No description
Find a file
Peter Zijlstra 2ea1a37d01 sched/x86: Save [ER]FLAGS on context switch
commit 6690e86be8 upstream.

Effectively reverts commit:

  2c7577a758 ("sched/x86_64: Don't save flags on context switch")

Specifically because SMAP uses FLAGS.AC which invalidates the claim
that the kernel has clean flags.

In particular; while preemption from interrupt return is fine (the
IRET frame on the exception stack contains FLAGS) it breaks any code
that does synchonous scheduling, including preempt_enable().

This has become a significant issue ever since commit:

  5b24a7a2aa ("Add 'unsafe' user access functions for batched accesses")

provided for means of having 'normal' C code between STAC / CLAC,
exposing the FLAGS.AC state. So far this hasn't led to trouble,
however fix it before it comes apart.

Reported-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org
Fixes: 5b24a7a2aa ("Add 'unsafe' user access functions for batched accesses")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-22 07:37:36 +02:00
arch sched/x86: Save [ER]FLAGS on context switch 2019-05-22 07:37:36 +02:00
block bfq: update internal depth state when queue depth changes 2019-05-16 19:41:17 +02:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: x86/poly1305 - fix overflow during partial reduction 2019-04-27 09:36:37 +02:00
Documentation x86/speculation/mds: Improve CPU buffer clear documentation 2019-05-22 07:37:35 +02:00
drivers power: supply: axp288_fuel_gauge: Add ACEPC T8 and T11 mini PCs to the blacklist 2019-05-22 07:37:35 +02:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs afs: Unlock pages for __pagevec_release() 2019-05-16 19:41:21 +02:00
include nfc: nci: Potential off by one in ->pipes[] array 2019-05-16 19:41:27 +02:00
init init: initialize jump labels before command line option parsing 2019-05-16 19:41:23 +02:00
ipc ipc/shm.c: use ERR_CAST() for shm_lock() error return 2018-10-05 16:32:04 -07:00
kernel locking/rwsem: Prevent decrement of reader count before increment 2019-05-22 07:37:34 +02:00
lib ubsan: Fix nasty -Wbuiltin-declaration-mismatch GCC-9 warnings 2019-05-10 17:54:04 +02:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/memory.c: fix modifying of page protection by insert_pfn() 2019-05-16 19:41:26 +02:00
net tipc: fix hanging clients using poll with EPOLLOUT flag 2019-05-16 19:41:31 +02:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-02-15 08:10:11 +01:00
scripts fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock 2019-05-08 07:21:51 +02:00
security selinux: do not report error on connect(AF_UNSPEC) 2019-05-16 19:41:30 +02:00
sound x86/cpu: Sanitize FAM6_ATOM naming 2019-05-14 19:17:53 +02:00
tools objtool: Fix function fallthrough detection 2019-05-22 07:37:35 +02:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: fix spectrev1 gadgets 2019-05-16 19:41:22 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS platform/x86: Add Intel AtomISP2 dummy / power-management driver 2019-04-20 09:16:02 +02:00
Makefile Linux 4.19.44 2019-05-16 19:41:32 +02:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.