-02-274-0/+0
| | | | | | | | | linux, gcc, etc. all use "sh" as the name for the superh arch. there was already some inconsistency internally in musl: the dynamic linker was searching for "ld-musl-sh.path" as its path file despite its own name being "ld-musl-superh.so.1". there was some sentiment in both directions as to how to resolve the inconsistency, but overall "sh" was favored.
* superh portBobby Bingham2014-02-234-0/+113
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* mostly-cosmetic fixups to x32 port mergeRich Felker2014-02-232-6/+9
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* x32 port (diff against vanilla x86_64)rofl0r2014-02-234-10/+8
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* import vanilla x86_64 code as x32rofl0r2014-02-234-0/+70
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* use syscall_arg_t type for syscall prototypes in pthread coderofl0r2014-02-222-3/+8
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* clone: make clone a wrapper around __cloneBobby Bingham2014-02-095-18/+3
| | | | | | | | | | | | The architecture-specific assembly versions of clone did not set errno on failure, which is inconsistent with glibc. __clone still returns the error via its return value, and clone is now a wrapper that sets errno as needed. The public clone has also been moved to src/linux, as it's not directly related to the pthreads API. __clone is called by pthread_create, which does not report errors via errno. Though not strictly necessary, it's nice to avoid clobbering errno here.
* eliminate explicit (long) casts when making syscallsRich Felker2014-01-061-1/+1
| | | | | | | | this practice came from very early, before internal/syscall.h defined macros that could accept pointer arguments directly and handle them correctly. aside from being ugly and unnecessary, it looks like it will be problematic when we add support for 32-bit ABIs on archs where registers (and syscall arguments) are 64-bit, e.g. x32 and mips n32.
* include cleanups: remove unused headers and add feature test macrosSzabolcs Nagy2013-12-123-3/+0
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* fix invalid implicit pointer conversion in pthread_key_createRich Felker2013-10-041-1/+1
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* fix potential deadlock bug in libc-internal locking logicRich Felker2013-09-201-3/+6
| | | | | | | | | | | | | | | | | | | | if a multithreaded program became non-multithreaded (i.e. all other threads exited) while one thread held an internal lock, the remaining thread would fail to release the lock. the the program then became multithreaded again at a later time, any further attempts to obtain the lock would deadlock permanently. the underlying cause is that the value of libc.threads_minus_1 at unlock time might not match the value at lock time. one solution would be returning a flag to the caller indicating whether the lock was taken and needs to be unlocked, but there is a simpler solution: using the lock itself as such a flag. note that this flag is not needed anyway for correctness; if the lock is not held, the unlock code is harmless. however, the memory synchronization properties associated with a_store are costly on some archs, so it's best to avoid executing the unlock code when it is unnecessary.
* fix clobbering of caller's stack in mips __clone functionRich Felker2013-09-161-0/+3
| | | | | | | | | this was resulting in crashes in posix_spawn on mips, and would have affected applications calling clone too. since the prototype for __clone has it as a variadic function, it may not assume that 16($sp) is writable for use in making the syscall. instead, it needs to allocate additional stack space, and then adjust the stack pointer back in both of the code paths for the parent process/thread.
* omit CLONE_PARENT flag to clone in pthread_createRich Felker2013-09-161-1/+1
| | | | | | | | CLONE_PARENT is not necessary (CLONE_THREAD provides all the useful parts of it) and Linux treats CLONE_PARENT as an error in certain situations, without noticing that it would be a no-op due to CLONE_THREAD. this error case prevents, for example, use of a multi-threaded init process and certain usages with containers.
* use symbolic names for clone flags in pthread_createRich Felker2013-09-161-2/+5
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* support configurable page size on mips, powerpc and microblazeSzabolcs Nagy2013-09-152-0/+2
| | | | | | | | | | | | | | | | PAGE_SIZE was hardcoded to 4096, which is historically what most systems use, but on several archs it is a kernel config parameter, user space can only know it at execution time from the aux vector. PAGE_SIZE and PAGESIZE are not defined on archs where page size is a runtime parameter, applications should use sysconf(_SC_PAGE_SIZE) to query it. Internally libc code defines PAGE_SIZE to libc.page_size, which is set to aux[AT_PAGESZ] in __init_libc and early in __dynlink as well. (Note that libc.page_size can be accessed without GOT, ie. before relocations are done) Some fpathconf settings are hardcoded to 4096, these should be actually queried from the filesystem using statfs.
* fix child stack alignment on mips cloneRich Felker2013-09-141-0/+1
| | | | | | unlike other archs, the mips version of clone was not doing anything to align the stack pointer. this seems to have been the cause for some SIGBUS crashes that were observed in posix_spawn.
* fix mips-specific bug in synccall (too little space for signal mask)Rich Felker2013-09-021-5/+3
| | | | | switch to the new __block_all_sigs/__restore_sigs internal API to clean up the code too.
* in synccall, ignore the signal before any threads' signal handlers returnRich Felker2013-09-021-4/+4
| | | | | | this protects against deadlock from spurious signals (e.g. sent by another process) arriving after the controlling thread releases the other threads from the sync operation.
* fix invalid pointer in synccall (multithread setuid, etc.)Rich Felker2013-09-021-0/+1
| | | | | | | the head pointer was not being reset between calls to synccall, so any use of this interface more than once would build the linked list incorrectly, keeping the (now invalid) list nodes from the previous call.
* in pthread_getattr_np, use mremap rather than madvise to measure stackRich Felker2013-07-311-1/+2
| | | | | | | | | | | the original motivation for this patch was that qemu (and possibly other syscall emulators) nop out madvise, resulting in an infinite loop. however, there is another benefit to this change: madvise may actually undo an explicit madvise the application intended for its stack, whereas the mremap operation is a true nop. the logic here is that mremap must fail if it cannot resize the mapping in-place, and the caller knows that it cannot resize in-place because it knows the next page of virtual memory is already occupied.
* make pthread attribute types structs, even when they just have one fieldRich Felker2013-07-2211-22/+22
| | | | | this change is to get the right tags for C++ ABI matching. it should have no other effects.
* fix syscall argument bug in pthread_getschedparamRich Felker2013-06-261-1/+1
| | | | | the address of the pointer to the sched param, rather than the pointer, was being passed to the kernel.
* fix temp file leak in sem_open on successful creation of new semaphoreRich Felker2013-06-261-2/+2
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* fix bug whereby sem_open leaked its own internal slots on failureRich Felker2013-06-261-3/+6
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* in sem_open, don't leak vm mapping if fstat failsRich Felker2013-06-261-2/+2
| | | | | fstat should not fail under normal circumstances, so this fix is mostly theoretical.
* fix failure of pthread_setschedparam to pass correct param to kernelRich Felker2013-06-261-1/+1
| | | | | the address of the pointer, rather than the pointer, was being passed. this was probably a copy-and-paste error from corresponding get code.
* support cputime clocks for processes/threads other than selfRich Felker2013-06-081-1/+2
| | | | | | | apparently these features have been in Linux for a while now, so it makes sense to support them. the bit twiddling seems utterly illogical and wasteful, especially the negation, but that's how the kernel folks chose to encode pids/tids into the clock id.
* ensure that thread dtv pointer is never null to optimize __tls_get_addrRich Felker2013-06-031-0/+2
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* transition to using functions for internal signal blocking/restoringRich Felker2013-04-261-8/+5
| | | | | | | | | | there are several reasons for this change. one is getting rid of the repetition of the syscall signature all over the place. another is sharing the constant masks without costly GOT accesses in PIC. the main motivation, however, is accurately representing whether we want to block signals that might be handled by the application, or all signals.
* prevent code from running under a thread id which already gave ESRCHRich Felker2013-04-261-1/+7
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* synccall signal handler need not handle dead threads anymoreRich Felker2013-04-261-9/+0
| | | | | | they have already blocked signals before decrementing the thread count, so the code being removed is unreachable in the case where the thread is no longer counted.
* fix clobbering of signal mask when creating thread with sched attributesRich Felker2013-04-261-1/+1
| | | | this was simply a case of saving the state in the wrong place.
* make last thread's pthread_exit give exit(0) a consistent stateRich Felker2013-04-261-3/+13
| | | | | the previous few commits ended up leaving the thread count and signal mask wrong for atexit handlers and stdio cleanup.
* use atomic decrement rather than cas in pthread_exit thread countRich Felker2013-04-261-4/+1
| | | | | | now that blocking signals prevents any application code from running while the last thread is exiting, the cas logic is no longer needed to prevent decrementing below zero.
* add comments on some of the pthread_exit logicRich Felker2013-04-261-2/+15
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* always block signals in pthread_exit before decrementing thread countRich Felker2013-04-261-2/+2
| | | | | | | | | | | | | | | | | | | | | | the thread count (1+libc.threads_minus_1) must always be greater than or equal to the number of threads which could have application code running, even in an async-signal-safe sense. there is at least one dangerous race condition if this invariant fails to hold: dlopen could allocate too little TLS for existing threads, and a signal handler running in the exiting thread could claim the allocated TLS for itself (via __tls_get_addr), leaving too little for the other threads it was allocated for and thereby causing out-of-bounds access. there may be other situations where it's dangerous for the thread count to be too low, particularly in the case where only one thread should be left, in which case locking may be omitted. however, all such code paths seem to arise from undefined behavior, since async-signal-unsafe functions are not permitted to be called from a signal handler that interrupts pthread_exit (which is itself async-signal-unsafe). this change may also simplify logic in __synccall and improve the chances of making __synccall async-signal-safe.
* fix type error in pthread_create, introduced with pthread_getattr_npRich Felker2013-04-061-1/+1
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* implement pthread_getattr_npRich Felker2013-03-312-2/+29
| | | | | | this function is mainly (purely?) for obtaining stack address information, but we also provide the detach state since it's easy to do anyway.
* remove __SYSCALL_SSLEN arch macro in favor of using public _NSIGRich Felker2013-03-264-9/+9
| | | | | | | | | | | | | | the issue at hand is that many syscalls require as an argument the kernel-ABI size of sigset_t, intended to allow the kernel to switch to a larger sigset_t in the future. previously, each arch was defining this size in syscall_arch.h, which was redundant with the definition of _NSIG in bits/signal.h. as it's used in some not-quite-portable application code as well, _NSIG is much more likely to be recognized and understood immediately by someone reading the code, and it's also shorter and less cluttered. note that _NSIG is actually 65/129, not 64/128, but the division takes care of throwing away the off-by-one part.
* 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.