Eric Lee / smarc-fsl-linux-kernel

22 Jul, 2011

1 commit

  • 0ca87f05b   net: filter: BPF 'JIT' compiler for PPC64 ... Browse Code ยป
    43

    An implementation of a code generator for BPF programs to speed up packet
    filtering on PPC64, inspired by Eric Dumazet's x86-64 version.

    Filter code is generated as an ABI-compliant function in module_alloc()'d mem
    with stackframe & prologue/epilogue generated if required (simple filters don't
    need anything more than an li/blr). The filter's local variables, M[], live in
    registers. Supports all BPF opcodes, although "complicated" loads from negative
    packet offsets (e.g. SKF_LL_OFF) are not yet supported.

    There are a couple of further optimisations left for future work; many-pass
    assembly with branch-reach reduction and a register allocator to push M[]
    variables into volatile registers would improve the code quality further.

    This currently supports big-endian 64-bit PowerPC only (but is fairly simple
    to port to PPC32 or LE!).

    Enabled in the same way as x86-64:

    echo 1 > /proc/sys/net/core/bpf_jit_enable

    Or, enabled with extra debug output:

    echo 2 > /proc/sys/net/core/bpf_jit_enable

    Signed-off-by: Matt Evans
    Acked-by: Eric Dumazet
    Signed-off-by: David S. Miller

    Matt Evans