2018-09-11 01:52:06 +00:00
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From: Ben Hutchings <ben@decadent.org.uk>
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Date: Tue, 11 Sep 2018 02:38:36 +0100
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Subject: tools: x86_energy_perf_policy: Fix "uninitialized variable"
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warnings at -O2
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2018-09-16 15:27:59 +00:00
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Forwarded: https://marc.info/?l=linux-pm&m=153711035626776
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2018-09-11 01:52:06 +00:00
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x86_energy_perf_policy first uses __get_cpuid() to check the maximum
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CPUID level and exits if it is too low. It then assumes that later
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calls will succeed (which I think is architecturally guaranteed). It
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also assumes that CPUID works at all (which is not guaranteed on
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x86_32).
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If optimisations are enabled, gcc warns about potentially
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uninitialized variables. Fix this by adding an exit-on-error after
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every call to __get_cpuid() instead of just checking the maximum
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level.
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Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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---
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.../x86_energy_perf_policy.c | 26 +++++++++++--------
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1 file changed, 15 insertions(+), 11 deletions(-)
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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
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index 65bbe627a425..bbef8bcf44d6 100644
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--- a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
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+++ b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
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@@ -1260,6 +1260,15 @@ void probe_dev_msr(void)
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if (system("/sbin/modprobe msr > /dev/null 2>&1"))
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err(-5, "no /dev/cpu/0/msr, Try \"# modprobe msr\" ");
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}
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+
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+static void get_cpuid_or_exit(unsigned int leaf,
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+ unsigned int *eax, unsigned int *ebx,
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+ unsigned int *ecx, unsigned int *edx)
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+{
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+ if (!__get_cpuid(leaf, eax, ebx, ecx, edx))
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+ errx(1, "Processor not supported\n");
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+}
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+
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/*
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* early_cpuid()
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* initialize turbo_is_enabled, has_hwp, has_epb
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@@ -1267,15 +1276,10 @@ void probe_dev_msr(void)
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*/
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void early_cpuid(void)
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{
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- unsigned int eax, ebx, ecx, edx, max_level;
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+ unsigned int eax, ebx, ecx, edx;
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unsigned int fms, family, model;
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- __get_cpuid(0, &max_level, &ebx, &ecx, &edx);
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-
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- if (max_level < 6)
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- errx(1, "Processor not supported\n");
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-
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- __get_cpuid(1, &fms, &ebx, &ecx, &edx);
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+ get_cpuid_or_exit(1, &fms, &ebx, &ecx, &edx);
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family = (fms >> 8) & 0xf;
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model = (fms >> 4) & 0xf;
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if (family == 6 || family == 0xf)
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@@ -1289,7 +1293,7 @@ void early_cpuid(void)
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bdx_highest_ratio = msr & 0xFF;
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}
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- __get_cpuid(0x6, &eax, &ebx, &ecx, &edx);
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+ get_cpuid_or_exit(0x6, &eax, &ebx, &ecx, &edx);
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turbo_is_enabled = (eax >> 1) & 1;
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has_hwp = (eax >> 7) & 1;
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has_epb = (ecx >> 3) & 1;
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@@ -1307,7 +1311,7 @@ void parse_cpuid(void)
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eax = ebx = ecx = edx = 0;
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- __get_cpuid(0, &max_level, &ebx, &ecx, &edx);
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+ get_cpuid_or_exit(0, &max_level, &ebx, &ecx, &edx);
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if (ebx == 0x756e6547 && edx == 0x49656e69 && ecx == 0x6c65746e)
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genuine_intel = 1;
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@@ -1316,7 +1320,7 @@ void parse_cpuid(void)
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fprintf(stderr, "CPUID(0): %.4s%.4s%.4s ",
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(char *)&ebx, (char *)&edx, (char *)&ecx);
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- __get_cpuid(1, &fms, &ebx, &ecx, &edx);
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+ get_cpuid_or_exit(1, &fms, &ebx, &ecx, &edx);
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family = (fms >> 8) & 0xf;
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model = (fms >> 4) & 0xf;
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stepping = fms & 0xf;
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@@ -1341,7 +1345,7 @@ void parse_cpuid(void)
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errx(1, "CPUID: no MSR");
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- __get_cpuid(0x6, &eax, &ebx, &ecx, &edx);
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+ get_cpuid_or_exit(0x6, &eax, &ebx, &ecx, &edx);
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/* turbo_is_enabled already set */
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/* has_hwp already set */
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has_hwp_notify = eax & (1 << 8);
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