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// Copyright (c) 2018-2023, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#if defined __GNUC__ && !defined _WIN32
#define HAVE_MLOCK 1
#endif
#include <unistd.h>
#if defined HAVE_MLOCK
#include <sys/mman.h>
#endif
#include "misc_log_ex.h"
#include "syncobj.h"
#include "mlocker.h"
#include <atomic>
#undef MONERO_DEFAULT_LOG_CATEGORY
#define MONERO_DEFAULT_LOG_CATEGORY "mlocker"
// did an mlock operation previously fail? we only
// want to log an error once and be done with it
static std::atomic<bool> previously_failed{ false };
static size_t query_page_size()
{
#if defined HAVE_MLOCK
long ret = sysconf(_SC_PAGESIZE);
if (ret <= 0)
{
MERROR("Failed to determine page size");
return 0;
}
return ret;
#else
#warning Missing query_page_size implementation
#endif
return 0;
}
static void do_lock(void *ptr, size_t len)
{
#if defined HAVE_MLOCK
int ret = mlock(ptr, len);
if (ret < 0 && !previously_failed.exchange(true))
MERROR("Error locking page at " << ptr << ": " << strerror(errno) << ", subsequent mlock errors will be silenced");
#else
#warning Missing do_lock implementation
#endif
}
static void do_unlock(void *ptr, size_t len)
{
#if defined HAVE_MLOCK
int ret = munlock(ptr, len);
// check whether we previously failed, but don't set it, this is just
// to pacify the errors of mlock()ing failed, in which case unlocking
// is also not going to work of course
if (ret < 0 && !previously_failed.load())
MERROR("Error unlocking page at " << ptr << ": " << strerror(errno));
#else
#warning Missing implementation of page size detection
#endif
}
namespace epee
{
size_t mlocker::page_size = 0;
size_t mlocker::num_locked_objects = 0;
boost::mutex &mlocker::mutex()
{
static boost::mutex *vmutex = new boost::mutex();
return *vmutex;
}
std::map<size_t, unsigned int> &mlocker::map()
{
static std::map<size_t, unsigned int> *vmap = new std::map<size_t, unsigned int>();
return *vmap;
}
size_t mlocker::get_page_size()
{
CRITICAL_REGION_LOCAL(mutex());
if (page_size == 0)
page_size = query_page_size();
return page_size;
}
mlocker::mlocker(void *ptr, size_t len): ptr(ptr), len(len)
{
lock(ptr, len);
}
mlocker::~mlocker()
{
try { unlock(ptr, len); }
catch (...) { /* ignore and do not propagate through the dtor */ }
}
void mlocker::lock(void *ptr, size_t len)
{
TRY_ENTRY();
size_t page_size = get_page_size();
if (page_size == 0)
return;
CRITICAL_REGION_LOCAL(mutex());
const size_t first = ((uintptr_t)ptr) / page_size;
const size_t last = (((uintptr_t)ptr) + len - 1) / page_size;
for (size_t page = first; page <= last; ++page)
lock_page(page);
++num_locked_objects;
CATCH_ENTRY_L1("mlocker::lock", void());
}
void mlocker::unlock(void *ptr, size_t len)
{
TRY_ENTRY();
size_t page_size = get_page_size();
if (page_size == 0)
return;
CRITICAL_REGION_LOCAL(mutex());
const size_t first = ((uintptr_t)ptr) / page_size;
const size_t last = (((uintptr_t)ptr) + len - 1) / page_size;
for (size_t page = first; page <= last; ++page)
unlock_page(page);
--num_locked_objects;
CATCH_ENTRY_L1("mlocker::lock", void());
}
size_t mlocker::get_num_locked_pages()
{
CRITICAL_REGION_LOCAL(mutex());
return map().size();
}
size_t mlocker::get_num_locked_objects()
{
CRITICAL_REGION_LOCAL(mutex());
return num_locked_objects;
}
void mlocker::lock_page(size_t page)
{
std::pair<std::map<size_t, unsigned int>::iterator, bool> p = map().insert(std::make_pair(page, 1));
if (p.second)
{
do_lock((void*)(page * page_size), page_size);
}
else
{
++p.first->second;
}
}
void mlocker::unlock_page(size_t page)
{
std::map<size_t, unsigned int>::iterator i = map().find(page);
if (i == map().end())
{
MERROR("Attempt to unlock unlocked page at " << (void*)(page * page_size));
}
else
{
if (!--i->second)
{
map().erase(i);
do_unlock((void*)(page * page_size), page_size);
}
}
}
}
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