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Will Deacon c83557859e arm64: kpti: Fix "kpti=off" when KASLR is enabled 
Enabling KASLR forces the use of non-global page-table entries for kernel
mappings, as this is a decision that we have to make very early on before
mapping the kernel proper. When used in conjunction with the "kpti=off"
command-line option, it is possible to use non-global kernel mappings but
with the kpti trampoline disabled.

Since commit 09e3c22a86 ("arm64: Use a variable to store non-global
mappings decision"), arm64_kernel_unmapped_at_el0() reflects only the use of
non-global mappings and does not take into account whether the kpti
trampoline is enabled. This breaks context switching of the TPIDRRO_EL0
register for 64-bit tasks, where the clearing of the register is deferred to
the ret-to-user code, but it also breaks the ARM SPE PMU driver which
helpfully recommends passing "kpti=off" on the command line!

Report whether or not KPTI is actually enabled in
arm64_kernel_unmapped_at_el0() and check the 'arm64_use_ng_mappings' global
variable directly when determining the protection flags for kernel mappings.

Cc: Mark Brown <broonie@kernel.org>
Reported-by: Hongbo Yao <yaohongbo@huawei.com>
Tested-by: Hongbo Yao <yaohongbo@huawei.com>
Fixes: 09e3c22a86 ("arm64: Use a variable to store non-global mappings decision")
Signed-off-by: Will Deacon <will@kernel.org>
2020-03-19 08:28:43 +00:00
arch arm64: kpti: Fix "kpti=off" when KASLR is enabled 2020-03-19 08:28:43 +00:00
block block-5.6-2020-02-05 2020-02-06 06:15:23 +00:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto treewide: remove redundant IS_ERR() before error code check 2020-02-04 03:05:27 +00:00
Documentation mm: Avoid creating virtual address aliases in brk()/mmap()/mremap() 2020-02-20 10:03:14 +00:00
drivers drivers/perf: arm_pmu_acpi: Fix incorrect checking of gicc pointer 2020-03-02 12:07:35 +00:00
fs Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
include fs: New zonefs file system 2020-02-09 15:51:46 -08:00
init Tracing updates: 2020-02-06 07:12:11 +00:00
ipc proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
kernel Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
lib Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm: Avoid creating virtual address aliases in brk()/mmap()/mremap() 2020-02-20 10:03:14 +00:00
net Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
samples Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
scripts Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
security Merge branch 'merge.nfs-fs_parse.1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-02-08 13:26:41 -08:00
sound sound fixes for 5.6-rc1 2020-02-06 14:15:01 +00:00
tools A set of fixes and improvements for the perf subsystem: 2020-02-09 12:04:09 -08:00
usr Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
virt KVM: fix overflow of zero page refcount with ksm running 2020-02-05 15:27:46 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +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 modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap A handful of small documentation fixes that wandered in. 2020-02-07 13:03:10 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS open: introduce openat2(2) syscall 2020-01-18 09:19:18 -05:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS fs: New zonefs file system 2020-02-09 15:51:46 -08:00
Makefile Linux 5.6-rc1 2020-02-09 16:08:48 -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.