source: libcfa/src/concurrency/invoke.c@ eeb9f9f

//
// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// invoke.c --
//
// Author           : Thierry Delisle
// Created On       : Tue Jan 17 12:27:26 2016
// Last Modified By : Peter A. Buhr
// Last Modified On : Sat Oct 24 14:35:28 2020
// Update Count     : 32
//

#define __cforall_thread__

#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <unwind.h>

#include "invoke.h"

#define __CFA_INVOKE_PRIVATE__
#include "invoke.h"

// magically invoke the "main" of the most derived class
// Called from the kernel when starting a coroutine or task so must switch back to user mode.

extern struct $coroutine * __cfactx_cor_finish(void);
extern void __cfactx_cor_leave ( struct $coroutine * );
extern void __cfactx_thrd_leave();

extern void disable_interrupts() OPTIONAL_THREAD;
extern void enable_interrupts( _Bool poll );

void __cfactx_invoke_coroutine(
        void (*main)(void *),
        void *this
) {
        // Finish setting up the coroutine by setting its state
        struct $coroutine * cor = __cfactx_cor_finish();

        // Call the main of the coroutine
        main( this );

        //Final suspend, should never return
        __cfactx_cor_leave( cor );
        __cabi_abort( "Resumed dead coroutine" );
}

static _Unwind_Reason_Code __cfactx_coroutine_unwindstop(
        __attribute((__unused__)) int version,
        _Unwind_Action actions,
        __attribute((__unused__)) _Unwind_Exception_Class exceptionClass,
        __attribute((__unused__)) struct _Unwind_Exception * unwind_exception,
        __attribute((__unused__)) struct _Unwind_Context * context,
        void * param
) {
        if( actions & _UA_END_OF_STACK  ) {
                // We finished unwinding the coroutine,
                // leave it
                __cfactx_cor_leave( param );
                __cabi_abort( "Resumed dead coroutine" );
        }
        if( actions & _UA_CLEANUP_PHASE ) return _URC_NO_REASON;

        return _URC_FATAL_PHASE2_ERROR;
}

void __cfactx_coroutine_unwind(struct _Unwind_Exception * storage, struct $coroutine * cor) __attribute__ ((__noreturn__));
void __cfactx_coroutine_unwind(struct _Unwind_Exception * storage, struct $coroutine * cor) {
        _Unwind_Reason_Code ret = _Unwind_ForcedUnwind( storage, __cfactx_coroutine_unwindstop, cor );
        printf("UNWIND ERROR %d after force unwind\n", ret);
        abort();
}

void __cfactx_invoke_thread(
        void (*main)(void *),
        void *this
) {
        // Officially start the thread by enabling preemption
        enable_interrupts( true );

        // Call the main of the thread
        main( this );

        // To exit a thread we must :
        // 1 - Mark it as halted
        // 2 - Leave its monitor
        // 3 - Disable the interupts
        // 4 - Final suspend
        // The order of these 4 operations is very important
        //Final suspend, should never return
        __cfactx_thrd_leave();
        __cabi_abort( "Resumed dead thread" );
}

void __cfactx_start(
        void (*main)(void *),
        struct $coroutine * cor,
        void *this,
        void (*invoke)(void *)
) {
        struct __stack_t * stack = cor->stack.storage;

#if defined( __i386 )

        struct FakeStack {
            void *fixedRegisters[3];                                            // fixed registers ebx, edi, esi (popped on 1st uSwitch, values unimportant)
            void *rturn;                                                                        // where to go on return from uSwitch
            void *dummyReturn;                                                          // fake return compiler would have pushed on call to uInvoke
            void *argument[3];                                                          // for 16-byte ABI, 16-byte alignment starts here
            void *padding;                                                                      // padding to force 16-byte alignment, as "base" is 16-byte aligned
        };

        cor->context.SP = (char *)stack->base - sizeof( struct FakeStack );
        cor->context.FP = NULL;         // terminate stack with NULL fp

        struct FakeStack *fs = (struct FakeStack *)cor->context.SP;

        fs->dummyReturn = NULL;
        fs->argument[0] = main;                                                         // argument to invoke
        fs->argument[1] = this;                                                         // argument to invoke
        fs->rturn = invoke;

#elif defined( __x86_64 )

        struct FakeStack {
                void *fixedRegisters[5];                                                // fixed registers rbx, r12, r13, r14, r15
                void *rturn;                                                                    // where to go on return from uSwitch
                void *dummyReturn;                                                              // NULL return address to provide proper alignment
        };

        cor->context.SP = (char *)stack->base - sizeof( struct FakeStack );
        cor->context.FP = NULL;                                                         // terminate stack with NULL fp

        struct FakeStack *fs = (struct FakeStack *)cor->context.SP;

        fs->dummyReturn = NULL;
        fs->rturn = __cfactx_invoke_stub;
        fs->fixedRegisters[0] = main;                                           // argument to invoke
        fs->fixedRegisters[1] = this;                                           // argument to invoke
        fs->fixedRegisters[2] = invoke;

#elif defined( __ARM_ARCH_32 )
#error ARM needs to be upgrade to use two parameters like X86/X64 (A.K.A. : I broke this and do not know how to fix it)
        // More details about the error:
        // To avoid the thunk problem, I changed the invoke routine to pass the main explicitly
        // instead of relying on an assertion. This effectively hoists any required thunk one level
        // which was enough to get to global scope in most cases.
        // This means that __cfactx_invoke_... now takes two parameters and the FakeStack needs
        // to be adjusted as a consequence of that.
        // I don't know how to do that for ARM, hence the #error

        struct FakeStack {
                float fpRegs[16];                                                               // floating point registers
                void * intRegs[9];                                                              // integer/pointer registers
                void * arg[2];                                                                  // placeholder for this pointer
        };

        cor->context.SP = (char *)stack->base - sizeof( struct FakeStack );
        cor->context.FP = NULL;

        struct FakeStack *fs = (struct FakeStack *)cor->context.SP;

        fs->intRegs[8] = __cfactx_invoke_stub;
        fs->arg[0] = this;
        fs->arg[1] = invoke;

#elif defined( __ARM_ARCH )
        struct FakeStack {
                void * intRegs[12];                                                             // x19-x30 integer registers
                double fpRegs[8];                                                               // v8-v15 floating point
        };

        cor->context.SP = (char *)stack->base - sizeof( struct FakeStack );
        cor->context.FP = NULL;

        struct FakeStack *fs = (struct FakeStack *)cor->context.SP;

        fs->intRegs[0] = main;                                                          // argument to invoke x19 => x0
        fs->intRegs[1] = this;                                                          // argument to invoke x20 => x1
        fs->intRegs[2] = invoke;
        fs->intRegs[11] = __cfactx_invoke_stub;                         // link register x30 => ret moves to pc
#else
        #error uknown hardware architecture
#endif
}

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