path: root/arch/powerpc/reloc.h
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2019-08-11add support for powerpc/powerpc64 unaligned relocationsSamuel Holland-0/+1
R_PPC_UADDR32 (R_PPC64_UADDR64) has the same meaning as R_PPC_ADDR32 (R_PPC64_ADDR64), except that its address need not be aligned. For powerpc64, BFD ld(1) will automatically convert between ADDR<->UADDR relocations when the address is/isn't at its native alignment. This will happen if, for example, there is a pointer in a packed struct. gold and lld do not currently generate R_PPC64_UADDR64, but pass through misaligned R_PPC64_ADDR64 relocations from object files, possibly relaxing them to misaligned R_PPC64_RELATIVE. In both cases (relaxed or not) this violates the PSABI, which defines the relevant field type as "a 64-bit field occupying 8 bytes, the alignment of which is 8 bytes unless otherwise specified." All three linkers violate the PSABI on 32-bit powerpc, where the only difference is that the field is 32 bits wide, aligned to 4 bytes. Currently musl fails to load executables linked by BFD ld containing R_PPC64_UADDR64, with the error "unsupported relocation type 43". This change provides compatibility with BFD ld on powerpc64, and any static linker on either architecture that starts following the PSABI more closely.
2016-03-06add powerpc soft-float supportFelix Fietkau-1/+7
Some PowerPC CPUs (e.g. Freescale MPC85xx) have a completely different instruction set for floating point operations (SPE). Executing regular PowerPC floating point instructions results in "Illegal instruction" errors. Make it possible to run these devices in soft-float mode.
2015-09-17new dlstart stage-2 chaining for powerpcRich Felker-0/+9
2015-04-13dynamic linker bootstrap overhaulRich Felker-40/+11
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-24/+12
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.
2014-06-17fix powerpc dynamic linker thread-pointer-relative relocationsRich Felker-3/+3
processing of R_PPC_TPREL32 was ignoring the addend provided by the RELA-style relocation and instead using the inline value as the addend. this presumably broke dynamic-linked access to initial TLS in cases where the addend was nonzero.
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.
2013-09-15support configurable page size on mips, powerpc and microblazeSzabolcs Nagy-1/+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.
2013-07-26fix powerpc build breakage from dynamic linker path search changesRich Felker-1/+1
2013-07-18make the dynamic linker find its path file relative to its own locationRich Felker-1/+1
prior to this change, using a non-default syslibdir was impractical on systems where the ordinary library paths contain musl-incompatible library files. the file containing search paths was always taken from /etc, which would either correspond to a system-wide musl installation, or fail to exist at all, resulting in searching of the default library path. the new search strategy is safe even for suid programs because the pathname used comes from the PT_INTERP header of the program being run, rather than any external input. as part of this change, I have also begun differentiating the names of arch variants that differ by endianness or floating point calling convention. the corresponding changes in the build system and and gcc wrapper script (to use an alternate dynamic linker name) for these configurations have not yet been made.
2012-11-16dynamic linking support for powerpcRich Felker-8/+27
incomplete but at least partly working. requires all files to be compiled in the new "secure" plt model, not the old one that put plt code in the data segment. TLS is untested but may work. invoking the dynamic linker explicitly to load a program does not yet handle argv correctly.
2012-11-13PPC port cleaned up, static linking works well now.rofl0r-0/+36