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authorLinus Torvalds <torvalds@linux-foundation.org>2020-12-14 17:13:53 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-12-14 17:13:53 -0800
commit1ac0884d5474fea8dc6ceabbd0e870d1bf4b7b42 (patch)
tree5158d582c0f5040a9c8a28fe9051881c5ec7b5eb /arch/Kconfig
parentff6135959a9150ad45cb92ca38da270903a74343 (diff)
parentc6156e1da633f241e132eaea3b676d674376d770 (diff)
Merge tag 'core-entry-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core entry/exit updates from Thomas Gleixner: "A set of updates for entry/exit handling: - More generalization of entry/exit functionality - The consolidation work to reclaim TIF flags on x86 and also for non-x86 specific TIF flags which are solely relevant for syscall related work and have been moved into their own storage space. The x86 specific part had to be merged in to avoid a major conflict. - The TIF_NOTIFY_SIGNAL work which replaces the inefficient signal delivery mode of task work and results in an impressive performance improvement for io_uring. The non-x86 consolidation of this is going to come seperate via Jens. - The selective syscall redirection facility which provides a clean and efficient way to support the non-Linux syscalls of WINE by catching them at syscall entry and redirecting them to the user space emulation. This can be utilized for other purposes as well and has been designed carefully to avoid overhead for the regular fastpath. This includes the core changes and the x86 support code. - Simplification of the context tracking entry/exit handling for the users of the generic entry code which guarantee the proper ordering and protection. - Preparatory changes to make the generic entry code accomodate S390 specific requirements which are mostly related to their syscall restart mechanism" * tag 'core-entry-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits) entry: Add syscall_exit_to_user_mode_work() entry: Add exit_to_user_mode() wrapper entry_Add_enter_from_user_mode_wrapper entry: Rename exit_to_user_mode() entry: Rename enter_from_user_mode() docs: Document Syscall User Dispatch selftests: Add benchmark for syscall user dispatch selftests: Add kselftest for syscall user dispatch entry: Support Syscall User Dispatch on common syscall entry kernel: Implement selective syscall userspace redirection signal: Expose SYS_USER_DISPATCH si_code type x86: vdso: Expose sigreturn address on vdso to the kernel MAINTAINERS: Add entry for common entry code entry: Fix boot for !CONFIG_GENERIC_ENTRY x86: Support HAVE_CONTEXT_TRACKING_OFFSTACK context_tracking: Only define schedule_user() on !HAVE_CONTEXT_TRACKING_OFFSTACK archs sched: Detect call to schedule from critical entry code context_tracking: Don't implement exception_enter/exit() on CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK context_tracking: Introduce HAVE_CONTEXT_TRACKING_OFFSTACK x86: Reclaim unused x86 TI flags ...
Diffstat (limited to 'arch/Kconfig')
-rw-r--r--arch/Kconfig17
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index ba4e966484ab..7a3371d28508 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -618,6 +618,23 @@ config HAVE_CONTEXT_TRACKING
protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
handling on irq exit still need to be protected.
+config HAVE_CONTEXT_TRACKING_OFFSTACK
+ bool
+ help
+ Architecture neither relies on exception_enter()/exception_exit()
+ nor on schedule_user(). Also preempt_schedule_notrace() and
+ preempt_schedule_irq() can't be called in a preemptible section
+ while context tracking is CONTEXT_USER. This feature reflects a sane
+ entry implementation where the following requirements are met on
+ critical entry code, ie: before user_exit() or after user_enter():
+
+ - Critical entry code isn't preemptible (or better yet:
+ not interruptible).
+ - No use of RCU read side critical sections, unless rcu_nmi_enter()
+ got called.
+ - No use of instrumentation, unless instrumentation_begin() got
+ called.
+
config HAVE_TIF_NOHZ
bool
help