drivers/perf: arm_pmu: handle no platform_device

[ Upstream commit 7654137071fa706e5c91f4f27bc2a5cd7e435a9b ]

In armpmu_dispatch_irq() we look at arm_pmu::plat_device to acquire
platdata, so that we can defer to platform-specific IRQ handling,
required on some 32-bit parts. With the advent of ACPI we won't always
have a platform_device, and so we must avoid trying to dereference
fields from it.

This patch fixes up armpmu_dispatch_irq() to avoid doing so, introducing
a new armpmu_get_platdata() helper.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index b37b572..af82edc 100644 (file)
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -322,10 +322,16 @@ validate_group(struct perf_event *event)
        return 0;
 }
 
+static struct arm_pmu_platdata *armpmu_get_platdata(struct arm_pmu *armpmu)
+{
+       struct platform_device *pdev = armpmu->plat_device;
+
+       return pdev ? dev_get_platdata(&pdev->dev) : NULL;
+}
+
 static irqreturn_t armpmu_dispatch_irq(int irq, void *dev)
 {
        struct arm_pmu *armpmu;
-       struct platform_device *plat_device;
        struct arm_pmu_platdata *plat;
        int ret;
        u64 start_clock, finish_clock;
@@ -337,8 +343,8 @@ static irqreturn_t armpmu_dispatch_irq(int irq, void *dev)
         * dereference.
         */
        armpmu = *(void **)dev;
-       plat_device = armpmu->plat_device;
-       plat = dev_get_platdata(&plat_device->dev);
+
+       plat = armpmu_get_platdata(armpmu);
 
        start_clock = sched_clock();
        if (plat && plat->handle_irq)