On Tue, Sep 03, 2013 at 06:45:50AM +1000, Benjamin Herrenschmidt wrote: > On Mon, 2013-09-02 at 19:48 +0200, Vladimir Murzin wrote: > > Ping > > > > On Wed, Aug 28, 2013 at 02:49:52AM +0400, Vladimir Murzin wrote: > > > commit b6069a9570 (filter: add MOD operation) added generic > > > support for modulus operation in BPF. > > > > Sorry, nobody got a chance to review that yet. Unfortunately Matt > doesn't work for us anymore and none of us has experience with the > BPF code, so somebody (possibly me) will need to spend a bit of time > figuring it out before verifying that is correct. > > Do you have a test case/suite by any chance ? > > Ben. >
Hi Ben! Thanks for your feedback. This patch is only compile tested. I have no real hardware, but I'll probably bring up qemu ppc64 till end of the week... Meanwhile, I've made simple how-to for testing. You can use it if you wish. It is mainly based on the [1] and rechecked on x86-64. 1. get the tcpdump utility (git clone git://bpf.tcpdump.org/tcpdump) 2. get the libcap library (git clone git://bpf.tcpdump.org/libpcap) 2.1. apply patch for libcap [2] (against libcap-1.3 branch) 2.2. build libcap (./configure && make && ln -s libcap.so.1.3.0 libcap.so) 3. build tcpdump (LDFLAGS="-L/path/to/libcap" ./configure && make) 4. run # ./tcpdump -d "(ip[2:2] - 20) % 5 != 0 && ip[6] & 0x20 = 0x20" (000) ldh [14] (001) jeq #0x800 jt 2 jf 10 (002) ldh [18] (003) sub #20 (004) mod #5 (005) jeq #0x0 jt 10 jf 6 (006) ldb [22] (007) and #0x20 (008) jeq #0x20 jt 9 jf 10 (009) ret #65535 (010) ret #0 to get pseudo code (we are interested the most into line #4) 5. enable bpf jit compiler # echo 2 > /proc/sys/net/core/bpf_jit_enable 6. run ./tcpdump -nv "(ip[2:2] - 20) % 5 != 0 && ip[6] & 0x20 = 0x20" 7. check dmesg for lines starting with (output for x86-64 is provided as an example) [ 3768.329253] flen=11 proglen=99 pass=3 image=ffffffffa003c000 [ 3768.329254] JIT code: ffffffffa003c000: 55 48 89 e5 48 83 ec 60 48 89 5d f8 44 8b 4f 60 [ 3768.329255] JIT code: ffffffffa003c010: 44 2b 4f 64 4c 8b 87 c0 00 00 00 0f b7 47 76 86 [ 3768.329256] JIT code: ffffffffa003c020: c4 3d 00 08 00 00 75 37 be 02 00 00 00 e8 9f 3e [ 3768.329257] JIT code: ffffffffa003c030: 02 e1 83 e8 14 31 d2 b9 05 00 00 00 f7 f1 89 d0 [ 3768.329258] JIT code: ffffffffa003c040: 85 c0 74 1b be 06 00 00 00 e8 9f 3e 02 e1 25 20 [ 3768.329259] JIT code: ffffffffa003c050: 00 00 00 83 f8 20 75 07 b8 ff ff 00 00 eb 02 31 [ 3768.329259] JIT code: ffffffffa003c060: c0 c9 c3 8. make sure generated opcodes (JIT code) implement pseudo code form step 4. Reference [1] http://comments.gmane.org/gmane.linux.network/242456 [2] http://permalink.gmane.org/gmane.network.tcpdump.devel/5973 P.S. I hope net people will corect me if I'm wrong there Cheers Vladimir Murzin > > > This patch brings JIT support for PPC64 > > > > > > Signed-off-by: Vladimir Murzin <murzi...@gmail.com> > > > --- > > > arch/powerpc/net/bpf_jit_comp.c | 22 ++++++++++++++++++++++ > > > 1 file changed, 22 insertions(+) > > > > > > diff --git a/arch/powerpc/net/bpf_jit_comp.c > > > b/arch/powerpc/net/bpf_jit_comp.c > > > index bf56e33..96f24dc 100644 > > > --- a/arch/powerpc/net/bpf_jit_comp.c > > > +++ b/arch/powerpc/net/bpf_jit_comp.c > > > @@ -193,6 +193,28 @@ static int bpf_jit_build_body(struct sk_filter *fp, > > > u32 *image, > > > PPC_MUL(r_A, r_A, r_scratch1); > > > } > > > break; > > > + case BPF_S_ALU_MOD_X: /* A %= X; */ > > > + ctx->seen |= SEEN_XREG; > > > + PPC_CMPWI(r_X, 0); > > > + if (ctx->pc_ret0 != -1) { > > > + PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]); > > > + } else { > > > + PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12); > > > + PPC_LI(r_ret, 0); > > > + PPC_JMP(exit_addr); > > > + } > > > + PPC_DIVWU(r_scratch1, r_A, r_X); > > > + PPC_MUL(r_scratch1, r_X, r_scratch1); > > > + PPC_SUB(r_A, r_A, r_scratch1); > > > + break; > > > + case BPF_S_ALU_MOD_K: /* A %= K; */ > > > +#define r_scratch2 (r_scratch1 + 1) > > > + PPC_LI32(r_scratch2, K); > > > + PPC_DIVWU(r_scratch1, r_A, r_scratch2); > > > + PPC_MUL(r_scratch1, r_scratch2, r_scratch1); > > > + PPC_SUB(r_A, r_A, r_scratch1); > > > +#undef r_scratch2 > > > + break; > > > case BPF_S_ALU_DIV_X: /* A /= X; */ > > > ctx->seen |= SEEN_XREG; > > > PPC_CMPWI(r_X, 0); > > > -- > > > 1.8.1.5 > > > > > _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
