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Andrii Nakryiko 7a830b53c1 bpf: aggressively forget precise markings during state checkpointing
Exploit the property of about-to-be-checkpointed state to be able to
forget all precise markings up to that point even more aggressively. We
now clear all potentially inherited precise markings right before
checkpointing and branching off into child state. If any of children
states require precise knowledge of any SCALAR register, those will be
propagated backwards later on before this state is finalized, preserving
correctness.

There is a single selftests BPF program change, but tremendous one: 25x
reduction in number of verified instructions and states in
trace_virtqueue_add_sgs.

Cilium results are more modest, but happen across wider range of programs.

SELFTESTS RESULTS
=================

$ ./veristat -C -e file,prog,insns,states ~/imprecise-early-results.csv ~/imprecise-aggressive-results.csv | grep -v '+0'
File                 Program                  Total insns (A)  Total insns (B)  Total insns (DIFF)  Total states (A)  Total states (B)  Total states (DIFF)
-------------------  -----------------------  ---------------  ---------------  ------------------  ----------------  ----------------  -------------------
loop6.bpf.linked1.o  trace_virtqueue_add_sgs           398057            15114   -382943 (-96.20%)              8717               336      -8381 (-96.15%)
-------------------  -----------------------  ---------------  ---------------  ------------------  ----------------  ----------------  -------------------

CILIUM RESULTS
==============

$ ./veristat -C -e file,prog,insns,states ~/imprecise-early-results-cilium.csv ~/imprecise-aggressive-results-cilium.csv | grep -v '+0'
File           Program                           Total insns (A)  Total insns (B)  Total insns (DIFF)  Total states (A)  Total states (B)  Total states (DIFF)
-------------  --------------------------------  ---------------  ---------------  ------------------  ----------------  ----------------  -------------------
bpf_host.o     tail_handle_nat_fwd_ipv4                    23426            23221       -205 (-0.88%)              1537              1515         -22 (-1.43%)
bpf_host.o     tail_handle_nat_fwd_ipv6                    13009            12904       -105 (-0.81%)               719               708         -11 (-1.53%)
bpf_host.o     tail_nodeport_nat_ingress_ipv6               5261             5196        -65 (-1.24%)               247               243          -4 (-1.62%)
bpf_host.o     tail_nodeport_nat_ipv6_egress                3446             3406        -40 (-1.16%)               203               198          -5 (-2.46%)
bpf_lxc.o      tail_handle_nat_fwd_ipv4                    23426            23221       -205 (-0.88%)              1537              1515         -22 (-1.43%)
bpf_lxc.o      tail_handle_nat_fwd_ipv6                    13009            12904       -105 (-0.81%)               719               708         -11 (-1.53%)
bpf_lxc.o      tail_ipv4_ct_egress                          5074             4897       -177 (-3.49%)               255               248          -7 (-2.75%)
bpf_lxc.o      tail_ipv4_ct_ingress                         5100             4923       -177 (-3.47%)               255               248          -7 (-2.75%)
bpf_lxc.o      tail_ipv4_ct_ingress_policy_only             5100             4923       -177 (-3.47%)               255               248          -7 (-2.75%)
bpf_lxc.o      tail_ipv6_ct_egress                          4558             4536        -22 (-0.48%)               188               187          -1 (-0.53%)
bpf_lxc.o      tail_ipv6_ct_ingress                         4578             4556        -22 (-0.48%)               188               187          -1 (-0.53%)
bpf_lxc.o      tail_ipv6_ct_ingress_policy_only             4578             4556        -22 (-0.48%)               188               187          -1 (-0.53%)
bpf_lxc.o      tail_nodeport_nat_ingress_ipv6               5261             5196        -65 (-1.24%)               247               243          -4 (-1.62%)
bpf_overlay.o  tail_nodeport_nat_ingress_ipv6               5261             5196        -65 (-1.24%)               247               243          -4 (-1.62%)
bpf_overlay.o  tail_nodeport_nat_ipv6_egress                3482             3442        -40 (-1.15%)               204               201          -3 (-1.47%)
bpf_xdp.o      tail_nodeport_nat_egress_ipv4               17200            15619      -1581 (-9.19%)              1111              1010        -101 (-9.09%)
-------------  --------------------------------  ---------------  ---------------  ------------------  ----------------  ----------------  -------------------

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20221104163649.121784-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-11-04 11:51:45 -07:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-11-03 13:21:54 -07:00
block block-6.1-2022-10-28 2022-10-29 18:06:52 -07:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto treewide: use get_random_bytes() when possible 2022-10-11 17:42:58 -06:00
Documentation bpf: Document UAPI details for special BPF types 2022-11-03 19:31:13 -07:00
drivers Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-11-03 13:21:54 -07:00
fs NFS Client Bugfixes for Linux 6.1-rc 2022-11-02 11:18:13 -07:00
include bpf: Refactor map->off_arr handling 2022-11-03 23:09:40 -07:00
init init: Kconfig: fix spelling mistake "satify" -> "satisfy" 2022-10-20 21:27:22 -07:00
io_uring io_uring: unlock if __io_run_local_work locked inside 2022-10-27 09:52:12 -06:00
ipc ipc/msg.c: fix percpu_counter use after free 2022-10-28 13:37:22 -07:00
kernel bpf: aggressively forget precise markings during state checkpointing 2022-11-04 11:51:45 -07:00
lib Networking fixes for 6.1-rc4, including fixes from bluetooth and 2022-11-03 10:51:59 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mmap: fix remap_file_pages() regression 2022-10-28 13:37:23 -07:00
net bpf: Consolidate spin_lock, timer management into btf_record 2022-11-03 22:19:40 -07:00
rust Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
samples samples/bpf: Fix typo in README 2022-11-01 15:25:21 +01:00
scripts bpf-next-for-netdev 2022-11-02 08:18:27 -07:00
security lsm/stable-6.1 PR 20221031 2022-10-31 12:09:42 -07:00
sound ALSA: aoa: Fix I2S device accounting 2022-10-27 08:53:08 +02:00
tools selftests/bpf: support stat filtering in comparison mode in veristat 2022-11-03 21:54:14 -07:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Reject attempts to consume or refresh inactive gfn_to_pfn_cache 2022-10-27 06:48:18 -04:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap mailmap: update email for Qais Yousef 2022-10-20 21:27:21 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-11-03 13:21:54 -07:00
Makefile Linux 6.1-rc3 2022-10-30 15:19:28 -07:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.