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Heiko Carstens 484a8ed8b7 s390/extable: add dedicated uaccess handler 
This is more or less a combination of commit 2e77a62cb3 ("arm64:
extable: add a dedicated uaccess handler") and commit 4b5305decc
("x86/extable: Extend extable functionality").

To describe the problem that needs to solved let's cite the full arm64
commit message:

------
For inline assembly, we place exception fixups out-of-line in the
`.fixup` section such that these are out of the way of the fast path.
This has a few drawbacks:

* Since the fixup code is anonymous, backtraces will symbolize fixups
  as offsets from the nearest prior symbol, currently
  `__entry_tramp_text_end`. This is confusing, and painful to debug
  without access to the relevant vmlinux.

* Since the exception handler adjusts the PC to execute the fixup, and
  the fixup uses a direct branch back into the function it fixes,
  backtraces of fixups miss the original function. This is confusing,
  and violates requirements for RELIABLE_STACKTRACE (and therefore
  LIVEPATCH).

* Inline assembly and associated fixups are generated from templates,
  and we have many copies of logically identical fixups which only
  differ in which specific registers are written to and which address
  is branched to at the end of the fixup. This is potentially wasteful
  of I-cache resources, and makes it hard to add additional logic to
  fixups without significant bloat.

This patch address all three concerns for inline uaccess fixups by
adding a dedicated exception handler which updates registers in
exception context and subsequent returns back into the function which
faulted, removing the need for fixups specialized to each faulting
instruction.

Other than backtracing, there should be no functional change as a result
of this patch.
------

Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2022-03-08 00:33:00 +01:00
arch s390/extable: add dedicated uaccess handler 2022-03-08 00:33:00 +01:00
block block: bio-integrity: Advance seed correctly for larger interval sizes 2022-02-03 21:09:24 -07:00
certs certs: Fix build error when CONFIG_MODULE_SIG_KEY is empty 2022-01-23 00:08:44 +09:00
crypto lib/crypto: blake2s: avoid indirect calls to compression function for Clang CFI 2022-02-04 19:22:32 +01:00
Documentation xen: branch for v5.17-rc3 2022-02-05 10:40:17 -08:00
drivers s390/extable: move EX_TABLE define to asm-extable.h 2022-03-08 00:33:00 +01:00
fs Various bug fixes for ext4 fast commit and inline data handling. Also 2022-02-06 10:34:45 -08:00
include Various bug fixes for ext4 fast commit and inline data handling. Also 2022-02-06 10:34:45 -08:00
init lib/stackdepot: allow optional init and stack_table allocation by kvmalloc() 2022-01-22 08:33:37 +02:00
ipc ipc/sem: do not sleep with a spin lock held 2022-02-04 09:25:05 -08:00
kernel perf/urgent contains 3 fixups: 2022-02-06 10:11:14 -08:00
lib lib/crypto: blake2s: avoid indirect calls to compression function for Clang CFI 2022-02-04 19:22:32 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm/kmemleak: avoid scanning potential huge holes 2022-02-04 09:25:05 -08:00
net A patch to make it possible to disable zero copy path in the messenger 2022-02-04 09:54:02 -08:00
samples Merge branch 'akpm' (patches from Andrew) 2022-01-20 10:41:01 +02:00
scripts s390/extable: convert to relative table with data 2022-03-08 00:33:00 +01:00
security selinux/stable-5.17 PR 20220203 2022-02-03 16:44:12 -08:00
sound ASoC: Fixes for v5.17 2022-02-01 16:52:54 +01:00
tools s390: remove invalid email address of Heiko Carstens 2022-02-06 23:31:29 +01:00
usr kbuild: remove include/linux/cyclades.h from header file check 2022-01-27 08:51:08 +01:00
virt Two larger x86 series: 2022-01-28 19:00:26 +02:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update Christian Brauner's email address 2022-02-01 11:21:31 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Removing Ohad from remoteproc/rpmsg maintenance 2021-12-08 10:09:40 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge branch 'fixes' into features 2022-03-01 21:02:48 +01:00
Makefile Linux 5.17-rc3 2022-02-06 12:20:50 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.