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Eric Dumazet 0a14842f5a net: filter: Just In Time compiler for x86-64 
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>
 		2011-04-27 23:05:08 -07:00
..
boot x86, build: Make sure mkpiggy fails on read error 2011-03-01 16:32:03 -08:00
configs
…
crypto crypto: aesni-intel - fixed problem with packets that are not multiple of 64bytes 2011-03-27 10:29:39 +08:00
ia32 x86: mark associated mm when running a task in 32 bit compatibility mode 2011-03-23 16:36:53 -04:00
include/asm x86-32, fpu: Fix FPU exception handling on non-SSE systems 2011-04-06 16:53:01 -07:00
kernel Merge branches 'x86-fixes-for-linus', 'sched-fixes-for-linus', 'timers-fixes-for-linus', 'irq-fixes-for-linus' and 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-04-07 12:12:58 -07:00
kvm KVM: move and fix substitue search for missing CPUID entries 2011-04-06 13:15:56 +03:00
lguest x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
lib percpu: Omit segment prefix in the UP case for cmpxchg_double 2011-03-27 19:25:36 -07:00
math-emu
…
mm x86-32, NUMA: Fix ACPI NUMA init broken by recent x86-64 change 2011-04-04 16:56:33 +02:00
net net: filter: Just In Time compiler for x86-64 2011-04-27 23:05:08 -07:00
oprofile Merge branch 'core' of git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile into perf/urgent 2011-03-29 09:32:28 +02:00
pci Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2011-03-18 10:56:44 -07:00
platform Merge branches 'x86-fixes-for-linus', 'sched-fixes-for-linus', 'timers-fixes-for-linus', 'irq-fixes-for-linus' and 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2011-04-07 12:12:58 -07:00
power
…
tools
…
vdso mm: arch: rename in_gate_area_no_task to in_gate_area_no_mm 2011-03-23 16:36:55 -04:00
video
…
xen Merge branch 'stable/bug-fixes-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen 2011-03-29 11:36:52 -07:00
.gitignore
…
Kbuild net: filter: Just In Time compiler for x86-64 2011-04-27 23:05:08 -07:00
Kconfig net: filter: Just In Time compiler for x86-64 2011-04-27 23:05:08 -07:00
Kconfig.cpu x86: Fix common misspellings 2011-03-18 10:39:30 +01:00
Kconfig.debug kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
Makefile
…
Makefile_32.cpu jump label: Add work around to i386 gcc asm goto bug 2010-10-29 14:45:29 -04:00