perf/x86/intel/pt: Factor out pt_config_start()

PT trace is now enabled at the bottom of the event configuration
function that takes care of all configuration bits related to a given
event, including the address filter update. This is only needed where
the event configuration changes, that is, in ->add()/->start().

In the interrupt path we can use a lighter version that keeps the
configuration intact, since it hasn't changed, and only flips the
enable bit.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: adrian.hunter@intel.com
Cc: mathieu.poirier@linaro.org
Link: https://lkml.kernel.org/r/20191025140835.53665-3-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 05e43d0f430bcdfd89999dc3e31369b49ad0ca4c..170f3b4022749c1a4e90f2c83ad556c2342bf0b8 100644 (file)
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -397,6 +397,20 @@ static bool pt_event_valid(struct perf_event *event)
  * These all are cpu affine and operate on a local PT
  */
 
+static void pt_config_start(struct perf_event *event)
+{
+       struct pt *pt = this_cpu_ptr(&pt_ctx);
+       u64 ctl = event->hw.config;
+
+       ctl |= RTIT_CTL_TRACEEN;
+       if (READ_ONCE(pt->vmx_on))
+               perf_aux_output_flag(&pt->handle, PERF_AUX_FLAG_PARTIAL);
+       else
+               wrmsrl(MSR_IA32_RTIT_CTL, ctl);
+
+       WRITE_ONCE(event->hw.config, ctl);
+}
+
 /* Address ranges and their corresponding msr configuration registers */
 static const struct pt_address_range {
        unsigned long   msr_a;
@@ -468,7 +482,6 @@ static u64 pt_config_filters(struct perf_event *event)
 
 static void pt_config(struct perf_event *event)
 {
-       struct pt *pt = this_cpu_ptr(&pt_ctx);
        u64 reg;
 
        /* First round: clear STATUS, in particular the PSB byte counter. */
@@ -501,10 +514,7 @@ static void pt_config(struct perf_event *event)
        reg |= (event->attr.config & PT_CONFIG_MASK);
 
        event->hw.config = reg;
-       if (READ_ONCE(pt->vmx_on))
-               perf_aux_output_flag(&pt->handle, PERF_AUX_FLAG_PARTIAL);
-       else
-               wrmsrl(MSR_IA32_RTIT_CTL, reg);
+       pt_config_start(event);
 }
 
 static void pt_config_stop(struct perf_event *event)
@@ -1381,7 +1391,7 @@ void intel_pt_interrupt(void)
 
                pt_config_buffer(topa_to_page(buf->cur)->table, buf->cur_idx,
                                 buf->output_off);
-               pt_config(event);
+               pt_config_start(event);
        }
 }