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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/arch
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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
..
alpha Fix common misspellings 2011-03-31 11:26:23 -03:00
arm Merge branch 'rmobile-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6 2011-04-07 12:49:01 -07:00
avr32 avr32: Fix missing irq namespace conversion 2011-03-30 15:38:03 +02:00
blackfin Fix common misspellings 2011-03-31 11:26:23 -03:00
cris Fix common misspellings 2011-03-31 11:26:23 -03:00
frv Fix common misspellings 2011-03-31 11:26:23 -03:00
h8300 genirq: Remove the now obsolete config options and select statements 2011-03-30 14:13:23 +02:00
ia64 Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6 2011-04-07 11:14:49 -07:00
m32r Fix common misspellings 2011-03-31 11:26:23 -03:00
m68k Fix common misspellings 2011-03-31 11:26:23 -03:00
microblaze Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6 2011-04-07 11:14:49 -07:00
mips Fix common misspellings 2011-03-31 11:26:23 -03:00
mn10300 Fix common misspellings 2011-03-31 11:26:23 -03:00
parisc Fix common misspellings 2011-03-31 11:26:23 -03:00
powerpc powerpc: Fix multicast problem in fs_enet driver 2011-04-21 16:59:30 -07:00
s390 Merge branch 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6 2011-04-08 07:36:14 -07:00
score Fix common misspellings 2011-03-31 11:26:23 -03:00
sh Merge branch 'fbdev-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal/fbdev-2.6 2011-04-07 12:49:17 -07:00
sparc Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6 2011-04-07 11:14:49 -07:00
tile Fix common misspellings 2011-03-31 11:26:23 -03:00
um Fix common misspellings 2011-03-31 11:26:23 -03:00
unicore32 Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6 2011-04-07 11:14:49 -07:00
x86 net: filter: Just In Time compiler for x86-64 2011-04-27 23:05:08 -07:00
xtensa Fix common misspellings 2011-03-31 11:26:23 -03:00
.gitignore
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Kconfig oprofile, s390: Cleanups 2011-03-16 14:30:40 +01:00