path: root/src/internal
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2011-06-13remove all .size and .type directives for functions from the asmRich Felker-4/+0
these are useless and have caused problems for users trying to build with non-gnu tools like tcc's assembler.
2011-05-30implement uselocale function (minimal)Rich Felker-0/+2
2011-05-07optimize compound-literal sigset_t's not to contain useless hurd bitsRich Felker-2/+4
2011-05-07overhaul implementation-internal signal protectionsRich Felker-3/+6
the new approach relies on the fact that the only ways to create sigset_t objects without invoking UB are to use the sig*set() functions, or from the masks returned by sigprocmask, sigaction, etc. or in the ucontext_t argument to a signal handler. thus, as long as sigfillset and sigaddset avoid adding the "protected" signals, there is no way the application will ever obtain a sigset_t including these bits, and thus no need to add the overhead of checking/clearing them when sigprocmask or sigaction is called. note that the old code actually *failed* to remove the bits from sa_mask when sigaction was called. the new implementations are also significantly smaller, simpler, and faster due to ignoring the useless "GNU HURD signals" 65-1024, which are not used and, if there's any sanity in the world, never will be used.
2011-05-06completely new barrier implementation, addressing major correctness issuesRich Felker-4/+4
the previous implementation had at least 2 problems: 1. the case where additional threads reached the barrier before the first wave was finished leaving the barrier was untested and seemed not to be working. 2. threads leaving the barrier continued to access memory within the barrier object after other threads had successfully returned from pthread_barrier_wait. this could lead to memory corruption or crashes if the barrier object had automatic storage in one of the waiting threads and went out of scope before all threads finished returning, or if one thread unmapped the memory in which the barrier object lived. the new implementation avoids both problems by making the barrier state essentially local to the first thread which enters the barrier wait, and forces that thread to be the last to return.
2011-05-01workaround for preprocessor bug in pccRich Felker-7/+7
with this patch, musl compiles and mostly works with pcc 1.0.0. a few tests are still failing and i'm uncertain whether they are due to portability problems in musl, or bugs in pcc, but i suspect the latter.
2011-04-20fix minor bugs due to incorrect threaded-predicate semanticsRich Felker-0/+1
some functions that should have been testing whether pthread_self() had been called and initialized the thread pointer were instead testing whether pthread_create() had been called and actually made the program "threaded". while it's unlikely any mismatch would occur in real-world problems, this could have introduced subtle bugs. now, we store the address of the main thread's thread descriptor in the libc structure and use its presence as a flag that the thread register is initialized. note that after fork, the calling thread (not necessarily the original main thread) is the new main thread.
2011-04-17clean up handling of thread/nothread mode, lockingRich Felker-5/+4
2011-04-17optimize cancellation enable/disable codeRich Felker-0/+1
the goal is to be able to use pthread_setcancelstate internally in the implementation, whenever a function might want to use functions which are cancellation points but avoid becoming a cancellation point itself. i could have just used a separate internal function for temporarily inhibiting cancellation, but the solution in this commit is better because (1) it's one less implementation-specific detail in functions that need to use it, and (2) application code can also get the same benefit. previously, pthread_setcancelstate dependend on pthread_self, which would pull in unwanted thread setup overhead for non-threaded programs. now, it temporarily stores the state in the global libc struct if threads have not been initialized, and later moves it if needed. this way we can instead use __pthread_self, which has no dependencies and assumes that the thread register is already valid.
2011-04-17overhaul pthread cancellationRich Felker-8/+18
this patch improves the correctness, simplicity, and size of cancellation-related code. modulo any small errors, it should now be completely conformant, safe, and resource-leak free. the notion of entering and exiting cancellation-point context has been completely eliminated and replaced with alternative syscall assembly code for cancellable syscalls. the assembly is responsible for setting up execution context information (stack pointer and address of the syscall instruction) which the cancellation signal handler can use to determine whether the interrupted code was in a cancellable state. these changes eliminate race conditions in the previous generation of cancellation handling code (whereby a cancellation request received just prior to the syscall would not be processed, leaving the syscall to block, potentially indefinitely), and remedy an issue where non-cancellable syscalls made from signal handlers became cancellable if the signal handler interrupted a cancellation point. x86_64 asm is untested and may need a second try to get it right.
2011-04-14use a separate signal from SIGCANCEL for SIGEV_THREAD timersRich Felker-0/+1
otherwise we cannot support an application's desire to use asynchronous cancellation within the callback function. this change also slightly debloats pthread_create.c.
2011-04-09greatly improve SIGEV_THREAD timersRich Felker-0/+1
calling pthread_exit from, or pthread_cancel on, the timer callback thread will no longer destroy the timer.
2011-04-06move rsyscall out of pthread_create moduleRich Felker-1/+5
this is something of a tradeoff, as now set*id() functions, rather than pthread_create, are what pull in the code overhead for dealing with linux's refusal to implement proper POSIX thread-vs-process semantics. my motivations are: 1. it's cleaner this way, especially cleaner to optimize out the rsyscall locking overhead from pthread_create when it's not needed. 2. it's expected that only a tiny number of core system programs will ever use set*id() functions, whereas many programs may want to use threads, and making thread overhead tiny is an incentive for "light" programs to try threads.
2011-04-05new framework to inhibit thread cancellation when neededRich Felker-0/+2
with these small changes, libc functions which need to call functions which are cancellation points, but which themselves must not be cancellation points, can use the CANCELPT_INHIBIT and CANCELPT_RESUME macros to temporarily inhibit all cancellation.
2011-04-03simplify calling of timer signal handlerRich Felker-2/+1
2011-04-03simplify pthread tsd key handlingRich Felker-2/+1
2011-04-01reorganize the __libc structure for threaded performance issuesRich Felker-6/+6
we want to keep atomically updated fields (locks and thread count) and really anything writable far away from frequently-needed function pointers. stuff some rarely-needed function pointers in between to pad, hopefully up to a cache line boundary.
2011-03-30optimize timer creation and possibly protect against some minor racesRich Felker-2/+0
the major idea of this patch is not to depend on having the timer pointer delivered to the signal handler, and instead use the thread pointer to get the callback function address and argument. this way, the parent thread can make the timer_create syscall while the child thread is starting, and it should never have to block waiting for the barrier.
2011-03-29major improvements to cancellation handlingRich Felker-2/+6
- there is no longer any risk of spoofing cancellation requests, since the cancel flag is set in pthread_cancel rather than in the signal handler. - cancellation signal is no longer unblocked when running the cancellation handlers. instead, pthread_create will cause any new threads created from a cancellation handler to unblock their own cancellation signal. - various tweaks in preparation for POSIX timer support.
2011-03-29some preliminaries for adding POSIX timersRich Felker-0/+4
2011-03-28remove useless field in pthread struct (wasted a good bit of space)Rich Felker-1/+0
2011-03-28major stdio overhaul, using readv/writev, plus other changesRich Felker-12/+22
the biggest change in this commit is that stdio now uses readv to fill the caller's buffer and the FILE buffer with a single syscall, and likewise writev to flush the FILE buffer and write out the caller's buffer in a single syscall. making this change required fundamental architectural changes to stdio, so i also made a number of other improvements in the process: - the implementation no longer assumes that further io will fail following errors, and no longer blocks io when the error flag is set (though the latter could easily be changed back if desired) - unbuffered mode is no longer implemented as a one-byte buffer. as a consequence, scanf unreading has to use ungetc, to the unget buffer has been enlarged to hold at least 2 wide characters. - the FILE structure has been rearranged to maintain the locations of the fields that might be used in glibc getc/putc type macros, while shrinking the structure to save some space. - error cases for fflush, fseek, etc. should be more correct. - library-internal macros are used for getc_unlocked and putc_unlocked now, eliminating some ugly code duplication. __uflow and __overflow are no longer used anywhere but these macros. switch to read or write mode is also separated so the code can be better shared, e.g. with ungetc. - lots of other small things.
2011-03-24simplify and optimize FILE lock handlingRich Felker-3/+2
2011-03-24overhaul cancellation to fix resource leaks and dangerous behavior with signalsRich Felker-1/+2
this commit addresses two issues: 1. a race condition, whereby a cancellation request occurring after a syscall returned from kernelspace but before the subsequent CANCELPT_END would cause cancellable resource-allocating syscalls (like open) to leak resources. 2. signal handlers invoked while the thread was blocked at a cancellation point behaved as if asynchronous cancellation mode wer in effect, resulting in potentially dangerous state corruption if a cancellation request occurs. the glibc/nptl implementation of threads shares both of these issues. with this commit, both are fixed. however, cancellation points encountered in a signal handler will not be acted upon if the signal was received while the thread was already at a cancellation point. they will of course be acted upon after the signal handler returns, so in real-world usage where signal handlers quickly return, it should not be a problem. it's possible to solve this problem too by having sigaction() wrap all signal handlers with a function that uses a pthread_cleanup handler to catch cancellation, patch up the saved context, and return into the cancellable function that will catch and act upon the cancellation. however that would be a lot of complexity for minimal if any benefit...
2011-03-20global cleanup to use the new syscall interfaceRich Felker-22/+0
2011-03-19syscall overhaul part two - unify public and internal syscall interfaceRich Felker-0/+32
with this patch, the syscallN() functions are no longer needed; a variadic syscall() macro allows syscalls with anywhere from 0 to 6 arguments to be made with a single macro name. also, manually casting each non-integer argument with (long) is no longer necessary; the casts are hidden in the macros. some source files which depended on being able to define the old macro SYSCALL_RETURNS_ERRNO have been modified to directly use __syscall() instead of syscall(). references to SYSCALL_SIGSET_SIZE and SYSCALL_LL have also been changed. x86_64 has not been tested, and may need a follow-up commit to fix any minor bugs/oversights.
2011-03-19remove comment cruft that got left behind in x86_64 syscall.sRich Felker-1/+0
2011-03-19overhaul syscall interfaceRich Felker-11/+46
this commit shuffles around the location of syscall definitions so that we can make a syscall() library function with both SYS_* and __NR_* style syscall names available to user applications, provides the syscall() library function, and optimizes the code that performs the actual inline syscalls in the library itself. previously on i386 when built as PIC (shared library), syscalls were incurring bus lock (lock prefix) overhead at entry and exit, due to the way the ebx register was being loaded (xchg instruction with a memory operand). now the xchg takes place between two registers. further cleanup to arch/$(ARCH)/syscall.h is planned.
2011-03-18implement [v]swprintfRich Felker-1/+1
2011-03-17implement robust mutexesRich Felker-0/+5
some of this code should be cleaned up, e.g. using macros for some of the bit flags, masks, etc. nonetheless, the code is believed to be working and correct at this point.
2011-03-17reorder mutex struct fields to make room for pointers (upcoming robust mutexes)Rich Felker-1/+3
the layout has been chosen so that pointer slots 3 and 4 fit between the integer slots on 32-bit archs, and come after the integer slots on 64-bit archs.
2011-03-17unify lock and owner fields of mutex structureRich Felker-1/+0
this change is necessary to free up one slot in the mutex structure so that we can use doubly-linked lists in the implementation of robust mutexes.
2011-03-12implement flockfile api, rework stdio lockingRich Felker-12/+11
2011-03-10optimize pthread termination in the non-detached caseRich Felker-0/+1
we can avoid blocking signals by simply using a flag to mark that the thread has exited and prevent it from getting counted in the rsyscall signal-pingpong. this restores the original pthread create/join throughput from before the sigprocmask call was added.
2011-03-08fix and optimize non-default-type mutex behaviorRich Felker-0/+1
problem 1: mutex type from the attribute was being ignored by pthread_mutex_init, so recursive/errorchecking mutexes were never being used at all. problem 2: ownership of recursive mutexes was not being enforced at unlock time.
2011-03-07use the selected clock from the condattr for pthread_cond_timedwaitRich Felker-0/+1
2011-02-24various changes in preparation for dynamic linking supportRich Felker-5/+13
prefer using visibility=hidden for __libc internal data, rather than an accessor function, if the compiler has visibility. optimize with -O3 for PIC targets (shared library). without heavy inlining, reloading the GOT register in small functions kills performance. 20-30% size increase for a single is not a big deal, compared to comparaible size increase in every static binaries. use -Bsymbolic-functions, not -Bsymbolic. global variables are subject to COPY relocations, and thus binding their addresses in the library at link time will cause library functions to read the wrong (original) copies instead of the copies made in the main program's bss section. add entry point, _start, for dynamic linker.
2011-02-20use an accessor function for __libc data pointer when compiled as PICRich Felker-4/+19
prior to this change, a large portion of libc was unusable prior to relocation by the dynamic linker, due to dependence on the global data in the __libc structure and the need to obtain its address through the GOT. with this patch, the accessor function __libc_loc is now able to obtain the address of __libc via PC-relative addressing without using the GOT. this means the majority of libc functionality is now accessible right away. naturally, the above statements all depend on having an architecture where PC-relative addressing and jumps/calls are feasible, and a compiler that generates the appropriate code.
2011-02-18add pthread_atfork interfaceRich Felker-0/+1
note that this presently does not handle consistency of the libc's own global state during forking. as per POSIX 2008, if the parent process was threaded, the child process may only call async-signal-safe functions until one of the exec-family functions is called, so the current behavior is believed to be conformant even if non-ideal. it may be improved at some later time.
2011-02-17reorganize pthread data structures and move the definitions to alltypes.hRich Felker-0/+19
this allows sys/types.h to provide the pthread types, as required by POSIX. this design also facilitates forcing ABI-compatible sizes in the arch-specific alltypes.h, while eliminating the need for developers changing the internals of the pthread types to poke around with arch-specific headers they may not be able to test.
2011-02-15move arch-specific internal headers into placeRich Felker-637/+0
2011-02-15finish unifying thread register handling in preparation for portingRich Felker-8/+2
2011-02-15begin unifying clone/thread management interface in preparation for portingRich Felker-5/+3
2011-02-13cleaning up syscalls in preparation for x86_64 portRich Felker-9/+40
- hide all the legacy xxxxxx32 name cruft in syscall.h so the actual source files can be clean and uniform across all archs. - cleanup llseek/lseek and mmap2/mmap handling for 32/64 bit systems - alternate implementation for nice if the target lacks nice syscall
2011-02-12ensure that the compiler doesn't try to reorder around atomic opsRich Felker-13/+13
2011-02-12initial check-in, version 0.5.0v0.5.0Rich Felker-0/+852