Merge pull request #781 from palmtenor/api

C++ helper class for BCC

.clang-format

 ---
 BasedOnStyle: Google
 AllowShortIfStatementsOnASingleLine: false
+AllowShortLoopsOnASingleLine: false
 IndentCaseLabels: false
 AccessModifierOffset: -2

examples/CMakeLists.txt

 set(EXAMPLE_PROGRAMS hello_world.py)
 install(PROGRAMS ${EXAMPLE_PROGRAMS} DESTINATION share/bcc/examples)
 
+add_subdirectory(cpp)
+add_subdirectory(lua)
 add_subdirectory(networking)
 add_subdirectory(tracing)
-add_subdirectory(lua)
\ No newline at end of file

examples/cpp/CMakeLists.txt

+# Copyright (c) Facebook, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+include_directories(${CMAKE_SOURCE_DIR}/src/cc)
+
+add_executable(HelloWorld HelloWorld.cc)
+target_link_libraries(HelloWorld bcc-static)
+install (TARGETS HelloWorld DESTINATION share/bcc/examples/cpp)
+
+add_executable(CPUDistribution CPUDistribution.cc)
+target_link_libraries(CPUDistribution bcc-static)
+install (TARGETS CPUDistribution DESTINATION share/bcc/examples/cpp)
+
+add_executable(RecordMySQLQuery RecordMySQLQuery.cc)
+target_link_libraries(RecordMySQLQuery bcc-static)
+install (TARGETS RecordMySQLQuery DESTINATION share/bcc/examples/cpp)
+
+add_executable(TCPSendStack TCPSendStack.cc)
+target_link_libraries(TCPSendStack bcc-static)
+install (TARGETS TCPSendStack DESTINATION share/bcc/examples/cpp)
+
+add_executable(RandomRead RandomRead.cc)
+target_link_libraries(RandomRead bcc-static)
+install (TARGETS RandomRead DESTINATION share/bcc/examples/cpp)

examples/cpp/CPUDistribution.cc

+/*
+ * CPUDistribution Show load distribution across CPU cores during a period of
+ *                 time. For Linux, uses BCC, eBPF. Embedded C.
+ *
+ * Basic example of BCC and kprobes.
+ *
+ * USAGE: CPUDistribution [duration]
+ *
+ * Copyright (c) Facebook, Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+
+#include <unistd.h>
+#include <cstdlib>
+#include <iomanip>
+#include <iostream>
+#include <string>
+
+#include "BPF.h"
+
+const std::string BPF_PROGRAM = R"(
+#include <linux/sched.h>
+#include <uapi/linux/ptrace.h>
+
+BPF_HASH(pid_to_cpu, pid_t, int);
+BPF_HASH(pid_to_ts, pid_t, uint64_t);
+BPF_HASH(cpu_time, int, uint64_t);
+
+int task_switch_event(struct pt_regs *ctx, struct task_struct *prev) {
+  pid_t prev_pid = prev->pid;
+  int* prev_cpu = pid_to_cpu.lookup(&prev_pid);
+  uint64_t* prev_ts = pid_to_ts.lookup(&prev_pid);
+
+  pid_t cur_pid = bpf_get_current_pid_tgid();
+  int cur_cpu = bpf_get_smp_processor_id();
+  uint64_t cur_ts = bpf_ktime_get_ns();
+
+  uint64_t this_cpu_time = 0;
+  if (prev_ts) {
+    pid_to_ts.delete(&prev_pid);
+    this_cpu_time = (cur_ts - *prev_ts);
+  }
+  if (prev_cpu) {
+    pid_to_cpu.delete(&prev_pid);
+    if (this_cpu_time > 0) {
+      int cpu_key = *prev_cpu;
+      uint64_t* history_time = cpu_time.lookup(&cpu_key);
+      if (history_time)
+        this_cpu_time += *history_time;
+      cpu_time.update(&cpu_key, &this_cpu_time);
+    }
+  }
+
+  pid_to_cpu.update(&cur_pid, &cur_cpu);
+  pid_to_ts.update(&cur_pid, &cur_ts);
+
+  return 0;
+}
+)";
+
+int main(int argc, char** argv) {
+  ebpf::BPF bpf;
+  auto init_res = bpf.init(BPF_PROGRAM);
+  if (std::get<0>(init_res) != 0) {
+    std::cerr << std::get<1>(init_res) << std::endl;
+    return 1;
+  }
+
+  auto attach_res =
+      bpf.attach_kprobe("finish_task_switch", "task_switch_event");
+  if (std::get<0>(attach_res) != 0) {
+    std::cerr << std::get<1>(attach_res) << std::endl;
+    return 1;
+  }
+
+  int probe_time = 10;
+  if (argc == 2) {
+    probe_time = atoi(argv[1]);
+  }
+  std::cout << "Probing for " << probe_time << " seconds" << std::endl;
+  sleep(probe_time);
+
+  auto table = bpf.get_hash_table<int, uint64_t>("cpu_time");
+  auto num_cores = sysconf(_SC_NPROCESSORS_ONLN);
+  for (int i = 0; i < num_cores; i++) {
+    std::cout << "CPU " << std::setw(2) << i << " worked for ";
+    std::cout << (table[i] / 1000000.0) << " ms." << std::endl;
+  }
+
+  auto detach_res = bpf.detach_kprobe("finish_task_switch");
+  if (std::get<0>(detach_res) != 0) {
+    std::cerr << std::get<1>(detach_res) << std::endl;
+    return 1;
+  }
+
+  return 0;
+}

examples/cpp/HelloWorld.cc

+/*
+ * Copyright (c) Facebook, Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+
+#include <unistd.h>
+#include <fstream>
+#include <iostream>
+#include <string>
+
+#include "BPF.h"
+
+const std::string BPF_PROGRAM = R"(
+int on_sys_clone(void *ctx) {
+  bpf_trace_printk("Hello, World! Here I did a sys_clone call!\n");
+  return 0;
+}
+)";
+
+int main() {
+  ebpf::BPF bpf;
+  auto init_res = bpf.init(BPF_PROGRAM);
+  if (std::get<0>(init_res) != 0) {
+    std::cerr << std::get<1>(init_res) << std::endl;
+    return 1;
+  }
+
+  std::ifstream pipe("/sys/kernel/debug/tracing/trace_pipe");
+  std::string line;
+
+  auto attach_res = bpf.attach_kprobe("sys_clone", "on_sys_clone");
+  if (std::get<0>(attach_res) != 0) {
+    std::cerr << std::get<1>(attach_res) << std::endl;
+    return 1;
+  }
+
+  while (true) {
+    if (std::getline(pipe, line)) {
+      std::cout << line << std::endl;
+      // Detach the probe if we got at least one line.
+      auto detach_res = bpf.detach_kprobe("sys_clone");
+      if (std::get<0>(detach_res) != 0) {
+        std::cerr << std::get<1>(detach_res) << std::endl;
+        return 1;
+      }
+      break;
+    } else {
+      std::cout << "Waiting for a sys_clone event" << std::endl;
+      sleep(1);
+    }
+  }
+
+  return 0;
+}

examples/cpp/RandomRead.cc

+/*
+ * RandomRead Monitor random number read events.
+ *            For Linux, uses BCC, eBPF. Embedded C.
+ *
+ * Basic example of BCC Tracepoint and perf buffer.
+ *
+ * USAGE: RandomRead
+ *
+ * Copyright (c) Facebook, Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+
+#include <signal.h>
+#include <iostream>
+
+#include "BPF.h"
+
+const std::string BPF_PROGRAM = R"(
+#include <linux/sched.h>
+#include <uapi/linux/ptrace.h>
+
+struct urandom_read_args {
+  // See /sys/kernel/debug/tracing/events/random/urandom_read/format
+  uint64_t common__unused;
+  int got_bits;
+  int pool_left;
+  int input_left;
+};
+
+struct event_t {
+  int pid;
+  char comm[16];
+  int got_bits;
+};
+
+BPF_PERF_OUTPUT(events);
+
+int on_urandom_read(struct urandom_read_args* attr) {
+  struct event_t event = {};
+  event.pid = bpf_get_current_pid_tgid();
+  bpf_get_current_comm(&event.comm, sizeof(event.comm));
+  event.got_bits = attr->got_bits;
+
+  events.perf_submit(attr, &event, sizeof(event));
+  return 0;
+}
+)";
+
+// Define the same struct to use in user space.
+struct event_t {
+  int pid;
+  char comm[16];
+  int got_bits;
+};
+
+void handle_output(void* cb_cookie, void* data, int data_size) {
+  auto event = static_cast<event_t*>(data);
+  std::cout << "PID: " << event->pid << " (" << event->comm << ") "
+            << "Read " << event->got_bits << " bits" << std::endl;
+}
+
+ebpf::BPF* bpf;
+
+void signal_handler(int s) {
+  std::cerr << "Terminating..." << std::endl;
+  delete bpf;
+  exit(0);
+}
+
+int main(int argc, char** argv) {
+  bpf = new ebpf::BPF();
+  auto init_res = bpf->init(BPF_PROGRAM);
+  if (std::get<0>(init_res) != 0) {
+    std::cerr << std::get<1>(init_res) << std::endl;
+    return 1;
+  }
+
+  auto attach_res =
+      bpf->attach_tracepoint("random:urandom_read", "on_urandom_read");
+  if (std::get<0>(attach_res) != 0) {
+    std::cerr << std::get<1>(attach_res) << std::endl;
+    return 1;
+  }
+
+  auto open_res = bpf->open_perf_buffer("events", &handle_output);
+  if (std::get<0>(open_res) != 0) {
+    std::cerr << std::get<1>(open_res) << std::endl;
+    return 1;
+  }
+
+  signal(SIGINT, signal_handler);
+  std::cout << "Started tracing, hit Ctrl-C to terminate." << std::endl;
+  while (true)
+    bpf->poll_perf_buffer("events");
+
+  return 0;
+}

examples/cpp/RecordMySQLQuery.cc

+/*
+ * RecordMySQLQuery Record MySQL queries by probing the alloc_query() function
+ *                  in mysqld. For Linux, uses BCC, eBPF. Embedded C.
+ *
+ * Basic example of BCC and uprobes.
+ *
+ * Copyright (c) Facebook, Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+
+#include <unistd.h>
+#include <algorithm>
+#include <cstdlib>
+#include <iostream>
+#include <string>
+
+#include "BPF.h"
+
+const std::string BPF_PROGRAM = R"(
+#include <linux/ptrace.h>
+
+struct query_probe_t {
+  uint64_t ts;
+  pid_t pid;
+  char query[100];
+};
+
+BPF_HASH(queries, struct query_probe_t, int);
+
+int probe_mysql_query(struct pt_regs *ctx, void* thd, char* query, size_t len) {
+  if (query) {
+    struct query_probe_t key = {};
+
+    key.ts = bpf_ktime_get_ns();
+    key.pid = bpf_get_current_pid_tgid();
+
+    bpf_probe_read(&key.query, sizeof(key.query), query);
+
+    int one = 1;
+    queries.update(&key, &one);
+  }
+  return 0;
+}
+)";
+const std::string ALLOC_QUERY_FUNC = "_Z11alloc_queryP3THDPKcj";
+
+// Define the same struct to use in user space.
+struct query_probe_t {
+  uint64_t ts;
+  pid_t pid;
+  char query[100];
+};
+
+int main(int argc, char** argv) {
+  if (argc < 2) {
+    std::cout << "USAGE: RecordMySQLQuery PATH_TO_MYSQLD [duration]"
+              << std::endl;
+    exit(1);
+  }
+
+  std::string mysql_path(argv[1]);
+  std::cout << "Using mysqld path: " << mysql_path << std::endl;
+
+  ebpf::BPF bpf;
+  auto init_res = bpf.init(BPF_PROGRAM);
+  if (std::get<0>(init_res) != 0) {
+    std::cerr << std::get<1>(init_res) << std::endl;
+    return 1;
+  }
+
+  auto attach_res =
+      bpf.attach_uprobe(mysql_path, ALLOC_QUERY_FUNC, "probe_mysql_query");
+  if (std::get<0>(attach_res) != 0) {
+    std::cerr << std::get<1>(attach_res) << std::endl;
+    return 1;
+  }
+
+  int probe_time = 10;
+  if (argc >= 3)
+    probe_time = atoi(argv[2]);
+  std::cout << "Probing for " << probe_time << " seconds" << std::endl;
+  sleep(probe_time);
+
+  auto table_handle = bpf.get_hash_table<query_probe_t, int>("queries");
+  auto table = table_handle.get_table_offline();
+  std::sort(table.begin(), table.end(), [](std::pair<query_probe_t, int> a,
+                                           std::pair<query_probe_t, int> b) {
+    return a.first.ts < b.first.ts;
+  });
+  std::cout << table.size() << " queries recorded:" << std::endl;
+  for (auto it : table) {
+    std::cout << "Time: " << it.first.ts << " PID: " << it.first.pid
+              << " Query: " << it.first.query << std::endl;
+  }
+
+  auto detach_res = bpf.detach_uprobe(mysql_path, ALLOC_QUERY_FUNC);
+  if (std::get<0>(detach_res) != 0) {
+    std::cerr << std::get<1>(detach_res) << std::endl;
+    return 1;
+  }
+
+  return 0;
+}

examples/cpp/TCPSendStack.cc

+/*
+ * TCPSendStack Summarize tcp_sendmsg() calling stack traces.
+ *              For Linux, uses BCC, eBPF. Embedded C.
+ *
+ * Basic example of BCC in-kernel stack trace dedup.
+ *
+ * USAGE: TCPSendStack [duration]
+ *
+ * Copyright (c) Facebook, Inc.
+ * Licensed under the Apache License, Version 2.0 (the "License")
+ */
+
+#include <unistd.h>
+#include <algorithm>
+#include <iostream>
+
+#include "BPF.h"
+
+const std::string BPF_PROGRAM = R"(
+#include <linux/sched.h>
+#include <uapi/linux/ptrace.h>
+
+struct stack_key_t {
+  int pid;
+  char name[16];
+  int user_stack;
+  int kernel_stack;
+};
+
+BPF_STACK_TRACE(stack_traces, 10240)
+BPF_HASH(counts, struct stack_key_t, uint64_t);
+
+int on_tcp_send(struct pt_regs *ctx) {
+  struct stack_key_t key = {};
+  key.pid = bpf_get_current_pid_tgid();
+  bpf_get_current_comm(&key.name, sizeof(key.name));
+  key.kernel_stack = stack_traces.get_stackid(ctx, BPF_F_REUSE_STACKID);
+  key.user_stack = stack_traces.get_stackid(
+    ctx, BPF_F_REUSE_STACKID | BPF_F_USER_STACK
+  );
+
+  u64 zero = 0, *val;
+  val = counts.lookup_or_init(&key, &zero);
+  (*val)++;
+
+  return 0;
+}
+)";
+
+// Define the same struct to use in user space.
+struct stack_key_t {
+  int pid;
+  char name[16];
+  int user_stack;
+  int kernel_stack;
+};
+
+int main(int argc, char** argv) {
+  ebpf::BPF bpf;
+  auto init_res = bpf.init(BPF_PROGRAM);
+  if (std::get<0>(init_res) != 0) {
+    std::cerr << std::get<1>(init_res) << std::endl;
+    return 1;
+  }
+
+  auto attach_res = bpf.attach_kprobe("tcp_sendmsg", "on_tcp_send");
+  if (std::get<0>(attach_res) != 0) {
+    std::cerr << std::get<1>(attach_res) << std::endl;
+    return 1;
+  }
+
+  int probe_time = 10;
+  if (argc == 2) {
+    probe_time = atoi(argv[1]);
+  }
+  std::cout << "Probing for " << probe_time << " seconds" << std::endl;
+  sleep(probe_time);
+
+  auto table =
+      bpf.get_hash_table<stack_key_t, uint64_t>("counts").get_table_offline();
+  std::sort(table.begin(), table.end(), [](std::pair<stack_key_t, uint64_t> a,
+                                           std::pair<stack_key_t, uint64_t> b) {
+    return a.second < b.second;
+  });
+  auto stacks = bpf.get_stack_table("stack_traces");
+
+  for (auto it : table) {
+    std::cout << "PID: " << it.first.pid << " (" << it.first.name << ") "
+              << "made " << it.second
+              << " TCP sends on following stack: " << std::endl;
+    std::cout << "  Kernel Stack:" << std::endl;
+    if (it.first.kernel_stack >= 0) {
+      auto syms = stacks.get_stack_symbol(it.first.kernel_stack, -1);
+      for (auto sym : syms)
+        std::cout << "    " << sym << std::endl;
+    } else
+      std::cout << "    " << it.first.kernel_stack << std::endl;
+    std::cout << "  User Stack:" << std::endl;
+    if (it.first.user_stack >= 0) {
+      auto syms = stacks.get_stack_symbol(it.first.user_stack, it.first.pid);
+      for (auto sym : syms)
+        std::cout << "    " << sym << std::endl;
+    } else
+      std::cout << "    " << it.first.user_stack << std::endl;
+  }
+
+  auto detach_res = bpf.detach_kprobe("tcp_sendmsg");
+  if (std::get<0>(detach_res) != 0) {
+    std::cerr << std::get<1>(detach_res) << std::endl;
+    return 1;
+  }
+
+  return 0;
+}

src/cc/BPF.h

+/*
+ * Copyright (c) 2016 Facebook, Inc.
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include <cctype>
+#include <memory>
+#include <string>
+
+#include "BPFTable.h"
+#include "bcc_syms.h"
+#include "bpf_module.h"
+#include "common.h"
+#include "compat/linux/bpf.h"
+#include "libbpf.h"
+
+namespace ebpf {
+
+enum class bpf_attach_type {
+  probe_entry,
+  probe_return
+};
+
+struct open_probe_t {
+  void* reader_ptr;
+  std::string func;
+};
+
+class BPF {
+public:
+  static const int BPF_MAX_STACK_DEPTH = 127;
+
+  explicit BPF(unsigned int flag = 0) : bpf_module_(new BPFModule(flag)) {}
+  StatusTuple init(const std::string& bpf_program,
+                   std::vector<std::string> cflags = {});
+
+  ~BPF();
+  StatusTuple detach_all();
+
+  StatusTuple attach_kprobe(
+      const std::string& kernel_func, const std::string& probe_func,
+      bpf_attach_type attach_type = bpf_attach_type::probe_entry,
+      pid_t pid = -1, int cpu = 0, int group_fd = -1,
+      perf_reader_cb cb = nullptr, void* cb_cookie = nullptr);
+  StatusTuple detach_kprobe(
+      const std::string& kernel_func,
+      bpf_attach_type attach_type = bpf_attach_type::probe_entry);
+
+  StatusTuple attach_uprobe(
+      const std::string& binary_path, const std::string& symbol,
+      const std::string& probe_func, uint64_t symbol_addr = 0,
+      bpf_attach_type attach_type = bpf_attach_type::probe_entry,
+      pid_t pid = -1, int cpu = 0, int group_fd = -1,
+      perf_reader_cb cb = nullptr, void* cb_cookie = nullptr);
+  StatusTuple detach_uprobe(
+      const std::string& binary_path, const std::string& symbol,
+      uint64_t symbol_addr = 0,
+      bpf_attach_type attach_type = bpf_attach_type::probe_entry);
+
+  StatusTuple attach_tracepoint(const std::string& tracepoint,
+                                const std::string& probe_func,
+                                pid_t pid = -1, int cpu = 0, int group_fd = -1,
+                                perf_reader_cb cb = nullptr,
+                                void* cb_cookie = nullptr);
+  StatusTuple detach_tracepoint(const std::string& tracepoint);
+
+  template <class KeyType, class ValueType>
+  BPFHashTable<KeyType, ValueType> get_hash_table(const std::string& name) {
+    return BPFHashTable<KeyType, ValueType>(bpf_module_.get(), name);
+  }
+
+  BPFStackTable get_stack_table(const std::string& name) {
+    return BPFStackTable(bpf_module_.get(), name);
+  }
+
+  StatusTuple open_perf_buffer(const std::string& name, perf_reader_raw_cb cb,
+                               void* cb_cookie = nullptr);
+  StatusTuple close_perf_buffer(const std::string& name);
+  void poll_perf_buffer(const std::string& name, int timeout = -1);
+
+private:
+  StatusTuple load_func(const std::string& func_name, enum bpf_prog_type type,
+                        int& fd);
+  StatusTuple unload_func(const std::string& func_name);
+
+  std::string get_kprobe_event(const std::string& kernel_func,
+                               bpf_attach_type type);
+  std::string get_uprobe_event(const std::string& binary_path, uint64_t offset,
+                               bpf_attach_type type);
+
+  StatusTuple detach_kprobe_event(const std::string& event, open_probe_t& attr);
+  StatusTuple detach_uprobe_event(const std::string& event, open_probe_t& attr);
+  StatusTuple detach_tracepoint_event(const std::string& tracepoint,
+                                      open_probe_t& attr);
+
+  std::string attach_type_debug(bpf_attach_type type) {
+    switch (type) {
+    case bpf_attach_type::probe_entry:
+      return "";
+    case bpf_attach_type::probe_return:
+      return "return ";
+    }
+    return "ERROR";
+  }
+
+  std::string attach_type_prefix(bpf_attach_type type) {
+    switch (type) {
+    case bpf_attach_type::probe_entry:
+      return "p";
+    case bpf_attach_type::probe_return:
+      return "r";
+    }
+    return "ERROR";
+  }
+
+  static bool kprobe_event_validator(char c) {
+    return (c != '+') && (c != '.');
+  }
+
+  static bool uprobe_path_validator(char c) {
+    return std::isalpha(c) || std::isdigit(c) || (c == '_');
+  }
+
+  StatusTuple check_binary_symbol(const std::string& binary_path,
+                                  const std::string& symbol,
+                                  uint64_t symbol_addr, bcc_symbol* output);
+
+  std::unique_ptr<BPFModule> bpf_module_;
+
+  std::map<std::string, int> funcs_;
+
+  std::map<std::string, open_probe_t> kprobes_;
+  std::map<std::string, open_probe_t> uprobes_;
+  std::map<std::string, open_probe_t> tracepoints_;
+  std::map<std::string, BPFPerfBuffer*> perf_buffers_;
+};
+
+}  // namespace ebpf

src/cc/BPFTable.cc

+/*
+ * Copyright (c) 2016 Facebook, Inc.
+ *
+ * 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.
+ */
+
+#include <errno.h>
+#include <unistd.h>
+#include <cstring>
+#include <iostream>
+
+#include "BPFTable.h"
+
+#include "bcc_syms.h"
+#include "common.h"
+#include "exception.h"
+#include "libbpf.h"
+#include "perf_reader.h"
+
+namespace ebpf {
+
+BPFStackTable::~BPFStackTable() {
+  for (auto it : pid_sym_)
+    bcc_free_symcache(it.second, it.first);
+}
+
+std::vector<intptr_t> BPFStackTable::get_stack_addr(int stack_id) {
+  std::vector<intptr_t> res;
+  stacktrace_t stack;
+  if (!lookup(&stack_id, &stack))
+    return res;
+  for (int i = 0; (i < BPF_MAX_STACK_DEPTH) && (stack.ip[i] != 0); i++)
+    res.push_back(stack.ip[i]);
+  return res;
+}
+
+std::vector<std::string> BPFStackTable::get_stack_symbol(int stack_id,
+                                                         int pid) {
+  auto addresses = get_stack_addr(stack_id);
+  std::vector<std::string> res;
+  res.reserve(addresses.size());
+
+  if (pid < 0)
+    pid = -1;
+  if (pid_sym_.find(pid) == pid_sym_.end())
+    pid_sym_[pid] = bcc_symcache_new(pid);
+  void* cache = pid_sym_[pid];
+
+  bcc_symbol symbol;
+  for (auto addr : addresses)
+    if (bcc_symcache_resolve(cache, addr, &symbol) != 0)
+      res.push_back("[UNKNOWN]");
+    else
+      res.push_back(symbol.demangle_name);
+
+  return res;
+}
+
+StatusTuple BPFPerfBuffer::open_on_cpu(perf_reader_raw_cb cb, int cpu,
+                                       void* cb_cookie) {
+  if (cpu_readers_.find(cpu) != cpu_readers_.end())
+    return mkstatus(-1, "Perf buffer already open on CPU %d", cpu);
+  auto reader =
+      static_cast<perf_reader*>(bpf_open_perf_buffer(cb, cb_cookie, -1, cpu));
+  if (reader == nullptr)
+    return mkstatus(-1, "Unable to construct perf reader");
+  int reader_fd = perf_reader_fd(reader);
+  if (!update(&cpu, &reader_fd)) {
+    perf_reader_free(static_cast<void*>(reader));
+    return mkstatus(-1, "Unable to open perf buffer on CPU %d: %s", cpu,
+                    strerror(errno));
+  }
+  cpu_readers_[cpu] = static_cast<perf_reader*>(reader);
+  return mkstatus(0);
+}
+
+StatusTuple BPFPerfBuffer::open(perf_reader_raw_cb cb, void* cb_cookie) {
+  for (int i = 0; i < sysconf(_SC_NPROCESSORS_ONLN); i++)
+    TRY2(open_on_cpu(cb, i, cb_cookie));
+  return mkstatus(0);
+}
+
+StatusTuple BPFPerfBuffer::close_on_cpu(int cpu) {
+  auto it = cpu_readers_.find(cpu);
+  if (it == cpu_readers_.end())
+    return mkstatus(0);
+  perf_reader_free(static_cast<void*>(it->second));
+  if (!remove(const_cast<int*>(&(it->first))))
+    return mkstatus(-1, "Unable to close perf buffer on CPU %d", it->first);
+  cpu_readers_.erase(it);
+  return mkstatus(0);
+}
+
+StatusTuple BPFPerfBuffer::close() {
+  std::string errors;
+  bool has_error = false;
+  for (int i = 0; i < sysconf(_SC_NPROCESSORS_ONLN); i++) {
+    auto res = close_on_cpu(i);
+    if (std::get<0>(res) != 0) {
+      errors += "Failed to close CPU" + std::to_string(i) + " perf buffer: ";
+      errors += std::get<1>(res) + "\n";
+      has_error = true;
+    }
+  }
+  if (has_error)
+    return mkstatus(-1, errors);
+  return mkstatus(0);
+}
+
+void BPFPerfBuffer::poll(int timeout) {
+  perf_reader* readers[cpu_readers_.size()];
+  int i = 0;
+  for (auto it : cpu_readers_)
+    readers[i++] = it.second;
+  perf_reader_poll(cpu_readers_.size(), readers, timeout);
+}
+
+BPFPerfBuffer::~BPFPerfBuffer() {
+  auto res = close();
+  if (std::get<0>(res) != 0)
+    std::cerr << "Failed to close all perf buffer on destruction: "
+              << std::get<1>(res) << std::endl;
+}
+
+}  // namespace ebpf

src/cc/BPFTable.h

+/*
+ * Copyright (c) 2016 Facebook, Inc.
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include <exception>
+#include <map>
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "bpf_module.h"
+#include "common.h"
+#include "libbpf.h"
+#include "perf_reader.h"
+
+namespace ebpf {
+
+template <class KeyType, class ValueType>
+class BPFTableBase {
+public:
+  size_t capacity() { return capacity_; }
+
+protected:
+  BPFTableBase(BPFModule* bpf_module, const std::string& name) {
+    size_t id_ = bpf_module->table_id(name);
+    if (id_ >= bpf_module->num_tables())
+      throw std::invalid_argument("Table " + name + " does not exist");
+    fd_ = bpf_module->table_fd(id_);
+    capacity_ = bpf_module->table_max_entries(id_);
+  };
+
+  bool lookup(KeyType* key, ValueType* value) {
+    return bpf_lookup_elem(fd_, static_cast<void*>(key),
+                           static_cast<void*>(value)) >= 0;
+  }
+
+  bool next(KeyType* key, KeyType* next_key) {
+    return bpf_get_next_key(fd_, static_cast<void*>(key),
+                            static_cast<void*>(next_key)) >= 0;
+  }
+
+  bool update(KeyType* key, ValueType* value) {
+    return bpf_update_elem(fd_, static_cast<void*>(key),
+                           static_cast<void*>(value), 0) >= 0;
+  }
+
+  bool remove(KeyType* key) {
+    return bpf_delete_elem(fd_, static_cast<void*>(key)) >= 0;
+  }
+
+  int fd_;
+  size_t capacity_;
+};
+
+template <class KeyType, class ValueType>
+class BPFHashTable : protected BPFTableBase<KeyType, ValueType> {
+public:
+  BPFHashTable(BPFModule* bpf_module, const std::string& name)
+      : BPFTableBase<KeyType, ValueType>(bpf_module, name) {}
+
+  ValueType get_value(const KeyType& key) {
+    ValueType res;
+    if (!this->lookup(const_cast<KeyType*>(&key), &res))
+      throw std::invalid_argument("Key does not exist in the table");
+    return res;
+  }
+
+  ValueType operator[](const KeyType& key) { return get_value(key); }
+
+  std::vector<std::pair<KeyType, ValueType>> get_table_offline() {
+    std::vector<std::pair<KeyType, ValueType>> res;
+
+    KeyType cur, nxt;
+    ValueType value;
+
+    while (true) {
+      if (!this->next(&cur, &nxt))
+        break;
+      if (!this->lookup(&nxt, &value))
+        break;
+      res.emplace_back(nxt, value);
+      std::swap(cur, nxt);
+    }
+
+    return res;
+  }
+};
+
+// From src/cc/export/helpers.h
+static const int BPF_MAX_STACK_DEPTH = 127;
+struct stacktrace_t {
+  intptr_t ip[BPF_MAX_STACK_DEPTH];
+};
+
+class BPFStackTable : protected BPFTableBase<int, stacktrace_t> {
+public:
+  BPFStackTable(BPFModule* bpf_module, const std::string& name)
+      : BPFTableBase<int, stacktrace_t>(bpf_module, name) {}
+  ~BPFStackTable();
+
+  std::vector<intptr_t> get_stack_addr(int stack_id);
+  std::vector<std::string> get_stack_symbol(int stack_id, int pid);
+
+private:
+  std::map<int, void*> pid_sym_;
+};
+
+class BPFPerfBuffer : protected BPFTableBase<int, int> {
+public:
+  BPFPerfBuffer(BPFModule* bpf_module, const std::string& name)
+      : BPFTableBase<int, int>(bpf_module, name) {}
+  ~BPFPerfBuffer();
+
+  StatusTuple open(perf_reader_raw_cb cb, void* cb_cookie);
+  StatusTuple close();
+  void poll(int timeout);
+
+private:
+  StatusTuple open_on_cpu(perf_reader_raw_cb cb, int cpu, void* cb_cookie);
+  StatusTuple close_on_cpu(int cpu);
+
+  std::map<int, perf_reader*> cpu_readers_;
+};
+
+}  // namespace ebpf

src/cc/CMakeLists.txt

@@ -35,12 +35,12 @@ if (CMAKE_COMPILER_IS_GNUCC AND LIBCLANG_ISSTATIC)
   endif()
 endif()
 
-add_library(bcc-shared SHARED bpf_common.cc bpf_module.cc libbpf.c perf_reader.c shared_table.cc exported_files.cc bcc_elf.c bcc_perf_map.c bcc_proc.c bcc_syms.cc usdt_args.cc usdt.cc)
+add_library(bcc-shared SHARED bpf_common.cc bpf_module.cc libbpf.c perf_reader.c shared_table.cc exported_files.cc bcc_elf.c bcc_perf_map.c bcc_proc.c bcc_syms.cc usdt_args.cc usdt.cc BPF.cc BPFTable.cc)
 set_target_properties(bcc-shared PROPERTIES VERSION ${REVISION_LAST} SOVERSION 0)
 set_target_properties(bcc-shared PROPERTIES OUTPUT_NAME bcc)
 
 add_library(bcc-loader-static libbpf.c perf_reader.c bcc_elf.c bcc_perf_map.c bcc_proc.c)
-add_library(bcc-static STATIC bpf_common.cc bpf_module.cc shared_table.cc exported_files.cc bcc_syms.cc usdt_args.cc usdt.cc)
+add_library(bcc-static STATIC bpf_common.cc bpf_module.cc shared_table.cc exported_files.cc bcc_syms.cc usdt_args.cc usdt.cc BPF.cc BPFTable.cc)
 set_target_properties(bcc-static PROPERTIES OUTPUT_NAME bcc)
 
 set(llvm_raw_libs bitwriter bpfcodegen irreader linker
@@ -63,7 +63,7 @@ target_link_libraries(bcc-static b_frontend clang_frontend bcc-loader-static ${c
 
 install(TARGETS bcc-shared LIBRARY COMPONENT libbcc
   DESTINATION ${CMAKE_INSTALL_LIBDIR})
-install(FILES bpf_common.h bpf_module.h bcc_syms.h libbpf.h perf_reader.h COMPONENT libbcc
+install(FILES bpf_common.h bpf_module.h bcc_syms.h common.h exception.h libbpf.h perf_reader.h BPF.h BPFTable.h COMPONENT libbcc
   DESTINATION include/bcc)
 install(DIRECTORY compat/linux/ COMPONENT libbcc
   DESTINATION include/bcc/compat/linux

src/cc/exception.h

@@ -37,6 +37,12 @@ static inline std::tuple<int, std::string> mkstatus(int ret, const char *msg) {
   return std::make_tuple(ret, std::string(msg));
 }
 
+static inline std::tuple<int, std::string> mkstatus(
+  int ret, const std::string& msg
+) {
+  return std::make_tuple(ret, msg);
+}
+
 static inline std::tuple<int, std::string> mkstatus(int ret) {
   return std::make_tuple(ret, std::string());
 }