From 9c40c9a0e7e43577e77a372c18aa733ee17d81c2 Mon Sep 17 00:00:00 2001
From: Hisham Muhammad <hisham@gobolinux.org>
Date: Sun, 4 Feb 2018 16:29:27 +0100
Subject: [PATCH] Add perf counter object

---
 linux/PerfCounter.c | 135 ++++++++++++++++++++++++++++++++++++++++++++
 linux/PerfCounter.h |  54 ++++++++++++++++++
 2 files changed, 189 insertions(+)
 create mode 100644 linux/PerfCounter.c
 create mode 100644 linux/PerfCounter.h

diff --git a/linux/PerfCounter.c b/linux/PerfCounter.c
new file mode 100644
index 00000000..0f7a0aad
--- /dev/null
+++ b/linux/PerfCounter.c
@@ -0,0 +1,135 @@
+/*
+ * This file is based on tiptop.
+ * by Erven ROHOU
+ * Copyright (c) 2011, 2012, 2014 Inria
+ * License: GNU General Public License version 2.
+ */
+ 
+#include "PerfCounter.h"
+
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "XAlloc.h"
+
+/*{
+
+#include <config.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <asm/unistd.h>
+#include <inttypes.h>
+#include <stdbool.h>
+// The sys_perf_counter_open syscall and header files changed names
+// between Linux 2.6.31 and 2.6.32. Do the mangling here.
+#ifdef HAVE_LINUX_PERF_COUNTER_H
+#include <linux/perf_counter.h>
+#define STRUCT_NAME perf_counter_attr
+#define SYSCALL_NUM __NR_perf_counter_open
+
+#elif HAVE_LINUX_PERF_EVENT_H
+#include <linux/perf_event.h>
+#define STRUCT_NAME perf_event_attr
+#define SYSCALL_NUM __NR_perf_event_open
+
+#else
+#error Sorry, performance counters not supported on this system.
+#endif
+
+typedef struct PerfCounter_ {
+   struct STRUCT_NAME events;
+   pid_t pid;
+   int fd;
+   uint64_t prevValue;
+   uint64_t value;
+} PerfCounter;
+
+#define PerfCounter_delta(pc_) ((pc_)->value - (pc_)->prevValue)
+
+}*/
+
+int PerfCounter_openFds = 0;
+static int PerfCounter_fdLimit = -1;
+
+static void PerfCounter_initFdLimit() {
+   char name[100] = { 0 };  /* needs to fit the name /proc/xxxx/limits */
+   snprintf(name, sizeof(name) - 1, "/proc/%d/limits", getpid());
+   FILE* f = fopen(name, "r");
+   if (f) {
+     char line[100];
+     while (fgets(line, 100, f)) {
+       int n = sscanf(line, "Max open files %d", &PerfCounter_fdLimit);
+       if (n) {
+         break;
+       }
+     }
+     fclose(f);
+   }
+
+   PerfCounter_fdLimit -= 20; /* keep some slack */
+   if (PerfCounter_fdLimit == 0) {  /* something went wrong */
+      PerfCounter_fdLimit = 200;  /* reasonable default? */
+   }
+}
+
+static long perf_event_open(struct STRUCT_NAME *hw_event, pid_t pid, int cpu, int group_fd, unsigned long flags) {
+   int ret = syscall(SYSCALL_NUM, hw_event, pid, cpu, group_fd, flags);
+   #if defined(__x86_64__) || defined(__i386__)
+   if (ret < 0 && ret > -4096) {
+      errno = -ret;
+      ret = -1;
+   }
+   #endif
+   return ret;
+}
+
+PerfCounter* PerfCounter_new(pid_t pid, uint32_t type, uint64_t config) {
+   if (PerfCounter_fdLimit == -1) {
+      PerfCounter_initFdLimit();
+   }
+   PerfCounter* this = xCalloc(sizeof(PerfCounter), 1);
+   this->pid = pid;
+   this->events.disabled = 0;
+   this->events.pinned = 1;
+   this->events.exclude_hv = 1;
+   this->events.exclude_kernel = 1;
+   this->events.type = type;
+   this->events.config = config;
+   if (PerfCounter_openFds < PerfCounter_fdLimit) {
+      this->fd = perf_event_open(&this->events, pid, -1, -1, 0);
+   } else {
+      this->fd = -1;
+   }
+   if (this->fd != -1) {
+      PerfCounter_openFds++;
+   }
+   return this;
+}
+
+void PerfCounter_delete(PerfCounter* this) {
+   if (!this) {
+      return;
+   }
+   if (this->fd != -1) {
+      PerfCounter_openFds--;
+   }
+   close(this->fd);
+   free(this);
+}
+
+bool PerfCounter_read(PerfCounter* this) {
+   if (this->fd == -1) {
+      return false;
+   }
+   uint64_t value;
+   int r = read(this->fd, &value, sizeof(value));
+   if (r != sizeof(value)) {
+      close(this->fd);
+      this->fd = perf_event_open(&this->events, this->pid, -1, -1, 0);
+      return false;
+   }
+   this->prevValue = this->value;
+   this->value = value;
+   return true;
+}
diff --git a/linux/PerfCounter.h b/linux/PerfCounter.h
new file mode 100644
index 00000000..26352eca
--- /dev/null
+++ b/linux/PerfCounter.h
@@ -0,0 +1,54 @@
+/* Do not edit this file. It was automatically generated. */
+
+#ifndef HEADER_PerfCounter
+#define HEADER_PerfCounter
+/*
+ * This file is based on tiptop.
+ * by Erven ROHOU
+ * Copyright (c) 2011, 2012, 2014 Inria
+ * License: GNU General Public License version 2.
+ */
+ 
+
+
+#include <config.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <asm/unistd.h>
+#include <inttypes.h>
+#include <stdbool.h>
+// The sys_perf_counter_open syscall and header files changed names
+// between Linux 2.6.31 and 2.6.32. Do the mangling here.
+#ifdef HAVE_LINUX_PERF_COUNTER_H
+#include <linux/perf_counter.h>
+#define STRUCT_NAME perf_counter_attr
+#define SYSCALL_NUM __NR_perf_counter_open
+
+#elif HAVE_LINUX_PERF_EVENT_H
+#include <linux/perf_event.h>
+#define STRUCT_NAME perf_event_attr
+#define SYSCALL_NUM __NR_perf_event_open
+
+#else
+#error Sorry, performance counters not supported on this system.
+#endif
+
+typedef struct PerfCounter_ {
+   struct STRUCT_NAME events;
+   pid_t pid;
+   int fd;
+   uint64_t prevValue;
+   uint64_t value;
+} PerfCounter;
+
+#define PerfCounter_delta(pc_) ((pc_)->value - (pc_)->prevValue)
+
+
+extern int PerfCounter_openFds;
+PerfCounter* PerfCounter_new(pid_t pid, uint32_t type, uint64_t config);
+
+void PerfCounter_delete(PerfCounter* this);
+
+bool PerfCounter_read(PerfCounter* this);
+
+#endif