/*
 *  Portable interface to the CPU cycle counter
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  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 "common.h"

#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#define mbedtls_printf     printf
#endif

#if defined(MBEDTLS_TIMING_C)

#include "mbedtls/timing.h"

#if !defined(MBEDTLS_TIMING_ALT)

#if !defined(unix) && !defined(__unix__) && !defined(__unix) && \
    !defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__) && \
    !defined(__HAIKU__) && !defined(__midipix__)
#error "This module only works on Unix and Windows, see MBEDTLS_TIMING_C in config.h"
#endif

#ifndef asm
#define asm __asm
#endif

#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)

#include <windows.h>
#include <process.h>

struct _hr_time {
    LARGE_INTEGER start;
};

#else

#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>
#include <signal.h>
#include <time.h>

struct _hr_time {
    struct timeval start;
};

#endif /* _WIN32 && !EFIX64 && !EFI32 */

#if !defined(HAVE_HARDCLOCK) && defined(MBEDTLS_HAVE_ASM) &&  \
    ( defined(_MSC_VER) && defined(_M_IX86) ) || defined(__WATCOMC__)

#define HAVE_HARDCLOCK

unsigned long mbedtls_timing_hardclock(void) {
    unsigned long tsc;
    __asm   rdtsc
    __asm   mov  [tsc], eax
    return (tsc);
}
#endif /* !HAVE_HARDCLOCK && MBEDTLS_HAVE_ASM &&
          ( _MSC_VER && _M_IX86 ) || __WATCOMC__ */

/* some versions of mingw-64 have 32-bit longs even on x84_64 */
#if !defined(HAVE_HARDCLOCK) && defined(MBEDTLS_HAVE_ASM) &&  \
    defined(__GNUC__) && ( defined(__i386__) || (                       \
    ( defined(__amd64__) || defined( __x86_64__) ) && __SIZEOF_LONG__ == 4 ) )

#define HAVE_HARDCLOCK

unsigned long mbedtls_timing_hardclock(void) {
    unsigned long lo, hi;
    asm volatile("rdtsc" : "=a"(lo), "=d"(hi));
    return (lo);
}
#endif /* !HAVE_HARDCLOCK && MBEDTLS_HAVE_ASM &&
          __GNUC__ && __i386__ */

#if !defined(HAVE_HARDCLOCK) && defined(MBEDTLS_HAVE_ASM) &&  \
    defined(__GNUC__) && ( defined(__amd64__) || defined(__x86_64__) )

#define HAVE_HARDCLOCK

unsigned long mbedtls_timing_hardclock(void) {
    unsigned long lo, hi;
    asm volatile("rdtsc" : "=a"(lo), "=d"(hi));
    return (lo | (hi << 32));
}
#endif /* !HAVE_HARDCLOCK && MBEDTLS_HAVE_ASM &&
          __GNUC__ && ( __amd64__ || __x86_64__ ) */

#if !defined(HAVE_HARDCLOCK) && defined(MBEDTLS_HAVE_ASM) &&  \
    defined(__GNUC__) && ( defined(__powerpc__) || defined(__ppc__) )

#define HAVE_HARDCLOCK

unsigned long mbedtls_timing_hardclock(void) {
    unsigned long tbl, tbu0, tbu1;

    do {
        asm volatile("mftbu %0" : "=r"(tbu0));
        asm volatile("mftb  %0" : "=r"(tbl));
        asm volatile("mftbu %0" : "=r"(tbu1));
    } while (tbu0 != tbu1);

    return (tbl);
}
#endif /* !HAVE_HARDCLOCK && MBEDTLS_HAVE_ASM &&
          __GNUC__ && ( __powerpc__ || __ppc__ ) */

#if !defined(HAVE_HARDCLOCK) && defined(MBEDTLS_HAVE_ASM) &&  \
    defined(__GNUC__) && defined(__sparc64__)

#if defined(__OpenBSD__)
#warning OpenBSD does not allow access to tick register using software version instead
#else
#define HAVE_HARDCLOCK

unsigned long mbedtls_timing_hardclock(void) {
    unsigned long tick;
    asm volatile("rdpr %%tick, %0;" : "=&r"(tick));
    return (tick);
}
#endif /* __OpenBSD__ */
#endif /* !HAVE_HARDCLOCK && MBEDTLS_HAVE_ASM &&
          __GNUC__ && __sparc64__ */

#if !defined(HAVE_HARDCLOCK) && defined(MBEDTLS_HAVE_ASM) &&  \
    defined(__GNUC__) && defined(__sparc__) && !defined(__sparc64__)

#define HAVE_HARDCLOCK

unsigned long mbedtls_timing_hardclock(void) {
    unsigned long tick;
    asm volatile(".byte 0x83, 0x41, 0x00, 0x00");
    asm volatile("mov   %%g1, %0" : "=r"(tick));
    return (tick);
}
#endif /* !HAVE_HARDCLOCK && MBEDTLS_HAVE_ASM &&
          __GNUC__ && __sparc__ && !__sparc64__ */

#if !defined(HAVE_HARDCLOCK) && defined(MBEDTLS_HAVE_ASM) &&      \
    defined(__GNUC__) && defined(__alpha__)

#define HAVE_HARDCLOCK

unsigned long mbedtls_timing_hardclock(void) {
    unsigned long cc;
    asm volatile("rpcc %0" : "=r"(cc));
    return (cc & 0xFFFFFFFF);
}
#endif /* !HAVE_HARDCLOCK && MBEDTLS_HAVE_ASM &&
          __GNUC__ && __alpha__ */

#if !defined(HAVE_HARDCLOCK) && defined(MBEDTLS_HAVE_ASM) &&      \
    defined(__GNUC__) && defined(__ia64__)

#define HAVE_HARDCLOCK

unsigned long mbedtls_timing_hardclock(void) {
    unsigned long itc;
    asm volatile("mov %0 = ar.itc" : "=r"(itc));
    return (itc);
}
#endif /* !HAVE_HARDCLOCK && MBEDTLS_HAVE_ASM &&
          __GNUC__ && __ia64__ */

#if !defined(HAVE_HARDCLOCK) && defined(_MSC_VER) && \
    !defined(EFIX64) && !defined(EFI32)

#define HAVE_HARDCLOCK

unsigned long mbedtls_timing_hardclock(void) {
    LARGE_INTEGER offset;

    QueryPerformanceCounter(&offset);

    return ((unsigned long)(offset.QuadPart));
}
#endif /* !HAVE_HARDCLOCK && _MSC_VER && !EFIX64 && !EFI32 */

#if !defined(HAVE_HARDCLOCK)

#define HAVE_HARDCLOCK

static int hardclock_init = 0;
static struct timeval tv_init;

unsigned long mbedtls_timing_hardclock(void) {
    struct timeval tv_cur;

    if (hardclock_init == 0) {
        gettimeofday(&tv_init, NULL);
        hardclock_init = 1;
    }

    gettimeofday(&tv_cur, NULL);
    return ((tv_cur.tv_sec  - tv_init.tv_sec) * 1000000
            + (tv_cur.tv_usec - tv_init.tv_usec));
}
#endif /* !HAVE_HARDCLOCK */

volatile int mbedtls_timing_alarmed = 0;

#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)

unsigned long mbedtls_timing_get_timer(struct mbedtls_timing_hr_time *val, int reset) {
    struct _hr_time *t = (struct _hr_time *) val;

    if (reset) {
        QueryPerformanceCounter(&t->start);
        return (0);
    } else {
        unsigned long delta;
        LARGE_INTEGER now, hfreq;
        QueryPerformanceCounter(&now);
        QueryPerformanceFrequency(&hfreq);
        delta = (unsigned long)((now.QuadPart - t->start.QuadPart) * 1000ul
                                / hfreq.QuadPart);
        return (delta);
    }
}

/* It's OK to use a global because alarm() is supposed to be global anyway */
static DWORD alarmMs;

static void TimerProc(void *TimerContext) {
    (void) TimerContext;
    Sleep(alarmMs);
    mbedtls_timing_alarmed = 1;
    /* _endthread will be called implicitly on return
     * That ensures execution of thread funcition's epilogue */
}

void mbedtls_set_alarm(int seconds) {
    if (seconds == 0) {
        /* No need to create a thread for this simple case.
         * Also, this shorcut is more reliable at least on MinGW32 */
        mbedtls_timing_alarmed = 1;
        return;
    }

    mbedtls_timing_alarmed = 0;
    alarmMs = seconds * 1000;
    (void) _beginthread(TimerProc, 0, NULL);
}

#else /* _WIN32 && !EFIX64 && !EFI32 */

unsigned long mbedtls_timing_get_timer(struct mbedtls_timing_hr_time *val, int reset) {
    struct _hr_time *t = (struct _hr_time *) val;

    if (reset) {
        gettimeofday(&t->start, NULL);
        return (0);
    } else {
        unsigned long delta;
        struct timeval now;
        gettimeofday(&now, NULL);
        delta = (now.tv_sec  - t->start.tv_sec) * 1000ul
                + (now.tv_usec - t->start.tv_usec) / 1000;
        return (delta);
    }
}

static void sighandler(int signum) {
    mbedtls_timing_alarmed = 1;
    signal(signum, sighandler);
}

void mbedtls_set_alarm(int seconds) {
    mbedtls_timing_alarmed = 0;
    signal(SIGALRM, sighandler);
    alarm(seconds);
    if (seconds == 0) {
        /* alarm(0) cancelled any previous pending alarm, but the
           handler won't fire, so raise the flag straight away. */
        mbedtls_timing_alarmed = 1;
    }
}

#endif /* _WIN32 && !EFIX64 && !EFI32 */

/*
 * Set delays to watch
 */
void mbedtls_timing_set_delay(void *data, uint32_t int_ms, uint32_t fin_ms) {
    mbedtls_timing_delay_context *ctx = (mbedtls_timing_delay_context *) data;

    ctx->int_ms = int_ms;
    ctx->fin_ms = fin_ms;

    if (fin_ms != 0)
        (void) mbedtls_timing_get_timer(&ctx->timer, 1);
}

/*
 * Get number of delays expired
 */
int mbedtls_timing_get_delay(void *data) {
    mbedtls_timing_delay_context *ctx = (mbedtls_timing_delay_context *) data;
    unsigned long elapsed_ms;

    if (ctx->fin_ms == 0)
        return (-1);

    elapsed_ms = mbedtls_timing_get_timer(&ctx->timer, 0);

    if (elapsed_ms >= ctx->fin_ms)
        return (2);

    if (elapsed_ms >= ctx->int_ms)
        return (1);

    return (0);
}

#endif /* !MBEDTLS_TIMING_ALT */

#if defined(MBEDTLS_SELF_TEST)

/*
 * Busy-waits for the given number of milliseconds.
 * Used for testing mbedtls_timing_hardclock.
 */
static void busy_msleep(unsigned long msec) {
    struct mbedtls_timing_hr_time hires;
    unsigned long i = 0; /* for busy-waiting */
    volatile unsigned long j; /* to prevent optimisation */

    (void) mbedtls_timing_get_timer(&hires, 1);

    while (mbedtls_timing_get_timer(&hires, 0) < msec)
        i++;

    j = i;
    (void) j;
}

#define FAIL    do                                                      \
    {                                                                   \
        if( verbose != 0 )                                              \
        {                                                               \
            mbedtls_printf( "failed at line %d\n", __LINE__ );          \
            mbedtls_printf( " cycles=%lu ratio=%lu millisecs=%lu secs=%lu hardfail=%d a=%lu b=%lu\n", \
                            cycles, ratio, millisecs, secs, hardfail,   \
                            (unsigned long) a, (unsigned long) b );     \
            mbedtls_printf( " elapsed(hires)=%lu elapsed(ctx)=%lu status(ctx)=%d\n", \
                            mbedtls_timing_get_timer( &hires, 0 ),      \
                            mbedtls_timing_get_timer( &ctx.timer, 0 ),  \
                            mbedtls_timing_get_delay( &ctx ) );         \
        }                                                               \
        return( 1 );                                                    \
    } while( 0 )

/*
 * Checkup routine
 *
 * Warning: this is work in progress, some tests may not be reliable enough
 * yet! False positives may happen.
 */
int mbedtls_timing_self_test(int verbose) {
    unsigned long cycles = 0, ratio = 0;
    unsigned long millisecs = 0, secs = 0;
    int hardfail = 0;
    struct mbedtls_timing_hr_time hires;
    uint32_t a = 0, b = 0;
    mbedtls_timing_delay_context ctx;

    if (verbose != 0)
        mbedtls_printf("  TIMING tests note: will take some time!\n");

    if (verbose != 0)
        mbedtls_printf("  TIMING test #1 (set_alarm / get_timer): ");

    {
        secs = 1;

        (void) mbedtls_timing_get_timer(&hires, 1);

        mbedtls_set_alarm((int) secs);
        while (!mbedtls_timing_alarmed)
            ;

        millisecs = mbedtls_timing_get_timer(&hires, 0);

        /* For some reason on Windows it looks like alarm has an extra delay
         * (maybe related to creating a new thread). Allow some room here. */
        if (millisecs < 800 * secs || millisecs > 1200 * secs + 300)
            FAIL;
    }

    if (verbose != 0)
        mbedtls_printf("passed\n");

    if (verbose != 0)
        mbedtls_printf("  TIMING test #2 (set/get_delay        ): ");

    {
        a = 800;
        b = 400;
        mbedtls_timing_set_delay(&ctx, a, a + b);            /* T = 0 */

        busy_msleep(a - a / 4);                        /* T = a - a/4 */
        if (mbedtls_timing_get_delay(&ctx) != 0)
            FAIL;

        busy_msleep(a / 4 + b / 4);                    /* T = a + b/4 */
        if (mbedtls_timing_get_delay(&ctx) != 1)
            FAIL;

        busy_msleep(b);                            /* T = a + b + b/4 */
        if (mbedtls_timing_get_delay(&ctx) != 2)
            FAIL;
    }

    mbedtls_timing_set_delay(&ctx, 0, 0);
    busy_msleep(200);
    if (mbedtls_timing_get_delay(&ctx) != -1)
        FAIL;

    if (verbose != 0)
        mbedtls_printf("passed\n");

    if (verbose != 0)
        mbedtls_printf("  TIMING test #3 (hardclock / get_timer): ");

    /*
     * Allow one failure for possible counter wrapping.
     * On a 4Ghz 32-bit machine the cycle counter wraps about once per second;
     * since the whole test is about 10ms, it shouldn't happen twice in a row.
     */

hard_test:
    if (hardfail > 1) {
        if (verbose != 0)
            mbedtls_printf("failed (ignored)\n");

        goto hard_test_done;
    }

    /* Get a reference ratio cycles/ms */
    millisecs = 1;
    cycles = mbedtls_timing_hardclock();
    busy_msleep(millisecs);
    cycles = mbedtls_timing_hardclock() - cycles;
    ratio = cycles / millisecs;

    /* Check that the ratio is mostly constant */
    for (millisecs = 2; millisecs <= 4; millisecs++) {
        cycles = mbedtls_timing_hardclock();
        busy_msleep(millisecs);
        cycles = mbedtls_timing_hardclock() - cycles;

        /* Allow variation up to 20% */
        if (cycles / millisecs < ratio - ratio / 5 ||
                cycles / millisecs > ratio + ratio / 5) {
            hardfail++;
            goto hard_test;
        }
    }

    if (verbose != 0)
        mbedtls_printf("passed\n");

hard_test_done:

    if (verbose != 0)
        mbedtls_printf("\n");

    return (0);
}

#endif /* MBEDTLS_SELF_TEST */

#endif /* MBEDTLS_TIMING_C */
