[tip: core/entry] x86: Support HAVE_CONTEXT_TRACKING_OFFSTACK

[tip-bot2 for Frederic Weisbecker]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     d1f250e2205eca9f1264f8e2d3a41fcf38f92d91
Gitweb:        https://git.kernel.org/tip/d1f250e2205eca9f1264f8e2d3a41fcf38f92d91
Author:        Frederic Weisbecker <frederic@xxxxxxxxxx>
AuthorDate:    Tue, 17 Nov 2020 16:16:37 +01:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Thu, 19 Nov 2020 11:25:42 +01:00

x86: Support HAVE_CONTEXT_TRACKING_OFFSTACK

A lot of ground work has been performed on x86 entry code. Fragile path
between user_enter() and user_exit() have IRQs disabled. Uses of RCU and
intrumentation in these fragile areas have been explicitly annotated
and protected.

This architecture doesn't need exception_enter()/exception_exit()
anymore and has therefore earned CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK.

Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20201117151637.259084-6-frederic@xxxxxxxxxx
---
 arch/x86/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f6946b8..d793361 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -162,6 +162,7 @@ config X86
 	select HAVE_CMPXCHG_DOUBLE
 	select HAVE_CMPXCHG_LOCAL
 	select HAVE_CONTEXT_TRACKING		if X86_64
+	select HAVE_CONTEXT_TRACKING_OFFSTACK	if HAVE_CONTEXT_TRACKING
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_CONTIGUOUS