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cpuidle, arm64: Fix the ARM64 cpuidle logic 

The recent cpuidle changes started triggering RCU splats on
Juno development boards:

  | =============================
  | WARNING: suspicious RCU usage
  | -----------------------------
  | include/trace/events/ipi.h:19 suspicious rcu_dereference_check() usage!

Fix cpuidle on ARM64:

 - ... by introducing a new 'is_rcu' flag to the cpuidle helpers & make
   ARM64 use it, as ARM64 wants to keep RCU active longer and wants to
   do the ct_cpuidle_enter()/exit() dance itself.

 - Also update the PSCI driver accordingly.

 - This also removes the last known RCU_NONIDLE() user as a bonus.

Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/Y8Z31UbzG3LJgAXE@hirez.programming.kicks-ass.net

--
This commit is contained in:
Peter Zijlstra 2023-01-17 11:26:29 +01:00 committed by Ingo Molnar
parent 3b8645e9ec
commit 19235e4727
5 changed files with 40 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/arm64/kernel/cpuidle.c
View File

@ -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

12
arch/arm64/kernel/suspend.c
View File

@ -4,6 +4,7 @@
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/pgtable.h>
#include <linux/cpuidle.h>
#include <asm/alternative.h>
#include <asm/cacheflush.h>
#include <asm/cpufeature.h>
@ -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);

6
drivers/cpuidle/cpuidle-psci.c
View File

@ -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[] = {

11
drivers/firmware/psci/psci.c
View File

@ -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;

22
include/linux/cpuidle.h
View File

@ -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 */