On Jul 19, 2011, at 2:06 AM, Matt Evans wrote:
> 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.)
If its most 64-bit specific than just go with bpf_jit_comp_64.c for now. We
can refactor later.
>
> Sorry it's not 32bit-friendly just yet (I knew you'd ask, hehe), I've
> postponed
> that for when I get a mo :-)
:)
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