path: root/arch/sh/reloc.h
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2018-06-02fix TLS layout of TLS variant I when there is a gap above TPSzabolcs Nagy-1/+1
In TLS variant I the TLS is above TP (or above a fixed offset from TP) but on some targets there is a reserved gap above TP before TLS starts. This matters for the local-exec tls access model when the offsets of TLS variables from the TP are hard coded by the linker into the executable, so the libc must compute these offsets the same way as the linker. The tls offset of the main module has to be alignup(GAP_ABOVE_TP, main_tls_align). If there is no TLS in the main module then the gap can be ignored since musl does not use it and the tls access models of shared libraries are not affected. The previous setup only worked if (tls_align & -GAP_ABOVE_TP) == 0 (i.e. TLS did not require large alignment) because the gap was treated as a fixed offset from TP. Now the TP points at the end of the pthread struct (which is aligned) and there is a gap above it (which may also need alignment). The fix required changing TP_ADJ and __pthread_self on affected targets (aarch64, arm and sh) and in the tlsdesc asm the offset to access the dtv changed too.
2015-11-11fix dynamic loader library mapping for nommu systemsRich Felker-0/+2
on linux/nommu, non-writable private mappings of files may actually use memory shared with other processes or the fs cache. the old nommu loader code (used when mmap with MAP_FIXED fails) simply wrote over top of the original file mapping, possibly clobbering this shared memory. no such breakage was observed in practice, but it should have been possible. the new code starts by mapping anonymous writable memory on archs that might support nommu, then maps load segments over top of it, falling back to read if MAP_FIXED fails. we use an anonymous map rather than a writable file map to avoid reading more data from disk than needed. since pages cannot be loaded lazily on fault, in case of large data/bss, mapping the full file may read a lot of data that will subsequently be thrown away when processing additional LOAD segments. as a result, we cannot skip the first LOAD segment when operating in this mode. these changes affect only non-FDPIC nommu support.
2015-09-22add real fdpic loading of shared librariesRich Felker-0/+1
previously, the normal ELF library loading code was used even for fdpic, so only the kernel-loaded dynamic linker and main app could benefit from separate placement of segments and shared text.
2015-09-22add general fdpic support in dynamic linker and arch support for shRich Felker-3/+9
at this point not all functionality is complete. the dynamic linker itself, and main app if it is also loaded by the kernel, take advantage of fdpic and do not need constant displacement between segments, but additional libraries loaded by the dynamic linker follow normal ELF semantics for mapping still. this fully works, but does not admit shared text on nommu. in terms of actual functional correctness, dlsym's results are presently incorrect for function symbols, RTLD_NEXT fails to identify the caller correctly, and dladdr fails almost entirely. with the dynamic linker entry point working, support for static pie is automatically included, but linking the main application as ET_DYN (pie) probably does not make sense for fdpic anyway. ET_EXEC is equally relocatable but more efficient at representing relocations.
2015-09-12add sh fdpic subarch variantsRich Felker-1/+16
with this commit it should be possible to produce a working static-linked fdpic libc and application binaries for sh. the changes in reloc.h are largely unused at this point since dynamic linking is not supported, but the CRTJMP macro is used one place outside of dynamic linking, in __unmapself.
2015-04-24fix ldso name for sh-nofpu subarchRich Felker-1/+7
previously it was using the same name as the default ABI with hard float (floating point args and return value in registers). the test __SH_FPU_ANY__ || __SH4__ matches what's used in the configure script already, and seems correct under casual review against gcc's config/sh.h, but may need tweaks. the logic for predefined macros for sh, and what they all mean, is very complex. eventually this should be documented in comments here. configure already rejects "half-hard" configurations on sh where double=float since these do not conform to Annex F and are not suitable for musl, so these do not need to be considered here.
2015-04-24fix failure of sh reloc.h to properly detect endianness for ldso nameRich Felker-0/+2
versions of reloc.h that rely on endian macros much include endian.h to ensure they are available.
2015-04-13dynamic linker bootstrap overhaulRich Felker-24/+12
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 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.
2014-06-18refactor to remove arch-specific relocation code from dynamic linkerRich Felker-25/+13
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.
2014-06-17multiple fixes to sh (superh) dynamic linker relocationsRich Felker-10/+8
the following issues are fixed: - R_SH_REL32 was adding the load address of the module being relocated to the result. this seems to have been a mistake in the original port, since it does not match other dynamic linker implementations and since adding a difference between two addresses (the symbol value and the relocation address) to a load address does not make sense. - R_SH_TLS_DTPMOD32 was wrongly accepting an inline addend (i.e. using += rather than = on *reloc_addr) which makes no sense; addition is not an operation that's defined on module ids. - R_SH_TLS_DTPOFF32 and R_SH_TLS_TPOFF32 were wrongly using inline addends rather than the RELA-provided addends. in addition, handling of R_SH_GLOB_DAT, R_SH_JMP_SLOT, and R_SH_DIR32 are merged to all honor the addend. the first two should not need it for correct usage generated by toolchains, but other dynamic linkers allow addends here, and it simplifies the code anyway. these issues were spotted while reviewing the code for the purpose of refactoring this part of the dynamic linker. no testing was performed.
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.
2014-02-27fix endian subarchs for sh archRich Felker-2/+2
default endianness for sh on linux is little, and while conventions vary, "eb" seems to be the most widely used suffix for big endian.
2014-02-27rename superh port to "sh" for consistencyRich Felker-0/+47
linux, gcc, etc. all use "sh" as the name for the superh arch. there was already some inconsistency internally in musl: the dynamic linker was searching for "ld-musl-sh.path" as its path file despite its own name being "". there was some sentiment in both directions as to how to resolve the inconsistency, but overall "sh" was favored.