md-os.cpp

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/* src/vm/jit/i386/freebsd/md-os.c - machine dependent i386 FreeBSD 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 <stdint.h>
#include <ucontext.h>

#include "vm/types.hpp"

#include "vm/jit/i386/codegen.hpp"
#include "vm/jit/i386/md.hpp"

#include "threads/thread.hpp"

#include "vm/jit/builtin.hpp"
#include "vm/signallocal.hpp"

#include "vm/jit/asmpart.hpp"
#include "vm/jit/executionstate.hpp"
#include "vm/jit/patcher-common.hpp"
#include "vm/jit/stacktrace.hpp"
#include "vm/jit/trap.hpp"


/* md_signal_handler_sigsegv ***************************************************

   Signal handler for hardware exceptions.

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

void md_signal_handler_sigsegv(int sig, siginfo_t *siginfo, void *_p)
{
    ucontext_t     *_uc;
    mcontext_t     *_mc;
    u1             *pv;
    u1             *sp;
    u1             *ra;
    u1             *xpc;
    u1              opc;
    u1              mod;
    u1              rm;
    s4              d;
    s4              disp;
    ptrint          val;
    s4              type;
    void           *p;

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

    pv  = NULL;                 /* is resolved during stackframeinfo creation */
    sp  = (u1 *) _mc->mc_esp;
    xpc = (u1 *) _mc->mc_eip;
    ra  = xpc;                              /* return address is equal to XPC */

    /* get exception-throwing instruction */

    opc = M_ALD_MEM_GET_OPC(xpc);
    mod = M_ALD_MEM_GET_MOD(xpc);
    rm  = M_ALD_MEM_GET_RM(xpc);

    /* for values see emit_mov_mem_reg and emit_mem */

    if ((opc == 0x8b) && (mod == 0) && (rm == 5)) {
        /* this was a hardware-exception */

        d    = M_ALD_MEM_GET_REG(xpc);
        disp = M_ALD_MEM_GET_DISP(xpc);

        /* we use the exception type as load displacement */

        type = disp;

        switch (d) {
        case EAX:
            val = _mc->mc_eax;
            break;
        case ECX:
            val = _mc->mc_ecx;
            break;
        case EDX:
            val = _mc->mc_edx;
            break;
        case EBX:
            val = _mc->mc_ebx;
            break;
        case ESP:
            val = _mc->mc_esp;
            break;
        case EBP:
            val = _mc->mc_ebp;
            break;
        case ESI:
            val = _mc->mc_esi;
            break;
        case EDI:
            val = _mc->mc_edi;
            break;
        default:
            vm_abort("md_signal_handler_sigsegv: Unkown register %d", d);
        }

        if (type == TRAP_COMPILER) {
            /* The PV from the compiler stub is equal to the XPC. */

            pv = xpc;

            /* We use a framesize of zero here because the call pushed
               the return addres onto the stack. */

            ra = md_stacktrace_get_returnaddress(sp, 0);

            /* Skip the RA on the stack. */

            sp = sp + 1 * SIZEOF_VOID_P;

            /* The XPC is the RA minus 2, because the RA points to the
               instruction after the call. */

            xpc = ra - 2;
        }
    }
    else {
        /* this was a normal NPE */

        type = TRAP_NullPointerException;
        val  = 0;
    }

    /* Handle the trap. */

    p = trap_handle(type, val, pv, sp, ra, xpc, _p);

    /* Set registers. */

    if (type == TRAP_COMPILER) {
        if (p == NULL) {
            _mc->mc_esp = (uintptr_t) sp; // Remove RA from stack.
        }
    }
}


/* 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;
    mcontext_t     *_mc;
    u1             *pv;
    u1             *sp;
    u1             *ra;
    u1             *xpc;
    s4              type;
    ptrint          val;

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

    pv  = NULL;                 /* is resolved during stackframeinfo creation */
    sp  = (u1 *) _mc->mc_esp;
    xpc = (u1 *) _mc->mc_eip;
    ra  = xpc;                          /* return address is equal to xpc     */

    /* This is an ArithmeticException. */

    type = TRAP_ArithmeticException;
    val  = 0;

    /* Handle the trap. */

    trap_handle(type, val, pv, sp, ra, xpc, _p);
}


/* md_signal_handler_sigill ****************************************************

   Signal handler for hardware patcher traps (ud2).

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

void md_signal_handler_sigill(int sig, siginfo_t *siginfo, void *_p)
{
    ucontext_t        *_uc;
    mcontext_t        *_mc;
    u1                *pv;
    u1                *sp;
    u1                *ra;
    u1                *xpc;
    s4                 type;
    ptrint             val;

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

    pv  = NULL;                 /* is resolved during stackframeinfo creation */
    sp  = (u1 *) _mc->mc_esp;
    xpc = (u1 *) _mc->mc_eip;
    ra  = xpc;                            /* return address is equal to xpc   */

    // Check if the trap instruction is valid.
    // TODO Move this into patcher_handler.
    if (patcher_is_valid_trap_instruction_at(xpc) == false) {
        // Check if the PC has been patched during our way to this
        // signal handler (see PR85).
        if (patcher_is_patched_at(xpc) == true)
            return;

        // We have a problem...
        log_println("md_signal_handler_sigill: Unknown illegal instruction at 0x%lx", xpc);
#if defined(ENABLE_DISASSEMBLER)
        (void) disassinstr(xpc);
#endif
        vm_abort("Aborting...");
    }

    type = TRAP_PATCHER;
    val  = 0;

    /* Handle the trap. */

    trap_handle(type, val, pv, sp, ra, xpc, _p);
}


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

   Signal handler for profiling sampling.

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

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;

    pc = (u1 *) _mc->mc_eip;

    t->pc = pc;
}


/* md_executionstate_read ******************************************************

   Read the given context into an executionstate for Replacement.

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

void md_executionstate_read(executionstate_t* es, void* context)
{
    ucontext_t* _uc = (ucontext_t*) context;
    mcontext_t* _mc = &_uc->uc_mcontext;

    // Read special registers.
    es->pc = (u1 *) _mc->mc_eip;
    es->sp = (u1 *) _mc->mc_esp;
    es->pv = NULL;                   /* pv must be looked up via AVL tree */

    // Read integer registers.
    es->intregs[EAX] = _mc->mc_eax;
    es->intregs[ECX] = _mc->mc_ecx;
    es->intregs[EDX] = _mc->mc_edx;
    es->intregs[EBX] = _mc->mc_ebx;
    es->intregs[ESP] = _mc->mc_esp;
    es->intregs[EBP] = _mc->mc_ebp;
    es->intregs[ESI] = _mc->mc_esi;
    es->intregs[EDI] = _mc->mc_edi;

    // Read float registers.
    for (int i = 0; i < FLT_REG_CNT; i++)
        es->fltregs[i] = 0xdeadbeefdeadbeefULL;
}


/* md_executionstate_write *****************************************************

   Write the given executionstate back to the context for Replacement.

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

void md_executionstate_write(executionstate_t* es, void* context)
{
    ucontext_t* _uc = (ucontext_t*) context;
    mcontext_t* _mc = &_uc->uc_mcontext;

    // Write integer registers.
    _mc->mc_eax = es->intregs[EAX];
    _mc->mc_ecx = es->intregs[ECX];
    _mc->mc_edx = es->intregs[EDX];
    _mc->mc_ebx = es->intregs[EBX];
    _mc->mc_esp = es->intregs[ESP];
    _mc->mc_ebp = es->intregs[EBP];
    _mc->mc_esi = es->intregs[ESI];
    _mc->mc_edi = es->intregs[EDI];

    // Write special registers.
    _mc->mc_eip = (uintptr_t) es->pc;
    _mc->mc_esp = (uintptr_t) es->sp;
}


/*
 * 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:
 */