context_tracking: Generalize context tracking APIs to support user and guest
Generalize the context tracking APIs to support various nature of
contexts. This is performed by splitting out the mechanism from
context_tracking_user_enter and context_tracking_user_exit into
context_tracking_enter and context_tracking_exit.
The nature of the context we track is now detailed in a ctx_state
parameter pushed to these APIs, allowing the same functions to not just
track kernel <> user space switching, but also kernel <> guest transitions.
But leave the old functions in order to avoid breaking ARM, which calls
these functions from assembler code, and cannot easily use C enum
parameters.
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will deacon <will.deacon@arm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 8ad53c9..17715d8 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -39,15 +39,15 @@
}
/**
- * context_tracking_user_enter - Inform the context tracking that the CPU is going to
- * enter userspace mode.
+ * context_tracking_enter - Inform the context tracking that the CPU is going
+ * enter user or guest space mode.
*
* This function must be called right before we switch from the kernel
- * to userspace, when it's guaranteed the remaining kernel instructions
- * to execute won't use any RCU read side critical section because this
- * function sets RCU in extended quiescent state.
+ * to user or guest space, when it's guaranteed the remaining kernel
+ * instructions to execute won't use any RCU read side critical section
+ * because this function sets RCU in extended quiescent state.
*/
-void context_tracking_user_enter(void)
+void context_tracking_enter(enum ctx_state state)
{
unsigned long flags;
@@ -75,7 +75,7 @@
WARN_ON_ONCE(!current->mm);
local_irq_save(flags);
- if ( __this_cpu_read(context_tracking.state) != CONTEXT_USER) {
+ if ( __this_cpu_read(context_tracking.state) != state) {
if (__this_cpu_read(context_tracking.active)) {
trace_user_enter(0);
/*
@@ -101,24 +101,31 @@
* OTOH we can spare the calls to vtime and RCU when context_tracking.active
* is false because we know that CPU is not tickless.
*/
- __this_cpu_write(context_tracking.state, CONTEXT_USER);
+ __this_cpu_write(context_tracking.state, state);
}
local_irq_restore(flags);
}
+NOKPROBE_SYMBOL(context_tracking_enter);
+
+void context_tracking_user_enter(void)
+{
+ context_tracking_enter(CONTEXT_USER);
+}
NOKPROBE_SYMBOL(context_tracking_user_enter);
/**
- * context_tracking_user_exit - Inform the context tracking that the CPU is
- * exiting userspace mode and entering the kernel.
+ * context_tracking_exit - Inform the context tracking that the CPU is
+ * exiting user or guest mode and entering the kernel.
*
- * This function must be called after we entered the kernel from userspace
- * before any use of RCU read side critical section. This potentially include
- * any high level kernel code like syscalls, exceptions, signal handling, etc...
+ * This function must be called after we entered the kernel from user or
+ * guest space before any use of RCU read side critical section. This
+ * potentially include any high level kernel code like syscalls, exceptions,
+ * signal handling, etc...
*
* This call supports re-entrancy. This way it can be called from any exception
* handler without needing to know if we came from userspace or not.
*/
-void context_tracking_user_exit(void)
+void context_tracking_exit(enum ctx_state state)
{
unsigned long flags;
@@ -129,7 +136,7 @@
return;
local_irq_save(flags);
- if (__this_cpu_read(context_tracking.state) == CONTEXT_USER) {
+ if (__this_cpu_read(context_tracking.state) == state) {
if (__this_cpu_read(context_tracking.active)) {
/*
* We are going to run code that may use RCU. Inform
@@ -143,6 +150,12 @@
}
local_irq_restore(flags);
}
+NOKPROBE_SYMBOL(context_tracking_exit);
+
+void context_tracking_user_exit(void)
+{
+ context_tracking_exit(CONTEXT_USER);
+}
NOKPROBE_SYMBOL(context_tracking_user_exit);
/**