[PATCH 3/7] perf,x86: Fix possible Spectre-v1 for x86_pmu::event_map()

[Peter Zijlstra]

> arch/x86/events/intel/core.c:337 intel_pmu_event_map() warn: potential spectre issue 'intel_perfmon_event_map'
> arch/x86/events/intel/knc.c:122 knc_pmu_event_map() warn: potential spectre issue 'knc_perfmon_event_map'
> arch/x86/events/intel/p4.c:722 p4_pmu_event_map() warn: potential spectre issue 'p4_general_events'
> arch/x86/events/intel/p6.c:116 p6_pmu_event_map() warn: potential spectre issue 'p6_perfmon_event_map'
> arch/x86/events/amd/core.c:132 amd_pmu_event_map() warn: potential spectre issue 'amd_perfmon_event_map'

Userspace controls @attr, sanitize @attr->config before passing it on
to x86_pmu::event_map().

Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
 arch/x86/events/core.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -424,6 +424,8 @@ int x86_setup_perfctr(struct perf_event
 	if (attr->config >= x86_pmu.max_events)
 		return -EINVAL;
 
+	attr->config = array_index_nospec(attr->config, x86_pmu.max_events);
+
 	/*
 	 * The generic map:
 	 */