Adhemerval Zanella is cleaning up the preadv/pwritev implementation in glibc and came across an issue with the tilepro/tilegx32 implementation of argument passing for 64-bit arguments in split register pairs.
The glibc code base uses __LONG_LONG_PAIR to split 64-bit arguments, passing "hi, lo" for BE systems and "lo, hi" for LE systems. Tile is almost uniformly LE, but we do support BE for specific customers. The 32-bit compat mode on tilegx was getting passed "hi, lo" arguments by glibc but looking for them to be "lo, hi" arguments on the kernel side. I fixed this here: https://lkml.kernel.org/g/1466019219-10462-1-git-send-email-cmetc...@mellanox.com Reviewing what other platforms do, it seems like powerpc compat mode may have the opposite problem in little-endian mode, since arguments are passed in "hi, lo" order unconditionally in arch/powerpc/kernel/sys_ppc32.c. You may want to adopt the solution in the patch cited above, or similar solutions elsewhere, eg regs_to_64 in arch/arm64/include/asm/assembler.h, or merge_64 in arch/mips/kernel/linux32.c. Here's the email thread from libc-alpha: https://sourceware.org/ml/libc-alpha/2016-06/msg00638.html -- Chris Metcalf, Mellanox Technologies http://www.mellanox.com _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
