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Mark Brown ded16152d2 arm64/bti: Disable in kernel BTI when cross section thunks are broken
commit c0a454b904 upstream.

GCC does not insert a `bti c` instruction at the beginning of a function
when it believes that all callers reach the function through a direct
branch[1]. Unfortunately the logic it uses to determine this is not
sufficiently robust, for example not taking account of functions being
placed in different sections which may be loaded separately, so we may
still see thunks being generated to these functions. If that happens,
the first instruction in the callee function will result in a Branch
Target Exception due to the missing landing pad.

While this has currently only been observed in the case of modules
having their main code loaded sufficiently far from their init section
to require thunks it could potentially happen for other cases so the
safest thing is to disable BTI for the kernel when building with an
affected toolchain.

[1]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106671

Reported-by: D Scott Phillips <scott@os.amperecomputing.com>
[Bits of the commit message are lifted from his report & workaround]
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220905142255.591990-1-broonie@kernel.org
Cc: <stable@vger.kernel.org> # v5.10+
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2022-09-15 10:47:20 +02:00
arch arm64/bti: Disable in kernel BTI when cross section thunks are broken 2022-09-15 10:47:20 +02:00
block block: don't add partitions if GD_SUPPRESS_PART_SCAN is set 2022-09-15 10:47:15 +02:00
certs certs: make system keyring depend on x509 parser 2022-07-24 12:53:55 -07:00
crypto KEYS: asymmetric: enforce SM2 signature use pkey algo 2022-08-17 15:16:17 +02:00
Documentation hwmon: (asus-ec-sensors) add definitions for ROG ZENITH II EXTREME 2022-09-15 10:47:20 +02:00
drivers hwmon: (asus-ec-sensors) autoload module via DMI data 2022-09-15 10:47:20 +02:00
fs btrfs: fix the max chunk size and stripe length calculation 2022-09-15 10:47:16 +02:00
include iommu/vt-d: Fix possible recursive locking in intel_iommu_init() 2022-09-15 10:47:19 +02:00
init arm64: fix rodata=full 2022-08-31 17:18:19 +02:00
io_uring lsm,io_uring: add LSM hooks for the new uring_cmd file op 2022-09-15 10:47:18 +02:00
ipc ipc: Free mq_sysctls if ipc namespace creation failed 2022-06-22 17:47:41 -05:00
kernel swiotlb: avoid potential left shift overflow 2022-09-15 10:47:18 +02:00
lib crypto: lib - remove unneeded selection of XOR_BLOCKS 2022-09-05 10:31:26 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm Revert "mm: kmemleak: take a full lowmem check in kmemleak_*_phys()" 2022-09-15 10:47:07 +02:00
net time64.h: consolidate uses of PSEC_PER_NSEC 2022-09-15 10:47:19 +02:00
samples sample: bpf: xdp_router_ipv4: Allow the kernel to send arp requests 2022-08-17 15:14:25 +02:00
scripts kbuild: dummy-tools: avoid tmpdir leak in dummy gcc 2022-08-29 11:07:58 +02:00
security Smack: Provide read control for io_uring_cmd 2022-09-15 10:47:18 +02:00
sound ASoC: mchp-spdiftx: Fix clang -Wbitfield-constant-conversion 2022-09-15 10:47:18 +02:00
tools perf stat: Fix L2 Topdown metrics disappear for raw events 2022-09-15 10:47:19 +02:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt KVM: Unconditionally get a ref to /dev/kvm module when creating a VM 2022-08-25 11:45:05 +02:00
.clang-format clang-format: Fix space after for_each macros 2022-05-20 19:27:16 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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 kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap ARM: SoC fixes for 5.19, part 4 2022-07-27 09:43:07 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: mark ARM/PALM TREO SUPPORT orphan 2022-07-07 15:17:00 +02:00
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 io_uring: move to separate directory 2022-08-17 15:14:20 +02:00
Makefile kbuild: disable header exports for UML in a straightforward way 2022-09-15 10:47:18 +02:00
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.