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2012-04-30bpf jit: Let the powerpc jit handle negative offsetsJan Seiffert3-31/+111
Now the helper function from filter.c for negative offsets is exported, it can be used it in the jit to handle negative offsets. First modify the asm load helper functions to handle: - know positive offsets - know negative offsets - any offset then the compiler can be modified to explicitly use these helper when appropriate. This fixes the case of a negative X register and allows to lift the restriction that bpf programs with negative offsets can't be jited. Tested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Jan Seiffert <kaffeemonster@googlemail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-07-21net: filter: BPF 'JIT' compiler for PPC64Matt Evans4-0/+1063
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 <matt@ozlabs.org> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>