remove erroneous line

[AROS.git] / arch / all-mingw32 / kernel / host_intr.c

/*
    Copyright © 1995-2014, The AROS Development Team. All rights reserved.
    $Id$
*/

#include <stddef.h>
#include <stdio.h>
#include <windows.h>

/* PRINT_CPUCONTEXT() macro uses bug() because it can be useful on AROS side too. */
#define bug printf

#include "host_intern.h"
#include "kernel_arch.h"
#include "kernel_cpu.h"

/*
 * Console output in Windows seems to be protected via semaphores. SuspendThread() at the moment
 * of writing something to console leaves it in locked state. Attempt to write something to it from
 * within task scheduler may halt the system. Because of this only init debug actually works and
 * is safe to use.
 */
#define D(x)     /* Init debug          */
#define DS(x)    /* Task switcher debug */
#define DINT(x)  /* Interrupts debug    */
#define DTRAP(x) /* Traps debug         */

HANDLE MainThread;
DWORD MainThreadId;
unsigned short Ints_Num;
HANDLE IntObjects[256];
unsigned char PendingInts[256];
unsigned char AllocatedInts[256];

/* Virtual CPU control registers */
/* Note: variables need to have values set, otherwise they don't get exported from DLL */
         __declspec(dllexport) int           (*TrapVector)(unsigned int num, ULONG_PTR *args, CONTEXT *regs) = NULL;
         __declspec(dllexport) int           (*IRQVector)(unsigned char *irqs, CONTEXT *regs) = NULL;
         __declspec(dllexport) int           NonMaskableInt = -1;
volatile __declspec(dllexport) int           Ints_Enabled   = 0;
volatile __declspec(dllexport) int           Supervisor     = 0;
volatile __declspec(dllexport) unsigned char Sleep_Mode     = 0;
volatile __declspec(dllexport) DWORD *       LastErrorPtr   = 0;

/*
 * This can't be placed on stack because noone knows
 * what happens to it upon returning from Windows exception.
 * Luckily our trap handler is guaranteed to be single-threaded,
 * so we can safely declare this structure static.
 */
static struct LeaveInterruptContext leavecontext;

LONG WINAPI exceptionHandler(EXCEPTION_POINTERS *exptr)
{
    DWORD ExceptionCode = exptr->ExceptionRecord->ExceptionCode;
    CONTEXT *ContextRecord = exptr->ContextRecord;
    DWORD ThreadId;
    int intstate;

    /*
     * We are already in interrupt and we must not be preempted by task switcher. 
     * Note that up to this point we still can be preempted by task switcher, in
     * fact it's not good, but this will happen only upon CPU exception. core_raise()
     * disables interrupts before raising an exception, so i really hope AROS will fail
     * only in very rare cases and only upon software failure.
     */
    Ints_Enabled = INT_DISABLE;

    /* Exception in other thread, probably in virtual hardware. Die. */
    ThreadId = GetCurrentThreadId();
    if (ThreadId != MainThreadId)
    {
        printf("[KRN] Service thread 0x%lu, exception 0x%08lX\n", ThreadId, ExceptionCode);
        PRINT_CPUCONTEXT(ContextRecord);

        return EXCEPTION_CONTINUE_SEARCH;
    }

    /* Enter supervisor mode. We can already be in supervisor (crashed inside
       IRQ handler), so we increment in order to retain previous state. */
    Supervisor++;

    /* Call trap handler */
    DTRAP(bug("[KRN] Trap 0x%08lX\n", ExceptionCode));

    intstate = TrapVector(ExceptionCode, exptr->ExceptionRecord->ExceptionInformation, ContextRecord);

    if (intstate == INT_HALT)
    {
        printf("[KRN] **UNHANDLED EXCEPTION 0x%08lX** stopping here...\n", ExceptionCode);

        return EXCEPTION_CONTINUE_SEARCH;
    }

    DTRAP(printf("[KRN] Leaving trap, Supervisor %d, intstate %d, PC 0x%p\n", Supervisor, intstate, (void *)PC(ContextRecord)));

    /* Exit supervisor */
    if (--Supervisor == 0)
    {
        /* If we are leaving to user mode, we may need to enable interrupts */
        if (intstate)
        {
            /*
             * We must enable interrupts only after return from Windows
             * exception. Otherwise supervisor thread may preempt us
             * between enabling interrupts and actual exit, and this will
             * cause process abort. We use core_LeaveInterrupt() routine
             * written in asm to solve this task. We cause the task to jump
             * to it upon return, the routine enables interrupts and then
             * jumps to real task's PC, which is passed to it inside
             * struct LeaveInterruptContext.
             * The helper clobbers R0 register, so we also save it.
             */
            leavecontext.pc = PC(ContextRecord);
            leavecontext.r0 = R0(ContextRecord);
            R0(ContextRecord) = (UINT_PTR)&leavecontext;
            PC(ContextRecord) = (UINT_PTR)core_LeaveInterrupt;
            /*
             * If this is a newly created context, it may contain no integer registers.
             * Here we use R0, so explicitly turn on CONTEXT_INTEGER flag.
             */
            ContextRecord->ContextFlags |= CONTEXT_INTEGER;
        }
    }    

    return EXCEPTION_CONTINUE_EXECUTION;
}

#ifdef __x86_64__
/*
 * Magic: on x86-64 we can't preempt within a certain location. Not good,
 * but i can't offer something better. See leaveinterrupt_x86_64.s.
 */
#define INT_SAFE(ctx) ((ctx.Rip < (DWORD64)core_LeaveInterrupt) || (ctx.Rip >= (DWORD64)&core_LeaveInt_End))
#else
#define INT_SAFE(ctx) TRUE
#endif

DWORD WINAPI TaskSwitcher()
{
    DWORD obj;
    CONTEXT MainCtx;

    for (;;)
    {
        obj = WaitForMultipleObjects(Ints_Num, IntObjects, FALSE, INFINITE);
        PendingInts[obj] = 1;
        DINT(printf("[Task switcher] Object %lu signalled, interrupt enable %d\n", obj, Ints_Enabled));

        /* Stop main thread if it's not sleeping */
        if (Sleep_Mode != SLEEP_MODE_ON)
        {
            SuspendThread(MainThread);
            /*
             * People say that on SMP systems thread is not stopped immediately by SuspendThread().
             * So we have to do our best to ensure that is is really stopped. I hope GetThreadContext()
             * guarantees it.
             */
            CONTEXT_INIT_FLAGS(&MainCtx);
            GetThreadContext(MainThread, &MainCtx);
        }

        /* Process interrupts if we are allowed to */
        if ((Ints_Enabled && INT_SAFE(MainCtx)) || (obj == NonMaskableInt))
        {
            Supervisor = 1;
            /* 
             * We get and store the complete CPU context, but set only part of it
             * because changing some registers causes Windows to immediately shut down
             * our process. This can be a useful aid for future AROS debuggers.
             */
            DS(printf("[Task switcher] original CPU context: ****\n"));
            DS(PRINT_CPUCONTEXT(&MainCtx));

            /*
             * Call IRQ handlers for all pending interrupts.
             * This means that deferred interrupts may be processed with
             * delay, meximum of one timer period, but anyway, who told
             * that Windows is a realtime OS?
             */
            Ints_Enabled = IRQVector(PendingInts, &MainCtx);
            /* All IRQs have been processed */
            ZeroMemory(PendingInts, sizeof(PendingInts));
            /* Leave supervisor mode. Interrupt state is already updated by IRQVector(). */
            Supervisor = 0;

            /* Resume main thread if AROS is not sleeping */
            if (Sleep_Mode == SLEEP_MODE_OFF)
            {
                DS(printf("[Task switcher] new CPU context: ****\n"));
                DS(PRINT_CPUCONTEXT(&MainCtx));
                SetThreadContext(MainThread, &MainCtx);
                ResumeThread(MainThread);
            }
            else
            {
                /* We've entered sleep mode. Main thread is kept suspended. */
                Sleep_Mode = SLEEP_MODE_ON;
            }
        }
        else
        {
            /*
             * Interrupts are disabled here. Do not commit sleep mode, or we
             * end up in sleeping main thread before it enables interrupt.
             * This will cause a deadlock.
             */
            if (Sleep_Mode != SLEEP_MODE_ON)
                ResumeThread(MainThread);
        }
    }
    return 0;
}

/* ****** Interface functions ****** */

void __declspec(dllexport) __aros core_raise(DWORD code, const ULONG_PTR n)
{
    /*
     * This ensures that we are never preempted inside RaiseException().
     * Upon exit from the syscall interrupt state will be restored by
     * core_LeaveInterrupt().
     */
    Ints_Enabled = INT_DISABLE;

    DTRAP(printf("[KRN] Raising exception 0x%08lX, SP 0x%p\n", code, stack));
    RaiseException(code, 0, 1, &n);

    /* If after RaiseException we are still here, but Sleep_Mode != 0, this likely means
       we've just called SC_SCHEDULE, SC_SWITCH or SC_DISPATCH, and it is putting us to sleep.
       Sleep mode will be committed as soon as timer IRQ happens */
    while (Sleep_Mode);
}

unsigned long __declspec(dllexport) __aros StartClock(unsigned int irq, unsigned int TimerPeriod)
{
    LARGE_INTEGER TimerValue;

    TimerPeriod = 1000 / TimerPeriod;
    TimerValue.QuadPart  = -10000 * (LONGLONG)TimerPeriod;

    return SetWaitableTimer(IntObjects[irq], &TimerValue, TimerPeriod, NULL, NULL, 0);
}

/*
 * Start up virtual machine.
 * Initializes IRQ engine, runs virtual supervisor thread and starts up main system timer.
 * Trap and IRQ vectors must be already set up, we don't check them against NULLs.
 */
int __declspec(dllexport) __aros core_init(unsigned int TimerPeriod)
{
    HANDLE ThisProcess;
    HANDLE SwitcherThread;
    void *MainTEB;
    int i;
    DWORD SwitcherId;

    D(printf("[KRN] Setting up interrupts\n"));
    Ints_Enabled = INT_DISABLE;
    Supervisor = 0;
    Sleep_Mode = SLEEP_MODE_OFF;
    for (i = 1; i < 256; i++)
    {
        IntObjects[i] = NULL;
        AllocatedInts[i] = 0;
    }

    /* Set up traps */
    MainThreadId = GetCurrentThreadId();
#ifdef __x86_64__
    AddVectoredExceptionHandler(TRUE, exceptionHandler);
#else
    SetUnhandledExceptionFilter(exceptionHandler);
#endif

    /* Set up debug I/O */
    conin  = GetStdHandle(STD_INPUT_HANDLE);
    conout = GetStdHandle(STD_OUTPUT_HANDLE);

    /* Statically allocate main system timer */
    for (i = 0; i < 2; i++)
    {
        IntObjects[i] = CreateWaitableTimer(NULL, FALSE, NULL);
        if (!IntObjects[i])
        {
            D(printf("[KRN] Failed to create timer %u\n", i));
            return 0;
        }
        AllocatedInts[i] = 1;
        PendingInts[i]   = 0;
    }
    Ints_Num = 2;

    ThisProcess = GetCurrentProcess();
    if (DuplicateHandle(ThisProcess, GetCurrentThread(), ThisProcess, &MainThread, 0, TRUE, DUPLICATE_SAME_ACCESS))
    {
#ifdef __x86_64__
        #define LastErrOffset 0x68
#else
        /* On 32-bit x86 we have to figure out the offset depending on Windows version */
        OSVERSIONINFO osver = {0};
        ULONG LastErrOffset = 0;

        osver.dwOSVersionInfoSize = sizeof(osver);
        GetVersionEx(&osver);

        /*
         * LastError value is part of our context. In order to manipulate it we have to hack
         * into Windows TEB (thread environment block).
         * Since this structure is private, error code offset changes from version to version.
         * The following offsets are known:
         * - Windows 95 and 98 - 0x60
         * - Windows Me - 0x74
         * - Windows NT (all family, fixed at last) - 0x34
         */
        switch(osver.dwPlatformId)
        {
        case VER_PLATFORM_WIN32_WINDOWS:
            if (osver.dwMajorVersion == 4)
            {
                if (osver.dwMinorVersion > 10)
                    LastErrOffset = 0x74;
                else
                    LastErrOffset = 0x60;
            }
            break;

        case VER_PLATFORM_WIN32_NT:
            LastErrOffset = 0x34;
            break;
        }

        if (!LastErrOffset)
        {
            printf("Unsupported Windows version %lu.%lu, platform ID %lu\n", osver.dwMajorVersion, osver.dwMinorVersion, osver.dwPlatformId);
            return 0;
        }
#endif

        MainTEB = NtCurrentTeb();
        LastErrorPtr = MainTEB + LastErrOffset;

        SwitcherThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)TaskSwitcher, NULL, 0, &SwitcherId);
        if (SwitcherThread)
        {
            SYSTEM_INFO info;

            D(printf("[KRN] Task switcher started, ID %lu\n", SwitcherId));

            /* Start timer 0 */
            if (!StartClock(0, TimerPeriod))
                return 0;

            /* Return system page size */
            GetSystemInfo(&info);   
            return info.dwPageSize;
        }
            D(else printf("[KRN] Failed to run task switcher thread\n");)
    }
        D(else printf("[KRN] failed to get thread handle\n");)

    CloseHandle(IntObjects[IRQ_TIMER]);
    return 0;
}

/*
 * The following is host-side IRQ API.
 *
 * It is used by virtual hadrware implemented as asynchronous host operating
 * system threads.
 *
 */

int __declspec(dllexport) __aros KrnAllocIRQ(void)
{
    int irq;

    for (irq = 0; irq < 256; irq++)
    {
        if (!AllocatedInts[irq])
        {
            if (!IntObjects[irq])
            {
                IntObjects[irq] = CreateEvent(NULL, FALSE, FALSE, NULL);

                if (!IntObjects[irq])
                    return -1;
            }
            PendingInts[irq]   = 0;
            AllocatedInts[irq] = 1;

            if (irq == Ints_Num)
                Ints_Num++;

            return irq;
        }
    }
    return -1;
}


void __declspec(dllexport) __aros KrnFreeIRQ(unsigned char irq)
{
    AllocatedInts[irq] = 0;

    while (!AllocatedInts[Ints_Num - 1])
        Ints_Num--;
}

void *__declspec(dllexport) __aros KrnGetIRQObject(unsigned char irq)
{
    return IntObjects[irq];
}

unsigned long __declspec(dllexport) __aros KrnCauseIRQ(unsigned char irq)
{
    unsigned long res;

    D(printf("[kernel IRQ] Causing IRQ %u\n", irq));
    res = SetEvent(IntObjects[irq]);
    D(printf("[kernel IRQ] Result: %ld\n", res));
    return res;
}