md.cpp

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/* src/vm/jit/s390/md.cpp - machine dependent s390 Linux functions

   Copyright (C) 1996-2013
   CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO

   This file is part of CACAO.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.

*/


#include "config.h"


#include <cassert>
#include <stdint.h>

#include "vm/types.hpp"

#include "vm/jit/s390/codegen.hpp"
#include "vm/jit/s390/md-abi.hpp"

#include "vm/exceptions.hpp"
#include "vm/vm.hpp"

#include "vm/jit/abi.hpp"
#include "vm/jit/code.hpp"
#include "vm/jit/codegen-common.hpp"
#include "vm/jit/executionstate.hpp"
#include "vm/jit/jit.hpp"
#include "vm/jit/methodtree.hpp"
#include "vm/jit/patcher-common.hpp"
#include "vm/jit/trap.hpp"

/* md_init *********************************************************************

   Do some machine dependent initialization.

*******************************************************************************/

void md_init(void)
{
}

/**
 * NullPointerException signal handler for hardware null pointer check.
 */
void md_signal_handler_sigsegv(int sig, siginfo_t *siginfo, void *_p)
{
    ucontext_t* _uc = (ucontext_t *) _p;
    mcontext_t* _mc = &_uc->uc_mcontext;

    void* xpc = (u1 *) _mc->psw.addr;

    // Handle the trap.
    trap_handle(TRAP_SIGSEGV, xpc, _p);
}

/**
  * Illegal Instruction signal handler for hardware exception checks.
  */
void md_signal_handler_sigill(int sig, siginfo_t *siginfo, void *_p)
{
    ucontext_t* _uc = (ucontext_t *) _p;
    mcontext_t* _mc = &_uc->uc_mcontext;

    void* xpc = siginfo->si_addr;

    // Handle the trap.
    trap_handle(TRAP_SIGILL, xpc, _p);
}

/* md_signal_handler_sigfpe ****************************************************

   ArithmeticException signal handler for hardware divide by zero
   check.

*******************************************************************************/

void md_signal_handler_sigfpe(int sig, siginfo_t *siginfo, void *_p)
{
    ucontext_t* _uc = (ucontext_t *) _p;
    mcontext_t* _mc = &_uc->uc_mcontext;

    void* xpc = siginfo->si_addr;

    if (N_RR_GET_OPC((uint8_t*) xpc) == OPC_DR) { /* DR */

        int r1 = N_RR_GET_REG1((uint8_t*) xpc);
        int r2 = N_RR_GET_REG2((uint8_t*) xpc);

        if (
            (_mc->gregs[r1] == 0xFFFFFFFF) &&
            (_mc->gregs[r1 + 1] == 0x80000000) && 
            (_mc->gregs[r2] == 0xFFFFFFFF)
        ) {
            /* handle special case 0x80000000 / 0xFFFFFFFF that fails on hardware */
            /* next instruction */
            u1 *pc = (u1 *)_mc->psw.addr;
            /* remainder */
            _mc->gregs[r1] = 0;
            /* quotient */
            _mc->gregs[r1 + 1] = 0x80000000;
            /* continue at next instruction */
            _mc->psw.addr = (ptrint) pc;

            return;
        }
    }

    // Handle the trap.
    trap_handle(TRAP_SIGFPE, xpc, _p);
}


/* md_signal_handler_sigusr2 ***************************************************

   Signal handler for profiling sampling.

*******************************************************************************/

#if defined(ENABLE_THREADS)
void md_signal_handler_sigusr2(int sig, siginfo_t *siginfo, void *_p)
{
    threadobject *t;
    ucontext_t   *_uc;
    mcontext_t   *_mc;
    u1           *pc;

    t = THREADOBJECT;

    _uc = (ucontext_t *) _p;
    _mc = &_uc->uc_mcontext;

    /* ATTENTION: Don't use CACAO's internal REG_* defines as they are
       different to the ones in <ucontext.h>. */

    pc = (u1 *) _mc->psw.addr;

    t->pc = pc;
}
#endif


/**
 * Read the given context into an executionstate.
 *
 * @param es      execution state
 * @param context machine context
 */
void md_executionstate_read(executionstate_t* es, void* context)
{
    ucontext_t *_uc;
    mcontext_t *_mc;
    int         i;

    _uc = (ucontext_t *) context;
    _mc = &_uc->uc_mcontext;

    /* read special registers */
    es->pc = (u1 *) _mc->psw.addr;
    es->sp = (u1 *) _mc->gregs[REG_SP];
    es->pv = (u1 *) _mc->gregs[REG_PV] - N_PV_OFFSET;
    es->ra = (u1 *) _mc->gregs[REG_RA];

    /* read integer registers */
    for (i = 0; i < INT_REG_CNT; i++)
        es->intregs[i] = _mc->gregs[i];

    /* read float registers */
    /* Do not use the assignment operator '=', as the type of
     * the _mc->sc_fpregs[i] can cause invalid conversions. */

    assert(sizeof(_mc->fpregs.fprs) == sizeof(es->fltregs));
    os::memcpy(&es->fltregs, &_mc->fpregs.fprs, sizeof(_mc->fpregs.fprs));
}


/**
 * Write the given executionstate back to the context.
 *
 * @param es      execution state
 * @param context machine context
 */
void md_executionstate_write(executionstate_t* es, void* context)
{
    ucontext_t *_uc;
    mcontext_t *_mc;
    int         i;

    _uc = (ucontext_t *) context;
    _mc = &_uc->uc_mcontext;

    /* write integer registers */
    for (i = 0; i < INT_REG_CNT; i++)
        _mc->gregs[i] = es->intregs[i];

    /* write float registers */
    /* Do not use the assignment operator '=', as the type of
     * the _mc->sc_fpregs[i] can cause invalid conversions. */

    assert(sizeof(_mc->fpregs.fprs) == sizeof(es->fltregs));
    os::memcpy(&_mc->fpregs.fprs, &es->fltregs, sizeof(_mc->fpregs.fprs));

    /* write special registers */
    _mc->psw.addr      = (ptrint) es->pc;
    _mc->gregs[REG_SP] = (ptrint) es->sp;
    _mc->gregs[REG_PV] = (ptrint) es->pv + N_PV_OFFSET;
    _mc->gregs[REG_RA] = (ptrint) es->ra;
}


/* md_jit_method_patch_address *************************************************

   Gets the patch address of the currently compiled method. The offset
   is extracted from the load instruction(s) before the jump and added
   to the right base address (PV or REG_METHODPTR).

   INVOKESTATIC/SPECIAL:

0x7748d7b2:   a7 18 ff d4                      lhi      %r1,-44  
(load dseg offset)
0x7748d7b6:   58 d1 d0 00                      l        %r13,0(%r1,%r13)
(load pv)
0x7748d7ba:   0d ed                            basr     %r14,%r13
(jump to pv)

   INVOKEVIRTUAL:

0x7748d82a:   58 c0 20 00                      l        %r12,0(%r2)
(load mptr)
0x7748d82e:   58 d0 c0 00                      l        %r13,0(%r12)
(load pv from mptr)
0x7748d832:   0d ed                            basr     %r14,%r13
(jump to pv)


   INVOKEINTERFACE:

last 2 instructions the same as in invokevirtual

*******************************************************************************/

void *md_jit_method_patch_address(void* pv, void *ra, void *mptr)
{
    uint8_t *pc;
    uint8_t  base, index;
    int32_t  offset;
    void    *pa;                        /* patch address                      */

    /* go back to the load before the call instruction */

    pc = ((uint8_t *) ra) - SZ_BCR - SZ_L;

    /* get the base register of the load */

    base  = N_RX_GET_BASE(pc);
    index = N_RX_GET_INDEX(pc);

    /* check for the different calls */

    switch (base) {
        case REG_PV:
            /* INVOKESTATIC/SPECIAL */

            switch (index) {
                case R0:
                    /* the offset is in the load instruction */
                    offset = N_RX_GET_DISP(pc) + N_PV_OFFSET;
                    break;
                case REG_ITMP1:
                    /* the offset is in the immediate load before the load */
                    offset = N_RI_GET_IMM(pc - SZ_L);
                    break;
                default:
                    assert(0);
            }

            /* add the offset to the procedure vector */

            pa = ((uint8_t *) pv) + offset;
            break;

        case REG_METHODPTR:
            /* mptr relative */
            /* INVOKEVIRTUAL/INTERFACE */

            offset = N_RX_GET_DISP(pc);

            /* return NULL if no mptr was specified (used for replacement) */

            if (mptr == NULL)
                return NULL;

            /* add offset to method pointer */
            
            pa = (uint8_t *)mptr + offset;
            break;

        default:
            /* catch any problems */
            vm_abort("md_jit_method_patch_address");
            break;
    }

    return pa;
}


/**
 * Decode the trap instruction at the given PC.
 *
 * @param trp information about trap to be filled
 * @param sig signal number
 * @param xpc exception PC
 * @param es execution state of the machine
 * @return true if trap was decoded successfully, false otherwise.
 */
bool md_trap_decode(trapinfo_t* trp, int sig, void* xpc, executionstate_t* es)
{
    switch (sig) {
    case TRAP_SIGILL:
        if (N_RR_GET_OPC((uint8_t*) xpc) == OPC_ILL) {
            int32_t reg = N_ILL_GET_REG((uint8_t*) xpc);
            trp->type  = N_ILL_GET_TYPE((uint8_t*) xpc);
            trp->value = es->intregs[reg];
            return true;
        }
        return false;

    case TRAP_SIGSEGV:
    {
        int is_null;
        int32_t base;
        switch (N_RX_GET_OPC((uint8_t*) xpc)) {
            case OPC_L:
            case OPC_ST:
            case OPC_CL: /* array size check on NULL array */
                base = N_RX_GET_BASE((uint8_t*) xpc);
                if (base == 0) {
                    is_null = 1;
                } else if (es->intregs[base] == 0) {
                    is_null = 1;
                } else {
                    is_null = 0;
                }
                break;
            default:
                is_null = 0;
                break;
        }

        // Check for implicit NullPointerException.
        if (is_null) {
            trp->type  = TRAP_NullPointerException;
            trp->value = 0;
            return true;
        }

        return false;
    }

    case TRAP_SIGFPE:
    {
        if (N_RR_GET_OPC((uint8_t*) xpc) == OPC_DR) {
            int r2 = N_RR_GET_REG2((uint8_t*) xpc);
            if (es->intregs[r2] == 0) {
                trp->type = TRAP_ArithmeticException;
                trp->value = 0;
                return true;
            }
        }

        return false;
    }

    default:
        return false;
    }
}



/* md_patch_replacement_point **************************************************

   Patch the given replacement point.

*******************************************************************************/
#if defined(ENABLE_REPLACEMENT)
void md_patch_replacement_point(u1 *pc, u1 *savedmcode, bool revert)
{
    assert(0);
}
#endif

extern "C" {
void md_handle_exception(int32_t *regs, int64_t *fregs, int32_t *out) {

    uint8_t *xptr;
    uint8_t *xpc;
    uint8_t *sp;
    uint8_t *pv;
    uint8_t *ra;
    uint8_t *handler;
    int32_t framesize;
    int32_t intsave;
    int32_t fltsave;
    int64_t *savearea;
    int i;
    int reg;
    int loops = 0;

    /* get registers */

    xptr = *(uint8_t **)(regs + REG_ITMP1_XPTR);
    xpc = *(uint8_t **)(regs + REG_ITMP2_XPC);
    sp = *(uint8_t **)(regs + REG_SP);


    /* initialize number of calle saved int regs to restore to 0 */
    out[0] = 0;

    /* initialize number of calle saved flt regs to restore to 0 */
    out[1] = 0;

    do {

        ++loops;

        pv = (uint8_t*) methodtree_find(xpc);

        handler = (uint8_t*) exceptions_handle_exception((java_object_t *)xptr, xpc, pv, sp);

        if (handler == NULL) {

            /* exception was not handled
             * get values of calee saved registers and remove stack frame 
             */

            /* read stuff from data segment */

            framesize = *(int32_t *)(pv + FrameSize);

            intsave = *(int32_t *)(pv + IntSave);
            if (intsave > out[0]) {
                out[0] = intsave;
            }

            fltsave = *(int32_t *)(pv + FltSave);
            if (fltsave > out[1]) {
                out[1] = fltsave;
            }

            /* pointer to register save area */

            savearea = (int64_t *)(sp + framesize - 8);

            /* return address */

            ra = *(uint8_t **)(sp + framesize - 8);

            /* restore saved registers */

            for (i = 0; i < intsave; ++i) {
                --savearea;
                reg = abi_registers_integer_saved[INT_SAV_CNT - 1 - i];
                regs[reg] = *(int32_t *)(savearea);
            }

            for (i = 0; i < fltsave; ++i) {
                --savearea;
                reg = abi_registers_float_saved[FLT_SAV_CNT - 1 - i];
                fregs[reg] = *savearea;
            }

            /* remove stack frame */

            sp += framesize;

            /* new xpc is call before return address */

            xpc = ra - 2;

        } else {
            xpc = handler;
        }
    } while (handler == NULL);

    /* write new values for registers */

    *(uint8_t **)(regs + REG_ITMP1_XPTR) = xptr;
    *(uint8_t **)(regs + REG_ITMP2_XPC) = xpc;
    *(uint8_t **)(regs + REG_SP) = sp;
    *(uint8_t **)(regs + REG_PV) = pv - 0XFFC;

    /* maybe leaf flag */

    out[2] = (loops == 1);
}
}

/*
 * These are local overrides for various environment variables in Emacs.
 * Please do not remove this and leave it at the end of the file, where
 * Emacs will automagically detect them.
 * ---------------------------------------------------------------------
 * Local variables:
 * mode: c++
 * indent-tabs-mode: t
 * c-basic-offset: 4
 * tab-width: 4
 * End:
 * vim:noexpandtab:sw=4:ts=4:
 */