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Ilya Leoshkevich f1d5df84cd s390/bpf: Implement bpf_arch_text_poke()
bpf_arch_text_poke() is used to hotpatch eBPF programs and trampolines.
s390x has a very strict hotpatching restriction: the only thing that is
allowed to be hotpatched is conditional branch mask.

Take the same approach as commit de5012b41e ("s390/ftrace: implement
hotpatching"): create a conditional jump to a "plt", which loads the
target address from memory and jumps to it; then first patch this
address, and then the mask.

Trampolines (introduced in the next patch) respect the ftrace calling
convention: the return address is in %r0, and %r1 is clobbered. With
that in mind, bpf_arch_text_poke() does not differentiate between jumps
and calls.

However, there is a simple optimization for jumps (for the epilogue_ip
case): if a jump already points to the destination, then there is no
"plt" and we can just flip the mask.

For simplicity, the "plt" template is defined in assembly, and its size
is used to define C arrays. There doesn't seem to be a way to convey
this size to C as a constant, so it's hardcoded and double-checked
during runtime.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20230129190501.1624747-4-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-29 19:16:28 -08:00
arch s390/bpf: Implement bpf_arch_text_poke() 2023-01-29 19:16:28 -08:00
block block-6.2-2023-01-20 2023-01-20 12:44:41 -08:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto wifi: cfg80211: Deduplicate certificate loading 2023-01-19 14:46:45 +01:00
Documentation Documentation: bpf: correct spelling 2023-01-28 12:22:20 -08:00
drivers bpf-next-for-netdev 2023-01-28 00:00:14 -08:00
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-01-27 22:56:18 -08:00
include bpf: btf: Add BTF_FMODEL_SIGNED_ARG flag 2023-01-28 12:45:15 -08:00
init bpf-next-for-netdev 2023-01-28 00:00:14 -08:00
io_uring io_uring/poll: don't reissue in case of poll race on multishot request 2023-01-20 15:11:54 -07:00
ipc Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
kernel bpf: btf: Add BTF_FMODEL_SIGNED_ARG flag 2023-01-28 12:45:15 -08:00
lib bpf-next-for-netdev 2023-01-28 00:00:14 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm slab fixes for 6.2-rc5 2023-01-19 12:24:39 -08:00
net selftests/bpf: Add a sign-extension test for kfuncs 2023-01-28 12:30:09 -08:00
rust rust: print: avoid evaluating arguments in pr_* macros in unsafe blocks 2023-01-16 00:54:35 +01:00
samples samples/bpf: change _kern suffix to .bpf with BPF test programs 2023-01-15 13:32:45 -08:00
scripts bpf-next-for-netdev 2023-01-28 00:00:14 -08:00
security tomoyo: Update website link 2023-01-13 23:11:38 +09:00
sound treewide: fix up files incorrectly marked executable 2023-01-26 10:05:39 -08:00
tools selftests/bpf: Fix sk_assign on s390x 2023-01-29 19:16:28 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt VFIO fixes for v6.2-rc6 2023-01-23 11:56:07 -08:00
.clang-format iommufd for 6.2 2022-12-14 09:15:43 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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 .gitignore: ignore *.rpm 2022-12-30 17:22:14 +09:00
.mailmap 21 hotfixes. Thirteen of these address pre-6.1 issues and hence have 2023-01-16 16:36:39 -08:00
.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 MAINTAINERS: Update MPTCP maintainer list and CREDITS 2023-01-23 21:42:13 -08:00
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 2023-01-27 22:56:18 -08:00
Makefile Linux 6.2-rc5 2023-01-21 16:27:01 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
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.