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* dynamic linker bootstrap overhaulRich Felker2015-04-133-34/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | this overhaul further reduces the amount of arch-specific code needed by the dynamic linker and removes a number of assumptions, including: - that symbolic function references inside libc are bound at link time via the linker option -Bsymbolic-functions. - that libc functions used by the dynamic linker do not require access to data symbols. - that static/internal function calls and data accesses can be made without performing any relocations, or that arch-specific startup code handled any such relocations needed. removing these assumptions paves the way for allowing libc.so itself to be built with stack protector (among other things), and is achieved by a three-stage bootstrap process: 1. relative relocations are processed with a flat function. 2. symbolic relocations are processed with no external calls/data. 3. main program and dependency libs are processed with a fully-functional libc/ldso. reduction in arch-specific code is achived through the following: - crt_arch.h, used for generating crt1.o, now provides the entry point for the dynamic linker too. - asm is no longer responsible for skipping the beginning of argv[] when ldso is invoked as a command. - the functionality previously provided by __reloc_self for heavily GOT-dependent RISC archs is now the arch-agnostic stage-1. - arch-specific relocation type codes are mapped directly as macros rather than via an inline translation function/switch statement.
* move O_PATH definition back to arch bitsRich Felker2015-04-011-0/+1
| | | | | | | while it's the same for all presently supported archs, it differs at least on sparc, and conceptually it's no less arch-specific than the other O_* macros. O_SEARCH and O_EXEC are still defined in terms of O_PATH in the main fcntl.h.
* fix MINSIGSTKSZ values for archs with large signal contextsRich Felker2015-03-181-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | the previous values (2k min and 8k default) were too small for some archs. aarch64 reserves 4k in the signal context for future extensions and requires about 4.5k total, and powerpc reportedly uses over 2k. the new minimums are chosen to fit the saved context and also allow a minimal signal handler to run. since the default (SIGSTKSZ) has always been 6k larger than the minimum, it is also increased to maintain the 6k usable by the signal handler. this happens to be able to store one pathname buffer and should be sufficient for calling any function in libc that doesn't involve conversion between floating point and decimal representations. x86 (both 32-bit and 64-bit variants) may also need a larger minimum (around 2.5k) in the future to support avx-512, but the values on these archs are left alone for now pending further analysis. the value for PTHREAD_STACK_MIN is not increased to match MINSIGSTKSZ at this time. this is so as not to preclude applications from using extremely small thread stacks when they know they will not be handling signals. unfortunately cancellation and multi-threaded set*id() use signals as an implementation detail and therefore require a stack large enough for a signal context, so applications which use extremely small thread stacks may still need to avoid using these features.
* fix FLT_ROUNDS to reflect the current rounding modeSzabolcs Nagy2015-03-071-1/+0
| | | | | Implemented as a wrapper around fegetround introducing a new function to the ABI: __flt_rounds. (fegetround cannot be used directly from float.h)
* fix POLLWRNORM and POLLWRBAND on mipsTrutz Behn2015-03-041-0/+0
| | | | | | these macros have the same distinct definition on blackfin, frv, m68k, mips, sparc and xtensa kernels. POLLMSG and POLLRDHUP additionally differ on sparc.
* make all objects used with atomic operations volatileRich Felker2015-03-031-7/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | the memory model we use internally for atomics permits plain loads of values which may be subject to concurrent modification without requiring that a special load function be used. since a compiler is free to make transformations that alter the number of loads or the way in which loads are performed, the compiler is theoretically free to break this usage. the most obvious concern is with atomic cas constructs: something of the form tmp=*p;a_cas(p,tmp,f(tmp)); could be transformed to a_cas(p,*p,f(*p)); where the latter is intended to show multiple loads of *p whose resulting values might fail to be equal; this would break the atomicity of the whole operation. but even more fundamental breakage is possible. with the changes being made now, objects that may be modified by atomics are modeled as volatile, and the atomic operations performed on them by other threads are modeled as asynchronous stores by hardware which happens to be acting on the request of another thread. such modeling of course does not itself address memory synchronization between cores/cpus, but that aspect was already handled. this all seems less than ideal, but it's the best we can do without mandating a C11 compiler and using the C11 model for atomics. in the case of pthread_once_t, the ABI type of the underlying object is not volatile-qualified. so we are assuming that accessing the object through a volatile-qualified lvalue via casts yields volatile access semantics. the language of the C standard is somewhat unclear on this matter, but this is an assumption the linux kernel also makes, and seems to be the correct interpretation of the standard.
* move MREMAP_MAYMOVE and MREMAP_FIXED out of bitsTrutz Behn2015-01-301-3/+0
| | | | | | the definitions are generic for all kernel archs. exposure of these macros now only occurs on the same feature test as for the function accepting them, which is believed to be more correct.
* move wint_t definition to the shared part of alltypes.h.inRich Felker2014-12-211-1/+0
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* add explicit barrier operation to internal atomic.h APIRich Felker2014-10-101-1/+3
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* add threads.h and needed per-arch types for mtx_t and cnd_tRich Felker2014-09-061-0/+2
| | | | | | | | | | | | | | | | based on patch by Jens Gustedt. mtx_t and cnd_t are defined in such a way that they are formally "compatible types" with pthread_mutex_t and pthread_cond_t, respectively, when accessed from a different translation unit. this makes it possible to implement the C11 functions using the pthread functions (which will dereference them with the pthread types) without having to use the same types, which would necessitate either namespace violations (exposing pthread type names in threads.h) or incompatible changes to the C++ name mangling ABI for the pthread types. for the rest of the types, things are much simpler; using identical types is possible without any namespace considerations.
* add working a_spin() atomic for non-x86 targetsRich Felker2014-08-251-0/+1
| | | | | | | | | | | | | conceptually, a_spin needs to be at least a compiler barrier, so the compiler will not optimize out loops (and the load on each iteration) while spinning. it should also be a memory barrier, or the spinning thread might keep spinning without noticing stores from other threads, thus delaying for longer than it should. ideally, an optimal a_spin implementation that avoids unnecessary cache/memory contention should be chosen for each arch, but for now, the easiest thing is to perform a useless a_cas on the calling thread's stack.
* add max_align_t definition for C11 and C++11Rich Felker2014-08-201-0/+2
| | | | | | | | | | | | | | | | | unfortunately this needs to be able to vary by arch, because of a huge mess GCC made: the GCC definition, which became the ABI, depends on quirks in GCC's definition of __alignof__, which does not match the formal alignment of the type. GCC's __alignof__ unexpectedly exposes the an implementation detail, its "preferred alignment" for the type, rather than the formal/ABI alignment of the type, which it only actually uses in structures. on most archs the two values are the same, but on some (at least i386) the preferred alignment is greater than the ABI alignment. I considered using _Alignas(8) unconditionally, but on at least one arch (or1k), the alignment of max_align_t with GCC's definition is only 4 (even the "preferred alignment" for these types is only 4).
* make pointers used in robust list volatileRich Felker2014-08-171-1/+1
| | | | | | | | | | | | | | | | | | | | when manipulating the robust list, the order of stores matters, because the code may be asynchronously interrupted by a fatal signal and the kernel will then access the robust list in what is essentially an async-signal context. previously, aliasing considerations made it seem unlikely that a compiler could reorder the stores, but proving that they could not be reordered incorrectly would have been extremely difficult. instead I've opted to make all the pointers used as part of the robust list, including those in the robust list head and in the individual mutexes, volatile. in addition, the format of the robust list has been changed to point back to the head at the end, rather than ending with a null pointer. this is to match the documented kernel robust list ABI. the null pointer, which was previously used, only worked because faults during access terminate the robust list processing.
* fix terminal control ioctl constants for shRich Felker2014-07-291-4/+8
| | | | | | | | | | | | this commit changes the names to match the kernel names, exposing under the normal names the "old" versions which work with a smaller termios structure compatible with the userspace structure, and renaming the "new" versions with "2" on the end like the kernel has. this fixes spurious warnings "Unsupported ioctl: cmd=0x802c542a" from qemu-sh4 and should be more correct anyway, since our userspace termios structure does not have meaningful information in the part which the kernel would be interpreting as speeds with the new ioctl.
* clean up unused and inconsistent atomics in arch dirsRich Felker2014-07-271-5/+0
| | | | | | | | | | | the a_cas_l, a_swap_l, a_swap_p, and a_store_l operations were probably used a long time ago when only i386 and x86_64 were supported. as other archs were added, support for them was inconsistent, and they are obviously not in use at present. having them around potentially confuses readers working on new ports, and the type-punning hacks and inconsistent use of types in their definitions is not a style I wish to perpetuate in the source tree, so removing them seems appropriate.
* fix insufficient synchronization in sh atomic asmRich Felker2014-07-271-1/+2
| | | | | | | while other usage I've seen only has the synco instruction after the atomic operation, I cannot find any documentation indicating that this is correct. certainly all stores before the atomic need to have been synchronized before the atomic operation takes place.
* refactor to remove arch-specific relocation code from dynamic linkerRich Felker2014-06-181-25/+13
| | | | | | | | | | | this was one of the main instances of ugly code duplication: all archs use basically the same types of relocations, but roughly equivalent logic was duplicated for each arch to account for the different naming and numbering of relocation types and variation in whether REL or RELA records are used. as an added bonus, both REL and RELA are now supported on all archs, regardless of which is used by the standard toolchain.
* multiple fixes to sh (superh) dynamic linker relocationsRich Felker2014-06-171-10/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | the following issues are fixed: - R_SH_REL32 was adding the load address of the module being relocated to the result. this seems to have been a mistake in the original port, since it does not match other dynamic linker implementations and since adding a difference between two addresses (the symbol value and the relocation address) to a load address does not make sense. - R_SH_TLS_DTPMOD32 was wrongly accepting an inline addend (i.e. using += rather than = on *reloc_addr) which makes no sense; addition is not an operation that's defined on module ids. - R_SH_TLS_DTPOFF32 and R_SH_TLS_TPOFF32 were wrongly using inline addends rather than the RELA-provided addends. in addition, handling of R_SH_GLOB_DAT, R_SH_JMP_SLOT, and R_SH_DIR32 are merged to all honor the addend. the first two should not need it for correct usage generated by toolchains, but other dynamic linkers allow addends here, and it simplifies the code anyway. these issues were spotted while reviewing the code for the purpose of refactoring this part of the dynamic linker. no testing was performed.
* dynamic linker: permit error returns from arch-specific reloc functionRich Felker2014-06-161-1/+2
| | | | | | | | the immediate motivation is supporting TLSDESC relocations which require allocation and thus may fail (unless we pre-allocate), but this mechanism should also be used for throwing an error on unsupported or invalid relocation types, and perhaps in certain cases, for reporting when a relocation is not satisfiable.
* fix RLIMIT_ constants for mipsSzabolcs Nagy2014-04-151-0/+0
| | | | | | | The mips arch is special in that it uses different RLIMIT_ numbers than other archs, so allow bits/resource.h to override the default RLIMIT_ numbers (empty on all archs except mips). Reported by orc.
* fix signal.h breakage from moving stack_t to arch-specific bitsRich Felker2014-03-181-6/+6
| | | | | | in the previous changes, I missed the fact that both the prototype of the sigaltstack function and the definition of ucontext_t depend on stack_t.
* move signal.h definition of stack_t to arch-specific bitsRich Felker2014-03-181-0/+6
| | | | | it's different at least on mips. mips version will be fixed in a separate commit to show the change.
* fix typo in filename used in sh portRich Felker2014-03-181-0/+0
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* superh: fix dynamic linking of __fpscr_valuesBobby Bingham2014-03-162-1/+7
| | | | | | | | | | | | | | Applications ended up with copy relocations for this array, which resulted in libc's references to this array pointing to the application's copy. The dynamic linker, however, can require this array before the application is relocated, and therefore before the application's copy of this array is initialized. This resulted in garbage being loaded into FPSCR before executing main, which violated the ABI. We fix this by putting the array in crt1 and making the libc copy private. This prevents libc's reference to the array from pointing to an uninitialized copy in the application.
* move struct semid_ds to from shared sys/sem.h to bitsRich Felker2014-03-111-0/+16
| | | | | | | | | | | | the definition was found to be incorrect at least for powerpc, and fixing this cleanly requires making the definition arch-specific. this will allow cleaning up the definition for other archs to make it more specific, and reversing some of the ugliness (time_t hacks) introduced with the x32 port. this first commit simply copies the existing definition to each arch without any changes. this is intentional, to make it easier to review changes made on a per-arch basis.
* add bits/user.h for sh portRich Felker2014-03-081-0/+75
| | | | | this seems to have been overlooked, and resulted in breakage in anything including sys/user.h.
* add nofpu subarchs to the sh arch, and properly detect compiler's fpu configRich Felker2014-02-271-0/+9
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* fix endian subarchs for sh archRich Felker2014-02-272-5/+5
| | | | | default endianness for sh on linux is little, and while conventions vary, "eb" seems to be the most widely used suffix for big endian.
* rename superh port to "sh" for consistencyRich Felker2014-02-2730-0/+1950
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.