patcher.cpp

Go to the documentation of this file.

/* src/vm/jit/i386/patcher.cpp - i386 code patching 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 "vm/types.hpp"

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

#include "mm/memory.hpp"

#include "native/native.hpp"

#include "vm/jit/builtin.hpp"
#include "vm/class.hpp"
#include "vm/field.hpp"
#include "vm/initialize.hpp"
#include "vm/options.hpp"
#include "vm/references.hpp"
#include "vm/resolve.hpp"

#include "vm/jit/patcher-common.hpp"


/* patcher_patch_code **********************************************************

   Just patches back the original machine code.

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

void patcher_patch_code(patchref_t *pr)
{
    *((uint16_t*) pr->mpc) = (uint16_t) pr->mcode;
    md_icacheflush((void*) pr->mpc, PATCHER_CALL_SIZE);
}

/**
 * Check if the trap instruction at the given PC is valid.
 *
 * @param pc Program counter.
 *
 * @return true if valid, false otherwise.
 */
bool patcher_is_valid_trap_instruction_at(void* pc)
{
    uint16_t mcode = *((uint16_t*) pc);

    // Check for the undefined instruction we use.
    return (mcode == 0x0b0f);
}


/* patcher_get_putstatic *******************************************************

   Machine code:

   <patched call position>
   c7 c0 00 00 00 00          mov    $0x00000000,%eax

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

bool patcher_get_putstatic(patchref_t *pr)
{
    u1               *ra;
    unresolved_field *uf;
    fieldinfo        *fi;

    /* get stuff from the stack */

    ra    = (u1 *)               pr->mpc;
    uf    = (unresolved_field *) pr->ref;

    /* get the fieldinfo */

    if (!(fi = resolve_field_eager(uf)))
        return false;

    /* check if the field's class is initialized */

    if (!(fi->clazz->state & CLASS_INITIALIZED))
        if (!initialize_class(fi->clazz))
            return false;

    /* patch the field value's address */

    *((intptr_t *) (ra + 2)) = (intptr_t) fi->value;
    md_icacheflush((void*) (ra + 2), SIZEOF_VOID_P);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_getfield ************************************************************

   Machine code:

   <patched call position>
   8b 88 00 00 00 00          mov    0x00000000(%eax),%ecx

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

bool patcher_getfield(patchref_t *pr)
{
    u1               *ra;
    unresolved_field *uf;
    fieldinfo        *fi;

    /* get stuff from the stack */

    ra    = (u1 *)               pr->mpc;
    uf    = (unresolved_field *) pr->ref;

    /* get the fieldinfo */

    if (!(fi = resolve_field_eager(uf)))
        return false;

    /* patch the field's offset */

    *((u4 *) (ra + 2)) = (u4) (fi->offset);
    int clen = SIZEOF_VOID_P;

    /* if the field has type long, we need to patch the second move too */

    if (fi->type == TYPE_LNG) {
        *((u4 *) (ra + 6 + 2)) = (u4) (fi->offset + 4);
        clen += 6;
    }

    md_icacheflush((void*) (ra + 2), clen);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_putfield ************************************************************

   Machine code:

   <patched call position>
   8b 88 00 00 00 00          mov    0x00000000(%eax),%ecx

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

bool patcher_putfield(patchref_t *pr)
{
    u1               *ra;
    unresolved_field *uf;
    fieldinfo        *fi;

    /* get stuff from the stack */

    ra    = (u1 *)               pr->mpc;
    uf    = (unresolved_field *) pr->ref;

    /* get the fieldinfo */

    if (!(fi = resolve_field_eager(uf)))
        return false;

    /* patch the field's offset */

    int clen = SIZEOF_VOID_P;
    if (fi->type != TYPE_LNG) {
        *((u4 *) (ra + 2)) = (u4) (fi->offset);
    }
    else {
        /* The long code is special:
         *
         * 89 8d 00 00 00 00          mov    %ecx,0x00000000(%ebp)
         * 89 95 00 00 00 00          mov    %edx,0x00000000(%ebp)
         */

        *((u4 *) (ra + 2))     = (u4) (fi->offset);
        *((u4 *) (ra + 6 + 2)) = (u4) (fi->offset + 4);
        clen += 6;
    }

    md_icacheflush((void*) (ra + 2), clen);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_putfieldconst *******************************************************

   Machine code:

   <patched call position>
   c7 85 00 00 00 00 7b 00 00 00    movl   $0x7b,0x0(%ebp)

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

bool patcher_putfieldconst(patchref_t *pr)
{
    u1               *ra;
    unresolved_field *uf;
    fieldinfo        *fi;

    /* get stuff from the stack */

    ra    = (u1 *)               pr->mpc;
    uf    = (unresolved_field *) pr->ref;

    /* get the fieldinfo */

    if (!(fi = resolve_field_eager(uf)))
        return false;

    /* patch the field's offset */

    int clen = SIZEOF_VOID_P;
    if (!IS_2_WORD_TYPE(fi->type)) {
        *((u4 *) (ra + 2)) = (u4) (fi->offset);
    }
    else {
        /* long/double code is different:
         *
         * c7 80 00 00 00 00 c8 01 00 00    movl   $0x1c8,0x0(%eax)
         * c7 80 04 00 00 00 00 00 00 00    movl   $0x0,0x4(%eax)
         */

        *((u4 *) (ra + 2))      = (u4) (fi->offset);
        *((u4 *) (ra + 10 + 2)) = (u4) (fi->offset + 4);
        clen += 10;
    }

    md_icacheflush((void*) (ra + 2), clen);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_aconst **************************************************************

   Machine code:

   <patched call postition>
   c7 c0 00 00 00 00          mov    $0x00000000,%eax

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

bool patcher_aconst(patchref_t *pr)
{
    u1                *ra;
    constant_classref *cr;
    classinfo         *c;

    /* get stuff from the stack */

    ra    = (u1 *)                pr->mpc;
    cr    = (constant_classref *) pr->ref;

    /* get the classinfo */

    if (!(c = resolve_classref_eager(cr)))
        return false;

    /* patch the classinfo pointer */

    *((ptrint *) (ra + 2)) = (ptrint) c;
    md_icacheflush((void*) (ra + 2), SIZEOF_VOID_P);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_builtin_multianewarray **********************************************

   Machine code:

   <patched call position>
   c7 04 24 02 00 00 00       movl   $0x2,(%esp)
   c7 44 24 04 00 00 00 00    movl   $0x00000000,0x4(%esp)
   89 e0                      mov    %esp,%eax
   83 c0 0c                   add    $0xc,%eax
   89 44 24 08                mov    %eax,0x8(%esp)
   b8 00 00 00 00             mov    $0x00000000,%eax
   ff d0                      call   *%eax

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

bool patcher_builtin_multianewarray(patchref_t *pr)
{
    u1                *ra;
    constant_classref *cr;
    classinfo         *c;

    /* get stuff from the stack */

    ra    = (u1 *)                pr->mpc;
    cr    = (constant_classref *) pr->ref;

    /* get the classinfo */

    if (!(c = resolve_classref_eager(cr)))
        return false;

    /* patch the classinfo pointer */

    *((ptrint *) (ra + 7 + 4)) = (ptrint) c;
    md_icacheflush((void*) (ra + 7 + 4), SIZEOF_VOID_P);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_builtin_arraycheckcast **********************************************

   Machine code:

   <patched call position>
   c7 44 24 04 00 00 00 00    movl   $0x00000000,0x4(%esp)
   ba 00 00 00 00             mov    $0x00000000,%edx
   ff d2                      call   *%edx

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

bool patcher_builtin_arraycheckcast(patchref_t *pr)
{
    u1                *ra;
    constant_classref *cr;
    classinfo         *c;

    /* get stuff from the stack */

    ra    = (u1 *)                pr->mpc;
    cr    = (constant_classref *) pr->ref;

    /* get the classinfo */

    if (!(c = resolve_classref_eager(cr)))
        return false;

    /* patch the classinfo pointer */

    *((ptrint *) (ra + 4)) = (ptrint) c;

    /* patch new function address */

    *((ptrint *) (ra + 8 + 1)) = (ptrint) BUILTIN_arraycheckcast;
    md_icacheflush((void*) (ra + 4), SIZEOF_VOID_P + 8 + 1 - 4);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_invokestatic_special ************************************************

   Machine code:

   <patched call position>
   c7 c1 00 00 00 00          mov    $0x00000000,%ecx
   ff d1                      call   *%ecx

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

bool patcher_invokestatic_special(patchref_t *pr)
{
    u1                *ra;
    unresolved_method *um;
    methodinfo        *m;

    /* get stuff from the stack */

    ra    = (u1 *)                pr->mpc;
    um    = (unresolved_method *) pr->ref;

    /* get the fieldinfo */

    if (!(m = resolve_method_eager(um)))
        return false;

    /* patch stubroutine */

    *((ptrint *) (ra + 2)) = (ptrint) m->stubroutine;
    md_icacheflush((void*) (ra + 2), SIZEOF_VOID_P);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_invokevirtual *******************************************************

   Machine code:

   <patched call position>
   8b 08                      mov    (%eax),%ecx
   8b 81 00 00 00 00          mov    0x00000000(%ecx),%eax
   ff d0                      call   *%eax

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

bool patcher_invokevirtual(patchref_t *pr)
{
    u1                *ra;
    unresolved_method *um;
    methodinfo        *m;

    /* get stuff from the stack */

    ra    = (u1 *)                pr->mpc;
    um    = (unresolved_method *) pr->ref;

    /* get the fieldinfo */

    if (!(m = resolve_method_eager(um)))
        return false;

    /* patch vftbl index */

    *((s4 *) (ra + 2 + 2)) = (s4) (OFFSET(vftbl_t, table[0]) +
                                   sizeof(methodptr) * m->vftblindex);
    md_icacheflush((void*) (ra + 2 + 2), SIZEOF_VOID_P);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_invokeinterface *****************************************************

   Machine code:

   <patched call position>
   8b 00                      mov    (%eax),%eax
   8b 88 00 00 00 00          mov    0x00000000(%eax),%ecx
   8b 81 00 00 00 00          mov    0x00000000(%ecx),%eax
   ff d0                      call   *%eax

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

bool patcher_invokeinterface(patchref_t *pr)
{
    u1                *ra;
    unresolved_method *um;
    methodinfo        *m;

    /* get stuff from the stack */

    ra    = (u1 *)                pr->mpc;
    um    = (unresolved_method *) pr->ref;

    /* get the fieldinfo */

    if (!(m = resolve_method_eager(um)))
        return false;

    /* patch interfacetable index */

    *((s4 *) (ra + 2 + 2)) = (s4) (OFFSET(vftbl_t, interfacetable[0]) -
                                   sizeof(methodptr) * m->clazz->index);

    /* patch method offset */

    *((s4 *) (ra + 2 + 6 + 2)) =
        (s4) (sizeof(methodptr) * (m - m->clazz->methods));
    md_icacheflush((void*) (ra + 2 + 2), SIZEOF_VOID_P + 6);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_checkcast_instanceof_flags ******************************************

   Machine code:

   <patched call position>
   c7 c1 00 00 00 00          mov    $0x00000000,%ecx

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

bool patcher_checkcast_instanceof_flags(patchref_t *pr)
{
    u1                *ra;
    constant_classref *cr;
    classinfo         *c;

    /* get stuff from the stack */

    ra    = (u1 *)                pr->mpc;
    cr    = (constant_classref *) pr->ref;

    /* get the fieldinfo */

    if (!(c = resolve_classref_eager(cr)))
        return false;

    /* patch class flags */

    *((s4 *) (ra + 2)) = (s4) c->flags;
    md_icacheflush((void*) (ra + 2), SIZEOF_VOID_P);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_checkcast_interface *************************************************

   Machine code:

   <patched call position>
   8b 91 00 00 00 00          mov    0x00000000(%ecx),%edx
   81 ea 00 00 00 00          sub    $0x00000000,%edx
   85 d2                      test   %edx,%edx
   0f 8f 06 00 00 00          jg     0x00000000
   8b 35 03 00 00 00          mov    0x3,%esi
   8b 91 00 00 00 00          mov    0x00000000(%ecx),%edx

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

bool patcher_checkcast_interface(patchref_t *pr)
{
    u1                *ra;
    constant_classref *cr;
    classinfo         *c;

    /* get stuff from the stack */

    ra    = (u1 *)                pr->mpc;
    cr    = (constant_classref *) pr->ref;

    /* get the fieldinfo */

    if (!(c = resolve_classref_eager(cr)))
        return false;

    /* patch super class index */

    *((s4 *) (ra + 6 + 2)) = (s4) c->index;

    *((s4 *) (ra + 6 + 6 + 2 + 6 + 6 + 2)) =
        (s4) (OFFSET(vftbl_t, interfacetable[0]) -
              c->index * sizeof(methodptr*));
    md_icacheflush((void*) (ra + 6 + 2), SIZEOF_VOID_P + 6 + 6 + 6 + 2);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_instanceof_interface ************************************************

   Machine code:

   <patched call position>
   8b 91 00 00 00 00          mov    0x00000000(%ecx),%edx
   81 ea 00 00 00 00          sub    $0x00000000,%edx
   85 d2                      test   %edx,%edx
   0f 8e 13 00 00 00          jle    0x00000000
   8b 91 00 00 00 00          mov    0x00000000(%ecx),%edx

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

bool patcher_instanceof_interface(patchref_t *pr)
{
    u1                *ra;
    constant_classref *cr;
    classinfo         *c;

    /* get stuff from the stack */

    ra    = (u1 *)                pr->mpc;
    cr    = (constant_classref *) pr->ref;

    /* get the fieldinfo */

    if (!(c = resolve_classref_eager(cr)))
        return false;

    /* patch super class index */

    *((s4 *) (ra + 6 + 2)) = (s4) c->index;

    *((s4 *) (ra + 6 + 6 + 2 + 6 + 2)) =
        (s4) (OFFSET(vftbl_t, interfacetable[0]) -
              c->index * sizeof(methodptr*));
    md_icacheflush((void*) (ra + 6 + 2), SIZEOF_VOID_P + 6 + 6 + 2);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_checkcast_class *****************************************************

   Machine code:

   <patched call position>
   c7 c1 00 00 00 00          mov    $0x00000000,%ecx

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

bool patcher_checkcast_class(patchref_t *pr)
{
    u1                *ra;
    constant_classref *cr;
    classinfo         *c;

    /* get stuff from the stack */

    ra    = (u1 *)                pr->mpc;
    cr    = (constant_classref *) pr->ref;

    /* get the fieldinfo */

    if (!(c = resolve_classref_eager(cr)))
        return false;

    /* patch super class' vftbl */

    *((ptrint *) (ra + 2)) = (ptrint) c->vftbl;
    md_icacheflush((void*) (ra + 2), SIZEOF_VOID_P);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


/* patcher_instanceof_class ****************************************************

   Machine code:

   <patched call position>
   c7 c1 00 00 00 00          mov    $0x00000000,%ecx

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

bool patcher_instanceof_class(patchref_t *pr)
{
    u1                *ra;
    constant_classref *cr;
    classinfo         *c;

    /* get stuff from the stack */

    ra    = (u1 *)                pr->mpc;
    cr    = (constant_classref *) pr->ref;

    /* get the fieldinfo */

    if (!(c = resolve_classref_eager(cr)))
        return false;

    /* patch super class' vftbl */

    *((ptrint *) (ra + 2)) = (ptrint) c->vftbl;
    md_icacheflush((void*) (ra + 2), SIZEOF_VOID_P);

    // Patch back the original code.
    patcher_patch_code(pr);

    return true;
}


#if !defined(NDEBUG)
patcher_function_list_t patcher_function_list[] = {
    { PATCHER_initialize_class,              "initialize_class" },
#ifdef ENABLE_VERIFIER
    { PATCHER_resolve_class,                 "resolve_class" },
#endif /* ENABLE_VERIFIER */
    { PATCHER_resolve_native_function,       "resolve_native_function" },
    { PATCHER_invokestatic_special,          "invokestatic_special" },
    { PATCHER_invokevirtual,                 "invokevirtual" },
    { PATCHER_invokeinterface,               "invokeinterface" },
    { PATCHER_breakpoint,                    "breakpoint" },
    { PATCHER_checkcast_interface,           "checkcast_interface" },
    { PATCHER_instanceof_interface,          "instanceof_interface" },
    { PATCHER_get_putstatic,                 "get_putstatic" },
    { PATCHER_getfield,                      "getfield" },
    { PATCHER_putfield,                      "putfield" },
    { PATCHER_putfieldconst,                 "putfieldconst" },
    { PATCHER_builtin_multianewarray,        "builtin_multianewarray" },
    { PATCHER_builtin_arraycheckcast,        "builtin_arraycheckcast" },
    { PATCHER_checkcast_instanceof_flags,    "checkcast_instanceof_flags" },
    { PATCHER_checkcast_class,               "checkcast_class" },
    { PATCHER_instanceof_class,              "instanceof_class" },
    { NULL,                                  "-UNKNOWN PATCHER FUNCTION-" }
};
#endif


/*
 * 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:
 */