perf/x86/intel/uncore: Validate MMIO address before accessing

An oops will be triggered, if perf tries to access an invalid address
which exceeds the mapped area.

Check the address before the actual access to MMIO sapce of an uncore
unit.

Suggested-by: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/1590679169-61823-3-git-send-email-kan.liang@linux.intel.com

arch/x86/events/intel/uncore.c

@@ -132,6 +132,9 @@ u64 uncore_mmio_read_counter(struct intel_uncore_box *box,
 	if (!box->io_addr)
 		return 0;
 
+	if (!uncore_mmio_is_valid_offset(box, event->hw.event_base))
+		return 0;
+
 	return readq(box->io_addr + event->hw.event_base);
 }
 

arch/x86/events/intel/uncore.h

@@ -197,6 +197,18 @@ static inline bool uncore_pmc_freerunning(int idx)
 	return idx == UNCORE_PMC_IDX_FREERUNNING;
 }
 
+static inline bool uncore_mmio_is_valid_offset(struct intel_uncore_box *box,
+					       unsigned long offset)
+{
+	if (offset < box->pmu->type->mmio_map_size)
+		return true;
+
+	pr_warn_once("perf uncore: Invalid offset 0x%lx exceeds mapped area of %s.\n",
+		     offset, box->pmu->type->name);
+
+	return false;
+}
+
 static inline
 unsigned int uncore_mmio_box_ctl(struct intel_uncore_box *box)
 {

arch/x86/events/intel/uncore_snbep.c

@@ -4483,6 +4483,9 @@ static void snr_uncore_mmio_enable_event(struct intel_uncore_box *box,
 	if (!box->io_addr)
 		return;
 
+	if (!uncore_mmio_is_valid_offset(box, hwc->config_base))
+		return;
+
 	writel(hwc->config | SNBEP_PMON_CTL_EN,
 	       box->io_addr + hwc->config_base);
 }
@@ -4495,6 +4498,9 @@ static void snr_uncore_mmio_disable_event(struct intel_uncore_box *box,
 	if (!box->io_addr)
 		return;
 
+	if (!uncore_mmio_is_valid_offset(box, hwc->config_base))
+		return;
+
 	writel(hwc->config, box->io_addr + hwc->config_base);
 }