perfevent.cc

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/*
 * Copyright (c) 2012 ARM Limited
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 *
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 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
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 * modified or unmodified, in source code or in binary form.
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 * Redistribution and use in source and binary forms, with or without
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 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
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#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <syscall.h>
#include <unistd.h>
 
#include <cassert>
#include <cerrno>
#include <csignal>
#include <cstring>
 
#include "base/logging.hh"
#include "perfevent.hh"
 
namespace gem5
{
 
PerfKvmCounterConfig::PerfKvmCounterConfig(uint32_t type, uint64_t config)
{
    memset(&attr, 0, sizeof(attr));
 
    attr.size = PERF_ATTR_SIZE_VER0;
    attr.type = type;
    attr.config = config;
}
 
PerfKvmCounterConfig::~PerfKvmCounterConfig()
{
}
 
 
PerfKvmCounter::PerfKvmCounter(PerfKvmCounterConfig &config, pid_t tid)
    : fd(-1), ringBuffer(NULL), pageSize(-1)
{
    attach(config, tid, -1);
}
 
PerfKvmCounter::PerfKvmCounter(PerfKvmCounterConfig &config,
                         pid_t tid, const PerfKvmCounter &parent)
    : fd(-1), ringBuffer(NULL), pageSize(-1)
{
    attach(config, tid, parent);
}
 
PerfKvmCounter::PerfKvmCounter()
    : fd(-1), ringBuffer(NULL), pageSize(-1)
{
}
 
PerfKvmCounter::~PerfKvmCounter()
{
    if (attached())
        detach();
}
 
void
PerfKvmCounter::detach()
{
    assert(attached());
 
    if (munmap(ringBuffer, ringNumPages * pageSize) == -1)
        warn("PerfKvmCounter: Failed to unmap ring buffer (%i)\n",
             errno);
    close(fd);
 
    fd = -1;
    ringBuffer = NULL;
}
 
void
PerfKvmCounter::start()
{
    if (ioctl(PERF_EVENT_IOC_ENABLE, PERF_IOC_FLAG_GROUP) == -1)
        panic("KVM: Failed to enable performance counters (%i)\n", errno);
}
 
void
PerfKvmCounter::stop()
{
    if (ioctl(PERF_EVENT_IOC_DISABLE, PERF_IOC_FLAG_GROUP) == -1)
        panic("KVM: Failed to disable performance counters (%i)\n", errno);
}
 
void
PerfKvmCounter::period(uint64_t period)
{
    if (ioctl(PERF_EVENT_IOC_PERIOD, &period) == -1)
        panic("KVM: Failed to set period of performance counter (%i)\n", errno);
}
 
void
PerfKvmCounter::refresh(int refresh)
{
    if (ioctl(PERF_EVENT_IOC_REFRESH, refresh) == -1)
        panic("KVM: Failed to refresh performance counter (%i)\n", errno);
}
 
uint64_t
PerfKvmCounter::read() const
{
    uint64_t value;
 
    read(&value, sizeof(uint64_t));
    return value;
}
 
void
PerfKvmCounter::enableSignals(pid_t tid, int signal)
{
    struct f_owner_ex sigowner;
 
    sigowner.type = F_OWNER_TID;
    sigowner.pid = tid;
 
    if (fcntl(F_SETOWN_EX, &sigowner) == -1 ||
        fcntl(F_SETSIG, signal) == -1 ||
        fcntl(F_SETFL, O_ASYNC) == -1)
        panic("PerfKvmCounter: Failed to enable signals for counter (%i)\n",
              errno);
}
 
void
PerfKvmCounter::attach(PerfKvmCounterConfig &config,
                    pid_t tid, int group_fd)
{
    assert(!attached());
 
    fd = syscall(__NR_perf_event_open,
                 &config.attr, tid,
                 -1, // CPU (-1 => Any CPU that the task happens to run on)
                 group_fd,
                 0); // Flags
    if (fd == -1)
    {
        if (errno == EACCES)
        {
            panic("PerfKvmCounter::attach received error EACCESS.\n"
            "  This error may be caused by a too restrictive setting\n"
            "  in the file '/proc/sys/kernel/perf_event_paranoid'.\n"
            "  The default value was changed to 2 in kernel 4.6.\n"
            "  A value greater than 1 prevents gem5 from making\n"
            "  the syscall to perf_event_open.\n"
            "    Alternatively, you can set the usePerf flag of the KVM\n"
            "  CPU to False. Setting this flag to False will limit some\n"
            "  functionalities of KVM CPU, such as counting the number of\n"
            "  cycles and the number of instructions, as well as the\n"
            "  ability of exiting to gem5 after a certain amount of cycles\n"
            "  or instructions when using KVM CPU. An example can be found\n"
            "  here, configs/example/gem5_library/"
            "x86-ubuntu-run-with-kvm-no-perf.py.");
        }
        panic("PerfKvmCounter::attach failed (%i)\n", errno);
    }
 
    mmapPerf(1);
}
 
pid_t
PerfKvmCounter::sysGettid()
{
    return syscall(__NR_gettid);
}
 
void
PerfKvmCounter::mmapPerf(int pages)
{
    assert(attached());
    assert(ringBuffer == NULL);
 
    if (pageSize == -1) {
        pageSize = sysconf(_SC_PAGE_SIZE);
        if (pageSize == -1)
            panic("PerfKvmCounter: Failed to determine page size (%i)\n",
                  errno);
    }
 
    ringNumPages = pages + 1;
    ringBuffer = (struct perf_event_mmap_page *)mmap(
        NULL, ringNumPages * 4096,
        PROT_READ | PROT_WRITE, MAP_SHARED,
        fd, 0);
    if (ringBuffer == MAP_FAILED)
        panic("PerfKvmCounter: MMAP failed (%i)\n",
              errno);
}
 
int
PerfKvmCounter::fcntl(int cmd, long p1)
{
    assert(attached());
    return ::fcntl(fd, cmd, p1);
}
 
int
PerfKvmCounter::ioctl(int request, long p1)
{
    assert(attached());
    return ::ioctl(fd, request, p1);
}
 
void
PerfKvmCounter::read(void *buf, size_t size) const
{
    char *_buf = (char *)buf;
    size_t _size = size;
 
    assert(attached());
 
    do {
        ssize_t ret;
        ret = ::read(fd, _buf, _size);
        switch (ret) {
          case -1:
            if (errno != EAGAIN)
                panic("PerfKvmCounter::read failed (%i)\n", errno);
            break;
 
          case 0:
            panic("PerfKvmCounter::read unexpected EOF.\n");
 
          default:
            _size -= ret;
            _buf += ret;
            break;
        }
    } while (_size);
}
 
} // namespace gem5