The MSA architecture specification allows for hardware to not implement unaligned vector memory accesses in some or all cases. A typical example of this is the I6400 core which does not implement unaligned vector memory access when the memory crosses a page boundary. The architecture also requires that such memory accesses complete successfully as far as userland is concerned, so the kernel is required to emulate them. This patch implements support for emulating unaligned MSA ld & st instructions by copying between the user memory & the tasks FP context in struct thread_struct, updating hardware registers from there as appropriate in order to avoid saving & restoring the entire vector context for each unaligned memory access. Tested both using an I6400 CPU and with a QEMU build hacked to produce AdEL exceptions for unaligned vector memory accesses. [paul.burton@imgtec.com: - Remove #ifdef's - Move msa_op into enum major_op rather than #define - Replace msa_{to,from}_wd with {read,write}_msa_wr_{b,h,w,l} and the format-agnostic wrappers, removing the custom endian mangling for big endian systems. - Restructure the msa_op case in emulate_load_store_insn to share more code between the load & store cases. - Avoid the need for a temporary union fpureg on the stack by simply reusing the already suitably aligned context in struct thread_struct. - Use sizeof(*fpr) rather than hardcoding 16 as the size for user memory checks & copies. - Stop recalculating the address of the unaligned vector memory access and rely upon the value read from BadVAddr as we do for other unaligned memory access instructions. - Drop the now unused val8 & val16 fields in union fpureg. - Rewrite commit message. - General formatting cleanups.] Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> Cc: Huacai Chen <chenhc@lemote.com> Cc: Maciej W. Rozycki <macro@linux-mips.org> Cc: linux-kernel@vger.kernel.org Cc: Jie Chen <chenj@lemote.com> Cc: Markos Chandras <markos.chandras@imgtec.com> Patchwork: https://patchwork.linux-mips.org/patch/10573/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>