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Mostafa Saleh dcf89d1111 KVM: arm64: Add missing BTI instructions 
Some bti instructions were missing from
commit b53d4a2723 ("KVM: arm64: Use BTI for nvhe")

1) kvm_host_psci_cpu_entry
kvm_host_psci_cpu_entry is called from __kvm_hyp_init_cpu through "br"
instruction as __kvm_hyp_init_cpu resides in idmap section while
kvm_host_psci_cpu_entry is in hyp .text so the offset is larger than
128MB range covered by "b".
Which means that this function should start with "bti j" instruction.

LLVM which is the only compiler supporting BTI for Linux, adds "bti j"
for jump tables or by when taking the address of the block [1].
Same behaviour is observed with GCC.

As kvm_host_psci_cpu_entry is a C function, this must be done in
assembly.

Another solution is to use X16/X17 with "br", as according to ARM
ARM DDI0487I.a RLJHCL/IGMGRS, PACIASP has an implicit branch
target identification instruction that is compatible with
PSTATE.BTYPE 0b01 which includes "br X16/X17"
And the kvm_host_psci_cpu_entry has PACIASP as it is an external
function.
Although, using explicit "bti" makes it more clear than relying on
which register is used.

A third solution is to clear SCTLR_EL2.BT, which would make PACIASP
compatible PSTATE.BTYPE 0b11 ("br" to other registers).
However this deviates from the kernel behaviour (in bti_enable()).

2) Spectre vector table
"br" instructions are generated at runtime for the vector table
(__bp_harden_hyp_vecs).
These branches would land on vectors in __kvm_hyp_vector at offset 8.
As all the macros are defined with valid_vect/invalid_vect, it is
sufficient to add "bti j" at the correct offset.

[1] https://reviews.llvm.org/D52867

Fixes: b53d4a2723 ("KVM: arm64: Use BTI for nvhe")
Signed-off-by: Mostafa Saleh <smostafa@google.com>
Reported-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20230706152240.685684-1-smostafa@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
 		2023-07-12 22:15:36 +00:00
Documentation Fixes for pci_clean_master, error handling in driver inits, and various 2023-07-09 09:35:51 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
arch KVM: arm64: Add missing BTI instructions 2023-07-12 22:15:36 +00:00
block block-6.5-2023-07-03 2023-07-03 18:48:38 -07:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto This update includes the following changes: 2023-06-30 21:27:13 -07:00
drivers Fixes for pci_clean_master, error handling in driver inits, and various 2023-07-09 09:35:51 -07:00
fs Minor cleanups for 6.5: 2023-07-09 09:50:42 -07:00
include 16 hotfixes. Six are cc:stable and the remainder address post-6.4 issues. 2023-07-08 14:30:25 -07:00
init Kbuild updates for v6.5 2023-07-01 09:24:31 -07:00
io_uring io_uring-6.5-2023-07-03 2023-07-03 18:43:10 -07:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel dma-mapping fixes for Linux 6.5 2023-07-09 10:24:22 -07:00
lib 16 hotfixes. Six are cc:stable and the remainder address post-6.4 issues. 2023-07-08 14:30:25 -07:00
mm mm: lock newly mapped VMA with corrected ordering 2023-07-08 16:44:11 -07:00
net Including fixes from bluetooth, bpf and wireguard. 2023-07-05 15:44:45 -07:00
rust rust: error: `impl Debug` for `Error` with `errname()` integration 2023-06-13 01:24:42 +02:00
samples Including fixes from bluetooth, bpf and wireguard. 2023-07-05 15:44:45 -07:00
scripts A half-dozen late arriving docs patches. They are mostly fixes, but we 2023-07-06 22:15:38 -07:00
security + Bug Fixes 2023-07-07 09:55:31 -07:00
sound sound fixes for 6.5-rc1 2023-07-07 15:40:17 -07:00
tools perf tools changes and fixes for v6.5: 2nd batch 2023-07-08 10:21:51 -07:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM64: 2023-07-03 15:32:22 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
…
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Revert ".gitignore: ignore *.cover and *.mbx" 2023-07-04 15:05:12 -07:00
.mailmap 16 hotfixes. Six are cc:stable and the remainder address post-6.4 issues. 2023-07-08 14:30:25 -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 - Address -Wmissing-prototype warnings 2023-06-26 16:43:54 -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 MAINTAINERS 2: Electric Boogaloo 2023-07-09 10:29:53 -07:00
Makefile Linux 6.5-rc1 2023-07-09 13:53:13 -07:00
README
…

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.