os_macos.cpp

/*
 * Copyright 2018 Andrei Pangin
 *
 * 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.
 */

#ifdef __APPLE__

#include <libkern/OSByteOrder.h>
#include <libproc.h>
#include <mach/mach.h>
#include <mach/mach_host.h>
#include <mach/mach_time.h>
#include <mach/processor_info.h>
#include <pthread.h>
#include <sys/mman.h>
#include <sys/sysctl.h>
#include <sys/time.h>
#include <sys/times.h>
#include <time.h>
#include <unistd.h>
#include "os.h"


class MacThreadList : public ThreadList {
  private:
    task_t _task;
    thread_array_t _thread_array;
    unsigned int _thread_count;
    unsigned int _thread_index;

    void ensureThreadArray() {
        if (_thread_array == NULL) {
            _thread_count = 0;
            _thread_index = 0;
            task_threads(_task, &_thread_array, &_thread_count);
        }
    }

  public:
    MacThreadList() : _task(mach_task_self()), _thread_array(NULL), _thread_count(0), _thread_index(0) {
    }

    ~MacThreadList() {
        rewind();
    }

    void rewind() {
        if (_thread_array != NULL) {
            for (int i = 0; i < _thread_count; i++) {
                mach_port_deallocate(_task, _thread_array[i]);
            }
            vm_deallocate(_task, (vm_address_t)_thread_array, _thread_count * sizeof(thread_t));
            _thread_array = NULL;
        }
    }

    int next() {
        ensureThreadArray();
        if (_thread_index < _thread_count) {
            return (int)_thread_array[_thread_index++];
        }
        return -1;
    }

    int size() {
        ensureThreadArray();
        return _thread_count;
    }
};


JitWriteProtection::JitWriteProtection(bool enable) {
#ifdef __aarch64__
    // Mimic pthread_jit_write_protect_np(), but save the previous state
    if (*(volatile char*)0xfffffc10c) {
        u64 val = enable ? *(volatile u64*)0xfffffc118 : *(volatile u64*)0xfffffc110;
        u64 prev;
        asm volatile("mrs %0, s3_6_c15_c1_5" : "=r" (prev) : : );
        if (prev != val) {
            _prev = prev;
            _restore = true;
            asm volatile("msr s3_6_c15_c1_5, %0\n"
                         "isb"
                         : "+r" (val) : : "memory");
            return;
        }
    }
    // Already in the required mode, or write protection is not supported
    _restore = false;
#endif
}

JitWriteProtection::~JitWriteProtection() {
#ifdef __aarch64__
    if (_restore) {
        u64 prev = _prev;
        asm volatile("msr s3_6_c15_c1_5, %0\n"
                     "isb"
                     : "+r" (prev) : : "memory");
    }
#endif
}


const size_t OS::page_size = sysconf(_SC_PAGESIZE);
const size_t OS::page_mask = OS::page_size - 1;

static mach_timebase_info_data_t timebase = {0, 0};

u64 OS::nanotime() {
    if (timebase.denom == 0) {
        mach_timebase_info(&timebase);
    }
    return (u64)mach_absolute_time() * timebase.numer / timebase.denom;
}

u64 OS::cputime() {
    return (u64)clock_gettime_nsec_np(CLOCK_THREAD_CPUTIME_ID);
}

u64 OS::micros() {
    struct timeval tv;
    gettimeofday(&tv, NULL);
    return (u64)tv.tv_sec * 1000000 + tv.tv_usec;
}

void OS::sleep(u64 nanos) {
    struct timespec ts = {(time_t)(nanos / 1000000000), (long)(nanos % 1000000000)};
    nanosleep(&ts, NULL);
}

u64 OS::processStartTime() {
    static u64 start_time = 0;

    if (start_time == 0) {
        struct proc_bsdinfo info;
        if (proc_pidinfo(processId(), PROC_PIDTBSDINFO, 0, &info, sizeof(info)) > 0) {
            start_time = (u64)info.pbi_start_tvsec * 1000 + info.pbi_start_tvusec / 1000;
        }
    }

    return start_time;
}

u64 OS::hton64(u64 x) {
    return OSSwapHostToBigInt64(x);
}

u64 OS::ntoh64(u64 x) {
    return OSSwapBigToHostInt64(x);
}

int OS::getMaxThreadId() {
    return 0x7fffffff;
}

int OS::processId() {
    static const int self_pid = getpid();

    return self_pid;
}

int OS::threadId() {
    // Used to be pthread_mach_thread_np(pthread_self()),
    // but pthread_mach_thread_np is not async signal safe
    mach_port_t port = mach_thread_self();
    mach_port_deallocate(mach_task_self(), port);
    return (int)port;
}

const char* OS::schedPolicy(int thread_id) {
    // Not used on macOS
    return "SCHED_OTHER";
}

bool OS::threadName(int thread_id, char* name_buf, size_t name_len) {
    pthread_t thread = pthread_from_mach_thread_np(thread_id);
    return thread && pthread_getname_np(thread, name_buf, name_len) == 0 && name_buf[0] != 0;
}

ThreadList* OS::listThreads() {
    return new MacThreadList();
}

bool OS::isLinux() {
    return false;
}

SigAction OS::installSignalHandler(int signo, SigAction action, SigHandler handler) {
    struct sigaction sa;
    struct sigaction oldsa;
    sigemptyset(&sa.sa_mask);

    if (handler != NULL) {
        sa.sa_handler = handler;
        sa.sa_flags = 0;
    } else {
        sa.sa_sigaction = action;
        sa.sa_flags = SA_SIGINFO | SA_RESTART;
    }

    sigaction(signo, &sa, &oldsa);
    return oldsa.sa_sigaction;
}

SigAction OS::replaceSigsegvHandler(SigAction action) {
    struct sigaction sa;
    sigaction(SIGSEGV, NULL, &sa);
    SigAction old_action = sa.sa_sigaction;
    sa.sa_sigaction = action;
    sigaction(SIGSEGV, &sa, NULL);
    return old_action;
}

SigAction OS::replaceSigbusHandler(SigAction action) {
    struct sigaction sa;
    sigaction(SIGBUS, NULL, &sa);
    SigAction old_action = sa.sa_sigaction;
    sa.sa_sigaction = action;
    sigaction(SIGBUS, &sa, NULL);
    return old_action;
}

bool OS::sendSignalToThread(int thread_id, int signo) {
#ifdef __aarch64__
    register long x0 asm("x0") = thread_id;
    register long x1 asm("x1") = signo;
    register long x16 asm("x16") = 328;
    asm volatile("svc #0x80"
                 : "+r" (x0)
                 : "r" (x1), "r" (x16)
                 : "memory");
    return x0 == 0;
#else
    int result;
    asm volatile("syscall"
                 : "=a" (result)
                 : "a" (0x2000148), "D" (thread_id), "S" (signo)
                 : "rcx", "r11", "memory");
    return result == 0;
#endif
}

void* OS::safeAlloc(size_t size) {
    // mmap() is not guaranteed to be async signal safe, but in practice, it is.
    // There is no a reasonable alternative anyway.
    void* result = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    if (result == MAP_FAILED) {
        return NULL;
    }
    return result;
}

void OS::safeFree(void* addr, size_t size) {
    munmap(addr, size);
}

bool OS::getCpuDescription(char* buf, size_t size) {
    return sysctlbyname("machdep.cpu.brand_string", buf, &size, NULL, 0) == 0;
}

u64 OS::getProcessCpuTime(u64* utime, u64* stime) {
    struct tms buf;
    clock_t real = times(&buf);
    *utime = buf.tms_utime;
    *stime = buf.tms_stime;
    return real;
}

u64 OS::getTotalCpuTime(u64* utime, u64* stime) {
    natural_t cpu_count;
    processor_info_array_t cpu_info_array;
    mach_msg_type_number_t cpu_info_count;

    host_name_port_t host = mach_host_self();
    kern_return_t ret = host_processor_info(host, PROCESSOR_CPU_LOAD_INFO, &cpu_count, &cpu_info_array, &cpu_info_count);
    mach_port_deallocate(mach_task_self(), host);
    if (ret != 0) {
        return (u64)-1;
    }

    processor_cpu_load_info_data_t* cpu_load = (processor_cpu_load_info_data_t*)cpu_info_array;
    u64 user = 0;
    u64 system = 0;
    u64 idle = 0;
    for (natural_t i = 0; i < cpu_count; i++) {
        user += cpu_load[i].cpu_ticks[CPU_STATE_USER] + cpu_load[i].cpu_ticks[CPU_STATE_NICE];
        system += cpu_load[i].cpu_ticks[CPU_STATE_SYSTEM];
        idle += cpu_load[i].cpu_ticks[CPU_STATE_IDLE];
    }
    vm_deallocate(mach_task_self(), (vm_address_t)cpu_info_array, cpu_info_count * sizeof(int));

    *utime = user;
    *stime = system;
    return user + system + idle;
}

void OS::copyFile(int src_fd, int dst_fd, off_t offset, size_t size) {
    char* buf = (char*)mmap(NULL, size + offset, PROT_READ, MAP_PRIVATE, src_fd, 0);
    if (buf == NULL) {
        return;
    }

    while (size > 0) {
        ssize_t bytes = write(dst_fd, buf + offset, size < 262144 ? size : 262144);
        if (bytes <= 0) {
            break;
        }
        offset += (size_t)bytes;
        size -= (size_t)bytes;
    }

    munmap(buf, offset);
}

int OS::truncateFile(int fd) {
    int rslt = ftruncate(fd, 0);
    if (rslt == 0) {
        return lseek(fd, 0, SEEK_SET);
    }
    return rslt;
}

int OS::fileSize(int fd) {
    struct stat fileinfo = {0};
    fstat(fd, &fileinfo);
    return fileinfo.st_size;
}

void OS::freePageCache(int fd, off_t start_offset) {
    // Not supported on macOS
}

#endif // __APPLE__