Re: [PATCH v3] net: filter: BPF 'JIT' compiler for PPC64

Le jeudi 21 juillet 2011 à 11:51 +1000, Matt Evans a écrit :

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 <redacted>
---

V3: Added BUILD_BUG_ON to assert PACA CPU ID is 16bits, made a comment (in
    LD_MSH) a bit clearer, ratelimited "Unknown opcode" error and moved
    bpf_jit.S to bpf_jit_64.S (it doesn't make sense to rename bpf_jit_comp.c as
    small portions will eventually get split out into _32/_64.c files when we do
    32bit support).

 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.h            |  227 +++++++++++
 arch/powerpc/net/bpf_jit_64.S         |  138 +++++++
 arch/powerpc/net/bpf_jit_comp.c       |  694 +++++++++++++++++++++++++++++++++
 7 files changed, 1106 insertions(+), 1 deletions(-)

Nice work Matt ;)

Acked-by: Eric Dumazet <redacted>

Thanks