| Message ID | 1393910304-4004-2-git-send-email-ast@plumgrid.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
On 03/04/2014 06:18 AM, Alexei Starovoitov wrote: > Extended BPF extends old BPF in the following ways: > - from 2 to 10 registers > Original BPF has two registers (A and X) and hidden frame pointer. > Extended BPF has ten registers and read-only frame pointer. > - from 32-bit registers to 64-bit registers > semantics of old 32-bit ALU operations are preserved via 32-bit > subregisters > - if (cond) jump_true; else jump_false; > old BPF insns are replaced with: > if (cond) jump_true; /* else fallthrough */ > - adds signed > and >= insns > - 16 4-byte stack slots for register spill-fill replaced with > up to 512 bytes of multi-use stack space > - introduces bpf_call insn and register passing convention for zero > overhead calls from/to other kernel functions (not part of this patch) > - adds arithmetic right shift insn > - adds swab32/swab64 insns > - adds atomic_add insn > - old tax/txa insns are replaced with 'mov dst,src' insn > > Extended BPF is designed to be JITed with one to one mapping, which > allows GCC/LLVM backends to generate optimized BPF code that performs > almost as fast as natively compiled code > > sk_convert_filter() remaps old style insns into extended: > 'sock_filter' instructions are remapped on the fly to > 'sock_filter_ext' extended instructions when > sysctl net.core.bpf_ext_enable=1 > > Old filter comes through sk_attach_filter() or sk_unattached_filter_create() > if (bpf_ext_enable) { > convert to new > sk_chk_filter() - check old bpf > use sk_run_filter_ext() - new interpreter > } else { > sk_chk_filter() - check old bpf > if (bpf_jit_enable) > use old jit > else > use sk_run_filter() - old interpreter > } > > sk_run_filter_ext() interpreter is noticeably faster > than sk_run_filter() for two reasons: > > 1.fall-through jumps > Old BPF jump instructions are forced to go either 'true' or 'false' > branch which causes branch-miss penalty. > Extended BPF jump instructions have one branch and fall-through, > which fit CPU branch predictor logic better. > 'perf stat' shows drastic difference for branch-misses. > > 2.jump-threaded implementation of interpreter vs switch statement > Instead of single tablejump at the top of 'switch' statement, GCC will > generate multiple tablejump instructions, which helps CPU branch predictor > > Performance of two BPF filters generated by libpcap was measured > on x86_64, i386 and arm32. > > fprog #1 is taken from Documentation/networking/filter.txt: > tcpdump -i eth0 port 22 -dd > > fprog #2 is taken from 'man tcpdump': > tcpdump -i eth0 'tcp port 22 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - > ((tcp[12]&0xf0)>>2)) != 0)' -dd > > Other libpcap programs have similar performance differences. > > Raw performance data from BPF micro-benchmark: > SK_RUN_FILTER on same SKB (cache-hit) or 10k SKBs (cache-miss) > time in nsec per call, smaller is better > --x86_64-- > fprog #1 fprog #1 fprog #2 fprog #2 > cache-hit cache-miss cache-hit cache-miss > old BPF 90 101 192 202 > ext BPF 31 71 47 97 > old BPF jit 12 34 17 44 > ext BPF jit TBD > > --i386-- > fprog #1 fprog #1 fprog #2 fprog #2 > cache-hit cache-miss cache-hit cache-miss > old BPF 107 136 227 252 > ext BPF 40 119 69 172 > > --arm32-- > fprog #1 fprog #1 fprog #2 fprog #2 > cache-hit cache-miss cache-hit cache-miss > old BPF 202 300 475 540 > ext BPF 139 270 296 470 > old BPF jit 26 182 37 202 > new BPF jit TBD > > Tested with trinify BPF fuzzer > > Future work: > > 0. seccomp > > 1. add extended BPF JIT for x86_64 > > 2. add inband old/new demux and extended BPF verifier, so that new programs > can be loaded through old sk_attach_filter() and sk_unattached_filter_create() > interfaces > > 3. tracing filters systemtap-like with extended BPF > > 4. OVS with extended BPF > > 5. nftables with extended BPF > > Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Looks great, imho, some comments/questions inline: Nit: subject line of your patches should be, e.g. "filter: add Extended BPF interpreter and converter" "doc: filter: add Extended BPF documentation" ... so first "<subsystem>: <summary phrase>". > --- > include/linux/filter.h | 8 +- > include/linux/netdevice.h | 1 + > include/uapi/linux/filter.h | 34 +- > net/core/filter.c | 802 ++++++++++++++++++++++++++++++++++++++++++- > net/core/sysctl_net_core.c | 7 + > 5 files changed, 830 insertions(+), 22 deletions(-) > > diff --git a/include/linux/filter.h b/include/linux/filter.h > index e568c8ef896b..0e84ff6e991b 100644 > --- a/include/linux/filter.h > +++ b/include/linux/filter.h > @@ -52,7 +52,13 @@ extern int sk_detach_filter(struct sock *sk); > extern int sk_chk_filter(struct sock_filter *filter, unsigned int flen); > extern int sk_get_filter(struct sock *sk, struct sock_filter __user *filter, unsigned len); > extern void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to); > +/* function remaps 'sock_filter' insns to 'sock_filter_ext' insns */ > +int sk_convert_filter(struct sock_filter *old_prog, int len, > + struct sock_filter_ext *new_prog, int *p_new_len); > +/* execute extended bpf program */ I think this and the above comment can be omitted, as both have a kernel doc in its implementation in net/core/filter.c that is more precise. ... > +struct sock_filter_ext { > + __u8 code; /* opcode */ > + __u8 a_reg:4; /* dest register */ > + __u8 x_reg:4; /* source register */ > + __s16 off; /* signed offset */ > + __s32 imm; /* signed immediate constant */ > +}; > + > struct sock_fprog { /* Required for SO_ATTACH_FILTER. */ > unsigned short len; /* Number of filter blocks */ > struct sock_filter __user *filter; > @@ -45,12 +54,15 @@ struct sock_fprog { /* Required for SO_ATTACH_FILTER. */ > #define BPF_JMP 0x05 > #define BPF_RET 0x06 > #define BPF_MISC 0x07 > +#define BPF_ALU64 0x07 > + > Please do not add empty newline above. > /* ld/ldx fields */ > #define BPF_SIZE(code) ((code) & 0x18) > #define BPF_W 0x00 > #define BPF_H 0x08 > #define BPF_B 0x10 ... > diff --git a/net/core/filter.c b/net/core/filter.c > index ad30d626a5bd..1494421486b7 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -1,5 +1,6 @@ > /* > * Linux Socket Filter - Kernel level socket filtering > + * Extended BPF is Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com > * > * Author: > * Jay Schulist <jschlst@samba.org> > @@ -40,6 +41,8 @@ > #include <linux/seccomp.h> > #include <linux/if_vlan.h> > > +int bpf_ext_enable __read_mostly; > + > /* No hurry in this branch > * > * Exported for the bpf jit load helper. > @@ -399,6 +402,7 @@ load_b: > } > > return 0; > +#undef K > } > EXPORT_SYMBOL(sk_run_filter); ... > + /* RET_K, RET_A are remaped into 2 insns */ > + case BPF_RET | BPF_A: > + case BPF_RET | BPF_K: > + insn->code = BPF_ALU | BPF_MOV | > + (BPF_SRC(fp->code) == BPF_K ? BPF_K : BPF_X); Hmm, so the case statement is about BPF_RET | BPF_A and BPF_RET | BPF_K but BPF_RET | BPF_X is not mentioned. However, in BPF_SRC(fp->code) selection you fall back to BPF_X if it doesn't equal BPF_K? Is that correct? And, you probably also need to handle BPF_RET | BPF_X ? > + insn->a_reg = 0; > + insn->x_reg = 6; > + insn->imm = fp->k; > + > + insn++; > + insn->code = BPF_RET | BPF_K; > + break; ... > + /* RET */ > +BPF_RET_BPF_K_0: > + return regs[0/* R0 */]; -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
If all issues raised by Daniel are addresed: Acked-by: Hagen Paul Pfeifer <hagen@jauu.net> But ... >Future work: > >0. seccomp > >1. add extended BPF JIT for x86_64 > >2. add inband old/new demux and extended BPF verifier, so that new programs > can be loaded through old sk_attach_filter() and sk_unattached_filter_create() > interfaces > >3. tracing filters systemtap-like with extended BPF > >4. OVS with extended BPF > >5. nftables with extended BPF ... this is shit (not your fault). (Jitted) BPF envolved into a direction which is just not the right way to do it. You try to fix things, bypass architectural shortcomings of BPF, perf issues because and so on. The right direction is to write a new general purpose in-kernel interpreter from scratch. Capability layers should provide an compatible API for BPF and seccomp. You have the knowledge to do exactly this, you nearly already did this - you should start this undertake!
On Tue, Mar 4, 2014 at 1:59 AM, Daniel Borkmann <dborkman@redhat.com> wrote: > On 03/04/2014 06:18 AM, Alexei Starovoitov wrote: >> >> Extended BPF extends old BPF in the following ways: >> - from 2 to 10 registers >> Original BPF has two registers (A and X) and hidden frame pointer. >> Extended BPF has ten registers and read-only frame pointer. >> - from 32-bit registers to 64-bit registers >> semantics of old 32-bit ALU operations are preserved via 32-bit >> subregisters >> - if (cond) jump_true; else jump_false; >> old BPF insns are replaced with: >> if (cond) jump_true; /* else fallthrough */ >> - adds signed > and >= insns >> - 16 4-byte stack slots for register spill-fill replaced with >> up to 512 bytes of multi-use stack space >> - introduces bpf_call insn and register passing convention for zero >> overhead calls from/to other kernel functions (not part of this patch) >> - adds arithmetic right shift insn >> - adds swab32/swab64 insns >> - adds atomic_add insn >> - old tax/txa insns are replaced with 'mov dst,src' insn >> >> Extended BPF is designed to be JITed with one to one mapping, which >> allows GCC/LLVM backends to generate optimized BPF code that performs >> almost as fast as natively compiled code >> >> sk_convert_filter() remaps old style insns into extended: >> 'sock_filter' instructions are remapped on the fly to >> 'sock_filter_ext' extended instructions when >> sysctl net.core.bpf_ext_enable=1 >> >> Old filter comes through sk_attach_filter() or >> sk_unattached_filter_create() >> if (bpf_ext_enable) { >> convert to new >> sk_chk_filter() - check old bpf >> use sk_run_filter_ext() - new interpreter >> } else { >> sk_chk_filter() - check old bpf >> if (bpf_jit_enable) >> use old jit >> else >> use sk_run_filter() - old interpreter >> } >> >> sk_run_filter_ext() interpreter is noticeably faster >> than sk_run_filter() for two reasons: >> >> 1.fall-through jumps >> Old BPF jump instructions are forced to go either 'true' or 'false' >> branch which causes branch-miss penalty. >> Extended BPF jump instructions have one branch and fall-through, >> which fit CPU branch predictor logic better. >> 'perf stat' shows drastic difference for branch-misses. >> >> 2.jump-threaded implementation of interpreter vs switch statement >> Instead of single tablejump at the top of 'switch' statement, GCC will >> generate multiple tablejump instructions, which helps CPU branch >> predictor >> >> Performance of two BPF filters generated by libpcap was measured >> on x86_64, i386 and arm32. >> >> fprog #1 is taken from Documentation/networking/filter.txt: >> tcpdump -i eth0 port 22 -dd >> >> fprog #2 is taken from 'man tcpdump': >> tcpdump -i eth0 'tcp port 22 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - >> ((tcp[12]&0xf0)>>2)) != 0)' -dd >> >> Other libpcap programs have similar performance differences. >> >> Raw performance data from BPF micro-benchmark: >> SK_RUN_FILTER on same SKB (cache-hit) or 10k SKBs (cache-miss) >> time in nsec per call, smaller is better >> --x86_64-- >> fprog #1 fprog #1 fprog #2 fprog #2 >> cache-hit cache-miss cache-hit cache-miss >> old BPF 90 101 192 202 >> ext BPF 31 71 47 97 >> old BPF jit 12 34 17 44 >> ext BPF jit TBD >> >> --i386-- >> fprog #1 fprog #1 fprog #2 fprog #2 >> cache-hit cache-miss cache-hit cache-miss >> old BPF 107 136 227 252 >> ext BPF 40 119 69 172 >> >> --arm32-- >> fprog #1 fprog #1 fprog #2 fprog #2 >> cache-hit cache-miss cache-hit cache-miss >> old BPF 202 300 475 540 >> ext BPF 139 270 296 470 >> old BPF jit 26 182 37 202 >> new BPF jit TBD >> >> Tested with trinify BPF fuzzer >> >> Future work: >> >> 0. seccomp >> >> 1. add extended BPF JIT for x86_64 >> >> 2. add inband old/new demux and extended BPF verifier, so that new >> programs >> can be loaded through old sk_attach_filter() and >> sk_unattached_filter_create() >> interfaces >> >> 3. tracing filters systemtap-like with extended BPF >> >> 4. OVS with extended BPF >> >> 5. nftables with extended BPF >> >> Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> > > > Looks great, imho, some comments/questions inline: > > Nit: subject line of your patches should be, e.g. > > "filter: add Extended BPF interpreter and converter" > "doc: filter: add Extended BPF documentation" > ... > > so first "<subsystem>: <summary phrase>". sure. Will send v5 :) >> --- >> include/linux/filter.h | 8 +- >> include/linux/netdevice.h | 1 + >> include/uapi/linux/filter.h | 34 +- >> net/core/filter.c | 802 >> ++++++++++++++++++++++++++++++++++++++++++- >> net/core/sysctl_net_core.c | 7 + >> 5 files changed, 830 insertions(+), 22 deletions(-) >> >> diff --git a/include/linux/filter.h b/include/linux/filter.h >> index e568c8ef896b..0e84ff6e991b 100644 >> --- a/include/linux/filter.h >> +++ b/include/linux/filter.h >> @@ -52,7 +52,13 @@ extern int sk_detach_filter(struct sock *sk); >> extern int sk_chk_filter(struct sock_filter *filter, unsigned int flen); >> extern int sk_get_filter(struct sock *sk, struct sock_filter __user >> *filter, unsigned len); >> extern void sk_decode_filter(struct sock_filter *filt, struct >> sock_filter *to); >> +/* function remaps 'sock_filter' insns to 'sock_filter_ext' insns */ >> +int sk_convert_filter(struct sock_filter *old_prog, int len, >> + struct sock_filter_ext *new_prog, int *p_new_len); >> +/* execute extended bpf program */ > > > I think this and the above comment can be omitted, as both have a kernel doc > in its implementation in net/core/filter.c that is more precise. ok. I like comments in .h, because this is how 'make tags' orders them and 'vim -t sk_convert_filter' jumps there instead of .c but ok, will remove them, since they indeed look out of place there. > ... > >> +struct sock_filter_ext { >> + __u8 code; /* opcode */ >> + __u8 a_reg:4; /* dest register */ >> + __u8 x_reg:4; /* source register */ >> + __s16 off; /* signed offset */ >> + __s32 imm; /* signed immediate constant */ >> +}; >> + >> struct sock_fprog { /* Required for SO_ATTACH_FILTER. */ >> unsigned short len; /* Number of filter blocks */ >> struct sock_filter __user *filter; >> @@ -45,12 +54,15 @@ struct sock_fprog { /* Required for SO_ATTACH_FILTER. >> */ >> #define BPF_JMP 0x05 >> #define BPF_RET 0x06 >> #define BPF_MISC 0x07 >> +#define BPF_ALU64 0x07 >> + >> > > Please do not add empty newline above. ohh. yes. good catch. Right below this line in my temp_filter.h I have few macros (similar to BPF_STMT and BPF_JUMP) that makes manual coding of ebpf easier, but I sed them out of this diff just to include in the future diffs. will double check for empty lines. > >> /* ld/ldx fields */ >> #define BPF_SIZE(code) ((code) & 0x18) >> #define BPF_W 0x00 >> #define BPF_H 0x08 >> #define BPF_B 0x10 > > ... > >> diff --git a/net/core/filter.c b/net/core/filter.c >> index ad30d626a5bd..1494421486b7 100644 >> --- a/net/core/filter.c >> +++ b/net/core/filter.c >> @@ -1,5 +1,6 @@ >> /* >> * Linux Socket Filter - Kernel level socket filtering >> + * Extended BPF is Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com >> * >> * Author: >> * Jay Schulist <jschlst@samba.org> >> @@ -40,6 +41,8 @@ >> #include <linux/seccomp.h> >> #include <linux/if_vlan.h> >> >> +int bpf_ext_enable __read_mostly; >> + >> /* No hurry in this branch >> * >> * Exported for the bpf jit load helper. >> @@ -399,6 +402,7 @@ load_b: >> } >> >> return 0; >> +#undef K >> } >> EXPORT_SYMBOL(sk_run_filter); > > ... > >> + /* RET_K, RET_A are remaped into 2 insns */ >> + case BPF_RET | BPF_A: >> + case BPF_RET | BPF_K: >> + insn->code = BPF_ALU | BPF_MOV | >> + (BPF_SRC(fp->code) == BPF_K ? BPF_K : >> BPF_X); > > > Hmm, so the case statement is about BPF_RET | BPF_A and BPF_RET | BPF_K > but BPF_RET | BPF_X is not mentioned. However, in BPF_SRC(fp->code) > selection you fall back to BPF_X if it doesn't equal BPF_K? Is that > correct? And, you probably also need to handle BPF_RET | BPF_X ? :) that design choice of original BPF always puzzled me. BPF_A macro only used in one insn: BPF_RET + BPF_A and all other insns use BPF_K and BPF_X and though comment in uapi/filter.h says "ret - BPF_K and BPF_X also apply" this is not true, since sk_chk_filter() only allows ret+a and ret+k libpcap is equally confused. It never generates ret+x, but has few places in the code that can recognize it. I guess that's an artifact of distant past. epbf has only one RET insn that takes register R0 and returns it. That is similar to real CPU 'ret' insn and done to make epbf easier to generate from gcc/llvm point of view. ebpf jit converts 'ret' into 'leave; ret' on x86_64. so original bpf+k and bpf+a are converted into 'mov r0, [a or k]; ret r0' btw, if there is interest I can put ebpf testsuite into tools/net/ Thanks! Alexei -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Mar 4, 2014 at 6:28 AM, Hagen Paul Pfeifer <hagen@jauu.net> wrote: > If all issues raised by Daniel are addresed: > > Acked-by: Hagen Paul Pfeifer <hagen@jauu.net> Thanks! > But ... > >>Future work: >> >>0. seccomp >> >>1. add extended BPF JIT for x86_64 >> >>2. add inband old/new demux and extended BPF verifier, so that new programs >> can be loaded through old sk_attach_filter() and sk_unattached_filter_create() >> interfaces >> >>3. tracing filters systemtap-like with extended BPF >> >>4. OVS with extended BPF >> >>5. nftables with extended BPF > > ... this is shit (not your fault). (Jitted) BPF envolved into a direction > which is just not the right way to do it. You try to fix things, bypass > architectural shortcomings of BPF, perf issues because and so on. > > The right direction is to write a new general purpose in-kernel interpreter > from scratch. Capability layers should provide an compatible API for BPF and > seccomp. You have the knowledge to do exactly this, you nearly already did > this - you should start this undertake! this insn set evolved over few years. Initially we had nft-like high level state machine, but it wasn't fast, then kprobe-like pure x86_64 which was fast, but very hard to analyze from safety point of view. Then reduced x86-64 insn set and finally ebpf. I think any brand new instruction set will have steep learning curve, just because it's all new. ebpf tries to reuse as much as possible. opcode encoding is the same, instruction size is fixed at 8 bytes and so on. Yeah, these restrictions make few things not 100% optimal, but imo common look and feel is more important. What ebpf has already should be enough to do all of the above 'future work'. Built-in JIT-ability of ebpf is the key to performance. Ability to call some kernel functions from ebpf make it ultimately extensible. socket filters and seccomp don't use this feature yet, but tracing filters will. Regards, Alexei > > -- > Hagen Paul Pfeifer -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 03/04/2014 06:09 PM, Alexei Starovoitov wrote: > On Tue, Mar 4, 2014 at 1:59 AM, Daniel Borkmann <dborkman@redhat.com> wrote: ... >> Hmm, so the case statement is about BPF_RET | BPF_A and BPF_RET | BPF_K >> but BPF_RET | BPF_X is not mentioned. However, in BPF_SRC(fp->code) >> selection you fall back to BPF_X if it doesn't equal BPF_K? Is that >> correct? And, you probably also need to handle BPF_RET | BPF_X ? > > :) that design choice of original BPF always puzzled me. > BPF_A macro only used in one insn: BPF_RET + BPF_A > and all other insns use BPF_K and BPF_X > and though comment in uapi/filter.h says "ret - BPF_K and BPF_X also apply" > this is not true, since sk_chk_filter() only allows ret+a and ret+k > libpcap is equally confused. It never generates ret+x, but has few > places in the code > that can recognize it. I guess that's an artifact of distant past. Good point, ret+a and ret+k are main users anyway, though we could fix that limitation actually. ;) > epbf has only one RET insn that takes register R0 and returns it. > That is similar to real CPU 'ret' insn and done to make epbf easier > to generate from gcc/llvm point of view. > ebpf jit converts 'ret' into 'leave; ret' on x86_64. > > so original bpf+k and bpf+a are converted into 'mov r0, [a or k]; ret r0' > > btw, if there is interest I can put ebpf testsuite into tools/net/ Yes, please. Would be great if you can place the test suite under: tools/testing/selftests/net/bpf/ I believe some stuff there could get its own folder e.g. "packet" for PF_PACKET test cases etc, so that we can easily arrange them. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 03/04/2014 06:53 PM, Alexei Starovoitov wrote: > On Tue, Mar 4, 2014 at 6:28 AM, Hagen Paul Pfeifer <hagen@jauu.net> wrote: >> If all issues raised by Daniel are addresed: >> >> Acked-by: Hagen Paul Pfeifer <hagen@jauu.net> > > Thanks! > >> But ... >> >>> Future work: >>> >>> 0. seccomp >>> >>> 1. add extended BPF JIT for x86_64 >>> >>> 2. add inband old/new demux and extended BPF verifier, so that new programs >>> can be loaded through old sk_attach_filter() and sk_unattached_filter_create() >>> interfaces >>> >>> 3. tracing filters systemtap-like with extended BPF >>> >>> 4. OVS with extended BPF >>> >>> 5. nftables with extended BPF >> >> ... this is shit (not your fault). (Jitted) BPF envolved into a direction >> which is just not the right way to do it. You try to fix things, bypass >> architectural shortcomings of BPF, perf issues because and so on. >> >> The right direction is to write a new general purpose in-kernel interpreter >> from scratch. Capability layers should provide an compatible API for BPF and I think ebpf would have the potential to be *the* general purpose in-kernel interpreter actually (if we undertake all this effort of migration) as its already designed to be in a more generic context than the traditional interpreter which is restricted to skb (or NULL). >> seccomp. You have the knowledge to do exactly this, you nearly already did >> this - you should start this undertake! > > this insn set evolved over few years. > Initially we had nft-like high level state machine, but it wasn't fast, > then kprobe-like pure x86_64 which was fast, but very hard to analyze > from safety point of view. Then reduced x86-64 insn set and finally ebpf. > I think any brand new instruction set will have steep learning curve, > just because > it's all new. ebpf tries to reuse as much as possible. opcode encoding > is the same, > instruction size is fixed at 8 bytes and so on. Yeah, these > restrictions make few > things not 100% optimal, but imo common look and feel is more important. > What ebpf has already should be enough to do all of the above 'future work'. > Built-in JIT-ability of ebpf is the key to performance. > Ability to call some kernel functions from ebpf make it ultimately extensible. > socket filters and seccomp don't use this feature yet, but tracing filters will. > > Regards, > Alexei -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/filter.h b/include/linux/filter.h index e568c8ef896b..0e84ff6e991b 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -52,7 +52,13 @@ extern int sk_detach_filter(struct sock *sk); extern int sk_chk_filter(struct sock_filter *filter, unsigned int flen); extern int sk_get_filter(struct sock *sk, struct sock_filter __user *filter, unsigned len); extern void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to); +/* function remaps 'sock_filter' insns to 'sock_filter_ext' insns */ +int sk_convert_filter(struct sock_filter *old_prog, int len, + struct sock_filter_ext *new_prog, int *p_new_len); +/* execute extended bpf program */ +unsigned int sk_run_filter_ext(void *ctx, const struct sock_filter_ext *insn); +#define SK_RUN_FILTER(FILTER, SKB) (*FILTER->bpf_func)(SKB, FILTER->insns) #ifdef CONFIG_BPF_JIT #include <stdarg.h> #include <linux/linkage.h> @@ -70,7 +76,6 @@ static inline void bpf_jit_dump(unsigned int flen, unsigned int proglen, print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_OFFSET, 16, 1, image, proglen, false); } -#define SK_RUN_FILTER(FILTER, SKB) (*FILTER->bpf_func)(SKB, FILTER->insns) #else #include <linux/slab.h> static inline void bpf_jit_compile(struct sk_filter *fp) @@ -80,7 +85,6 @@ static inline void bpf_jit_free(struct sk_filter *fp) { kfree(fp); } -#define SK_RUN_FILTER(FILTER, SKB) sk_run_filter(SKB, FILTER->insns) #endif static inline int bpf_tell_extensions(void) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 1a869488b8ae..2c13d000389c 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3054,6 +3054,7 @@ extern int netdev_max_backlog; extern int netdev_tstamp_prequeue; extern int weight_p; extern int bpf_jit_enable; +extern int bpf_ext_enable; bool netdev_has_upper_dev(struct net_device *dev, struct net_device *upper_dev); struct net_device *netdev_all_upper_get_next_dev_rcu(struct net_device *dev, diff --git a/include/uapi/linux/filter.h b/include/uapi/linux/filter.h index 8eb9ccaa5b48..0dbe0b67c72c 100644 --- a/include/uapi/linux/filter.h +++ b/include/uapi/linux/filter.h @@ -1,5 +1,6 @@ /* * Linux Socket Filter Data Structures + * Extended BPF is Copyright (c) 2011-2014, PLUMgrid, http://plumgrid.com */ #ifndef _UAPI__LINUX_FILTER_H__ @@ -19,7 +20,7 @@ * Try and keep these values and structures similar to BSD, especially * the BPF code definitions which need to match so you can share filters */ - + struct sock_filter { /* Filter block */ __u16 code; /* Actual filter code */ __u8 jt; /* Jump true */ @@ -27,6 +28,14 @@ struct sock_filter { /* Filter block */ __u32 k; /* Generic multiuse field */ }; +struct sock_filter_ext { + __u8 code; /* opcode */ + __u8 a_reg:4; /* dest register */ + __u8 x_reg:4; /* source register */ + __s16 off; /* signed offset */ + __s32 imm; /* signed immediate constant */ +}; + struct sock_fprog { /* Required for SO_ATTACH_FILTER. */ unsigned short len; /* Number of filter blocks */ struct sock_filter __user *filter; @@ -45,12 +54,15 @@ struct sock_fprog { /* Required for SO_ATTACH_FILTER. */ #define BPF_JMP 0x05 #define BPF_RET 0x06 #define BPF_MISC 0x07 +#define BPF_ALU64 0x07 + /* ld/ldx fields */ #define BPF_SIZE(code) ((code) & 0x18) #define BPF_W 0x00 #define BPF_H 0x08 #define BPF_B 0x10 +#define BPF_DW 0x18 #define BPF_MODE(code) ((code) & 0xe0) #define BPF_IMM 0x00 #define BPF_ABS 0x20 @@ -58,6 +70,7 @@ struct sock_fprog { /* Required for SO_ATTACH_FILTER. */ #define BPF_MEM 0x60 #define BPF_LEN 0x80 #define BPF_MSH 0xa0 +#define BPF_XADD 0xc0 /* exclusive add */ /* alu/jmp fields */ #define BPF_OP(code) ((code) & 0xf0) @@ -68,16 +81,24 @@ struct sock_fprog { /* Required for SO_ATTACH_FILTER. */ #define BPF_OR 0x40 #define BPF_AND 0x50 #define BPF_LSH 0x60 -#define BPF_RSH 0x70 +#define BPF_RSH 0x70 /* logical shift right */ #define BPF_NEG 0x80 #define BPF_MOD 0x90 #define BPF_XOR 0xa0 +#define BPF_MOV 0xb0 /* mov reg to reg */ +#define BPF_ARSH 0xc0 /* sign extending arithmetic shift right */ +#define BPF_BSWAP32 0xd0 /* swap lower 4 bytes of 64-bit register */ +#define BPF_BSWAP64 0xe0 /* swap all 8 bytes of 64-bit register */ #define BPF_JA 0x00 -#define BPF_JEQ 0x10 -#define BPF_JGT 0x20 -#define BPF_JGE 0x30 -#define BPF_JSET 0x40 +#define BPF_JEQ 0x10 /* jump == */ +#define BPF_JGT 0x20 /* GT is unsigned '>', JA in x86 */ +#define BPF_JGE 0x30 /* GE is unsigned '>=', JAE in x86 */ +#define BPF_JSET 0x40 /* if (A & X) */ +#define BPF_JNE 0x50 /* jump != */ +#define BPF_JSGT 0x60 /* SGT is signed '>', GT in x86 */ +#define BPF_JSGE 0x70 /* SGE is signed '>=', GE in x86 */ +#define BPF_CALL 0x80 /* function call */ #define BPF_SRC(code) ((code) & 0x08) #define BPF_K 0x00 #define BPF_X 0x08 @@ -134,5 +155,4 @@ struct sock_fprog { /* Required for SO_ATTACH_FILTER. */ #define SKF_NET_OFF (-0x100000) #define SKF_LL_OFF (-0x200000) - #endif /* _UAPI__LINUX_FILTER_H__ */ diff --git a/net/core/filter.c b/net/core/filter.c index ad30d626a5bd..1494421486b7 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1,5 +1,6 @@ /* * Linux Socket Filter - Kernel level socket filtering + * Extended BPF is Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com * * Author: * Jay Schulist <jschlst@samba.org> @@ -40,6 +41,8 @@ #include <linux/seccomp.h> #include <linux/if_vlan.h> +int bpf_ext_enable __read_mostly; + /* No hurry in this branch * * Exported for the bpf jit load helper. @@ -399,6 +402,7 @@ load_b: } return 0; +#undef K } EXPORT_SYMBOL(sk_run_filter); @@ -637,6 +641,10 @@ void sk_filter_release_rcu(struct rcu_head *rcu) { struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); + if ((void *)fp->bpf_func == (void *)sk_run_filter_ext) + /* arch specific jit_free are expecting this value */ + fp->bpf_func = sk_run_filter; + bpf_jit_free(fp); } EXPORT_SYMBOL(sk_filter_release_rcu); @@ -655,6 +663,81 @@ static int __sk_prepare_filter(struct sk_filter *fp) return 0; } +static int sk_prepare_filter_ext(struct sk_filter **pfp, + struct sock_fprog *fprog, struct sock *sk) +{ + unsigned int fsize = sizeof(struct sock_filter) * fprog->len; + struct sock_filter *old_prog; + unsigned int sk_fsize; + struct sk_filter *fp; + int new_len; + int err; + + /* store old program into buffer, since chk_filter will remap opcodes */ + old_prog = kmalloc(fsize, GFP_KERNEL); + if (!old_prog) + return -ENOMEM; + + if (sk) { + if (copy_from_user(old_prog, fprog->filter, fsize)) { + err = -EFAULT; + goto free_prog; + } + } else { + memcpy(old_prog, fprog->filter, fsize); + } + + /* calculate bpf_ext program length */ + err = sk_convert_filter(fprog->filter, fprog->len, NULL, &new_len); + if (err) + goto free_prog; + + sk_fsize = sk_filter_size(new_len); + /* allocate sk_filter to store bpf_ext program */ + if (sk) + fp = sock_kmalloc(sk, sk_fsize, GFP_KERNEL); + else + fp = kmalloc(sk_fsize, GFP_KERNEL); + if (!fp) { + err = -ENOMEM; + goto free_prog; + } + + /* remap sock_filter insns into sock_filter_ext insns */ + err = sk_convert_filter(old_prog, fprog->len, + (struct sock_filter_ext *)fp->insns, &new_len); + if (err) + /* 2nd sk_convert_filter() can fail only if it fails + * to allocate memory, remapping must succeed + */ + goto free_fp; + + /* now chk_filter can overwrite old_prog while checking */ + err = sk_chk_filter(old_prog, fprog->len); + if (err) + goto free_fp; + + /* discard old prog */ + kfree(old_prog); + + atomic_set(&fp->refcnt, 1); + fp->len = new_len; + + /* sock_filter_ext insns must be executed by sk_run_filter_ext */ + fp->bpf_func = (typeof(fp->bpf_func))sk_run_filter_ext; + + *pfp = fp; + return 0; +free_fp: + if (sk) + sock_kfree_s(sk, fp, sk_fsize); + else + kfree(fp); +free_prog: + kfree(old_prog); + return err; +} + /** * sk_unattached_filter_create - create an unattached filter * @fprog: the filter program @@ -676,6 +759,9 @@ int sk_unattached_filter_create(struct sk_filter **pfp, if (fprog->filter == NULL) return -EINVAL; + if (bpf_ext_enable) + return sk_prepare_filter_ext(pfp, fprog, NULL); + fp = kmalloc(sk_filter_size(fprog->len), GFP_KERNEL); if (!fp) return -ENOMEM; @@ -726,21 +812,27 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) if (fprog->filter == NULL) return -EINVAL; - fp = sock_kmalloc(sk, sk_fsize, GFP_KERNEL); - if (!fp) - return -ENOMEM; - if (copy_from_user(fp->insns, fprog->filter, fsize)) { - sock_kfree_s(sk, fp, sk_fsize); - return -EFAULT; - } + if (bpf_ext_enable) { + err = sk_prepare_filter_ext(&fp, fprog, sk); + if (err) + return err; + } else { + fp = sock_kmalloc(sk, sk_fsize, GFP_KERNEL); + if (!fp) + return -ENOMEM; + if (copy_from_user(fp->insns, fprog->filter, fsize)) { + sock_kfree_s(sk, fp, sk_fsize); + return -EFAULT; + } - atomic_set(&fp->refcnt, 1); - fp->len = fprog->len; + atomic_set(&fp->refcnt, 1); + fp->len = fprog->len; - err = __sk_prepare_filter(fp); - if (err) { - sk_filter_uncharge(sk, fp); - return err; + err = __sk_prepare_filter(fp); + if (err) { + sk_filter_uncharge(sk, fp); + return err; + } } old_fp = rcu_dereference_protected(sk->sk_filter, @@ -882,3 +974,687 @@ out: release_sock(sk); return ret; } + +/** + * sk_convert_filter - convert filter program + * @old_prog: the filter program + * @len: the length of filter program + * @new_prog: buffer where converted program will be stored + * @p_new_len: pointer to store length of converted program + * + * remap 'sock_filter' style BPF instruction set to 'sock_filter_ext' style + * + * first, call sk_convert_filter(old_prog, len, NULL, &new_len) to calculate new + * program length in one pass + * + * then new_prog = kmalloc(sizeof(struct sock_filter_ext) * new_len); + * + * and call it again: sk_convert_filter(old_prog, len, new_prog, &new_len); + * to remap in two passes: 1st pass finds new jump offsets, 2nd pass remaps + */ +int sk_convert_filter(struct sock_filter *old_prog, int len, + struct sock_filter_ext *new_prog, int *p_new_len) +{ + struct sock_filter_ext *new_insn; + struct sock_filter *fp; + int *addrs = NULL; + int new_len = 0; + int pass = 0; + int tgt, i; + u8 bpf_src; + + if (len <= 0 || len >= BPF_MAXINSNS) + return -EINVAL; + + if (new_prog) { + addrs = kzalloc(len * sizeof(*addrs), GFP_KERNEL); + if (!addrs) + return -ENOMEM; + } + +do_pass: + new_insn = new_prog; + fp = old_prog; + for (i = 0; i < len; fp++, i++) { + struct sock_filter_ext tmp_insns[3] = {}; + struct sock_filter_ext *insn = tmp_insns; + + if (addrs) + addrs[i] = new_insn - new_prog; + + switch (fp->code) { + /* all arithmetic insns and skb loads map as-is */ + case BPF_ALU | BPF_ADD | BPF_X: + case BPF_ALU | BPF_ADD | BPF_K: + case BPF_ALU | BPF_SUB | BPF_X: + case BPF_ALU | BPF_SUB | BPF_K: + case BPF_ALU | BPF_AND | BPF_X: + case BPF_ALU | BPF_AND | BPF_K: + case BPF_ALU | BPF_OR | BPF_X: + case BPF_ALU | BPF_OR | BPF_K: + case BPF_ALU | BPF_LSH | BPF_X: + case BPF_ALU | BPF_LSH | BPF_K: + case BPF_ALU | BPF_RSH | BPF_X: + case BPF_ALU | BPF_RSH | BPF_K: + case BPF_ALU | BPF_XOR | BPF_X: + case BPF_ALU | BPF_XOR | BPF_K: + case BPF_ALU | BPF_MUL | BPF_X: + case BPF_ALU | BPF_MUL | BPF_K: + case BPF_ALU | BPF_DIV | BPF_X: + case BPF_ALU | BPF_DIV | BPF_K: + case BPF_ALU | BPF_MOD | BPF_X: + case BPF_ALU | BPF_MOD | BPF_K: + case BPF_ALU | BPF_NEG: + case BPF_LD | BPF_ABS | BPF_W: + case BPF_LD | BPF_ABS | BPF_H: + case BPF_LD | BPF_ABS | BPF_B: + case BPF_LD | BPF_IND | BPF_W: + case BPF_LD | BPF_IND | BPF_H: + case BPF_LD | BPF_IND | BPF_B: + insn->code = fp->code; + insn->a_reg = 6; + insn->x_reg = 7; + insn->imm = fp->k; + break; + + /* jump opcodes map as-is, but offsets need adjustment */ + case BPF_JMP | BPF_JA: + tgt = i + fp->k + 1; + insn->code = fp->code; +#define EMIT_JMP \ + do { \ + if (tgt >= len || tgt < 0) \ + goto err; \ + insn->off = addrs ? addrs[tgt] - addrs[i] - 1 : 0; \ + /* adjust pc relative offset for 2nd or 3rd insn */ \ + insn->off -= insn - tmp_insns; \ + } while (0) + + EMIT_JMP; + break; + + case BPF_JMP | BPF_JEQ | BPF_K: + case BPF_JMP | BPF_JEQ | BPF_X: + case BPF_JMP | BPF_JSET | BPF_K: + case BPF_JMP | BPF_JSET | BPF_X: + case BPF_JMP | BPF_JGT | BPF_K: + case BPF_JMP | BPF_JGT | BPF_X: + case BPF_JMP | BPF_JGE | BPF_K: + case BPF_JMP | BPF_JGE | BPF_X: + if (BPF_SRC(fp->code) == BPF_K && + (int)fp->k < 0) { + /* extended BPF immediates are signed, + * zero extend immediate into tmp register + * and use it in compare insn + */ + insn->code = BPF_ALU | BPF_MOV | BPF_K; + insn->a_reg = 2; + insn->imm = fp->k; + insn++; + + insn->a_reg = 6; + insn->x_reg = 2; + bpf_src = BPF_X; + } else { + insn->a_reg = 6; + insn->x_reg = 7; + insn->imm = fp->k; + bpf_src = BPF_SRC(fp->code); + } + /* common case where 'jump_false' is next insn */ + if (fp->jf == 0) { + insn->code = BPF_JMP | BPF_OP(fp->code) | + bpf_src; + tgt = i + fp->jt + 1; + EMIT_JMP; + break; + } + /* convert JEQ into JNE when 'jump_true' is next insn */ + if (fp->jt == 0 && BPF_OP(fp->code) == BPF_JEQ) { + insn->code = BPF_JMP | BPF_JNE | bpf_src; + tgt = i + fp->jf + 1; + EMIT_JMP; + break; + } + /* other jumps are mapped into two insns: Jxx and JA */ + tgt = i + fp->jt + 1; + insn->code = BPF_JMP | BPF_OP(fp->code) | bpf_src; + EMIT_JMP; + + insn++; + insn->code = BPF_JMP | BPF_JA; + tgt = i + fp->jf + 1; + EMIT_JMP; + break; + + /* ldxb 4*([14]&0xf) is remaped into 3 insns */ + case BPF_LDX | BPF_MSH | BPF_B: + insn->code = BPF_LD | BPF_ABS | BPF_B; + insn->a_reg = 7; + insn->imm = fp->k; + + insn++; + insn->code = BPF_ALU | BPF_AND | BPF_K; + insn->a_reg = 7; + insn->imm = 0xf; + + insn++; + insn->code = BPF_ALU | BPF_LSH | BPF_K; + insn->a_reg = 7; + insn->imm = 2; + break; + + /* RET_K, RET_A are remaped into 2 insns */ + case BPF_RET | BPF_A: + case BPF_RET | BPF_K: + insn->code = BPF_ALU | BPF_MOV | + (BPF_SRC(fp->code) == BPF_K ? BPF_K : BPF_X); + insn->a_reg = 0; + insn->x_reg = 6; + insn->imm = fp->k; + + insn++; + insn->code = BPF_RET | BPF_K; + break; + + /* store to stack */ + case BPF_ST: + case BPF_STX: + insn->code = BPF_STX | BPF_MEM | BPF_W; + insn->a_reg = 10; + insn->x_reg = fp->code == BPF_ST ? 6 : 7; + insn->off = -(BPF_MEMWORDS - fp->k) * 4; + break; + + /* load from stack */ + case BPF_LD | BPF_MEM: + case BPF_LDX | BPF_MEM: + insn->code = BPF_LDX | BPF_MEM | BPF_W; + insn->a_reg = BPF_CLASS(fp->code) == BPF_LD ? 6 : 7; + insn->x_reg = 10; + insn->off = -(BPF_MEMWORDS - fp->k) * 4; + break; + + /* A = K or X = K */ + case BPF_LD | BPF_IMM: + case BPF_LDX | BPF_IMM: + insn->code = BPF_ALU | BPF_MOV | BPF_K; + insn->a_reg = BPF_CLASS(fp->code) == BPF_LD ? 6 : 7; + insn->imm = fp->k; + break; + + /* X = A */ + case BPF_MISC | BPF_TAX: + insn->code = BPF_ALU64 | BPF_MOV | BPF_X; + insn->a_reg = 7; + insn->x_reg = 6; + break; + + /* A = X */ + case BPF_MISC | BPF_TXA: + insn->code = BPF_ALU64 | BPF_MOV | BPF_X; + insn->a_reg = 6; + insn->x_reg = 7; + break; + + /* A = skb->len or X = skb->len */ + case BPF_LD | BPF_W | BPF_LEN: + case BPF_LDX | BPF_W | BPF_LEN: + insn->code = BPF_LDX | BPF_MEM | BPF_W; + insn->a_reg = BPF_CLASS(fp->code) == BPF_LD ? 6 : 7; + insn->x_reg = 1; + insn->off = offsetof(struct sk_buff, len); + break; + + /* access seccomp_data fields */ + case BPF_LDX | BPF_ABS | BPF_W: + insn->code = BPF_LDX | BPF_MEM | BPF_W; + insn->a_reg = 6; + insn->x_reg = 1; + insn->off = fp->k; + break; + + default: + /* pr_err("unknown opcode %02x\n", fp->code); */ + goto err; + } + + insn++; + if (new_prog) { + memcpy(new_insn, tmp_insns, + sizeof(*insn) * (insn - tmp_insns)); + } + new_insn += insn - tmp_insns; + } + + if (!new_prog) { + /* only calculating new length */ + *p_new_len = new_insn - new_prog; + return 0; + } + + pass++; + if (new_len != new_insn - new_prog) { + new_len = new_insn - new_prog; + if (pass > 2) + goto err; + goto do_pass; + } + kfree(addrs); + if (*p_new_len != new_len) + /* inconsistent new program length */ + pr_err("sk_convert_filter() usage error\n"); + return 0; +err: + kfree(addrs); + return -EINVAL; +} + +/** + * sk_run_filter_ext - run an extended filter + * @ctx: buffer to run the filter on + * @insn: filter to apply + * + * Decode and execute extended BPF instructions. + * @ctx is the data we are operating on. + * @filter is the array of filter instructions. + */ +notrace u32 sk_run_filter_ext(void *ctx, const struct sock_filter_ext *insn) +{ + u64 stack[64]; + u64 regs[16]; + void *ptr; + u64 tmp; + int off; + +#ifdef __x86_64 +#define LOAD_IMM /**/ +#define K insn->imm +#else +#define LOAD_IMM (K = insn->imm) + s32 K = insn->imm; +#endif + +#define A regs[insn->a_reg] +#define X regs[insn->x_reg] + +#define CONT ({insn++; LOAD_IMM; goto select_insn; }) +#define CONT_JMP ({insn++; LOAD_IMM; goto select_insn; }) +/* some compilers may need help: + * #define CONT_JMP ({insn++; LOAD_IMM; goto *jumptable[insn->code]; }) + */ + + static const void *jumptable[256] = { + [0 ... 255] = &&default_label, +#define DL(A, B, C) [A|B|C] = &&A##_##B##_##C, + DL(BPF_ALU, BPF_ADD, BPF_X) + DL(BPF_ALU, BPF_ADD, BPF_K) + DL(BPF_ALU, BPF_SUB, BPF_X) + DL(BPF_ALU, BPF_SUB, BPF_K) + DL(BPF_ALU, BPF_AND, BPF_X) + DL(BPF_ALU, BPF_AND, BPF_K) + DL(BPF_ALU, BPF_OR, BPF_X) + DL(BPF_ALU, BPF_OR, BPF_K) + DL(BPF_ALU, BPF_LSH, BPF_X) + DL(BPF_ALU, BPF_LSH, BPF_K) + DL(BPF_ALU, BPF_RSH, BPF_X) + DL(BPF_ALU, BPF_RSH, BPF_K) + DL(BPF_ALU, BPF_XOR, BPF_X) + DL(BPF_ALU, BPF_XOR, BPF_K) + DL(BPF_ALU, BPF_MUL, BPF_X) + DL(BPF_ALU, BPF_MUL, BPF_K) + DL(BPF_ALU, BPF_MOV, BPF_X) + DL(BPF_ALU, BPF_MOV, BPF_K) + DL(BPF_ALU, BPF_DIV, BPF_X) + DL(BPF_ALU, BPF_DIV, BPF_K) + DL(BPF_ALU, BPF_MOD, BPF_X) + DL(BPF_ALU, BPF_MOD, BPF_K) + DL(BPF_ALU64, BPF_ADD, BPF_X) + DL(BPF_ALU64, BPF_ADD, BPF_K) + DL(BPF_ALU64, BPF_SUB, BPF_X) + DL(BPF_ALU64, BPF_SUB, BPF_K) + DL(BPF_ALU64, BPF_AND, BPF_X) + DL(BPF_ALU64, BPF_AND, BPF_K) + DL(BPF_ALU64, BPF_OR, BPF_X) + DL(BPF_ALU64, BPF_OR, BPF_K) + DL(BPF_ALU64, BPF_LSH, BPF_X) + DL(BPF_ALU64, BPF_LSH, BPF_K) + DL(BPF_ALU64, BPF_RSH, BPF_X) + DL(BPF_ALU64, BPF_RSH, BPF_K) + DL(BPF_ALU64, BPF_XOR, BPF_X) + DL(BPF_ALU64, BPF_XOR, BPF_K) + DL(BPF_ALU64, BPF_MUL, BPF_X) + DL(BPF_ALU64, BPF_MUL, BPF_K) + DL(BPF_ALU64, BPF_MOV, BPF_X) + DL(BPF_ALU64, BPF_MOV, BPF_K) + DL(BPF_ALU64, BPF_ARSH, BPF_X) + DL(BPF_ALU64, BPF_ARSH, BPF_K) + DL(BPF_ALU64, BPF_DIV, BPF_X) + DL(BPF_ALU64, BPF_DIV, BPF_K) + DL(BPF_ALU64, BPF_MOD, BPF_X) + DL(BPF_ALU64, BPF_MOD, BPF_K) + DL(BPF_ALU64, BPF_BSWAP32, BPF_X) + DL(BPF_ALU64, BPF_BSWAP64, BPF_X) + DL(BPF_ALU, BPF_NEG, 0) + DL(BPF_JMP, BPF_CALL, 0) + DL(BPF_JMP, BPF_JA, 0) + DL(BPF_JMP, BPF_JEQ, BPF_X) + DL(BPF_JMP, BPF_JEQ, BPF_K) + DL(BPF_JMP, BPF_JNE, BPF_X) + DL(BPF_JMP, BPF_JNE, BPF_K) + DL(BPF_JMP, BPF_JGT, BPF_X) + DL(BPF_JMP, BPF_JGT, BPF_K) + DL(BPF_JMP, BPF_JGE, BPF_X) + DL(BPF_JMP, BPF_JGE, BPF_K) + DL(BPF_JMP, BPF_JSGT, BPF_X) + DL(BPF_JMP, BPF_JSGT, BPF_K) + DL(BPF_JMP, BPF_JSGE, BPF_X) + DL(BPF_JMP, BPF_JSGE, BPF_K) + DL(BPF_JMP, BPF_JSET, BPF_X) + DL(BPF_JMP, BPF_JSET, BPF_K) + DL(BPF_STX, BPF_MEM, BPF_B) + DL(BPF_STX, BPF_MEM, BPF_H) + DL(BPF_STX, BPF_MEM, BPF_W) + DL(BPF_STX, BPF_MEM, BPF_DW) + DL(BPF_ST, BPF_MEM, BPF_B) + DL(BPF_ST, BPF_MEM, BPF_H) + DL(BPF_ST, BPF_MEM, BPF_W) + DL(BPF_ST, BPF_MEM, BPF_DW) + DL(BPF_LDX, BPF_MEM, BPF_B) + DL(BPF_LDX, BPF_MEM, BPF_H) + DL(BPF_LDX, BPF_MEM, BPF_W) + DL(BPF_LDX, BPF_MEM, BPF_DW) + DL(BPF_STX, BPF_XADD, BPF_W) +#ifdef CONFIG_64BIT + DL(BPF_STX, BPF_XADD, BPF_DW) +#endif + DL(BPF_LD, BPF_ABS, BPF_W) + DL(BPF_LD, BPF_ABS, BPF_H) + DL(BPF_LD, BPF_ABS, BPF_B) + DL(BPF_LD, BPF_IND, BPF_W) + DL(BPF_LD, BPF_IND, BPF_H) + DL(BPF_LD, BPF_IND, BPF_B) + DL(BPF_RET, BPF_K, 0) +#undef DL + }; + + regs[10/* BPF R10 */] = (u64)(ulong)&stack[64]; + regs[1/* BPF R1 */] = (u64)(ulong)ctx; + + /* execute 1st insn */ +select_insn: + goto *jumptable[insn->code]; + + /* ALU */ +#define ALU(OPCODE, OP) \ + BPF_ALU64_##OPCODE##_BPF_X: \ + A = A OP X; \ + CONT; \ + BPF_ALU_##OPCODE##_BPF_X: \ + A = (u32)A OP (u32)X; \ + CONT; \ + BPF_ALU64_##OPCODE##_BPF_K: \ + A = A OP K; \ + CONT; \ + BPF_ALU_##OPCODE##_BPF_K: \ + A = (u32)A OP (u32)K; \ + CONT; + + ALU(BPF_ADD, +) + ALU(BPF_SUB, -) + ALU(BPF_AND, &) + ALU(BPF_OR, |) + ALU(BPF_LSH, <<) + ALU(BPF_RSH, >>) + ALU(BPF_XOR, ^) + ALU(BPF_MUL, *) +#undef ALU + +BPF_ALU_BPF_NEG_0: + A = (u32)-A; + CONT; +BPF_ALU_BPF_MOV_BPF_X: + A = (u32)X; + CONT; +BPF_ALU_BPF_MOV_BPF_K: + A = (u32)K; + CONT; +BPF_ALU64_BPF_MOV_BPF_X: + A = X; + CONT; +BPF_ALU64_BPF_MOV_BPF_K: + A = K; + CONT; +BPF_ALU64_BPF_ARSH_BPF_X: + (*(s64 *) &A) >>= X; + CONT; +BPF_ALU64_BPF_ARSH_BPF_K: + (*(s64 *) &A) >>= K; + CONT; +BPF_ALU64_BPF_MOD_BPF_X: + tmp = A; + if (X) + A = do_div(tmp, X); + CONT; +BPF_ALU_BPF_MOD_BPF_X: + tmp = (u32)A; + if (X) + A = do_div(tmp, (u32)X); + CONT; +BPF_ALU64_BPF_MOD_BPF_K: + tmp = A; + if (K) + A = do_div(tmp, K); + CONT; +BPF_ALU_BPF_MOD_BPF_K: + tmp = (u32)A; + if (K) + A = do_div(tmp, (u32)K); + CONT; +BPF_ALU64_BPF_DIV_BPF_X: + if (X) + do_div(A, X); + CONT; +BPF_ALU_BPF_DIV_BPF_X: + tmp = (u32)A; + if (X) + do_div(tmp, (u32)X); + A = (u32)tmp; + CONT; +BPF_ALU64_BPF_DIV_BPF_K: + if (K) + do_div(A, K); + CONT; +BPF_ALU_BPF_DIV_BPF_K: + tmp = (u32)A; + if (K) + do_div(tmp, (u32)K); + A = (u32)tmp; + CONT; +BPF_ALU64_BPF_BSWAP32_BPF_X: + A = swab32(A); + CONT; +BPF_ALU64_BPF_BSWAP64_BPF_X: + A = swab64(A); + CONT; + + /* CALL */ +BPF_JMP_BPF_CALL_0: + return 0; /* not implemented yet */ + + /* JMP */ +BPF_JMP_BPF_JA_0: + insn += insn->off; + CONT; +BPF_JMP_BPF_JEQ_BPF_X: + if (A == X) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JEQ_BPF_K: + if (A == K) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JNE_BPF_X: + if (A != X) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JNE_BPF_K: + if (A != K) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JGT_BPF_X: + if (A > X) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JGT_BPF_K: + if (A > K) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JGE_BPF_X: + if (A >= X) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JGE_BPF_K: + if (A >= K) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JSGT_BPF_X: + if (((s64)A) > ((s64)X)) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JSGT_BPF_K: + if (((s64)A) > ((s64)K)) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JSGE_BPF_X: + if (((s64)A) >= ((s64)X)) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JSGE_BPF_K: + if (((s64)A) >= ((s64)K)) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JSET_BPF_X: + if (A & X) { + insn += insn->off; + CONT_JMP; + } + CONT; +BPF_JMP_BPF_JSET_BPF_K: + if (A & (u32)K) { + insn += insn->off; + CONT_JMP; + } + CONT; + + /* STX and ST and LDX*/ +#define LDST(SIZEOP, SIZE) \ + BPF_STX_BPF_MEM_##SIZEOP: \ + *(SIZE *)(ulong)(A + insn->off) = X; \ + CONT; \ + BPF_ST_BPF_MEM_##SIZEOP: \ + *(SIZE *)(ulong)(A + insn->off) = K; \ + CONT; \ + BPF_LDX_BPF_MEM_##SIZEOP: \ + A = *(SIZE *)(ulong)(X + insn->off); \ + CONT; + + LDST(BPF_B, u8) + LDST(BPF_H, u16) + LDST(BPF_W, u32) + LDST(BPF_DW, u64) +#undef LDST + +BPF_STX_BPF_XADD_BPF_W: /* lock xadd *(u32 *)(A + insn->off) += X */ + atomic_add((u32)X, (atomic_t *)(ulong)(A + insn->off)); + CONT; +#ifdef CONFIG_64BIT +BPF_STX_BPF_XADD_BPF_DW: /* lock xadd *(u64 *)(A + insn->off) += X */ + atomic64_add((u64)X, (atomic64_t *)(ulong)(A + insn->off)); + CONT; +#endif + +BPF_LD_BPF_ABS_BPF_W: /* A = *(u32 *)(SKB + K) */ + off = K; +load_word: + ptr = load_pointer((struct sk_buff *)ctx, off, 4, &tmp); + if (likely(ptr != NULL)) { + A = get_unaligned_be32(ptr); + CONT; + } + return 0; + +BPF_LD_BPF_ABS_BPF_H: /* A = *(u16 *)(SKB + K) */ + off = K; +load_half: + ptr = load_pointer((struct sk_buff *)ctx, off, 2, &tmp); + if (likely(ptr != NULL)) { + A = get_unaligned_be16(ptr); + CONT; + } + return 0; + +BPF_LD_BPF_ABS_BPF_B: /* A = *(u8 *)(SKB + K) */ + off = K; +load_byte: + ptr = load_pointer((struct sk_buff *)ctx, off, 1, &tmp); + if (likely(ptr != NULL)) { + A = *(u8 *)ptr; + CONT; + } + return 0; + +BPF_LD_BPF_IND_BPF_W: /* A = *(u32 *)(SKB + X + K) */ + off = K + X; + goto load_word; + +BPF_LD_BPF_IND_BPF_H: /* A = *(u16 *)(SKB + X + K) */ + off = K + X; + goto load_half; + +BPF_LD_BPF_IND_BPF_B: /* A = *(u8 *)(SKB + X + K) */ + off = K + X; + goto load_byte; + + /* RET */ +BPF_RET_BPF_K_0: + return regs[0/* R0 */]; + +default_label: + /* sk_chk_filter_ext() and sk_convert_filter() guarantee + * that we never reach here + */ + WARN_RATELIMIT(1, "unknown opcode %02x\n", insn->code); + return 0; +#undef CONT +#undef A +#undef X +#undef K +#undef LOAD_IMM +} +EXPORT_SYMBOL(sk_run_filter_ext); + diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index cf9cd13509a7..e1b979312588 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -273,6 +273,13 @@ static struct ctl_table net_core_table[] = { }, #endif { + .procname = "bpf_ext_enable", + .data = &bpf_ext_enable, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, + { .procname = "netdev_tstamp_prequeue", .data = &netdev_tstamp_prequeue, .maxlen = sizeof(int),
Extended BPF extends old BPF in the following ways: - from 2 to 10 registers Original BPF has two registers (A and X) and hidden frame pointer. Extended BPF has ten registers and read-only frame pointer. - from 32-bit registers to 64-bit registers semantics of old 32-bit ALU operations are preserved via 32-bit subregisters - if (cond) jump_true; else jump_false; old BPF insns are replaced with: if (cond) jump_true; /* else fallthrough */ - adds signed > and >= insns - 16 4-byte stack slots for register spill-fill replaced with up to 512 bytes of multi-use stack space - introduces bpf_call insn and register passing convention for zero overhead calls from/to other kernel functions (not part of this patch) - adds arithmetic right shift insn - adds swab32/swab64 insns - adds atomic_add insn - old tax/txa insns are replaced with 'mov dst,src' insn Extended BPF is designed to be JITed with one to one mapping, which allows GCC/LLVM backends to generate optimized BPF code that performs almost as fast as natively compiled code sk_convert_filter() remaps old style insns into extended: 'sock_filter' instructions are remapped on the fly to 'sock_filter_ext' extended instructions when sysctl net.core.bpf_ext_enable=1 Old filter comes through sk_attach_filter() or sk_unattached_filter_create() if (bpf_ext_enable) { convert to new sk_chk_filter() - check old bpf use sk_run_filter_ext() - new interpreter } else { sk_chk_filter() - check old bpf if (bpf_jit_enable) use old jit else use sk_run_filter() - old interpreter } sk_run_filter_ext() interpreter is noticeably faster than sk_run_filter() for two reasons: 1.fall-through jumps Old BPF jump instructions are forced to go either 'true' or 'false' branch which causes branch-miss penalty. Extended BPF jump instructions have one branch and fall-through, which fit CPU branch predictor logic better. 'perf stat' shows drastic difference for branch-misses. 2.jump-threaded implementation of interpreter vs switch statement Instead of single tablejump at the top of 'switch' statement, GCC will generate multiple tablejump instructions, which helps CPU branch predictor Performance of two BPF filters generated by libpcap was measured on x86_64, i386 and arm32. fprog #1 is taken from Documentation/networking/filter.txt: tcpdump -i eth0 port 22 -dd fprog #2 is taken from 'man tcpdump': tcpdump -i eth0 'tcp port 22 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' -dd Other libpcap programs have similar performance differences. Raw performance data from BPF micro-benchmark: SK_RUN_FILTER on same SKB (cache-hit) or 10k SKBs (cache-miss) time in nsec per call, smaller is better --x86_64-- fprog #1 fprog #1 fprog #2 fprog #2 cache-hit cache-miss cache-hit cache-miss old BPF 90 101 192 202 ext BPF 31 71 47 97 old BPF jit 12 34 17 44 ext BPF jit TBD --i386-- fprog #1 fprog #1 fprog #2 fprog #2 cache-hit cache-miss cache-hit cache-miss old BPF 107 136 227 252 ext BPF 40 119 69 172 --arm32-- fprog #1 fprog #1 fprog #2 fprog #2 cache-hit cache-miss cache-hit cache-miss old BPF 202 300 475 540 ext BPF 139 270 296 470 old BPF jit 26 182 37 202 new BPF jit TBD Tested with trinify BPF fuzzer Future work: 0. seccomp 1. add extended BPF JIT for x86_64 2. add inband old/new demux and extended BPF verifier, so that new programs can be loaded through old sk_attach_filter() and sk_unattached_filter_create() interfaces 3. tracing filters systemtap-like with extended BPF 4. OVS with extended BPF 5. nftables with extended BPF Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> --- include/linux/filter.h | 8 +- include/linux/netdevice.h | 1 + include/uapi/linux/filter.h | 34 +- net/core/filter.c | 802 ++++++++++++++++++++++++++++++++++++++++++- net/core/sysctl_net_core.c | 7 + 5 files changed, 830 insertions(+), 22 deletions(-)