From c6df517796189723ffbdd7679206c97d3642c2ef Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Tue, 21 Jul 2026 10:02:52 +0300 Subject: [PATCH] perf/x86/intel/pt: Factor out pt_config_enable() pt_config() enables tracing by allowing NMIs and pause/resume, issuing the necessary barriers, and calling pt_config_start(). A later change needs to re-enable tracing on a (re-)start path without repeating the full pt_config() setup (filters, RTIT_CTL, buffer configuration). Factor that enabling sequence out into a new helper, pt_config_enable(), so it can be called on its own. No functional change intended. Signed-off-by: Adrian Hunter Signed-off-by: Peter Zijlstra (Intel) Tested-by: Yi Lai Link: https://patch.msgid.link/20260721070254.13557-2-adrian.hunter@intel.com --- arch/x86/events/intel/pt.c | 41 ++++++++++++++++++++++---------------- 1 file changed, 24 insertions(+), 17 deletions(-) diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c index b5726b50e77d..dc1be7f6e04b 100644 --- a/arch/x86/events/intel/pt.c +++ b/arch/x86/events/intel/pt.c @@ -502,6 +502,29 @@ static u64 pt_config_filters(struct perf_event *event) return rtit_ctl; } +static void pt_config_enable(struct perf_event *event) +{ + struct pt *pt = this_cpu_ptr(&pt_ctx); + + /* + * Allow resume before starting so as not to overwrite a value set by a + * PMI. + */ + barrier(); + WRITE_ONCE(pt->resume_allowed, 1); + /* Configuration is complete, it is now OK to handle an NMI */ + barrier(); + WRITE_ONCE(pt->handle_nmi, 1); + barrier(); + pt_config_start(event); + barrier(); + /* + * Allow pause after starting so its pt_config_stop() doesn't race with + * pt_config_start(). + */ + WRITE_ONCE(pt->pause_allowed, 1); +} + static void pt_config(struct perf_event *event) { struct pt *pt = this_cpu_ptr(&pt_ctx); @@ -541,23 +564,7 @@ static void pt_config(struct perf_event *event) event->hw.aux_config = reg; - /* - * Allow resume before starting so as not to overwrite a value set by a - * PMI. - */ - barrier(); - WRITE_ONCE(pt->resume_allowed, 1); - /* Configuration is complete, it is now OK to handle an NMI */ - barrier(); - WRITE_ONCE(pt->handle_nmi, 1); - barrier(); - pt_config_start(event); - barrier(); - /* - * Allow pause after starting so its pt_config_stop() doesn't race with - * pt_config_start(). - */ - WRITE_ONCE(pt->pause_allowed, 1); + pt_config_enable(event); } static void pt_config_stop(struct perf_event *event)