Merge remote-tracking branch 'powerpc/next'

[karo-tx-linux.git] / arch / x86 / kernel / cpu / perf_event_intel_bts.c

diff --git a/arch/x86/kernel/cpu/perf_event_intel_bts.c b/arch/x86/kernel/cpu/perf_event_intel_bts.c
index d1c0f254afbeefe61fcfaeeb7625664d7d352918..2cad71d1b14cfb36df83674dac992f51c37db63a 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event_intel_bts.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_bts.c
@@ -495,6 +495,19 @@ static int bts_event_init(struct perf_event *event)
        if (x86_add_exclusive(x86_lbr_exclusive_bts))
                return -EBUSY;
 
+       /*
+        * BTS leaks kernel addresses even when CPL0 tracing is
+        * disabled, so disallow intel_bts driver for unprivileged
+        * users on paranoid systems since it provides trace data
+        * to the user in a zero-copy fashion.
+        *
+        * Note that the default paranoia setting permits unprivileged
+        * users to profile the kernel.
+        */
+       if (event->attr.exclude_kernel && perf_paranoid_kernel() &&
+           !capable(CAP_SYS_ADMIN))
+               return -EACCES;
+
        ret = x86_reserve_hardware();
        if (ret) {
                x86_del_exclusive(x86_lbr_exclusive_bts);