From fbea122e3ff597c35adbdad04415765b26be8d85 Mon Sep 17 00:00:00 2001 From: Lorenzo Pieralisi Date: Tue, 23 Feb 2016 18:22:39 +0000 Subject: UPSTREAM: drivers/perf: arm_pmu: implement CPU_PM notifier (cherry picked from commit da4e4f18afe0f3729d68f3785c5802f786d36e34) When a CPU is suspended (either through suspend-to-RAM or CPUidle), its PMU registers content can be lost, which means that counters registers values that were initialized on power down entry have to be reprogrammed on power-up to make sure the counters set-up is preserved (ie on power-up registers take the reset values on Cold or Warm reset, which can be architecturally UNKNOWN). To guarantee seamless profiling conditions across a core power down this patch adds a CPU PM notifier to ARM pmus, that upon CPU PM entry/exit from low-power states saves/restores the pmu registers set-up (by using the ARM perf API), so that the power-down/up cycle does not affect the perf behaviour (apart from a black-out period between power-up/down CPU PM notifications that is unavoidable). Change-Id: Ifbd73b82ca9dc172c58e2488cda1af9af975b14f Cc: Will Deacon Cc: Sudeep Holla Cc: Daniel Lezcano Cc: Mathieu Poirier Cc: Mark Rutland Acked-by: Ashwin Chaugule Acked-by: Kevin Hilman Signed-off-by: Lorenzo Pieralisi Signed-off-by: Will Deacon --- include/linux/perf/arm_pmu.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h index bfa673bb822d..0e55e4016f49 100644 --- a/include/linux/perf/arm_pmu.h +++ b/include/linux/perf/arm_pmu.h @@ -107,6 +107,7 @@ struct arm_pmu { struct platform_device *plat_device; struct pmu_hw_events __percpu *hw_events; struct notifier_block hotplug_nb; + struct notifier_block cpu_pm_nb; }; #define to_arm_pmu(p) (container_of(p, struct arm_pmu, pmu)) -- cgit v1.2.3 From 1fecf3977defb3161ba194e5ddbdeca9be638377 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Thu, 8 Jun 2017 16:44:20 -0700 Subject: time: Fix clock->read(clock) race around clocksource changes commit ceea5e3771ed2378668455fa21861bead7504df5 upstream. In tests, which excercise switching of clocksources, a NULL pointer dereference can be observed on AMR64 platforms in the clocksource read() function: u64 clocksource_mmio_readl_down(struct clocksource *c) { return ~(u64)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask; } This is called from the core timekeeping code via: cycle_now = tkr->read(tkr->clock); tkr->read is the cached tkr->clock->read() function pointer. When the clocksource is changed then tkr->clock and tkr->read are updated sequentially. The code above results in a sequential load operation of tkr->read and tkr->clock as well. If the store to tkr->clock hits between the loads of tkr->read and tkr->clock, then the old read() function is called with the new clock pointer. As a consequence the read() function dereferences a different data structure and the resulting 'reg' pointer can point anywhere including NULL. This problem was introduced when the timekeeping code was switched over to use struct tk_read_base. Before that, it was theoretically possible as well when the compiler decided to reload clock in the code sequence: now = tk->clock->read(tk->clock); Add a helper function which avoids the issue by reading tk_read_base->clock once into a local variable clk and then issue the read function via clk->read(clk). This guarantees that the read() function always gets the proper clocksource pointer handed in. Since there is now no use for the tkr.read pointer, this patch also removes it, and to address stopping the fast timekeeper during suspend/resume, it introduces a dummy clocksource to use rather then just a dummy read function. Signed-off-by: John Stultz Acked-by: Ingo Molnar Cc: Prarit Bhargava Cc: Richard Cochran Cc: Stephen Boyd Cc: Miroslav Lichvar Cc: Daniel Mentz Link: http://lkml.kernel.org/r/1496965462-20003-2-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- include/linux/timekeeper_internal.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h index 25247220b4b7..f0f1793cfa49 100644 --- a/include/linux/timekeeper_internal.h +++ b/include/linux/timekeeper_internal.h @@ -29,7 +29,6 @@ */ struct tk_read_base { struct clocksource *clock; - cycle_t (*read)(struct clocksource *cs); cycle_t mask; cycle_t cycle_last; u32 mult; -- cgit v1.2.3