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

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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>
This commit is contained in:
Ben Hutchings 2018-09-16 16:05:53 +01:00 committed by Len Brown
parent a55aa89aab
commit adb8049097
1 changed files with 15 additions and 11 deletions
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26
tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
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@ -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);