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Daniel Borkmann 92b31a9af7 bpf: add BPF_J{LT,LE,SLT,SLE} instructions 
Currently, eBPF only understands BPF_JGT (>), BPF_JGE (>=),
BPF_JSGT (s>), BPF_JSGE (s>=) instructions, this means that
particularly *JLT/*JLE counterparts involving immediates need
to be rewritten from e.g. X < [IMM] by swapping arguments into
[IMM] > X, meaning the immediate first is required to be loaded
into a register Y := [IMM], such that then we can compare with
Y > X. Note that the destination operand is always required to
be a register.

This has the downside of having unnecessarily increased register
pressure, meaning complex program would need to spill other
registers temporarily to stack in order to obtain an unused
register for the [IMM]. Loading to registers will thus also
affect state pruning since we need to account for that register
use and potentially those registers that had to be spilled/filled
again. As a consequence slightly more stack space might have
been used due to spilling, and BPF programs are a bit longer
due to extra code involving the register load and potentially
required spill/fills.

Thus, add BPF_JLT (<), BPF_JLE (<=), BPF_JSLT (s<), BPF_JSLE (s<=)
counterparts to the eBPF instruction set. Modifying LLVM to
remove the NegateCC() workaround in a PoC patch at [1] and
allowing it to also emit the new instructions resulted in
cilium's BPF programs that are injected into the fast-path to
have a reduced program length in the range of 2-3% (e.g.
accumulated main and tail call sections from one of the object
file reduced from 4864 to 4729 insns), reduced complexity in
the range of 10-30% (e.g. accumulated sections reduced in one
of the cases from 116432 to 88428 insns), and reduced stack
usage in the range of 1-5% (e.g. accumulated sections from one
of the object files reduced from 824 to 784b).

The modification for LLVM will be incorporated in a backwards
compatible way. Plan is for LLVM to have i) a target specific
option to offer a possibility to explicitly enable the extension
by the user (as we have with -m target specific extensions today
for various CPU insns), and ii) have the kernel checked for
presence of the extensions and enable them transparently when
the user is selecting more aggressive options such as -march=native
in a bpf target context. (Other frontends generating BPF byte
code, e.g. ply can probe the kernel directly for its code
generation.)

  [1] https://github.com/borkmann/llvm/tree/bpf-insns

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-09 16:53:56 -07:00
..
ABI MTD updates for v4.13-rc1: 2017-07-13 12:07:44 -07:00
accounting
acpi This is the bulk of GPIO changes for the v4.13 series: 2017-07-07 12:40:27 -07:00
admin-guide cpufreq: docs: Add missing cpuinfo_cur_freq description 2017-07-27 23:54:14 +02:00
aoe
arm
arm64 IOMMU Updates for Linux v4.13 2017-07-12 10:00:04 -07:00
auxdisplay
backlight
blackfin
block bio-integrity: fold bio_integrity_enabled to bio_integrity_prep 2017-07-03 16:56:24 -06:00
blockdev
bus-devices
cdrom
cgroup-v1 mm, vmpressure: pass-through notification support 2017-07-10 16:32:31 -07:00
cma
connector
console
core-api A set of fixes for various warnings, including the one caused by the 2017-07-13 13:44:54 -07:00
cpu-freq
cpuidle
cris
crypto KEYS: Add documentation for asymmetric keyring restrictions 2017-07-14 11:01:38 +10:00
dev-tools linux-kselftest-4.13-rc1-update 2017-07-07 14:04:47 -07:00
device-mapper dm raid: bump target version 2017-07-25 14:54:20 -04:00
devicetree mlx5-shared-2017-08-07 2017-08-07 10:42:09 -07:00
dmaengine
doc-guide
driver-api A set of fixes for various warnings, including the one caused by the 2017-07-13 13:44:54 -07:00
driver-model pci-v4.13-changes 2017-07-08 15:51:57 -07:00
early-userspace
EDID
extcon
fault-injection fault-inject: add /proc/<pid>/fail-nth 2017-07-14 15:05:13 -07:00
fb
features
filesystems Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-15 12:00:42 -07:00
firmware_class
fmc
fpga
frv
gpio
gpu main drm pull for v4.13 2017-07-09 18:48:37 -07:00
hid
hwmon
i2c i2c: i801: Add support for Intel Cannon Lake 2017-06-19 16:17:41 +02:00
ia64
ide
iio
infiniband
input A set of fixes for various warnings, including the one caused by the 2017-07-13 13:44:54 -07:00
ioctl scsi: cxlflash: Introduce host ioctl support 2017-06-26 15:01:11 -04:00
isdn
kbuild Kbuild thin archives updates for v4.13 2017-07-07 15:11:12 -07:00
kdump kexec/kdump: minor Documentation updates for arm64 and Image 2017-07-12 16:26:00 -07:00
kernel-hacking There has been a fair amount of activity in the docs tree this time 2017-07-03 21:13:25 -07:00
laptops
leds
lightnvm
livepatch
locking
m68k
md
media media: svg: avoid too long lines 2017-07-26 05:46:41 -04:00
memory-devices
metag
mic
mips
misc-devices
mmc
mn10300
mtd
namespaces
netlabel
networking bpf: add BPF_J{LT,LE,SLT,SLE} instructions 2017-08-09 16:53:56 -07:00
nfc
nios2
nvdimm
nvmem
parisc
PCI
pcmcia
perf
phy
platform
power PM / runtime: Document new pm_runtime_set_suspended() constraint 2017-07-27 23:57:40 +02:00
powerpc powerpc updates for 4.13 2017-07-07 13:55:45 -07:00
pps
process Kbuild thin archives updates for v4.13 2017-07-07 15:11:12 -07:00
pti
ptp
rapidio
RCU
s390
scheduler
scsi
security KEYS: Add documentation for asymmetric keyring restrictions 2017-07-14 11:01:38 +10:00
serial
sh
sound sound updates for 4.13-rc1 2017-07-06 10:56:51 -07:00
sparc
sphinx Docs: clean up some DocBook loose ends 2017-06-23 14:17:38 -06:00
sphinx-static
spi
sysctl mm: document highmem_is_dirtyable sysctl 2017-07-10 16:32:32 -07:00
target
thermal
timers
trace A few more minor updates: 2017-07-13 13:17:19 -07:00
translations kokr/memory-barriers.txt: Fix obsolete link to atomic_ops.txt 2017-07-12 16:56:40 -06:00
usb usb: gadget: add f_uac1 variant based on a new u_audio api 2017-06-19 09:22:47 +03:00
userspace-api
virtual kvm: x86: hyperv: make VP_INDEX managed by userspace 2017-07-14 16:28:18 +02:00
vm ksm: introduce ksm_max_page_sharing per page deduplication limit 2017-07-06 16:24:31 -07:00
w1
watchdog watchdog: uniphier: add UniPhier watchdog driver 2017-07-03 13:58:55 +02:00
wimax
x86
xtensa of: update ePAPR references to point to Devicetree Specification 2017-06-22 11:22:06 -05:00
.gitignore
00-INDEX linux-kselftest-4.13-rc1-update 2017-07-07 14:04:47 -07:00
bcache.txt bcache.txt: standardize document format 2017-07-14 13:51:27 -06:00
bt8xxgpio.txt bt8xxgpio.txt: standardize document format 2017-07-14 13:51:27 -06:00
btmrvl.txt btmrvl.txt: standardize document format 2017-07-14 13:51:27 -06:00
bus-virt-phys-mapping.txt bus-virt-phys-mapping.txt: standardize document format 2017-07-14 13:51:28 -06:00
cachetlb.txt cachetlb.txt: standardize document format 2017-07-14 13:51:28 -06:00
cgroup-v2.txt cgroup-v2.txt: standardize document format 2017-07-14 13:58:13 -06:00
Changes
circular-buffers.txt circular-buffers.txt: standardize document format 2017-07-14 13:51:29 -06:00
clk.txt clk.txt: standardize document format 2017-07-14 13:51:29 -06:00
CodingStyle
conf.py Docs: Fix breakage with Sphinx 1.5 and upper 2017-06-23 13:45:37 -06:00
cpu-load.txt cpu-load: standardize document format 2017-07-14 13:51:30 -06:00
cputopology.txt cputopology.txt: standardize document format 2017-07-14 13:51:30 -06:00
crc32.txt crc32.txt: standardize document format 2017-07-14 13:51:30 -06:00
dcdbas.txt dcdbas.txt: standardize document format 2017-07-14 13:51:31 -06:00
debugging-modules.txt
debugging-via-ohci1394.txt debugging-via-ohci1394.txt: standardize document format 2017-07-14 13:51:34 -06:00
dell_rbu.txt dell_rbu.txt: standardize document format 2017-07-14 13:58:12 -06:00
digsig.txt digsig.txt: standardize document format 2017-07-14 13:51:31 -06:00
DMA-API-HOWTO.txt DMA-API-HOWTO.txt: standardize document format 2017-07-14 13:51:32 -06:00
DMA-API.txt DMA-API.txt: standardize document format 2017-07-14 13:51:32 -06:00
DMA-attributes.txt DMA-attributes.txt: standardize document format 2017-07-14 13:51:33 -06:00
DMA-ISA-LPC.txt DMA-ISA-LPC.txt: standardize document format 2017-07-14 13:51:33 -06:00
docutils.conf
dontdiff GCC plugin updates: 2017-07-05 11:46:59 -07:00
efi-stub.txt efi-stub.txt: standardize document format 2017-07-14 13:51:34 -06:00
eisa.txt eisa.txt: standardize document format 2017-07-14 13:51:34 -06:00
flexible-arrays.txt flexible-arrays.txt: standardize document format 2017-07-14 13:51:35 -06:00
futex-requeue-pi.txt futex-requeue-pi.txt: standardize document format 2017-07-14 13:51:35 -06:00
gcc-plugins.txt gcc-plugins.txt: standardize document format 2017-07-14 13:51:36 -06:00
highuid.txt highuid.txt: standardize document format 2017-07-14 13:51:36 -06:00
hw_random.txt hw_random.txt: standardize document format 2017-07-14 13:51:37 -06:00
hwspinlock.txt hwspinlock.txt: standardize document format 2017-07-14 13:51:37 -06:00
index.rst Make the main documentation title less Geocities 2017-06-23 14:02:27 -06:00
intel_txt.txt intel_txt.txt: standardize document format 2017-07-14 13:51:38 -06:00
Intel-IOMMU.txt Intel-IOMMU.txt: standardize document format 2017-07-14 13:51:38 -06:00
io_ordering.txt io_ordering.txt: standardize document format 2017-07-14 13:51:39 -06:00
io-mapping.txt io-mapping.txt: standardize document format 2017-07-14 13:51:38 -06:00
iostats.txt iostats.txt: update it to cover recent Kernels 2017-07-14 13:51:40 -06:00
IPMI.txt IPMI.txt: standardize document format 2017-07-14 13:51:40 -06:00
IRQ-affinity.txt IRQ-affinity.txt: standardize document format 2017-07-14 13:51:41 -06:00
IRQ-domain.txt IRQ-domain.txt: standardize document format 2017-07-14 13:51:41 -06:00
IRQ.txt IRQ.txt: add a markup for its title 2017-07-14 13:51:42 -06:00
irqflags-tracing.txt irqflags-tracing.txt: standardize document format 2017-07-14 13:51:42 -06:00
isa.txt isa.txt: standardize document format 2017-07-14 13:51:43 -06:00
isapnp.txt isapnp.txt: promote title level 2017-07-14 13:51:43 -06:00
kernel-doc-nano-HOWTO.txt
kernel-per-CPU-kthreads.txt kernel-per-CPU-kthreads.txt: standardize document format 2017-07-14 13:51:43 -06:00
kobject.txt kobject.txt: standardize document format 2017-07-14 13:51:44 -06:00
kprobes.txt docs: kprobes.txt: Fix whitespacing 2017-07-14 13:58:14 -06:00
kref.txt kref.txt: standardize document format 2017-07-14 13:51:45 -06:00
ldm.txt ldm.txt: standardize document format 2017-07-14 13:51:45 -06:00
lockup-watchdogs.txt lockup-watchdogs.txt: standardize document format 2017-07-14 13:51:46 -06:00
logo.gif
logo.txt
lsm.txt
lzo.txt lzo.txt: standardize document format 2017-07-14 13:51:46 -06:00
mailbox.txt mailbox.txt: standardize document format 2017-07-14 13:51:47 -06:00
Makefile
memory-barriers.txt A set of fixes for various warnings, including the one caused by the 2017-07-13 13:44:54 -07:00
memory-hotplug.txt memory-hotplug.txt: standardize document format 2017-07-14 13:57:53 -06:00
men-chameleon-bus.txt men-chameleon-bus.txt: standardize document format 2017-07-14 13:57:54 -06:00
nommu-mmap.txt nommu-mmap.txt: don't use all upper case on titles 2017-07-14 13:57:55 -06:00
ntb.txt This series converts a number of top-level documents to the RST format 2017-07-15 12:58:58 -07:00
numastat.txt numastat.txt: standardize document format 2017-07-14 13:57:56 -06:00
padata.txt padata.txt: standardize document format 2017-07-14 13:57:56 -06:00
parport-lowlevel.txt parport-lowlevel.txt: standardize document format 2017-07-14 13:57:57 -06:00
percpu-rw-semaphore.txt percpu-rw-semaphore.txt: standardize document format 2017-07-14 13:57:58 -06:00
phy.txt phy.txt: standardize document format 2017-07-14 13:57:58 -06:00
pi-futex.txt pi-futex.txt: standardize document format 2017-07-14 13:57:59 -06:00
pnp.txt pnp.txt: standardize document format 2017-07-14 13:57:59 -06:00
preempt-locking.txt preempt-locking.txt: standardize document format 2017-07-14 13:58:00 -06:00
printk-formats.txt printk-formats.txt: standardize document format 2017-07-14 13:58:00 -06:00
pwm.txt pwm: Standardize document format 2017-07-06 08:23:30 +02:00
rbtree.txt rbtree.txt: standardize document format 2017-07-14 13:58:01 -06:00
remoteproc.txt remoteproc.txt: standardize document format 2017-07-14 13:58:02 -06:00
rfkill.txt rfkill.txt: standardize document format 2017-07-14 13:58:02 -06:00
robust-futex-ABI.txt robust-futex-ABI.txt: standardize document format 2017-07-14 13:58:03 -06:00
robust-futexes.txt robust-futexes.txt: standardize document format 2017-07-14 13:58:03 -06:00
rpmsg.txt rpmsg.txt: standardize document format 2017-07-14 13:58:04 -06:00
rtc.txt rtc: add generic nvmem support 2017-07-07 13:14:14 +02:00
SAK.txt SAK.txt: standardize document format 2017-07-14 13:58:04 -06:00
sgi-ioc4.txt sgi-ioc4.txt: standardize document format 2017-07-14 13:58:05 -06:00
siphash.txt siphash.txt: standardize document format 2017-07-14 13:58:06 -06:00
SM501.txt SM501.txt: standardize document format 2017-07-14 13:58:06 -06:00
smsc_ece1099.txt smsc_ece1099.txt: standardize document format 2017-07-14 13:58:07 -06:00
static-keys.txt static-keys.txt: standardize document format 2017-07-14 13:58:07 -06:00
SubmittingPatches
svga.txt svga.txt: standardize document format 2017-07-14 13:58:08 -06:00
switchtec.txt
sync_file.txt
tee.txt tee.txt: standardize document format 2017-07-14 13:58:14 -06:00
this_cpu_ops.txt this_cpu_ops.txt: standardize document format 2017-07-14 13:58:08 -06:00
unaligned-memory-access.txt unaligned-memory-access.txt: standardize document format 2017-07-14 13:58:09 -06:00
vfio-mediated-device.txt vfio-mediated-device.txt: standardize document format 2017-07-14 13:58:10 -06:00
vfio.txt vfio.txt: standardize document format 2017-07-14 13:58:10 -06:00
video-output.txt
xillybus.txt xillybus.txt: standardize document format 2017-07-14 13:58:11 -06:00
xz.txt xz.txt: standardize document format 2017-07-14 13:58:11 -06:00
zorro.txt zorro.txt: standardize document format 2017-07-14 13:58:12 -06:00