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* add system for resetting TLS to initial valuesRich Felker2013-08-031-14/+18
| | | | | | | | | | | | | | | this is needed for reused threads in the SIGEV_THREAD timer notification system, and could be reused elsewhere in the future if needed, though it should be refactored for such use. for static linking, __init_tls.c is simply modified to export the TLS info in a structure with external linkage, rather than using statics. this perhaps makes the code more clear, since the statics were poorly named for statics. the new __reset_tls.c is only linked if it is used. for dynamic linking, the code is in dynlink.c. sharing code with __copy_tls is not practical since __reset_tls must also re-zero thread-local bss.
* fix omission of dtv setup in static linked programs on TLS variant I archsRich Felker2013-07-131-1/+1
| | | | | | | | | apparently this was never noticed before because the linker normally optimizes dynamic TLS models to non-dynamic ones when static linking, thus eliminating the calls to __tls_get_addr which crash when the dtv is missing. however, some libsupc++ code on ARM was calling __tls_get_addr when static linked and crashing. the reason is unclear to me, but with this issue fixed it should work now anyway.
* fix reference to libc struct in static tls init codeRich Felker2012-12-251-1/+1
| | | | | | | libc is the macro, __libc is the internal symbol, but under some configurations on old/broken compilers, the symbol might not actually exist and the libc macro might instead use __libc_loc() to obtain access to the object.
* clean up sloppy nested inclusion from pthread_impl.hRich Felker2012-11-081-0/+2
| | | | | | | | | | | | | | 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 unused variable warningsRich Felker2012-11-011-1/+1
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* fix crashes in static-linked multithreaded programs without TLSRich Felker2012-10-191-0/+2
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* add support for TLS variant I, presently needed for arm and mipsRich Felker2012-10-151-1/+8
| | | | | | | | | | | | | | | | | | | | | | 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.
* clean up and refactor program initializationRich Felker2012-10-071-9/+2
| | | | | | | | | | | | | | | 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.
* fix buggy TLS size/alignment computations in static-linked TLSRich Felker2012-10-061-5/+22
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* support for TLS in dynamic-loaded (dlopen) modulesRich Felker2012-10-051-2/+2
| | | | | | | | | | | | | | | | | | | | | 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.
* partial TLS support for dynamic-linked programsRich Felker2012-10-041-5/+5
| | | | | only TLS in the main program is supported so far; TLS defined in shared libraries will not work yet.
* TLS (GNU/C11 thread-local storage) support for static-linked programsRich Felker2012-10-041-0/+71
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.