• Paul Burton's avatar
    MIPS: lib: Provide MIPS64r6 __multi3() for GCC < 7 · 690d9163
    Paul Burton authored
    Some versions of GCC suboptimally generate calls to the __multi3()
    intrinsic for MIPS64r6 builds, resulting in link failures due to the
    missing function:
    
        LD      vmlinux.o
        MODPOST vmlinux.o
      kernel/bpf/verifier.o: In function `kmalloc_array':
      include/linux/slab.h:631: undefined reference to `__multi3'
      fs/select.o: In function `kmalloc_array':
      include/linux/slab.h:631: undefined reference to `__multi3'
      ...
    
    We already have a workaround for this in which we provide the
    instrinsic, but we do so selectively for GCC 7 only. Unfortunately the
    issue occurs with older GCC versions too - it has been observed with
    both GCC 5.4.0 & GCC 6.4.0.
    
    MIPSr6 support was introduced in GCC 5, so all major GCC versions prior
    to GCC 8 are affected and we extend our workaround accordingly to all
    MIPS64r6 builds using GCC versions older than GCC 8.
    Signed-off-by: default avatarPaul Burton <paul.burton@mips.com>
    Reported-by: default avatarVladimir Kondratiev <vladimir.kondratiev@intel.com>
    Fixes: ebabcf17 ("MIPS: Implement __multi3 for GCC7 MIPS64r6 builds")
    Patchwork: https://patchwork.linux-mips.org/patch/20297/
    Cc: James Hogan <jhogan@kernel.org>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: linux-mips@linux-mips.org
    Cc: stable@vger.kernel.org # 4.15+
    690d9163
multi3.c 1.31 KB