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path: root/src/thread/arm/atomics.s
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2017-02-15fix build regression in arm atomics asm with new binutilsRich Felker-1/+1
binutils commit bada43421274615d0d5f629a61a60b7daa71bc15 tightened immediate fixup handling in gas in such a way that the final .arch of an object file must be compatible with the fixups used when the instruction was assembled; this in turn broke assembling of atomics.s, at least in thumb mode. it's not clear whether this should be considered a bug in gas, but .object_arch is preferable anyway for our purpose here of controlling the ISA level tag on the object file being produced, and it's the intended directive for use in object files with runtime code selection. research by Szabolcs Nagy confirmed that .object_arch is supported in all relevant versions of binutils and clang's integrated assembler. patch by Reiner Herrmann.
2016-12-19rework arm atomic/tp backends to be thumb-compatible and fdpic-readyRich Felker-41/+34
three problems are addressed: - use of pc arithmetic, which was difficult if not impossible to make correct in thumb mode on all models, so that relative rather than absolute pointers to the backends could be used. this was designed back when there was no coherent model for the early stages of the dynamic linker before relocations, and is no longer necessary. - assumption that data (the relative pointers to the backends) can be accessed at a constant displacement from the code. this will not be possible on future fdpic subarchs (for cortex-m), so move responsibility for loading the backend code address to the caller. - hard-coded arm opcodes using the .word directive. instead, use the .arch directive to work around the assembler's refusal to assemble instructions not available (or in some cases, available but just considered deprecated) in the target isa level. the obscure v6t2 arch is used for v6 code so as to (1) allow generation of thumb2 output if -mthumb is active, and (2) avoid warnings/errors for mcr barriers that clang would produce if we just set arch to v7-a. in addition, the __aeabi_read_tp function is moved out of the inner workings and implemented as an asm wrapper around a C function, so that asm code does not need to read global data. the asm wrapper serves to satisfy the ABI calling convention requirements for this function.
2016-01-30fix misaligned pointer-like objects in arm atomics asm source fileRich Felker-0/+2
this file's .data section was not aligned, and just happened to get the correct alignment with past builds. it's likely that the move of atomic.s from arch/arm/src to src/thread/arm caused the change in alignment, which broke the atomic and thread-pointer access fragments on actual armv5 hardware.
2016-01-22move arm-specific translation units out of arch/arm/src, to src/*/armRich Felker-0/+111
this is possible with the new build system that allows src/*/$(ARCH)/* files which do not shadow a file in the parent directory, and yields a more logical organization. eventually it will be possible to remove arch/*/src from the build system.