- 16 5月, 2015 2 次提交
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由 Rich Felker 提交于
the code being removed used atomics to track whether any threads might be using a locale other than the current global locale, and whether any threads might have abstract 8-bit (non-UTF-8) LC_CTYPE active, a feature which was never committed (still pending). the motivations were to support early execution prior to setup of the thread pointer, to partially support systems (ancient kernels) where thread pointer setup is not possible, and to avoid high performance cost on archs where accessing the thread pointer may be very slow. since commit 19a1fe67, the thread pointer is always available, so these hacks are no longer needed. removing them greatly simplifies the affected code.
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由 Rich Felker 提交于
commit f630df09 added logic to handle the case where __set_thread_area is called more than once by reusing the GDT slot already in the %gs register, and only setting up a new GDT slot when %gs is zero. this created a hidden assumption that %gs is zero when a new process image starts, which is true in practice on Linux, but does not seem to be documented ABI, and fails to hold under qemu app-level emulation. while it would in theory be possible to zero %gs in the entry point code, this code is shared between static and dynamic binaries, and dynamic binaries must not clobber the value of %gs already setup by the dynamic linker. the alternative solution implemented in this commit simply uses global data to store the GDT index that's selected. __set_thread_area should only be called in the initial thread anyway (subsequent threads get their thread pointer setup by __clone), but even if it were called by another thread, it would simply read and write back the same GDT index that was already assigned to the initial thread, and thus (in the x86 memory model) there is no data race.
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- 07 5月, 2015 2 次提交
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由 Rich Felker 提交于
a null pointer is valid here and indicates that the current time should be used. based on patch by Felix Janda, simplified.
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由 Rich Felker 提交于
i386, x86_64, x32, and powerpc all use TLS for stack protector canary values in the default stack protector ABI, but the location only matched the ABI on i386 and x86_64. on x32, the expected location for the canary contained the tid, thus producing spurious mismatches (resulting in process termination) upon fork. on powerpc, the expected location contained the stdio_locks list head, so returning from a function after calling flockfile produced spurious mismatches. in both cases, the random canary was not present, and a predictable value was used instead, making the stack protector hardening much less effective than it should be. in the current fix, the thread structure has been expanded to have canary fields at all three possible locations, and archs that use a non-default location must define a macro in pthread_arch.h to choose which location is used. for most archs (which lack TLS canary ABI) the choice does not matter.
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- 02 5月, 2015 4 次提交
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由 Rich Felker 提交于
the 64-bit push reads not only the 32-bit return address but also the first 32 signal mask bits. if any were nonzero, the return address obtained will be invalid. at some point storage of the return address should probably be moved to follow the saved mask so that there's plenty room and the same code can be used on x32 and regular x86_64, but for now I want a fix that does not risk breaking x86_64, and this simple re-zeroing works.
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由 Rich Felker 提交于
the kernel does not properly clear the upper bits of the syscall argument, so we have to do it before the syscall.
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由 Szabolcs Nagy 提交于
These cases were incorrect in C11 as described by http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1886.htm
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由 Rich Felker 提交于
due to an incorrect return statement in this error case, the previously blocked cancellation state was not restored and no result was stored. this could lead to invalid (read) accesses in the caller resulting in crashes or nonsensical result data in the event of memory exhaustion.
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- 28 4月, 2015 1 次提交
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由 Rich Felker 提交于
while the sh port is still experimental and subject to ABI instability, this is not actually an application/libc boundary ABI change. it only affects third-party APIs where jmp_buf is used in a shared structure at the ABI boundary, because nothing anywhere near the end of the jmp_buf object (which includes the oversized sigset_t) is accessed by libc. both glibc and uclibc have 15-slot jmp_buf for sh. presumably the smaller version was used in musl because the slots for fpu status register and thread pointer register (gbr) were incorrect and must not be restored by longjmp, but the size should have been preserved, as it's generally treated as a libc-agnostic ABI property for the arch, and having extra slots free in case we ever need them for something is useful anyway.
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- 25 4月, 2015 1 次提交
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由 Rich Felker 提交于
at least some assembler versions do not accept the register name lr. use the name x30 instead.
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- 24 4月, 2015 4 次提交
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由 Rich Felker 提交于
commit 646cb9a4 switched sigsetjmp to use the new hidden ___setjmp symbol for setjmp, but the nofpu variant of setjmp.s was not updated to match.
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由 Rich Felker 提交于
both static and dynamic linked versions of the __copy_tls function have a hidden assumption that the alignment of the beginning or end of the memory passed is suitable for storing an array of pointers for the dtv. pthread_create satisfies this requirement except when libc.tls_size is misaligned, which cannot happen with dynamic linking due to way update_tls_size computes the total size, but could happen with static linking and odd-sized TLS.
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由 Rich Felker 提交于
commit dab441ae, which made thread pointer init mandatory for all programs, rendered this store obsolete by removing the early-return path for static programs with no TLS.
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由 Rich Felker 提交于
this slightly reduces the code size cost of TLS/thread-pointer for static linking since __init_tp can be inlined into its only caller and removed. this is analogous to the handling of __init_libc in __libc_start_main, where the function only has external linkage when it needs to be called from the dynamic linker.
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- 23 4月, 2015 1 次提交
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由 Rich Felker 提交于
the implicit-operand form of fucomip is rejected by binutils 2.19 and perhaps other versions still in use. writing both operands explicitly fixes the issue. there is no change to the resulting output. commit a732e80d was the source of this regression.
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- 22 4月, 2015 13 次提交
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由 Rich Felker 提交于
use CAS instead of swap since it's lighter for most archs, and keep EBUSY in the lock value so that the old value obtained by CAS can be used directly as the return value for pthread_spin_trylock.
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由 Rich Felker 提交于
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由 Rich Felker 提交于
the motivation for this change is that the extra declaration (with or without visibility) using "struct _IO_FILE" instead of "FILE" seems to trigger a bug in gcc 3.x where it considers the types mismatched. however, this change also results in slightly better code and it is valid because (1) these three objects are constant, and (2) applying the & operator to any of them is invalid C, since they are not even specified to be objects. thus it does not matter if the application and libc see different addresses for them, as long as the (initial, unchanging) value is seen the same by both.
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由 Rich Felker 提交于
these are used as hidden by asm files (and such use is the whole reason they exist), but their actual definitions were not hidden.
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由 Rich Felker 提交于
commit f9cccfc1 left behind the part in libc.c; remove it too.
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由 Rich Felker 提交于
part of the goal here is to eliminate use of the ATTR_LIBC_VISIBILITY macro outside of libc.h, since it was never intended to be 'public'.
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由 Rich Felker 提交于
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由 Rich Felker 提交于
these were hacks to work around toolchains that could not properly optimize PIC accesses based on visibility and would generate GOT lookups even for hidden data, which broke the old dynamic linker. since commit f3ddd173 it no longer matters; the dynamic linker does not assume accessibility of this data until stage 3.
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由 Rich Felker 提交于
when the non-stub duplocale code was added as part of the locale framework in commit 0bc03091, the old code to memcpy the old locale object to the new one was left behind. the conditional for the memcpy no longer makes sense, because the conditions are now always-true when it's reached, and the memcpy is wrong because it clobbers the new->messages_name pointer setup just above. since the messages_name and ctype_utf8 members have already been copied, all that remains is the cat[] array. these pointers are volatile, so using memcpy to copy them is formally wrong; use a for loop instead.
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由 Rich Felker 提交于
the first switch already returns in the F_SETLKW code path so it need not be handled in the second switch. moreover the code in the second switch is wrong for the F_SETLKW command: it's not cancellable.
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由 Rich Felker 提交于
the leak was found by static analysis (reported by Alexander Monakov), not tested/observed, but seems to have occured both when failing due to O_EXCL, and in a race condition with O_CREAT but not O_EXCL where a semaphore by the same name was created concurrently.
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由 Rich Felker 提交于
the allocating path which can fail is for dynamic TLS, which can only occur at runtime, and the check for runtime was already made in the outer conditional.
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由 Rich Felker 提交于
commit 637dd2d3 introduced the checks for RTLD_DEFAULT and RTLD_NEXT here, claiming they fixed a regression, but the above conditional block clearly already covered these cases, and removing the checks produces no difference in the generated code.
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- 20 4月, 2015 5 次提交
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由 Rich Felker 提交于
this is implemented via the build system and does not affect source files. the idea is to use protected or hidden visibility to prevent the compiler from pessimizing function calls within a shared (or position-independent static) libc in the form of overhead setting up for a call through the PLT. the ld-time symbol binding via the -Bsymbolic-functions option already optimized out the PLT itself, but not the code in the caller needed to support a call through the PLT. on some archs this overhead can be substantial; on others it's trivial.
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由 Rich Felker 提交于
analogous to commit 646cb9a4 for sh.
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由 Rich Felker 提交于
these are perfectly fine with ld-time symbol binding, but otherwise result in textrels. they cannot be replaced with @PLT jump targets because the PLT thunks require a GOT register to be setup, so use a hidden alias instead.
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由 Rich Felker 提交于
analogous to commit 646cb9a4 for sh.
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由 Rich Felker 提交于
these are perfectly fine with ld-time symbol binding, but if the calls go through a PLT thunk, they are invalid because the caller does not setup a GOT register. use a hidden alias to bypass the issue.
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- 19 4月, 2015 4 次提交
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由 Rich Felker 提交于
analogous to commit 8ed66ecb for i386.
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由 Rich Felker 提交于
none of these are actual textrels because of ld-time binding performed by -Bsymbolic-functions, but I'm changing them with the goal of making ld-time binding purely an optimization rather than relying on it for semantic purposes. in the case of memmove's call to memcpy, making it explicit that the memmove asm is assuming the forward-copying behavior of the memcpy asm is desirable anyway; in case memcpy is ever changed, the semantic mismatch would be apparent while editing memmcpy.s.
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由 Rich Felker 提交于
this fixes truncation of error messages containing long pathnames or symbol names. the dlerror state was previously required by POSIX to be global. the resolution of bug 97 relaxed the requirements to allow thread-safe implementations of dlerror with thread-local state and message buffer.
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由 Alexander Monakov 提交于
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- 18 4月, 2015 3 次提交
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由 Szabolcs Nagy 提交于
this reverts the commit f29fea00 which was based on a bug in C99 and POSIX and did not match IEEE-754 http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1515.pdf
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由 Rich Felker 提交于
these functions are never called directly; only their addresses are used, so PLT indirections should never happen unless a broken application tries to redefine them, but it's still best to make them hidden.
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由 Szabolcs Nagy 提交于
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