tools/power x86_energy_perf_policy: Fix "uninitialized variable" warnings at -O2

x86_energy_perf_policy first uses __get_cpuid() to check the maximum
CPUID level and exits if it is too low.  It then assumes that later
calls will succeed (which I think is architecturally guaranteed).  It
also assumes that CPUID works at all (which is not guaranteed on
x86_32).

If optimisations are enabled, gcc warns about potentially
uninitialized variables.  Fix this by adding an exit-on-error after
every call to __get_cpuid() instead of just checking the maximum
level.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
index 34a796b..7663abe 100644 (file)
--- a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
+++ b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
@@ -1259,6 +1259,15 @@ void probe_dev_msr(void)
                if (system("/sbin/modprobe msr > /dev/null 2>&1"))
                        err(-5, "no /dev/cpu/0/msr, Try \"# modprobe msr\" ");
 }
+
+static void get_cpuid_or_exit(unsigned int leaf,
+                            unsigned int *eax, unsigned int *ebx,
+                            unsigned int *ecx, unsigned int *edx)
+{
+       if (!__get_cpuid(leaf, eax, ebx, ecx, edx))
+               errx(1, "Processor not supported\n");
+}
+
 /*
  * early_cpuid()
  * initialize turbo_is_enabled, has_hwp, has_epb
@@ -1266,15 +1275,10 @@ void probe_dev_msr(void)
  */
 void early_cpuid(void)
 {
-       unsigned int eax, ebx, ecx, edx, max_level;
+       unsigned int eax, ebx, ecx, edx;
        unsigned int fms, family, model;
 
-       __get_cpuid(0, &max_level, &ebx, &ecx, &edx);
-
-       if (max_level < 6)
-               errx(1, "Processor not supported\n");
-
-       __get_cpuid(1, &fms, &ebx, &ecx, &edx);
+       get_cpuid_or_exit(1, &fms, &ebx, &ecx, &edx);
        family = (fms >> 8) & 0xf;
        model = (fms >> 4) & 0xf;
        if (family == 6 || family == 0xf)
@@ -1288,7 +1292,7 @@ void early_cpuid(void)
                bdx_highest_ratio = msr & 0xFF;
        }
 
-       __get_cpuid(0x6, &eax, &ebx, &ecx, &edx);
+       get_cpuid_or_exit(0x6, &eax, &ebx, &ecx, &edx);
        turbo_is_enabled = (eax >> 1) & 1;
        has_hwp = (eax >> 7) & 1;
        has_epb = (ecx >> 3) & 1;
@@ -1306,7 +1310,7 @@ void parse_cpuid(void)
 
        eax = ebx = ecx = edx = 0;
 
-       __get_cpuid(0, &max_level, &ebx, &ecx, &edx);
+       get_cpuid_or_exit(0, &max_level, &ebx, &ecx, &edx);
 
        if (ebx == 0x756e6547 && edx == 0x49656e69 && ecx == 0x6c65746e)
                genuine_intel = 1;
@@ -1315,7 +1319,7 @@ void parse_cpuid(void)
                fprintf(stderr, "CPUID(0): %.4s%.4s%.4s ",
                        (char *)&ebx, (char *)&edx, (char *)&ecx);
 
-       __get_cpuid(1, &fms, &ebx, &ecx, &edx);
+       get_cpuid_or_exit(1, &fms, &ebx, &ecx, &edx);
        family = (fms >> 8) & 0xf;
        model = (fms >> 4) & 0xf;
        stepping = fms & 0xf;
@@ -1340,7 +1344,7 @@ void parse_cpuid(void)
                errx(1, "CPUID: no MSR");
 
 
-       __get_cpuid(0x6, &eax, &ebx, &ecx, &edx);
+       get_cpuid_or_exit(0x6, &eax, &ebx, &ecx, &edx);
        /* turbo_is_enabled already set */
        /* has_hwp already set */
        has_hwp_notify = eax & (1 << 8);