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2016-01-22overhaul mips atomics for new atomics frameworkRich Felker-53/+31
2016-01-21refactor internal atomic.hRich Felker-205/+61
rather than having each arch provide its own atomic.h, there is a new shared atomic.h in src/internal which pulls arch-specific definitions from arc/$(ARCH)/atomic_arch.h. the latter can be extremely minimal, defining only a_cas or new ll/sc type primitives which the shared atomic.h will use to construct everything else. this commit avoids making heavy changes to the individual archs' atomic implementations. definitions which are identical or near-identical to what the new shared atomic.h would produce have been removed, but otherwise the changes made are just hooking up the arch-specific files to the new infrastructure. major changes to take advantage of the new system will come in subsequent commits.
2015-12-29adjust mips crt_arch entry point asm to avoid assembler bugsRich Felker-1/+4
apparently the .gpword directive does not work reliably with local text labels; values produced were offset by 64k from the correct value, resulting in incorrect computation of the got pointer at runtime. instead, use an external label so that the assembler does not munge the relocation; the linker will then get it right. commit 6fef8cafbd0f6f185897bc87feb1ff66e2e204e1 exposed this issue by removing the old, non-PIE-compatible handwritten crt1.s, which was not affected. presumably mips PIE executables (using Scrt1.o produced from crt_arch.h) were already affected at the time.
2015-12-15remove visibility suppression by SHARED macro in mips and x32 arch filesRich Felker-2/+0
commit 8a8fdf6398b85c99dffb237e47fa577e2ddc9e77 was intended to remove all such usage, but these arch-specific files were overlooked, leading to inconsistent declarations and definitions.
2015-11-02properly access mcontext_t program counter in cancellation handlerRich Felker-1/+1
using the actual mcontext_t definition rather than an overlaid pointer array both improves correctness/readability and eliminates some ugly hacks for archs with 64-bit registers bit 32-bit program counter. also fix UB due to comparison of pointers not in a common array object.
2015-10-15add comment documenting hard-coded opcode for reading mips thread pointerRich Felker-0/+1
2015-09-23fix signal return for sh/fdpicRich Felker-0/+2
the restorer function pointer provided in the kernel sigaction structure is interpreted by the kernel as a raw code address, not a function descriptor. this commit moves the declarations of the __restore and __restore_rt symbols to ksigaction.h so that arch versions of the file can override them, and introduces a version for sh which declares them as objects rather than functions. an alternate solution would have been defining SA_RESTORER to 0 so that the functions are not used, but this both requires executable stack (since the sh kernel does not have a vdso page with permanent restorer functions) and crashes on qemu user-level emulation.
2015-09-17new dlstart stage-2 chaining for mipsRich Felker-0/+15
2015-07-21socket.h: cleanup/reorder mips and powerpc bits/socket.hRoman Yeryomin-16/+18
....to be somewhat consistent and easily comparable with asm/socket.h Signed-off-by: Roman Yeryomin <roman@ubnt.com>
2015-07-21socket.h: fix SO_* for mipsRoman Yeryomin-0/+3
Signed-off-by: Roman Yeryomin <roman@ubnt.com>
2015-07-21mips: fix mcontext_t register array field nameFelix Fietkau-1/+1
glibc and uclibc use gregs instead of regs Signed-off-by: Felix Fietkau <nbd@openwrt.org>
2015-06-25fix local-dynamic model TLS on mips and powerpcRich Felker-0/+2
the TLS ABI spec for mips, powerpc, and some other (presently unsupported) RISC archs has the return value of __tls_get_addr offset by +0x8000 and the result of DTPOFF relocations offset by -0x8000. I had previously assumed this part of the ABI was actually just an implementation detail, since the adjustments cancel out. however, when the local dynamic model is used for accessing TLS that's known to be in the same DSO, either of the following may happen: 1. the -0x8000 offset may already be applied to the argument structure passed to __tls_get_addr at ld time, without any opportunity for runtime relocations. 2. __tls_get_addr may be used with a zero offset argument to obtain a base address for the module's TLS, to which the caller then applies immediate offsets for individual objects accessed using the local dynamic model. since the immediate offsets have the -0x8000 adjustment applied to them, the base address they use needs to include the +0x8000 offset. it would be possible, but more complex, to store the pointers in the dtv[] array with the +0x8000 offset pre-applied, to avoid the runtime cost of adding 0x8000 on each call to __tls_get_addr. this change could be made later if measurements show that it would help.
2015-05-24fix stack alignment code in mips crt_arch.hRich Felker-2/+2
the instruction used to align the stack, "and $sp, $sp, -8", does not actually exist; it's expanded to 2 instructions using the 'at' (assembler temporary) register, and thus cannot be used in a branch delay slot. since alignment mod 16 commutes with subtracting 8, simply swapping these two operations fixes the problem. crt1.o was not affected because it's still being generated from a dedicated asm source file. dlstart.lo was not affected because the stack pointer it receives is already aligned by the kernel. but Scrt1.o was affected in cases where the dynamic linker gave it a misaligned stack pointer.
2015-05-22add .text section directive to all crt_arch.h files missing itRich Felker-0/+1
i386 and x86_64 versions already had the .text directive; other archs did not. normally, top-level (file scope) __asm__ starts in the .text section anyway, but problems were reported with some versions of clang, and it seems preferable to set it explicitly anyway, at least for the sake of consistency between archs.
2015-04-30fix __syscall declaration with wrong visibility in syscall_arch.hSzabolcs Nagy-0/+3
remove __syscall declaration where it is not needed (aarch64, arm, microblaze, or1k) and add the hidden attribute where it is (mips).
2015-04-17fix missing quotation mark in mips crt_arch.h that broke buildRich Felker-1/+1
2015-04-13dynamic linker bootstrap overhaulRich Felker-89/+38
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.
2015-04-07fix possible clobbering of syscall return values on mipsRich Felker-3/+6
depending on the compiler's interpretation of __asm__ register names for register class objects, it may be possible for the return value in r2 to be clobbered by the function call to __stat_fix. I have not observed any such breakage in normal builds and suspect it only happens with -O0 or other unusual build options, but since there's an ambiguity as to the semantics of this feature, it's best to use an explicit temporary to avoid the issue. based on reporting and patch by Eugene.
2015-04-01move O_PATH definition back to arch bitsRich Felker-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.
2015-03-18fix MINSIGSTKSZ values for archs with large signal contextsRich Felker-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.
2015-03-07fix FLT_ROUNDS to reflect the current rounding modeSzabolcs Nagy-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)
2015-03-04fix POLLWRNORM and POLLWRBAND on mipsTrutz Behn-0/+2
these macros have the same distinct definition on blackfin, frv, m68k, mips, sparc and xtensa kernels. POLLMSG and POLLRDHUP additionally differ on sparc.
2015-03-03make all objects used with atomic operations volatileRich Felker-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.
2015-02-09add syscall numbers for the new execveat syscallSzabolcs Nagy-0/+2
this syscall allows fexecve to be implemented without /proc, it is new in linux v3.19, added in commit 51f39a1f0cea1cacf8c787f652f26dfee9611874 (sh and microblaze do not have allocated syscall numbers yet) added a x32 fix as well: the io_setup and io_submit syscalls are no longer common with x86_64, so use the x32 specific numbers.
2015-01-30move MREMAP_MAYMOVE and MREMAP_FIXED out of bitsTrutz Behn-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.
2015-01-30remove mips-only EINIT and EREMDEV errnosTrutz Behn-2/+0
the errno values are unused by the kernel and the macro definitions were never exposed by glibc.
2014-12-23add new syscall numbers for bpf and kexec_file_loadSzabolcs Nagy-0/+2
these syscalls are new in linux v3.18, bpf is present on all supported archs except sh, kexec_file_load is only allocted for x86_64 and x32 yet. bpf was added in linux commit 99c55f7d47c0dc6fc64729f37bf435abf43f4c60 kexec_file_load syscall number was allocated in commit f0895685c7fd8c938c91a9d8a6f7c11f22df58d2
2014-12-21move wint_t definition to the shared part of alltypes.h.inRich Felker-1/+0
2014-10-10add explicit barrier operation to internal atomic.h APIRich Felker-1/+3
2014-10-08add new syscall numbers for seccomp, getrandom, memfd_createSzabolcs Nagy-0/+6
these syscalls are new in linux v3.17 and present on all supported archs except sh. seccomp was added in commit 48dc92b9fc3926844257316e75ba11eb5c742b2c it has operation, flags and pointer arguments (if flags==0 then it is the same as prctl(PR_SET_SECCOMP,...)), the uapi header for flag definitions is linux/seccomp.h getrandom was added in commit c6e9d6f38894798696f23c8084ca7edbf16ee895 it provides an entropy source when open("/dev/urandom",..) would fail, the uapi header for flags is linux/random.h memfd_create was added in commit 9183df25fe7b194563db3fec6dc3202a5855839c it allows anon mmap to have an fd, that can be shared, sealed and needs no mount point, the uapi header for flags is linux/memfd.h
2014-09-06add threads.h and needed per-arch types for mtx_t and cnd_tRich Felker-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.
2014-08-25add working a_spin() atomic for non-x86 targetsRich Felker-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.
2014-08-20add max_align_t definition for C11 and C++11Rich Felker-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).
2014-08-17make pointers used in robust list volatileRich Felker-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.
2014-07-27clean up unused and inconsistent atomics in arch dirsRich Felker-6/+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.
2014-07-20add syscall numbers for the new renameat2 syscallSzabolcs Nagy-0/+2
it's like rename but with flags eg. to allow atomic exchange of two files, introduced in linux 3.15 commit 520c8b16505236fc82daa352e6c5e73cd9870cff
2014-07-20fix regression that negated some mips syscall error returnsRich Felker-5/+5
due to what was essentially a copy and paste error, the changes made in commit f61be1f875a2758509d6e9e2cf6f1d9603b28b65 caused syscalls with 5 or 6 arguments (and syscalls with 2, 3, or 4 arguments when compiled with clang compatibility) to negate the returned error code a second time, breaking errno reporting.
2014-07-19fix mips struct stat dev_t members for big endianRich Felker-20/+81
the mips version of this structure on the kernel side wrongly has 32-bit type rather than 64-bit type. fortunately there is adjacent padding to bring it up to 64 bits, and on little-endian, this allows us to treat the adjacent kernel st_dev and st_pad0[0] as as single 64-bit dev_t. however, on big endian, such treatment results in the upper and lower 32-bit parts of the dev_t value being swapped. for the purpose of just comparing st_dev values this did not break anything, but it precluded actually processing the device numbers as major/minor values. since the broken kernel behavior that needs to be worked around is isolated to one arch, I put the workarounds in syscall_arch.h rather than adding a stat fixup path in the common code. on little endian mips, the added code optimizes out completely. the changes necessary were incompatible with the way the __asm_syscall macro was factored so I just removed it and flattened the individual __syscallN functions. this arguably makes the code easier to read and understand, anyway.
2014-07-19fix missing barrier instructions in mips atomic asmRich Felker-14/+18
previously I had wrongly assumed the ll/sc instructions also provided memory synchronization; apparently they do not. this commit adds sync instructions before and after each atomic operation and changes the atomic store to simply use sync before and after a plain store, rather than a useless compare-and-swap.
2014-07-19use memory constraints for mips atomic asmRich Felker-24/+24
despite lacking the semantic content that the asm accesses the pointed-to object rather than just using its address as a value, the mips asm was not actually broken. the asm blocks were declared volatile, meaning that the compiler must treat them as having unknown side effects. however changing the asm to use memory constraints is desirable not just from a semantic correctness and consistency standpoint, but also produces better code. the compiler is able to use base/offset addressing expressions for the atomic object's address rather than having to load the address into a single register. this improves access to global locks in static libc, and access to non-zero-offset atomic fields in synchronization primitives, etc.
2014-06-30fix regression in mips dynamic linkerRich Felker-0/+1
this issue caused the address of functions in shared libraries to resolve to their PLT thunks in the main program rather than their correct addresses. it was observed causing crashes, though the mechanism of the crash was not thoroughly investigated. since the issue is very subtle, it calls for some explanation: on all well-behaved archs, GOT entries that belong to the PLT use a special relocation type, typically called JMP_SLOT, so that the dynamic linker can avoid having the jump destinations for the PLT resolve to PLT thunks themselves (they also provide a definition for the symbol, which must be used whenever the address of the function is taken so that all DSOs see the same address). however, the traditional mips PIC ABI lacked such a JMP_SLOT relocation type, presumably because, due to the way PIC works, the address of the PLT thunk was never needed and could always be ignored. prior to commit adf94c19666e687a728bbf398f9a88ea4ea19996, the mips version of reloc.h contained a hack that caused all symbol lookups to be treated like JMP_SLOT, inhibiting undefined symbols from ever being used to resolve symbolic relocations. this hack goes all the way back to commit babf820180368f00742ec65b2050a82380d7c542, when the mips dynamic linker was first made usable. during the recent refactoring to eliminate arch-specific relocation processing (commit adf94c19666e687a728bbf398f9a88ea4ea19996), this hack was overlooked and no equivalent functionality was provided in the new code. fixing the problem is not as simple as adding back an equivalent hack, since there is now also a "non-PIC ABI" that can be used for the main executable, which actually does use a PLT. the closest thing to official documentation I could find for this ABI is nonpic.txt, attached to Message-ID: 20080701202236.GA1534@caradoc.them.org, which can be found in the gcc mailing list archives and elsewhere. per this document, undefined symbols corresponding to PLT thunks have the STO_MIPS_PLT bit set in the symbol's st_other field. thus, I have added an arch-specific rule for mips, applied at the find_sym level rather than the relocation level, to reject undefined symbols with the STO_MIPS_PLT bit clear. the previous hack of treating all mips relocations as JMP_SLOT-like, rather than rejecting the unwanted symbols in find_sym, probably also caused dlsym to wrongly return PLT thunks in place of the correct address of a function under at least some conditions. this should now be fixed, at least for global-scope symbol lookups.
2014-06-18refactor to remove arch-specific relocation code from dynamic linkerRich Felker-23/+9
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.
2014-06-16dynamic linker: permit error returns from arch-specific reloc functionRich Felker-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.
2014-05-30add sched_{get,set}attr syscall numbers and SCHED_DEADLINE macroSzabolcs Nagy-0/+4
linux 3.14 introduced sched_getattr and sched_setattr syscalls in commit d50dde5a10f305253cbc3855307f608f8a3c5f73 and the related SCHED_DEADLINE scheduling policy in commit aab03e05e8f7e26f51dee792beddcb5cca9215a5 but struct sched_attr "extended scheduling parameters data structure" is not yet exported to userspace (necessary for using the syscalls) so related uapi definitions are not added yet.
2014-05-30fix for broken kernel side RLIM_INFINITY on mipsSzabolcs Nagy-0/+2
On 32 bit mips the kernel uses -1UL/2 to mark RLIM_INFINITY (and this is the definition in the userspace api), but since it is in the middle of the valid range of limits and limits are often compared with relational operators, various kernel side logic is broken if larger than -1UL/2 limits are used. So we truncate the limits to -1UL/2 in get/setrlimit and prlimit. Even if the kernel side logic consistently treated -1UL/2 as greater than any other limit value, there wouldn't be any clean workaround that allowed using large limits: * using -1UL/2 as RLIM_INFINITY in userspace would mean different infinity value for get/setrlimt and prlimit (where infinity is always -1ULL) and userspace logic could break easily (just like the kernel is broken now) and more special case code would be needed for mips. * translating -1UL/2 kernel side value to -1ULL in userspace would mean that -1UL/2 limit cannot be set (eg. -1UL/2+1 had to be passed to the kernel instead).
2014-04-30fix missing SO_RCVBUFFORCE and SO_SNDBUFFORCE in mips socket.hRich Felker-1/+2
2014-04-15fix RLIMIT_ constants for mipsSzabolcs Nagy-0/+5
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.
2014-03-18fix signal.h breakage from moving stack_t to arch-specific bitsRich Felker-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.
2014-03-18fix mips stack_tRich Felker-1/+1
like almost everything on mips, this is gratuitously different.
2014-03-18move signal.h definition of stack_t to arch-specific bitsRich Felker-0/+6
it's different at least on mips. mips version will be fixed in a separate commit to show the change.