Re: [PATCH v2] net: filter: BPF 'JIT' compiler for PPC64

On Jul 18, 2011, at 9:13 PM, Matt Evans wrote:

An implementation of a code generator for BPF programs to speed up =

packet

filtering on PPC64, inspired by Eric Dumazet's x86-64 version.
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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.
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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.

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This currently supports big-endian 64-bit PowerPC only (but is fairly =

simple

to port to PPC32 or LE!).
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Enabled in the same way as x86-64:
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	echo 1 > /proc/sys/net/core/bpf_jit_enable
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Or, enabled with extra debug output:
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	echo 2 > /proc/sys/net/core/bpf_jit_enable
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Signed-off-by: Matt Evans <redacted>
---
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V2: Removed some cut/paste woe in setting SEEN_X even on writes.
   Merci for le review, Eric!
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arch/powerpc/Kconfig                  |    1 +
arch/powerpc/Makefile                 |    3 +-
arch/powerpc/include/asm/ppc-opcode.h |   40 ++
arch/powerpc/net/Makefile             |    4 +
arch/powerpc/net/bpf_jit.S            |  138 +++++++

can we rename to bpf_jit_64.S, since this doesn't work on PPC32.

arch/powerpc/net/bpf_jit.h            |  227 +++++++++++
arch/powerpc/net/bpf_jit_comp.c       |  690 =

+++++++++++++++++++++++++++++++++

same here, or split between bpf_jit_comp.c (shared between ppc32 & =
ppc64) and bpf_jit_comp_64.c

- k