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authorJohannes Berg <johannes.berg@intel.com>2020-02-13 16:26:49 +0300
committerRichard Weinberger <richard@nod.at>2020-03-30 00:29:56 +0300
commit5bef0a153bf29150357ff60283315a933f05c994 (patch)
tree8a86ee3144cb1c67c3963a8bc5a1aba6cb220d21 /arch/x86/um
parent0bc8fb4dda2b461491ec567b2333d13897780d8c (diff)
downloadlinux-5bef0a153bf29150357ff60283315a933f05c994.tar.xz
um: Implement cpu_relax() as ndelay(1) for time-travel
In time-travel mode, cpu_relax() currently does actual CPU relax, but that doesn't affect the simulation. Ideally, we wouldn't run anything that uses it in simulation, but if we actually have virtio devices combined with the same simulation it's possible. Implement cpu_relax() as ndelay(1) in this case, using time_travel_ndelay(1) directly to catch errors if this is used erroneously in builds that don't set CONFIG_UML_TIME_TRAVEL_SUPPORT. While at it, convert it to an __always_inline and also add that to rep_nop() like the original does now. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/x86/um')
-rw-r--r--arch/x86/um/asm/processor.h12
1 files changed, 10 insertions, 2 deletions
diff --git a/arch/x86/um/asm/processor.h b/arch/x86/um/asm/processor.h
index 593d5f3902bd..478710384b34 100644
--- a/arch/x86/um/asm/processor.h
+++ b/arch/x86/um/asm/processor.h
@@ -1,6 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __UM_PROCESSOR_H
#define __UM_PROCESSOR_H
+#include <linux/time-internal.h>
/* include faultinfo structure */
#include <sysdep/faultinfo.h>
@@ -21,12 +22,19 @@
#include <asm/user.h>
/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
-static inline void rep_nop(void)
+static __always_inline void rep_nop(void)
{
__asm__ __volatile__("rep;nop": : :"memory");
}
-#define cpu_relax() rep_nop()
+static __always_inline void cpu_relax(void)
+{
+ if (time_travel_mode == TT_MODE_INFCPU ||
+ time_travel_mode == TT_MODE_EXTERNAL)
+ time_travel_ndelay(1);
+ else
+ rep_nop();
+}
#define task_pt_regs(t) (&(t)->thread.regs)