patcher.cpp

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/* src/vm/jit/powerpc/patcher.cpp - PowerPC code patching functions

   Copyright (C) 1996-2013
   CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO
   Copyright (C) 2008 Theobroma Systems Ltd.

   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/powerpc/md.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/asmpart.hpp"
#include "vm/jit/methodheader.hpp"
#include "vm/jit/patcher-common.hpp"


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

   Just patches back the original machine code.

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

void patcher_patch_code(patchref_t *pr)
{
    // Patch back original code.
    *((uint32_t*) pr->mpc) = pr->mcode;

    // Synchronize instruction cache.
    md_icacheflush((void*) pr->mpc, 1 * 4);
}


/**
 * 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)
{
    uint32_t mcode = *((uint32_t*) pc);

    // Check for the undefined instruction we use.
    return (mcode == 0x00000000);
}


/* patcher_resolve_classref_to_classinfo ***************************************

   ACONST:

   <patched call postition>
   806dffc4    lwz   r3,-60(r13)
   81adffc0    lwz   r13,-64(r13)
   7da903a6    mtctr r13
   4e800421    bctrl


   MULTIANEWARRAY:

   <patched call position>
   808dffc0    lwz   r4,-64(r13)
   38a10038    addi  r5,r1,56
   81adffbc    lwz   r13,-68(r13)
   7da903a6    mtctr r13
   4e800421    bctrl


   ARRAYCHECKCAST:

   <patched call position>
   808dffd8    lwz   r4,-40(r13)
   81adffd4    lwz   r13,-44(r13)
   7da903a6    mtctr r13
   4e800421    bctrl

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

bool patcher_resolve_classref_to_classinfo(patchref_t *pr)
{
    constant_classref * cr    = (constant_classref*) pr->ref;
    uintptr_t*          datap = (uintptr_t*)         pr->datap;

    // Resolve the class.
    classinfo* c = resolve_classref_eager(cr);

    if (c == NULL)
        return false;

    // Patch the class pointer.
    *datap = (uintptr_t) c;

    // Synchronize data cache.
    md_dcacheflush(datap, SIZEOF_VOID_P);

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

    return true;
}


/* patcher_resolve_classref_to_vftbl *******************************************

   CHECKCAST (class):

   <patched call position>
   81870000    lwz   r12,0(r7)
   800c0014    lwz   r0,20(r12)
   818dff78    lwz   r12,-136(r13)


   INSTANCEOF (class):

   <patched call position>
   817d0000    lwz   r11,0(r29)
   818dff8c    lwz   r12,-116(r13)

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

bool patcher_resolve_classref_to_vftbl(patchref_t *pr)
{
    constant_classref* cr    = (constant_classref*) pr->ref;
    uintptr_t*         datap = (uintptr_t*)         pr->datap;

    // Resolve the class.
    classinfo* c = resolve_classref_eager(cr);

    if (c == NULL)
        return false;

    // Patch super class' vftbl.
    *datap = (uintptr_t) c->vftbl;

    // Synchronize data cache.
    md_dcacheflush(datap, SIZEOF_VOID_P);

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

    return true;
}


/* patcher_resolve_classref_to_flags *******************************************

   CHECKCAST/INSTANCEOF:

   <patched call position>
   818dff7c    lwz   r12,-132(r13)

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

bool patcher_resolve_classref_to_flags(patchref_t *pr)
{
    constant_classref* cr    = (constant_classref*) pr->ref;
    int32_t*           datap = (int32_t*)           pr->datap;

    // Resolve the class.
    classinfo* c = resolve_classref_eager(cr);

    if (c == NULL)
        return false;

    // Patch class flags.
    *datap = c->flags;

    // Synchronize data cache.
    md_dcacheflush(datap, SIZEOF_VOID_P);

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

    return true;
}


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

   Machine code:

   <patched call position>
   816dffc8    lwz   r11,-56(r13)
   80ab0000    lwz   r5,0(r11)

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

bool patcher_get_putstatic(patchref_t *pr)
{
    unresolved_field* uf    = (unresolved_field*) pr->ref;
    uintptr_t*        datap = (uintptr_t*)        pr->datap;

    // Resolve the field.
    fieldinfo* fi = resolve_field_eager(uf);

    if (fi == NULL)
        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.
    *datap = (uintptr_t) fi->value;

    // Synchronize data cache.
    md_dcacheflush(datap, SIZEOF_VOID_P);

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

    return true;
}


/* patcher_get_putfield ********************************************************

   Machine code:

   <patched call position>
   811f0014    lwz   r8,20(r31)

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

bool patcher_get_putfield(patchref_t *pr)
{
    uint32_t*         pc = (uint32_t*)         pr->mpc;
    unresolved_field* uf = (unresolved_field*) pr->ref;

    // Resolve the field.
    fieldinfo* fi = resolve_field_eager(uf);

    if (fi == NULL)
        return false;

    // Patch the field's offset.
    if (IS_LNG_TYPE(fi->type)) {
        /* If the field has type long, we have to patch two
           instructions.  But we have to check which instruction
           is first.  We do that with the offset of the first
           instruction. */

        uint32_t disp = (pr->mcode & 0x0000ffff);

        if (disp == 4) {
            pr->mcode &= 0xffff0000;
            pr->mcode |= ((fi->offset + 4) & 0x0000ffff);
            pc[1] |= ((fi->offset + 0) & 0x0000ffff);
        }
        else {
            pr->mcode |= ((fi->offset + 0) & 0x0000ffff);
            pc[1] &= 0xffff0000;
            pc[1] |= ((fi->offset + 4) & 0x0000ffff);
        }

        // Synchronize instruction cache.
        md_icacheflush(pc + 1, 1 * 4);
    }
    else {
        pr->mcode |= (fi->offset & 0x0000ffff);
    }

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

    return true;
}


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

   Machine code:

   <patched call position>
   81adffd8    lwz   r13,-40(r13)
   7da903a6    mtctr r13
   4e800421    bctrl

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

bool patcher_invokestatic_special(patchref_t *pr)
{
    unresolved_method* um    = (unresolved_method*) pr->ref;
    uintptr_t*         datap = (uintptr_t*)         pr->datap;

    // Resolve the method.
    methodinfo* m = resolve_method_eager(um);

    if (m == NULL)
        return false;

    // Patch stubroutine.
    *datap = (uintptr_t) m->stubroutine;

    // Synchronize data cache.
    md_dcacheflush(datap, SIZEOF_VOID_P);

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

    return true;
}


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

   Machine code:

   <patched call position>
   81830000    lwz   r12,0(r3)
   81ac0088    lwz   r13,136(r12)
   7da903a6    mtctr r13
   4e800421    bctrl

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

bool patcher_invokevirtual(patchref_t *pr)
{
    uint32_t*          pc = (uint32_t*)          pr->mpc;
    unresolved_method* um = (unresolved_method*) pr->ref;

    // Resolve the method.
    methodinfo* m = resolve_method_eager(um);

    if (m == NULL)
        return false;

    // Patch vftbl index.
    int32_t disp = (OFFSET(vftbl_t, table[0]) + sizeof(methodptr) * m->vftblindex);

    pc[1] |= (disp & 0x0000ffff);

    // Synchronize instruction cache.
    md_icacheflush(pc + 1, 1 * 4);

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

    return true;
}


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

   Machine code:

   <patched call position>
   81830000    lwz   r12,0(r3)
   818cffd0    lwz   r12,-48(r12)
   81ac000c    lwz   r13,12(r12)
   7da903a6    mtctr r13
   4e800421    bctrl

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

bool patcher_invokeinterface(patchref_t *pr)
{
    uint32_t*          pc = (uint32_t*)          pr->mpc;
    unresolved_method* um = (unresolved_method*) pr->ref;

    // Resolve the method.
    methodinfo* m = resolve_method_eager(um);

    if (m == NULL)
        return false;

    // Patch interfacetable index.
    int32_t disp = OFFSET(vftbl_t, interfacetable[0]) - sizeof(methodptr*) * m->clazz->index;

    /* XXX TWISTI: check displacement */
    pc[1] |= (disp & 0x0000ffff);

    // Patch method offset.
    disp = sizeof(methodptr) * (m - m->clazz->methods);

    /* XXX TWISTI: check displacement */
    pc[2] |= (disp & 0x0000ffff);

    // Synchronize instruction cache.
    md_icacheflush(pc + 1, 2 * 4);

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

    return true;
}


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

   Machine code:

   <patched call position>
   81870000    lwz     r12,0(r7)
   800c0010    lwz     r0,16(r12)
   34000000    addic.  r0,r0,0
   41810008    bgt-    0x014135d8
   83c00003    lwz     r30,3(0)
   800c0000    lwz     r0,0(r12)

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

bool patcher_checkcast_interface(patchref_t *pr)
{
    uint32_t*          pc = (uint32_t*)          pr->mpc;
    constant_classref* cr = (constant_classref*) pr->ref;

    // Resolve the class.
    classinfo* c = resolve_classref_eager(cr);

    if (c == NULL)
        return false;

    // Patch super class index.
    int32_t disp = -(c->index);
    pc[2] |= (disp & 0x0000ffff);

    disp = OFFSET(vftbl_t, interfacetable[0]) - c->index * sizeof(methodptr*);
    pc[5] |= (disp & 0x0000ffff);

    // Synchronize instruction cache.
    md_icacheflush(pc + 2, 4 * 4);

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

    return true;
}


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

   Machine code:

   <patched call position>
   81870000    lwz     r12,0(r7)
   800c0010    lwz     r0,16(r12)
   34000000    addic.  r0,r0,0
   41810008    bgt-    0x014135d8
   83c00003    lwz     r30,3(0)
   800c0000    lwz     r0,0(r12)

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

bool patcher_instanceof_interface(patchref_t *pr)
{
    uint32_t*          pc = (uint32_t*)          pr->mpc;
    constant_classref* cr = (constant_classref*) pr->ref;

    // Resolve the class.
    classinfo* c = resolve_classref_eager(cr);

    if (c == NULL)
        return false;

    // Patch super class index.
    int32_t disp = -(c->index);
    pc[2] |= (disp & 0x0000ffff);

    disp = OFFSET(vftbl_t, interfacetable[0]) - c->index * sizeof(methodptr*);
    pc[4] |= (disp & 0x0000ffff);

    // Synchronize instruction cache.
    md_icacheflush(pc + 2, 3 * 4);

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

    return true;
}


/*
 * 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:
 */