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authorRik van Riel <riel@redhat.com>2015-02-10 15:27:50 -0500
committerFrederic Weisbecker <fweisbec@gmail.com>2015-03-09 15:42:52 +0100
commit3aab4f50bff89bdea5066a05d4f3c5fa25bc37c7 (patch)
treebb83901091481a72fbd5327718e8cbb079a91d3e /kernel/context_tracking.c
parentc467ea763fd5d8795b7d1b5a78eb94b6ad8f66ad (diff)
downloadlinux-sh-3aab4f50bff89bdea5066a05d4f3c5fa25bc37c7.tar.gz
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>
Diffstat (limited to 'kernel/context_tracking.c')
-rw-r--r--kernel/context_tracking.c43
1 files changed, 28 insertions, 15 deletions
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 8ad53c9d38b6..17715d811b71 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -39,15 +39,15 @@ void context_tracking_cpu_set(int cpu)
}
/**
- * 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 @@ void context_tracking_user_enter(void)
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 @@ void context_tracking_user_enter(void)
* 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 @@ void context_tracking_user_exit(void)
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 @@ void context_tracking_user_exit(void)
}
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);
/**