tools/power turbostat: Handle non-root legacy-uncore sysfs permissions

JIRA: https://issues.redhat.com/browse/RHEL-110614

commit e60a13b
Author: Len Brown <len.brown@intel.com>
Date:   Sat Aug 9 16:31:31 2025 -0400

    tools/power turbostat: Handle non-root legacy-uncore sysfs permissions

    /sys/devices/system/cpu/intel_uncore_frequency/package_X_die_Y/
    may be readable by all, but
    /sys/devices/system/cpu/intel_uncore_frequency/package_X_die_Y/current_freq_khz
    may be readable only by root.

    Non-root turbostat users see complaints in this scenario.

    Fail probe of the interface if we can't read current_freq_khz.

    Reported-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
    Original-patch-by: Zhang Rui <rui.zhang@intel.com>
    Signed-off-by: Len Brown <len.brown@intel.com>

Signed-off-by: David Arcari <darcari@redhat.com>

Author: darcari

tools/power/x86/turbostat/turbostat.c

@@ -7002,7 +7002,8 @@ static void probe_intel_uncore_frequency_legacy(void)
 			sprintf(path_base, "/sys/devices/system/cpu/intel_uncore_frequency/package_%02d_die_%02d", i,
 				j);
 
-			if (access(path_base, R_OK))
+			sprintf(path, "%s/current_freq_khz", path_base);
+			if (access(path, R_OK))
 				continue;
 
 			BIC_PRESENT(BIC_UNCORE_MHZ);