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This is a change to the dynamic linker to add prelinker support for the R_ARM_TLS_DESC relocation. Two cases can be considered here, the usual one where lazy binding is in use and the less frequent one, where immediate binding is requested via the use of the DF_BIND_NOW dynamic flag (e.g. by using the GNU linker's "-z now" option). This change only handles the first case. In this scenario the prelinker does what the dynamic linker would do, that is it preinitialises R_ARM_TLS_DESC relocations with a pointer to the lazy specialization as provided with the DT_TLSDESC_PLT dynamic tag. A conflict is additionally created and in the conflict resolution path the dynamic linker complements the work by initialising the object's pointer as indicated by the DT_TLSDESC_GOT dynamic tag to the linker's internal lazy specialization worker function and also providing the associated link map in the second entry of the GOT. This step is required, because if prelinking is successful at the run time, then the dynamic linker's elf_machine_runtime_setup() function isn't called that would normally do so. The second case remains unresolved, because support for that scenario has not been implemented in the prelinker. In this case the lazy specialization is unavailable and the DT_TLSDESC_PLT dynamic tag is not present. The prelinker could assume the common case of static specialization and resolve the relocation, but that would require the exposure of dynamic linker's specialization worker function. Furthermore the dynamic linker would have to handle the relocation in the conflict resolution path and see if the dynamic specialization should be used instead. This however would require access to data structures currently not made available to the conflict resolution path and therefore a redesign of this part of the dynamic linker. Alternatively the prelinker could defer all processing to the dynamic linker's conflict resolution path, but that would require similar access to the said data structures. Therefore the prelinker issues an error instead and the dynamic linker has assertions to check that DT_TLSDESC_PLT and DT_TLSDESC_GOT are in use in its conflict resolution path. This change resolves all TLS failures in the prelinker testsuite, as noted in the bug report, as well as the small test case provided there. Unfortunately we don't seem to have any hooks to factor in the prelinker (if present on a system) to testing, so at this time this fix has to rely on using the prelinker test suite and enabling TLS descriptors there for coverage. [BZ #17078] * sysdeps/arm/dl-machine.h (elf_machine_rela) [RESOLVE_CONFLICT_FIND_MAP]: Handle R_ARM_TLS_DESC relocation. (elf_machine_lazy_rel): Handle prelinked R_ARM_TLS_DESC entries. |
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| conf | ||
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| README | ||
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| WUR-REPORT | ||
This directory contains the sources of the GNU C Library. See the file "version.h" for what release version you have. The GNU C Library is the standard system C library for all GNU systems, and is an important part of what makes up a GNU system. It provides the system API for all programs written in C and C-compatible languages such as C++ and Objective C; the runtime facilities of other programming languages use the C library to access the underlying operating system. In GNU/Linux systems, the C library works with the Linux kernel to implement the operating system behavior seen by user applications. In GNU/Hurd systems, it works with a microkernel and Hurd servers. The GNU C Library implements much of the POSIX.1 functionality in the GNU/Hurd system, using configurations i[4567]86-*-gnu. The current GNU/Hurd support requires out-of-tree patches that will eventually be incorporated into an official GNU C Library release. When working with Linux kernels, this version of the GNU C Library requires Linux kernel version 2.6.32 or later. Also note that the shared version of the libgcc_s library must be installed for the pthread library to work correctly. The GNU C Library supports these configurations for using Linux kernels: aarch64*-*-linux-gnu alpha*-*-linux-gnu arm-*-linux-gnueabi hppa-*-linux-gnu Not currently functional without patches. i[4567]86-*-linux-gnu x86_64-*-linux-gnu Can build either x86_64 or x32 ia64-*-linux-gnu m68k-*-linux-gnu microblaze*-*-linux-gnu mips-*-linux-gnu mips64-*-linux-gnu powerpc-*-linux-gnu Hardware or software floating point, BE only. powerpc64*-*-linux-gnu Big-endian and little-endian. s390-*-linux-gnu s390x-*-linux-gnu sh[34]-*-linux-gnu sparc*-*-linux-gnu sparc64*-*-linux-gnu tilegx-*-linux-gnu tilepro-*-linux-gnu If you are interested in doing a port, please contact the glibc maintainers; see http://www.gnu.org/software/libc/ for more information. See the file INSTALL to find out how to configure, build, and install the GNU C Library. You might also consider reading the WWW pages for the C library at http://www.gnu.org/software/libc/. The GNU C Library is (almost) completely documented by the Texinfo manual found in the `manual/' subdirectory. The manual is still being updated and contains some known errors and omissions; we regret that we do not have the resources to work on the manual as much as we would like. For corrections to the manual, please file a bug in the `manual' component, following the bug-reporting instructions below. Please be sure to check the manual in the current development sources to see if your problem has already been corrected. Please see http://www.gnu.org/software/libc/bugs.html for bug reporting information. We are now using the Bugzilla system to track all bug reports. This web page gives detailed information on how to report bugs properly. The GNU C Library is free software. See the file COPYING.LIB for copying conditions, and LICENSES for notices about a few contributions that require these additional notices to be distributed. License copyright years may be listed using range notation, e.g., 2000-2013, indicating that every year in the range, inclusive, is a copyrightable year that would otherwise be listed individually.