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* bpf jit: Let the x86 jit handle negative offsetsJan Seiffert2012-04-032-48/+115
| | | | | | | | | | | | | | | | | | | | | Now the helper function from filter.c for negative offsets is exported, it can be used it in the jit to handle negative offsets. First modify the asm load helper functions to handle: - know positive offsets - know negative offsets - any offset then the compiler can be modified to explicitly use these helper when appropriate. This fixes the case of a negative X register and allows to lift the restriction that bpf programs with negative offsets can't be jited. Signed-of-by: Jan Seiffert <kaffeemonster@googlemail.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* x86 bpf_jit: fix a bug in emitting the 16-bit immediate operand of ANDzhuangfeiran@ict.ac.cn2012-03-291-1/+1
| | | | | | | | | | When K >= 0xFFFF0000, AND needs the two least significant bytes of K as its operand, but EMIT2() gives it the least significant byte of K and 0x2. EMIT() should be used here to replace EMIT2(). Signed-off-by: Feiran Zhuang <zhuangfeiran@ict.ac.cn> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: bpf_jit: fix BPF_S_LDX_B_MSH compilationEric Dumazet2012-03-191-9/+5
| | | | | | | | | | | | | | | | | Matt Evans spotted that x86 bpf_jit was incorrectly handling negative constant offsets in BPF_S_LDX_B_MSH instruction. We need to abort JIT compilation like we do in common_load so that filter uses the interpreter code and can call __load_pointer() Reference: http://lists.openwall.net/netdev/2011/07/19/11 Thanks to Indan Zupancic to bring back this issue. Reported-by: Matt Evans <matt@ozlabs.org> Reported-by: Indan Zupancic <indan@nul.nu> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: bpf_jit: fix divide by 0 generationEric Dumazet2012-01-181-14/+22
| | | | | | | | | | | | | | | | | | | Several problems fixed in this patch : 1) Target of the conditional jump in case a divide by 0 is performed by a bpf is wrong. 2) Must 'generate' the full function prologue/epilogue at pass=0, or else we can stop too early in pass=1 if the proglen doesnt change. (if the increase of prologue/epilogue equals decrease of all instructions length because some jumps are converted to near jumps) 3) Change the wrong length detection at the end of code generation to issue a more explicit message, no need for a full stack trace. Reported-by: Phil Oester <kernel@linuxace.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: bpf_jit: fix an off-one bug in x86_64 cond jump targetMarkus Kötter2011-12-191-2/+2
| | | | | | | | | | | | x86 jump instruction size is 2 or 5 bytes (near/long jump), not 2 or 6 bytes. In case a conditional jump is followed by a long jump, conditional jump target is one byte past the start of target instruction. Signed-off-by: Markus Kötter <nepenthesdev@gmail.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* net: filter: Just In Time compiler for x86-64Eric Dumazet2011-04-273-0/+798
In order to speedup packet filtering, here is an implementation of a JIT compiler for x86_64 It is disabled by default, and must be enabled by the admin. echo 1 >/proc/sys/net/core/bpf_jit_enable It uses module_alloc() and module_free() to get memory in the 2GB text kernel range since we call helpers functions from the generated code. EAX : BPF A accumulator EBX : BPF X accumulator RDI : pointer to skb (first argument given to JIT function) RBP : frame pointer (even if CONFIG_FRAME_POINTER=n) r9d : skb->len - skb->data_len (headlen) r8 : skb->data To get a trace of generated code, use : echo 2 >/proc/sys/net/core/bpf_jit_enable Example of generated code : # tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24 flen=18 proglen=147 pass=3 image=ffffffffa00b5000 JIT code: ffffffffa00b5000: 55 48 89 e5 48 83 ec 60 48 89 5d f8 44 8b 4f 60 JIT code: ffffffffa00b5010: 44 2b 4f 64 4c 8b 87 b8 00 00 00 be 0c 00 00 00 JIT code: ffffffffa00b5020: e8 24 7b f7 e0 3d 00 08 00 00 75 28 be 1a 00 00 JIT code: ffffffffa00b5030: 00 e8 fe 7a f7 e0 24 00 3d 00 14 a8 c0 74 49 be JIT code: ffffffffa00b5040: 1e 00 00 00 e8 eb 7a f7 e0 24 00 3d 00 14 a8 c0 JIT code: ffffffffa00b5050: 74 36 eb 3b 3d 06 08 00 00 74 07 3d 35 80 00 00 JIT code: ffffffffa00b5060: 75 2d be 1c 00 00 00 e8 c8 7a f7 e0 24 00 3d 00 JIT code: ffffffffa00b5070: 14 a8 c0 74 13 be 26 00 00 00 e8 b5 7a f7 e0 24 JIT code: ffffffffa00b5080: 00 3d 00 14 a8 c0 75 07 b8 ff ff 00 00 eb 02 31 JIT code: ffffffffa00b5090: c0 c9 c3 BPF program is 144 bytes long, so native program is almost same size ;) (000) ldh [12] (001) jeq #0x800 jt 2 jf 8 (002) ld [26] (003) and #0xffffff00 (004) jeq #0xc0a81400 jt 16 jf 5 (005) ld [30] (006) and #0xffffff00 (007) jeq #0xc0a81400 jt 16 jf 17 (008) jeq #0x806 jt 10 jf 9 (009) jeq #0x8035 jt 10 jf 17 (010) ld [28] (011) and #0xffffff00 (012) jeq #0xc0a81400 jt 16 jf 13 (013) ld [38] (014) and #0xffffff00 (015) jeq #0xc0a81400 jt 16 jf 17 (016) ret #65535 (017) ret #0 Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Ben Hutchings <bhutchings@solarflare.com> Cc: Hagen Paul Pfeifer <hagen@jauu.net> Signed-off-by: David S. Miller <davem@davemloft.net>
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