On 19/07/11 16:59, Kumar Gala wrote:
>
> 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.
>>
>> 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 <m...@ozlabs.org>
>> ---
>>
>> V2: Removed some cut/paste woe in setting SEEN_X even on writes.
>> Merci for le review, Eric!
>>
>> 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
A reasonable suggestion -- bpf_jit_64.S certainly. I think it may not be worth
splitting bpf_jit_comp.c until we support both tho? (I'm thinking
bpf_jit_comp_{32,64}.c would just house the stackframe generation code which is
the main difference, plus compile-time switched macros for the odd LD vs LWZ.)
Sorry it's not 32bit-friendly just yet (I knew you'd ask, hehe), I've postponed
that for when I get a mo :-)
Cheers,
Matt
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