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ARM: perf: Set ARMv7 SDER SUNIDEN bit

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ARMv7 counters other than the CPU cycle counter only work if the Secure
Debug Enable Register (SDER) SUNIDEN bit is set.

Since access to the SDER is only possible in secure state, it will
only be done if the device tree property "secure-reg-access" is set.

Without this:

 Performance counter stats for 'sleep 1':

          14606094 cycles                    #    0.000 GHz
                 0 instructions              #    0.00  insns per cycle

After applying:

 Performance counter stats for 'sleep 1':

           5843809 cycles
           2566484 instructions              #    0.44  insns per cycle

       1.020144000 seconds time elapsed

Some platforms (eg i.MX53) may also need additional platform specific
setup.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
Signed-off-by: Pooya Keshavarzi <Pooya.Keshavarzi@de.bosch.com>
Signed-off-by: George G. Davis <george_davis@mentor.com>
[will: add warning if property is found on arm64]
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Martin Fuzzey 2016-01-13 23:36:26 -05:00 committed by Will Deacon
parent 92e963f50f
commit 8d1a0ae724
4 changed files with 32 additions and 1 deletions
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10
Documentation/devicetree/bindings/arm/pmu.txt
View File

@ -46,6 +46,16 @@ Optional properties:
- qcom,no-pc-write : Indicates that this PMU doesn't support the 0xc and 0xd
events.
- secure-reg-access : Indicates that the ARMv7 Secure Debug Enable Register
(SDER) is accessible. This will cause the driver to do
any setup required that is only possible in ARMv7 secure
state. If not present the ARMv7 SDER will not be touched,
which means the PMU may fail to operate unless external
code (bootloader or security monitor) has performed the
appropriate initialisation. Note that this property is
not valid for non-ARMv7 CPUs or ARMv7 CPUs booting Linux
in Non-secure state.
Example:
pmu {

13
arch/arm/kernel/perf_event_v7.c
View File

@ -712,6 +712,11 @@ static const struct attribute_group *armv7_pmuv2_attr_groups[] = {
#define ARMV7_EXCLUDE_USER (1 << 30)
#define ARMV7_INCLUDE_HYP (1 << 27)
/*
* Secure debug enable reg
*/
#define ARMV7_SDER_SUNIDEN BIT(1) /* Permit non-invasive debug */
static inline u32 armv7_pmnc_read(void)
{
u32 val;
@ -1094,7 +1099,13 @@ static int armv7pmu_set_event_filter(struct hw_perf_event *event,
static void armv7pmu_reset(void *info)
{
struct arm_pmu *cpu_pmu = (struct arm_pmu *)info;
u32 idx, nb_cnt = cpu_pmu->num_events;
u32 idx, nb_cnt = cpu_pmu->num_events, val;
if (cpu_pmu->secure_access) {
asm volatile("mrc p15, 0, %0, c1, c1, 1" : "=r" (val));
val |= ARMV7_SDER_SUNIDEN;
asm volatile("mcr p15, 0, %0, c1, c1, 1" : : "r" (val));
}
/* The counter and interrupt enable registers are unknown at reset. */
for (idx = ARMV7_IDX_CYCLE_COUNTER; idx < nb_cnt; ++idx) {

9
drivers/perf/arm_pmu.c
View File

@ -889,6 +889,15 @@ int arm_pmu_device_probe(struct platform_device *pdev,
if (node && (of_id = of_match_node(of_table, pdev->dev.of_node))) {
init_fn = of_id->data;
pmu->secure_access = of_property_read_bool(pdev->dev.of_node,
"secure-reg-access");
/* arm64 systems boot only as non-secure */
if (IS_ENABLED(CONFIG_ARM64) && pmu->secure_access) {
pr_warn("ignoring \"secure-reg-access\" property for arm64\n");
pmu->secure_access = false;
}
ret = of_pmu_irq_cfg(pmu);
if (!ret)
ret = init_fn(pmu);

1
include/linux/perf/arm_pmu.h
View File

@ -104,6 +104,7 @@ struct arm_pmu {
atomic_t active_events;
struct mutex reserve_mutex;
u64 max_period;
bool secure_access; /* 32-bit ARM only */
struct platform_device *plat_device;
struct pmu_hw_events __percpu *hw_events;
struct notifier_block hotplug_nb;