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2015-04-13dynamic linker bootstrap overhaulRich Felker2-89/+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 Felker1-3/+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 Felker1-0/+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 Felker1-0/+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 Nagy1-1/+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 Behn1-0/+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 Felker1-7/+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 Nagy1-0/+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 Behn1-3/+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 Behn1-2/+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 Nagy1-0/+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 Felker1-1/+0
2014-10-10add explicit barrier operation to internal atomic.h APIRich Felker1-1/+3
2014-10-08add new syscall numbers for seccomp, getrandom, memfd_createSzabolcs Nagy1-0/+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 Felker1-0/+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 Felker1-0/+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 Felker1-0/+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 Felker1-1/+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 Felker1-6/+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 Nagy1-0/+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 Felker1-5/+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 Felker1-20/+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 Felker1-14/+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 Felker1-24/+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 Felker1-0/+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 Felker1-23/+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 Felker1-1/+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 Nagy1-0/+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 Nagy1-0/+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 Felker1-1/+2
2014-04-15fix RLIMIT_ constants for mipsSzabolcs Nagy1-0/+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 Felker1-6/+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 Felker1-1/+1
like almost everything on mips, this is gratuitously different.
2014-03-18move signal.h definition of stack_t to arch-specific bitsRich Felker1-0/+6
it's different at least on mips. mips version will be fixed in a separate commit to show the change.
2014-03-18fix size of mips jmp_bufRich Felker1-1/+1
the excess space was unused and unintentional. this change does not affect the ABI between applications and libc. while it does theoretically affect linkage between third-party translation units using jmp_buf as part of a structure, we've already changed jmp_buf at least once on all archs, and problems were never observed, likely because such usage would be very unusual. in any case it's best to get things right now rather than making changes sometime during the 1.0.x series or later.
2014-03-18remove useless and incorrect uc_regspace member from mips ucontext_tRich Felker1-1/+0
this seems to have been copied erroneously from the arm version of the file. it's fairly harmless but it's a mistake and better to fix now than later.
2014-03-12fix statfs struct on mipsSzabolcs Nagy1-3/+4
The mips statfs struct layout is different than on other archs, so the statfs, fstatfs, statvfs and fstatvfs APIs were broken on mips. Now the ordering is fixed, the types are kept consistent with other archs.
2014-03-12fix semid_ds structure on mipsSzabolcs Nagy1-2/+0
This used to be broken when all archs had the same semid_ds definition: there is no padding around the time_t members on mips.
2014-03-11move struct semid_ds to from shared sys/sem.h to bitsRich Felker1-0/+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.
2014-02-24mips: add mips-sf subarch support (soft-float)Szabolcs Nagy2-1/+12
Userspace emulated floating-point (gcc -msoft-float) is not compatible with the default mips abi (assumes an FPU or in kernel emulation of it). Soft vs hard float abi should not be mixed, __mips_soft_float is checked in musl's configure script and there is no runtime check. The -sf subarch does not save/restore floating-point registers in setjmp/longjmp and only provides dummy fenv implementation.
2014-02-24fixup general __syscall breakage introduced in x32 portrofl0r1-0/+2
the reordering of headers caused some risc archs to not see the __syscall declaration anymore. this caused build errors on mips with any compiler, and on arm and microblaze with clang. we now declare it locally just like the powerpc port does.
2014-02-23sys/shm.h: move arch specific structs to bits/rofl0r1-0/+11
2014-01-08fix namespace violations in termios.h, at least mostlyRich Felker1-12/+11
the fix should be complete on archs that use the generic definitions (i386, arm, x86_64, microblaze), but mips and powerpc have not been checked thoroughly and may need more fixes.
2013-11-23add O_TMPFILE flag, new in linux 3.11Szabolcs Nagy1-0/+1
definition in linux: #define O_TMPFILE (__O_TMPFILE | O_DIRECTORY) where __O_TMPFILE and O_DIRECTORY are arch specific
2013-11-20fix the nominal type of LDBL_* limits on archs with ld64Rich Felker1-4/+4
previously these macros wrongly had type double rather than long double. I see no way an application could detect the error in C99, but C11's _Generic can trivially detect it. at the same time, even though these archs do not have excess precision, the number of decimal places used to represent these constants has been increased to 21 to be consistent with the decimal representations used for the DBL_* macros.
2013-09-26remove duplicate lines from mips bits/syscall.hRich Felker1-48/+0
2013-09-15support configurable page size on mips, powerpc and microblazeSzabolcs Nagy2-2/+1
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.
2013-09-14fix mips sysv ipc bits headersRich Felker2-3/+9
msg.h was wrong for big-endian (wrong endiannness padding). shm.h was just plain wrong (mips is not supposed to have padding). both changes were tested using libc-test on qemu-system-mips.
2013-08-11add missing a_or_l to atomic.h for non-x86 archsRich Felker1-0/+5
this is needed for recently committed sigaction code
2013-08-10fix _NSIG and SIGRTMAX on mipsRich Felker1-1/+1
a mips signal mask contains 128 bits, enough for signals 1 through 128. however, the exit status obtained from the wait-family functions only has room for values up to 127. reportedly signal 128 was causing kernelspace bugs, so it was removed from the kernel recently; even without that issue, however, it was impossible to support it correctly in userspace. at the same time, the bug was masked on musl by SIGRTMAX incorrectly yielding 64 on mips, rather than the "correct" value of 128. now that the _NSIG issue is fixed, SIGRTMAX can be fixed at the same time, exposing the full range of signals for application use. note that the (nonstandardized) libc _NSIG value is actually one greater than the max signal number, and also one greater than the kernel headers' idea of _NSIG. this is the reason for the discrepency with the recent kernel changes. since reducing _NSIG by one brought it down from 129 to 128, rather than from 128 to 127, _NSIG/8, used widely in the musl sources, is unchanged.