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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org On Tue, Jan 17, 2023 at 11:26:29AM +0100, Peter Zijlstra wrote: > On Mon, Jan 16, 2023 at 04:59:04PM +0000, Mark Rutland wrote: > > > I'm sorry to have to bear some bad news on that front. :( > > Moo, something had to give.. > > > > IIUC what's happenign here is the PSCI cpuidle driver has entered idle and RCU > > is no longer watching when arm64's cpu_suspend() manipulates DAIF. Our > > local_daif_*() helpers poke lockdep and tracing, hence the call to > > trace_hardirqs_off() and the RCU usage. > > Right, strictly speaking not needed at this point, IRQs should have been > traced off a long time ago. True, but there are some other calls around here that *might* end up invoking RCU stuff (e.g. the MTE code). That all needs a noinstr cleanup too, which I'll sort out as a follow-up. > > I think we need RCU to be watching all the way down to cpu_suspend(), and it's > > cpu_suspend() that should actually enter/exit idle context. That and we need to > > make cpu_suspend() and the low-level PSCI invocation noinstr. > > > > I'm not sure whether 32-bit will have a similar issue or not. > > I'm not seeing 32bit or Risc-V have similar issues here, but who knows, > maybe I missed somsething. I reckon if they do, the core changes here give us the infrastructure to fix them if/when we get reports. > In any case, the below ought to cure the ARM64 case and remove that last > known RCU_NONIDLE() user as a bonus. The below works for me testing on a Juno R1 board with PSCI, using defconfig + CONFIG_PROVE_LOCKING=y + CONFIG_DEBUG_LOCKDEP=y + CONFIG_DEBUG_ATOMIC_SLEEP=y. I'm not sure how to test the LPI / FFH part, but it looks good to me. FWIW: Reviewed-by: Mark Rutland Tested-by: Mark Rutland Sudeep, would you be able to give the LPI/FFH side a spin with the kconfig options above? Thanks, Mark. > > --- > diff --git a/arch/arm64/kernel/cpuidle.c b/arch/arm64/kernel/cpuidle.c > index 41974a1a229a..42e19fff40ee 100644 > --- a/arch/arm64/kernel/cpuidle.c > +++ b/arch/arm64/kernel/cpuidle.c > @@ -67,10 +67,10 @@ __cpuidle int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi) > u32 state = lpi->address; > > if (ARM64_LPI_IS_RETENTION_STATE(lpi->arch_flags)) > - return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM(psci_cpu_suspend_enter, > + return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM_RCU(psci_cpu_suspend_enter, > lpi->index, state); > else > - return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter, > + return CPU_PM_CPU_IDLE_ENTER_PARAM_RCU(psci_cpu_suspend_enter, > lpi->index, state); > } > #endif > diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c > index e7163f31f716..0fbdf5fe64d8 100644 > --- a/arch/arm64/kernel/suspend.c > +++ b/arch/arm64/kernel/suspend.c > @@ -4,6 +4,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -104,6 +105,10 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) > * From this point debug exceptions are disabled to prevent > * updates to mdscr register (saved and restored along with > * general purpose registers) from kernel debuggers. > + * > + * Strictly speaking the trace_hardirqs_off() here is superfluous, > + * hardirqs should be firmly off by now. This really ought to use > + * something like raw_local_daif_save(). > */ > flags = local_daif_save(); > > @@ -120,6 +125,8 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) > */ > arm_cpuidle_save_irq_context(&context); > > + ct_cpuidle_enter(); > + > if (__cpu_suspend_enter(&state)) { > /* Call the suspend finisher */ > ret = fn(arg); > @@ -133,8 +140,11 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) > */ > if (!ret) > ret = -EOPNOTSUPP; > + > + ct_cpuidle_exit(); > } else { > - RCU_NONIDLE(__cpu_suspend_exit()); > + ct_cpuidle_exit(); > + __cpu_suspend_exit(); > } > > arm_cpuidle_restore_irq_context(&context); > diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c > index 4fc4e0381944..312a34ef28dc 100644 > --- a/drivers/cpuidle/cpuidle-psci.c > +++ b/drivers/cpuidle/cpuidle-psci.c > @@ -69,16 +69,12 @@ static __cpuidle int __psci_enter_domain_idle_state(struct cpuidle_device *dev, > else > pm_runtime_put_sync_suspend(pd_dev); > > - ct_cpuidle_enter(); > - > state = psci_get_domain_state(); > if (!state) > state = states[idx]; > > ret = psci_cpu_suspend_enter(state) ? -1 : idx; > > - ct_cpuidle_exit(); > - > if (s2idle) > dev_pm_genpd_resume(pd_dev); > else > @@ -192,7 +188,7 @@ static __cpuidle int psci_enter_idle_state(struct cpuidle_device *dev, > { > u32 *state = __this_cpu_read(psci_cpuidle_data.psci_states); > > - return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter, idx, state[idx]); > + return CPU_PM_CPU_IDLE_ENTER_PARAM_RCU(psci_cpu_suspend_enter, idx, state[idx]); > } > > static const struct of_device_id psci_idle_state_match[] = { > diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c > index e7bcfca4159f..f3a044fa4652 100644 > --- a/drivers/firmware/psci/psci.c > +++ b/drivers/firmware/psci/psci.c > @@ -462,11 +462,22 @@ int psci_cpu_suspend_enter(u32 state) > if (!psci_power_state_loses_context(state)) { > struct arm_cpuidle_irq_context context; > > + ct_cpuidle_enter(); > arm_cpuidle_save_irq_context(&context); > ret = psci_ops.cpu_suspend(state, 0); > arm_cpuidle_restore_irq_context(&context); > + ct_cpuidle_exit(); > } else { > + /* > + * ARM64 cpu_suspend() wants to do ct_cpuidle_*() itself. > + */ > + if (!IS_ENABLED(CONFIG_ARM64)) > + ct_cpuidle_enter(); > + > ret = cpu_suspend(state, psci_suspend_finisher); > + > + if (!IS_ENABLED(CONFIG_ARM64)) > + ct_cpuidle_exit(); > } > > return ret; > diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h > index 630c879143c7..3183aeb7f5b4 100644 > --- a/include/linux/cpuidle.h > +++ b/include/linux/cpuidle.h > @@ -307,7 +307,7 @@ extern s64 cpuidle_governor_latency_req(unsigned int cpu); > #define __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, \ > idx, \ > state, \ > - is_retention) \ > + is_retention, is_rcu) \ > ({ \ > int __ret = 0; \ > \ > @@ -319,9 +319,11 @@ extern s64 cpuidle_governor_latency_req(unsigned int cpu); > if (!is_retention) \ > __ret = cpu_pm_enter(); \ > if (!__ret) { \ > - ct_cpuidle_enter(); \ > + if (!is_rcu) \ > + ct_cpuidle_enter(); \ > __ret = low_level_idle_enter(state); \ > - ct_cpuidle_exit(); \ > + if (!is_rcu) \ > + ct_cpuidle_exit(); \ > if (!is_retention) \ > cpu_pm_exit(); \ > } \ > @@ -330,15 +332,21 @@ extern s64 cpuidle_governor_latency_req(unsigned int cpu); > }) > > #define CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx) \ > - __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, idx, 0) > + __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, idx, 0, 0) > > #define CPU_PM_CPU_IDLE_ENTER_RETENTION(low_level_idle_enter, idx) \ > - __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, idx, 1) > + __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, idx, 1, 0) > > #define CPU_PM_CPU_IDLE_ENTER_PARAM(low_level_idle_enter, idx, state) \ > - __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, state, 0) > + __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, state, 0, 0) > + > +#define CPU_PM_CPU_IDLE_ENTER_PARAM_RCU(low_level_idle_enter, idx, state) \ > + __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, state, 0, 1) > > #define CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM(low_level_idle_enter, idx, state) \ > - __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, state, 1) > + __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, state, 1, 0) > + > +#define CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM_RCU(low_level_idle_enter, idx, state) \ > + __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, state, 1, 1) > > #endif /* _LINUX_CPUIDLE_H */ _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um