[PATCH v2] arm64: perf: Add more support on caps under sysfs
From: Shaokun Zhang <hidden>
Date: 2021-05-29 06:23:05
Armv8.7 has introduced BUS_SLOTS and BUS_WIDTH in PMMIR_EL1 register,
add two entries in caps for bus_slots and bus_width under sysfs. It
will return the true slots and width if the information is available,
otherwise it will return 0.
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Shaokun Zhang <redacted>
---
ChangeLog:
v1-->v2:
1. Address Robin's comment on bus_width calculation.
2. Add the comment on calculation formula.
Will & Robin,
I don't change any about visible, if have more comments,
please let me know.
arch/arm64/include/asm/perf_event.h | 5 +++++
arch/arm64/kernel/perf_event.c | 35 +++++++++++++++++++++++++++++++++++
2 files changed, 40 insertions(+)
diff --git a/arch/arm64/include/asm/perf_event.h b/arch/arm64/include/asm/perf_event.h
index 60731f602d3e..4ef6f19331f9 100644
--- a/arch/arm64/include/asm/perf_event.h
+++ b/arch/arm64/include/asm/perf_event.h@@ -239,6 +239,11 @@ /* PMMIR_EL1.SLOTS mask */ #define ARMV8_PMU_SLOTS_MASK 0xff +#define ARMV8_PMU_BUS_SLOTS_SHIFT 8 +#define ARMV8_PMU_BUS_SLOTS_MASK 0xff +#define ARMV8_PMU_BUS_WIDTH_SHIFT 16 +#define ARMV8_PMU_BUS_WIDTH_MASK 0xf + #ifdef CONFIG_PERF_EVENTS struct pt_regs; extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index f594957e29bd..453e0d8a442e 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c@@ -317,8 +317,43 @@ static ssize_t slots_show(struct device *dev, struct device_attribute *attr, static DEVICE_ATTR_RO(slots); +static ssize_t bus_slots_show(struct device *dev, struct device_attribute *attr, + char *page) +{ + struct pmu *pmu = dev_get_drvdata(dev); + struct arm_pmu *cpu_pmu = container_of(pmu, struct arm_pmu, pmu); + u32 bus_slots = (cpu_pmu->reg_pmmir >> ARMV8_PMU_BUS_SLOTS_SHIFT) + & ARMV8_PMU_BUS_SLOTS_MASK; + + return snprintf(page, PAGE_SIZE, "0x%08x\n", bus_slots); +} + +static DEVICE_ATTR_RO(bus_slots); + +static ssize_t bus_width_show(struct device *dev, struct device_attribute *attr, + char *page) +{ + struct pmu *pmu = dev_get_drvdata(dev); + struct arm_pmu *cpu_pmu = container_of(pmu, struct arm_pmu, pmu); + u32 bus_width = (cpu_pmu->reg_pmmir >> ARMV8_PMU_BUS_WIDTH_SHIFT) + & ARMV8_PMU_BUS_WIDTH_MASK; + u32 val; + + /* Encoded as Log2(number of bytes), plus one */ + if (bus_width > 2 && bus_width < 13) + val = 1 << (bus_width - 1); + else + val = 0; + + return snprintf(page, PAGE_SIZE, "0x%08x\n", val); +} + +static DEVICE_ATTR_RO(bus_width); + static struct attribute *armv8_pmuv3_caps_attrs[] = { &dev_attr_slots.attr, + &dev_attr_bus_slots.attr, + &dev_attr_bus_width.attr, NULL, };
--
2.7.4
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