On Tue, Feb 10, 2015 at 03:27:50PM -0500, [email protected] wrote: > From: Rik van Riel <[email protected]> > > Split out the mechanism from context_tracking_user_enter and > context_tracking_user_exit into context_tracking_enter and > context_tracking_exit. Leave the old functions in order to avoid > breaking ARM, which calls these functions from assembler code, > and cannot easily use C enum parameters. > > Add the expected ctx_state as a parameter to context_tracking_enter and > context_tracking_exit, allowing the same functions to not just track > kernel <> user space switching, but also kernel <> guest transitions. > > Signed-off-by: Rik van Riel <[email protected]>
Reviewed-by: Paul E. McKenney <[email protected]> > --- > include/linux/context_tracking.h | 8 +++++--- > kernel/context_tracking.c | 43 > ++++++++++++++++++++++++++-------------- > 2 files changed, 33 insertions(+), 18 deletions(-) > > diff --git a/include/linux/context_tracking.h > b/include/linux/context_tracking.h > index 37b81bd51ec0..954253283709 100644 > --- a/include/linux/context_tracking.h > +++ b/include/linux/context_tracking.h > @@ -10,6 +10,8 @@ > #ifdef CONFIG_CONTEXT_TRACKING > extern void context_tracking_cpu_set(int cpu); > > +extern void context_tracking_enter(enum ctx_state state); > +extern void context_tracking_exit(enum ctx_state state); > extern void context_tracking_user_enter(void); > extern void context_tracking_user_exit(void); > extern void __context_tracking_task_switch(struct task_struct *prev, > @@ -35,7 +37,7 @@ static inline enum ctx_state exception_enter(void) > return 0; > > prev_ctx = this_cpu_read(context_tracking.state); > - context_tracking_user_exit(); > + context_tracking_exit(prev_ctx); > > return prev_ctx; > } > @@ -43,8 +45,8 @@ static inline enum ctx_state exception_enter(void) > static inline void exception_exit(enum ctx_state prev_ctx) > { > if (context_tracking_is_enabled()) { > - if (prev_ctx == IN_USER) > - context_tracking_user_enter(); > + if (prev_ctx != IN_KERNEL) > + context_tracking_enter(prev_ctx); > } > } > > diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c > index 937ecdfdf258..38e38aeac8b9 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) != IN_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, IN_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(IN_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) == IN_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(IN_USER); > +} > NOKPROBE_SYMBOL(context_tracking_user_exit); > > /** > -- > 1.9.3 > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
