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authorMichele Papalini <micpapal+fdio@cisco.com>2017-02-24 08:00:33 +0000
committerGerrit Code Review <gerrit@fd.io>2017-02-24 08:00:33 +0000
commit4df7f4cc98b6288177df256e1db70ddc3f7d00db (patch)
tree55e71277b419e4830ae641868ab8e751c8b86972 /libparc/parc/developer/parc_TimingIntel.c
parentf28308bd99381ef5f1e178e2e1f870f245e35873 (diff)
parentec688b4723a041044226358bcd4dd6e2da39da49 (diff)
Merge "Initial commit: cframework. Longbow and Libparc" into cframework/master
Diffstat (limited to 'libparc/parc/developer/parc_TimingIntel.c')
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1 files changed, 89 insertions, 0 deletions
diff --git a/libparc/parc/developer/parc_TimingIntel.c b/libparc/parc/developer/parc_TimingIntel.c
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+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Executes either the RDTSC or RDTSCP instruction, depending on platform availability
+ *
+ */
+
+#include <config.h>
+#include <stdio.h>
+
+#define PARCTIMING_ENABLE
+#include <parc/developer/parc_Timing.h>
+
+#ifdef PARCTIMING_INTEL
+static bool _useRdtscp = false;
+static bool _needCheckRdtscp = true;
+
+#include <cpuid.h>
+
+static void
+_checkRdtscp(void)
+{
+ // See the CPUID instruction for description of the codes.
+
+ // determine the maximum extended information set
+ unsigned maxextended = __get_cpuid_max(0x80000000, NULL);
+
+ // RDTSCP status flag is in the 0x800000001 feature set
+ const unsigned feature = 0x80000001;
+ const unsigned rdtscp_feature = 1 << 27;
+
+ if (maxextended >= feature) {
+ unsigned eax, ebx, ecx, edx;
+
+ int success = __get_cpuid(feature, &eax, &ebx, &ecx, &edx);
+ if (success) {
+ _useRdtscp = (edx & rdtscp_feature ? true : false);
+ }
+ }
+}
+#endif // PARCTIMING_INTEL
+
+void
+parcTiminIntel_RuntimeInit(void)
+{
+#ifdef PARCTIMING_INTEL
+ if (_needCheckRdtscp) {
+ _needCheckRdtscp = false;
+ _checkRdtscp();
+ }
+#endif // PARCTIMING_INTEL
+}
+
+void
+parcTimingIntel_rdtsc(unsigned *hi, unsigned *lo)
+{
+ /*
+ * Older CPUs do not support RDTSCP, which is the better instruction to use.
+ * If we did not detect this opcode in autoconf, use the older RDTSC
+ */
+
+#ifdef PARCTIMING_INTEL
+ if (_useRdtscp) {
+ __asm volatile ("RDTSCP\n\t"
+ "mov %%edx,%0\n\t"
+ "mov %%eax,%1\n\t"
+ "CPUID\n\t" : "=r" (*hi), "=r" (*lo):: "%rax", "%rbx", "%rcx", "%rdx");
+ } else {
+ __asm volatile ("RDTSC\n\t"
+ "mov %%edx,%0\n\t"
+ "mov %%eax,%1\n\t"
+ "CPUID\n\t" : "=r" (*hi), "=r" (*lo):: "%rax", "%rbx", "%rcx", "%rdx");
+ }
+#endif // PARCTIMING_INTEL
+}
+