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* overhaul i386 syscall mechanism not to depend on external asm sourceRich Felker2019-04-109-80/+51
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | this is the first part of a series of patches intended to make __syscall fully self-contained in the object file produced using syscall.h, which will make it possible for crt1 code to perform syscalls. the (confusingly named) i386 __vsyscall mechanism, which this commit removes, was introduced before the presence of a valid thread pointer was mandatory; back then the thread pointer was setup lazily only if threads were used. the intent was to be able to perform syscalls using the kernel's fast entry point in the VDSO, which can use the sysenter (Intel) or syscall (AMD) instruction instead of int $128, but without inlining an access to the __syscall global at the point of each syscall, which would incur a significant size cost from PIC setup everywhere. the mechanism also shuffled registers/calling convention around to avoid spills of call-saved registers, and to avoid allocating ebx or ebp via asm constraints, since there are plenty of broken-but-supported compiler versions which are incapable of allocating ebx with -fPIC or ebp with -fno-omit-frame-pointer. the new mechanism preserves the properties of avoiding spills and avoiding allocation of ebx/ebp in constraints, but does it inline, using some fairly simple register shuffling, and uses a field of the thread structure rather than global data for the vdso-provided syscall code address. for now, the external __syscall function is refactored not to use the old __vsyscall so it can be kept, but the intent is to remove it too.
* release 1.1.22 v1.1.22Rich Felker2019-04-092-1/+42
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* in membarrier fallback, allow for possibility that sigaction failsRich Felker2019-04-091-8/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | this is a workaround to avoid a crashing regression on qemu-user when dynamic TLS is installed at dlopen time. the sigaction syscall should not be able to fail, but it does fail for implementation-internal signals under qemu user-level emulation if the host libc qemu is running under reserves the same signals for implementation-internal use, since qemu makes no provision to redirect/emulate them. after sigaction fails, the subsequent tkill would terminate the process abnormally as the default action. no provision to account for membarrier failing is made in the dynamic linker code that installs new TLS. at the formal level, the missing barrier in this case is incorrect, and perhaps we should fail the dlopen operation, but in practice all the archs we support (and probably all real-world archs except alpha, which isn't yet supported) should give the right behavior with no barrier at all as a consequence of consume-order properties. in the long term, this workaround should be supplemented or replaced by something better -- a different fallback approach to ensuring memory consistency, or dynamic allocation of implementation-internal signals. the latter is appealing in that it would allow cancellation to work under qemu-user too, and would even allow many levels of nested emulation.
* fix the use of syscall result in dl_mmapIlya Matveychikov2019-04-061-1/+1
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* fix signature of function accepted by makecontextBobby Bingham2019-04-051-1/+1
| | | | | | | | This parameter was incorrectly declared to be a pointer to a function accepting zero parameters. The intent of makecontext is that it is possible to pass integer parameters to the function, so this should have been a pointer to a function accepting an unspecified set of parameters.
* fix unintended global symbols in atanl.cDan Gohman2019-04-031-3/+3
| | | | | | | | Mark atanhi, atanlo, and aT in atanl.c as static, as they're not intended to be part of the public API. These are already static in the LDBL_MANT_DIG == 64 code, so this patch is just making the LDBL_MANT_DIG == 113 code do the same thing.
* use __strchrnul instead of strchr and strlen in execvpeFrediano Ziglio2019-04-021-2/+1
| | | | | | The result is the same but takes less code. Note that __execvpe calls getenv which calls __strchrnul so even using static output the size of the executable won't grow.
* delete a redundant if in dynamic linker ctor execution loopRay2019-04-021-1/+0
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* fix harmless-by-chance typo in priority inheritance mutex codeRich Felker2019-04-011-1/+1
| | | | | | | commit 54ca677983d47529bab8752315ac1a2b49888870 inadvertently introduced bitwise and where logical and was intended. since the right-hand operand is always 0 or -1 whenever the left-hand operand is nonzero, the behavior happened to be equivalent.
* implement priority inheritance mutexesRich Felker2019-03-314-8/+93
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | priority inheritance is a feature to mitigate priority inversion situations, where a execution of a medium-priority thread can unboundedly block forward progress of a high-priority thread when a lock it needs is held by a low-priority thread. the natural way to do priority inheritance would be with a simple futex flag to donate the calling thread's priority to a target thread while it waits on the futex. unfortunately, linux does not offer such an interface, but instead insists on implementing the whole locking protocol in kernelspace with special futex commands that exist solely for the purpose of doing PI mutexes. this would require the entire "trylock" logic to be duplicated in the timedlock code path for PI mutexes, since, once the previous lock holder releases the lock and the futex call returns, the lock is already held by the caller. obviously such code duplication is undesirable. instead, I've made the PI timedlock success path set the mutex lock count to -1, which can be thought of as "not yet complete", since a lock count of 0 is "locked, with no recursive references". a simple branch in a non-hot path of pthread_mutex_trylock can then see and act on this state, skipping past the code that would check and take the lock to the same code path that runs after the lock is obtained for a non-PI mutex. because we're forced to let the kernel perform the actual lock and unlock operations whenever the mutex is contended, we have to patch things up when it does the wrong thing: 1. the lock operation is not aware of whether the mutex is error-checking, so it will always fail with EDEADLK rather than deadlocking. 2. the lock operation is not aware of whether the mutex is robust, so it will successfully obtain mutexes in the owner-died state even if they're non-robust, whereas this operation should deadlock. 3. the unlock operation always sets the lock value to zero, whereas for robust mutexes, we want to set it to a special value indicating that the mutex obtained after its owner died was unlocked without marking it consistent, so that future operations all fail with ENOTRECOVERABLE. the first of these is easy to solve, just by performing a futex wait on a dummy futex address to simulate deadlock or ETIMEDOUT as appropriate. but problems 2 and 3 interact in a nasty way. to solve problem 2, we need to back out the spurious success. but if waiters are present -- which we can't just ignore, because even if we don't want to wake them, the calling thread is incorrectly inheriting their priorities -- this requires using the kernel's unlock operation, which will zero the lock value, thereby losing the "owner died with lock held" state. to solve these problems, we overload the mutex's waiters field, which is unused for PI mutexes since they don't call the normal futex wait functions, as an indicator that the PI mutex is permanently non-lockable. originally I wanted to use the count field, but there is one code path that needs to access this flag without synchronization: trylock's CAS failure path needs to be able to decide whether to fail with EBUSY or ENOTRECOVERABLE, the waiters field is already treated as a relaxed-order atomic in our memory model, so this works out nicely.
* clean up access to mutex type in pthread_mutex_trylockRich Felker2019-03-291-2/+2
| | | | | | | there was no point in masking off the pshared bit when first loading the type, since every subsequent access involves a mask anyway. not masking it may avoid a subsequent load to check the pshared flag, and it's just simpler.
* support archs with no renameat syscall, only renameat2Drew DeVault2019-03-212-2/+8
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* support archs with no mlock syscall, only mlock2Drew DeVault2019-03-211-0/+4
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* fix data race choosing next key slot in pthread_key_createRich Felker2019-03-211-1/+1
| | | | | | | | | commit 84d061d5a31c9c773e29e1e2b1ffe8cb9557bc58 wrongly moved the access to the global next_key outside of the scope of the lock. the error manifested as spurious failure to find an available key slot under concurrent calls to pthread_key_create, since the stopping condition could be met after only a small number of slots were examined.
* fix crash/out-of-bound read in sscanfRich Felker2019-03-142-2/+3
| | | | | | | | | | | | | | | | | | | | | commit d6c855caa88ddb1ab6e24e23a14b1e7baf4ba9c7 caused this "regression", though the behavior was undefined before, overlooking that f->shend=0 was being used as a sentinel for "EOF" status (actual EOF or hitting the scanf field width) of the stream helper (shgetc) functions. obviously the shgetc macro could be adjusted to check for a null pointer in addition to the != comparison, but it's the hot path, and adding extra code/branches to it begins to defeat the purpose. so instead of setting shend to a null pointer to block further reads, which no longer works, set it to the current position (rpos). this makes the shgetc macro work with no change, but it breaks shunget, which can no longer look at the value of shend to determine whether to back up. Szabolcs Nagy suggested a solution which I'm using here: setting shlim to a negative value is inexpensive to test at shunget time, and automatically re-trips the cnt>=shlim stop condition in __shgetc no matter what the original limit was.
* fix namespace violation in dependencies of mtx_lockRich Felker2019-03-131-1/+1
| | | | | | commit 2de29bc994029b903a366b8a4a9f8c3c3ee2be90 left behind one reference to pthread_mutex_trylock. fixing this also improves code generation due to the namespace-safe version being hidde.
* aarch64: add HWCAP_ definitions from linux v5.0Szabolcs Nagy2019-03-131-0/+3
| | | | | | | | HWCAP_SB - speculation barrier instruction available added in linux commit bd4fb6d270bc423a9a4098108784f7f9254c4e6d HWCAP_PACA, HWCAP_PACG - pointer authentication instructions available (address and generic) added in linux commit 7503197562567b57ec14feb3a9d5400ebc56812f
* sys/prctl.h: add PR_PAC_RESET_KEYS from linux v5.0Szabolcs Nagy2019-03-131-0/+7
| | | | | | aarch64 pointer authentication code related prctl that allows reinitializing the key for the thread, added in linux commit ba830885656414101b2f8ca88786524d4bb5e8c1
* elf.h: add NT_ definitions from linux v5.0Szabolcs Nagy2019-03-131-0/+2
| | | | | | | NT_MIPS_MSA for ptrace access to mips simd arch reg set, added in linux commit 3cd640832894b85b5929d5bda74505452c800421 NT_ARM_PAC_MASK for ptrace access to pointer auth code mask, added in commit ec6e822d1a22d0eef1d1fa260dff751dba9a4258
* elf.h: update with C-SKY definitionsSzabolcs Nagy2019-03-131-1/+57
| | | | | | | C-SKY support was added to binutils 2.32 in commit b8891f8d622a31306062065813fc278d8a94fe21 the elf.h change was added to glibc 2.29 in commit 4975f0c3d0131fdf697be0b1631c265e5fd39088
* aarch64, or1k: add kexec_file_load syscall number from linux v5.0Szabolcs Nagy2019-03-132-0/+2
| | | | added in linux commit 4e21565b7fd4d9045765f697887e74a704135fe2
* netinet/tcp.h: add TCP_NLA_SRTT from linux v5.0Szabolcs Nagy2019-03-131-0/+1
| | | | | smoothed RTT for SCM_TIMESTAMPING_OPT_STATS control messages. added in linux commit e8bd8fca6773ef49390269bd467bf940a0841ccf
* netinet/udp.h: add UDP_GRO from linux v5.0Szabolcs Nagy2019-03-131-0/+1
| | | | | sockopt to enable gro for udp. added in linux commit e20cf8d3f1f763ad28a9cb3b41305b8a8a42653e
* powerpc: add PTRACE_SYSEMU from linux v4.20Szabolcs Nagy2019-03-132-0/+4
| | | | added in linux commit 5521eb4bca2db733952f068c37bdf3cd656ad23c
* aarch64: add HWCAP_SSBS from linux v4.20Szabolcs Nagy2019-03-131-0/+1
| | | | | for armv8.5 speculative store bypass PSTATE bit support, added in linux commit d71be2b6c0e19180b5f80a6d42039cc074a693a2
* bits/ioctl.h: add TIOC{G,S}ISO7816 from linux v4.20Szabolcs Nagy2019-03-131-0/+2
| | | | | | | | | | | | | | | | | | | | | ISO7816 smart cards ioctls. linux commit ad8c0eaa0a418ae8ef3f9217638bb86439399eac the actual kernel definitions are #define TIOCGISO7816 _IOR('T', 0x42, struct serial_iso7816) #define TIOCSISO7816 _IOWR('T', 0x43, struct serial_iso7816) where struct serial_iso7816 is defined in linux/serial.h as struct serial_iso7816 { __u32 flags; __u32 tg; __u32 sc_fi; __u32 sc_di; __u32 clk; __u32 reserved[5]; };
* sys/prctl.h: add PR_SPEC_INDIRECT_BRANCH from linux v4.20Szabolcs Nagy2019-03-131-0/+1
| | | | | | prctls to allow per task control of indirect branch speculation on x86. added in linux commit 9137bb27e60e554dab694eafa4cca241fa3a694f
* netinet/in.h add IPV6_MULTICAST_ALL from linux v4.20Szabolcs Nagy2019-03-131-0/+1
| | | | | | ipv6 analogue of IP_MULTICAST_ALL sockopt. added in linux commit 15033f0457dca569b284bef0c8d3ad55fb37eacb
* add PACKET_IGNORE_OUTGOING sockopt from linux v4.20Szabolcs Nagy2019-03-131-0/+1
| | | | new in linux commit fa788d986a3aac5069378ed04697bd06f83d3488
* sys/mman.h: add new hugetlb mmap flags from linux v4.19Szabolcs Nagy2019-03-132-0/+4
| | | | | aarch64 supports 32MB and 512MB hugetlb page sizes too. added in linux commit 20916d4636a9b3c1bf562b305f91d126771edaf9
* arm: add io_pgetevents syscall number from v4.19Szabolcs Nagy2019-03-131-0/+1
| | | | wired up in linux commit 73aeb2cbcdc9be391b3d32a55319a59ce425426f
* aarch64, or1k: define rseq syscall number following linux v4.19Szabolcs Nagy2019-03-132-0/+2
| | | | added in linux commit db7a2d1809a5b6b08d138ff68837f805fc073351
* elf.h: add new mips core dump note values from linux v4.19Szabolcs Nagy2019-03-131-0/+2
| | | | | | | | NT_MIPS_FP_MODE is new in linux commit 1ae22a0e35636efceab83728ba30b013df761592 NT_MIPS_DSP is new in linux commit 44109c60176ae73924a42a6bef64ef151aba9095
* netinet/udp.h: add UDP_ENCAP_RXRPC from linux v4.19Szabolcs Nagy2019-03-131-0/+1
| | | | | used for optimizing the rxrpc protocol added in linux commit 5271953cad31b97dea80f848c16e96ad66401199
* netinet/tcp.h: add tcp_info fields from linux v4.19Szabolcs Nagy2019-03-131-0/+8
| | | | | | | | | | | | new fields for RFC 4898 tcp stats in linux tcpi_bytes_sent added in commit ba113c3aa79a7f941ac162d05a3620bdc985c58d tcpi_bytes_retrans added in commit fb31c9b9f6c85b1bad569ecedbde78d9e37cd87b tcpi_dsack_dups added in commit 7e10b6554ff2ce7f86d5d3eec3af5db8db482caa tcpi_reord_seen added in commit 7ec65372ca534217b53fd208500cf7aac223a383 The new fields change the size of a public struct and thus an ABI break, but this is how the getsockopt TCP_INFO api is designed: the tcp_info type must only be used with a length parameter in extern interfaces.
* sys/inotify.h: add IN_MASK_CREATE from linux v4.19Szabolcs Nagy2019-03-131-0/+1
| | | | | | inotify_add_watch flag to prevent modifying existing watch descriptors, when used on an already watched inode it fails with EEXIST. added in linux commit 4d97f7d53da7dc830dbf416a3d2a6778d267ae68
* sys/socket.h: add SO_TXTIME from linux v4.19Szabolcs Nagy2019-03-131-0/+2
| | | | added in linux commit 80b14dee2bea128928537d61c333f24cb8cbb62f
* handle labels with 8-bit byte values in dn_skipnameRyan Fairfax2019-03-131-2/+5
| | | | | | | | | | | The original logic considered each byte until it either found a 0 value or a value >= 192. This means if a string segment contained any byte >= 192 it was interepretted as a compressed segment marker even if it wasn't in a position where it should be interpretted as such. The fix is to adjust dn_skipname to increment by each segments size rather than look at each character. This avoids misinterpretting string segment characters by not considering those bytes.
* fix POSIX_FADV_DONTNEED/_NOREUSE on s390xJonathan Neuschäfer2019-03-132-0/+5
| | | | | | | | | On s390x, POSIX_FADV_DONTNEED and POSIX_FADV_NOREUSE have different values than on all other architectures that Linux supports. Handle this difference by wrapping their definitions in include/fcntl.h in #ifdef, so that arch/s390x/bits/fcntl.h can override them.
* expose TSVTX unconditionally in tar.hRich Felker2019-03-131-4/+0
| | | | | | | | | | as noted in Austin Group issue #1236, the XSI shading for TSVTX is misplaced in the html version of the standard; it was only supposed to be on the description text. the intent was that the definition always be visible, which is reflected in the pdf version of the standard. this reverts commits d93c0740d86aaf7043e79b942a6c0b3f576af4c8 and 729fef0a9358e2f6f1cd8c75a1a0f7ee48b08c95.
* setvbuf: return failure if mode is invalidA. Wilcox2019-03-121-1/+3
| | | | | POSIX requires setvbuf to return non-zero if `mode` is not one of _IONBF, _IOLBF, or _IOFBF.
* make FILE a complete type for pre-C11 standard profilesRich Felker2019-03-125-0/+20
| | | | | | | | | | | | | | | | | | | | C11 removed the requirement that FILE be a complete type, which was deemed erroneous, as part of the changes introduced by N1439 regarding completeness of types (see footnote 6 for specific mention of FILE). however the current version of POSIX is still based on C99 and incorporates the old requirement that FILE be a complete type. expose an arbitrary, useless complete type definition because the actual object used to represent FILE streams cannot be public/ABI. thanks to commit 13d1afa46f8098df290008c681816c9eb89ffbdb, we now have a framework for suppressing the public complete-type definition of FILE when stdio.h is included internally, so that a different internal definition can be provided. this is perfectly well-defined, since the same struct tag can refer to different types in different translation units. it would be a problem if the implementation were accessing the application's FILE objects or vice versa, but either would be undefined behavior.
* fix invalid-/double-/use-after-free in new dlopen ctor executionRich Felker2019-03-101-1/+2
| | | | | | | | | | | | | | this affected the error path where dlopen successfully found and loaded the requested dso and all its dependencies, but failed to resolve one or more relocations, causing the operation to fail after storage for the ctor queue was allocated. commit 188759bbee057aa94db2bbb7cf7f5855f3b9ab53 wrongly put the free for the ctor_queue array in the error path inside a loop over each loaded dso that needed to be backed-out, rather than just doing it once. in addition, the exit path also observed the ctor_queue pointer still being nonzero, and would attempt to call ctors on the backed-out dsos unless the double-free crashed the process first.
* don't reject unknown/future flags in sigaltstack, allow SS_AUTODISARMRich Felker2019-03-051-1/+1
| | | | | | | | | | | | | | | | historically, and likely accidentally, sigaltstack was specified to fail with EINVAL if any flag bit other than SS_DISABLE was set. the resolution of Austin Group issue 1187 fixes this so that the requirement is only to fail for SS_ONSTACK (which cannot be set) or "invalid" flags. Linux fails on the kernel side for invalid flags, but historically accepts SS_ONSTACK as a no-op, so it needs to be rejected in userspace still. with this change, the Linux-specific SS_AUTODISARM, provided since commit 9680e1d03a794b0e0d5815c749478228ed40a36d but unusable due to rejection at runtime, is now usable.
* avoid malloc of ctor queue for programs with no external depsRich Felker2019-03-031-2/+9
| | | | | | together with the previous two commits, this completes restoration of the property that dynamic-linked apps with no external deps and no tls have no failure paths before entry.
* avoid malloc of deps arrays for ldso and vdsoRich Felker2019-03-031-0/+3
| | | | | | neither has or can have any dependencies, but since commit 403555690775f7c8806372644f543518e6664e3b, gratuitous zero-length deps arrays were being allocated for them. use a dummy array instead.
* avoid malloc of deps array for programs with no external depsRich Felker2019-03-031-3/+10
| | | | | | | | | traditionally, we've provided a guarantee that dynamic-linked applications with no external dependencies (nothing but libc) and no thread-local storage have no failure paths before the entry point. normally, thanks to reclaim_gaps, such a malloc will not require a syscall anyway, but if segment alignment is unlucky, it might. use a builtin array for this common special case.
* fix malloc misuse for startup ctor queue, breakage on fdpic archsRich Felker2019-03-031-5/+9
| | | | | | | | | | | | | in the case where malloc is being replaced, it's not valid to call malloc between final relocations and main app's crt1 entry point; on fdpic archs the main app's entry point will not yet have performed the self-fixups necessary to call its code. to fix, reorder queue_ctors before final relocations. an alternative solution would be doing the allocation from __libc_start_init, after the entry point but before any ctors run. this is less desirable, since it would leave a call to malloc that might be provided by the application happening at startup when doing so can be easily avoided.
* synchronize shared library dtor exec against concurrent loads/ctorsRich Felker2019-03-031-1/+17
| | | | | | | | | | | | | | | previously, going way back, there was simply no synchronization here. a call to exit concurrent with ctor execution from dlopen could cause a dtor to execute concurrently with its corresponding ctor, or could cause dtors for newly-constructed libraries to be skipped. introduce a shutting_down state that blocks further ctor execution, producing the quiescence the dtor execution loop needs to ensure any kind of consistency, and that blocks further calls to dlopen so that a call into dlopen from a dtor cannot deadlock. better approaches to some of this may be possible, but the changes here at least make things safe.
* overhaul shared library ctor execution for dependency order, concurrencyRich Felker2019-03-031-17/+101
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | previously, shared library constructors at program start and dlopen time were executed in reverse load order. some libraries, however, rely on a depth-first dependency order, which most other dynamic linker implementations provide. this is a much more reasonable, less arbitrary order, and it turns out to have much better properties with regard to how slow-running ctors affect multi-threaded programs, and how recursive dlopen behaves. this commit builds on previous work tracking direct dependencies of each dso (commit 403555690775f7c8806372644f543518e6664e3b), and performs a topological sort on the dependency graph at load time while the main ldso lock is held and before success is committed, producing a queue of constructors needed by the newly-loaded dso (or main application). in the case of circular dependencies, the dependency chain is simply broken at points where it becomes circular. when the ctor queue is run, the init_fini_lock is held only for iteration purposes; it's released during execution of each ctor, so that arbitrarily-long-running application code no longer runs with a lock held in the caller. this prevents a dlopen with slow ctors in one thread from arbitrarily delaying other threads that call dlopen. fully-independent ctors can run concurrently; when multiple threads call dlopen with a shared dependency, one will end up executing the ctor while the other waits on a condvar for it to finish. another corner case improved by these changes is recursive dlopen (call from a ctor). previously, recursive calls to dlopen could cause a ctor for a library to be executed before the ctor for its dependency, even when there was no relation between the calling library and the library it was loading, simply due to the naive reverse-load-order traversal. now, we can guarantee that recursive dlopen in non-circular-dependency usage preserves the desired ctor execution order properties, and that even in circular usage, at worst the libraries whose ctors call dlopen will fail to have completed construction when ctors that depend on them run. init_fini_lock is changed to a normal, non-recursive mutex, since it is no longer held while calling back into application code.
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