/* src/vm/jit/arm/md.c - machine dependent ARM functions Copyright (C) 1996-2005, 2006, 2007, 2008, 2010 CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO Copyright (C) 2009 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 #include #include "vm/jit/arm/codegen.h" #include "vm/jit/arm/md.h" #include "vm/jit/arm/md-abi.h" #include "vm/jit/executionstate.h" #include "vm/jit/trap.hpp" /* md_init ********************************************************************* Do some machine dependent initialization. *******************************************************************************/ void md_init(void) { /* do nothing here */ } /* 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). Machine code: e51cc040 ldr ip, [ip, #-64] e1a0e00f mov lr, pc e1a0f00c mov pc, ip or e590b000 ldr fp, [r0] e59bc004 ldr ip, [fp, #4] e1a0e00f mov lr, pc e1a0f00c mov pc, ip or e590b000 ldr fp, [r0] e28bca01 add ip, fp, #4096 ; 0x1000 e59cc004 ldr ip, [ip, #4] e1a0e00f mov lr, pc e1a0f00c mov pc, ip How we find out the patching address to store new method pointer: - loaded IP with LDR IP,[METHODPTR]? yes=INVOKEVIRTUAL or INVOKEINTERFACE (things are easy!) - loaded IP from data segment yes=INVOKESTATIC or INVOKESPECIAL (things are complicated) recompute pointer to data segment, maybe larger offset *******************************************************************************/ void *md_jit_method_patch_address(void *pv, void *ra, void *mptr) { uint32_t *pc; uint32_t mcode; int32_t disp; void *pa; /* patch address */ /* Go back to the actual load instruction. */ pc = ((uint32_t *) ra) - 3; /* Get first instruction word on current PC. */ mcode = pc[0]; /* Sanity check: Are we inside jit code? */ assert(pc[1] == 0xe1a0e00f /*MOV LR,PC*/); assert(pc[2] == 0xe1a0f00c /*MOV PC,IP*/); /* Sanity check: We unconditionally loaded a word into REG_PV? */ assert ((mcode & 0xff70f000) == 0xe510c000); /* Get load displacement. */ disp = (int32_t) (mcode & 0x0fff); /* Case: We loaded from base REG_PV with negative displacement. */ if (M_MEM_GET_Rbase(mcode) == REG_PV && (mcode & 0x00800000) == 0) { /* We loaded from data segment, displacement can be larger. */ mcode = pc[-1]; /* check for "SUB IP, IP, #??, ROTL 12" */ if ((mcode & 0xffffff00) == 0xe24cca00) disp += (int32_t) ((mcode & 0x00ff) << 12); /* and get the final data segment address */ pa = ((uint8_t *) pv) - disp; } /* Case: We loaded from base REG_METHODPTR with positive displacement. */ else if (M_MEM_GET_Rbase(mcode) == REG_METHODPTR && (mcode & 0x00800000) == 0x00800000) { /* return NULL if no mptr was specified (used for replacement) */ if (mptr == NULL) return NULL; /* we loaded from REG_METHODPTR */ pa = ((uint8_t *) mptr) + disp; } /* Case: We loaded from base REG_PV with positive offset. */ else if (M_MEM_GET_Rbase(mcode) == REG_PV && (mcode & 0x00800000) == 0x00800000) { /* We loaded with a larger displacement. Normally this means we loaded from REG_METHODPTR. However there is a corner case if we loaded from the data segment at an address aligned to 12 bit, which leads to a zero (positive) displacement for the last instruction. */ mcode = pc[-1]; /* check for "ADD IP, FP, #??, ROTL 12" */ if ((mcode & 0xffffff00) == 0xe28bca00) { /* We loaded from REG_METHODPTR with a larger displacement. */ assert(mptr != NULL); disp += (int32_t) ((mcode & 0x00ff) << 12); pa = ((uint8_t *) mptr) + disp; } /* check for "SUB IP, IP, #??, ROTL 12" (corner case) */ else if ((mcode & 0xffffff00) == 0xe24cca00 && disp == 0) { /* We loaded from data segment with a larger displacement aligned to 12 bit. */ disp += (int32_t) ((mcode & 0x00ff) << 12); pa = ((uint8_t *) pv) - disp; } /* Case is not covered, something is severely wrong. */ else { vm_abort_disassemble(pc - 1, 4, "md_jit_method_patch_address: unknown instruction %x", mcode); /* Keep compiler happy. */ pa = NULL; } } /* Case is not covered, something is severely wrong. */ else { vm_abort_disassemble(pc, 3, "md_jit_method_patch_address: unknown instruction %x", mcode); /* Keep compiler happy. */ pa = NULL; } 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) { // Get the exception-throwing instruction. uint32_t mcode = *((uint32_t*) xpc); switch (sig) { case TRAP_SIGILL: // Check for valid trap instruction. if (patcher_is_valid_trap_instruction_at(xpc)) { trp->type = (mcode >> 8) & 0x0fff; trp->value = es->intregs[mcode & 0x0f]; return true; } return false; case TRAP_SIGSEGV: { // Sanity check for load/store instruction. // FIXME Implement this! // Retrieve base address of load/store instruction. uintptr_t addr = es->intregs[(mcode >> 16) & 0x0f]; // Check for implicit NullPointerException. if (addr == 0) { trp->type = TRAP_NullPointerException; trp->value = 0; return true; } } default: return false; } } /** * Patch the given replacement point. */ #if defined(ENABLE_REPLACEMENT) void md_patch_replacement_point(u1 *pc, u1 *savedmcode, bool revert) { vm_abort("md_patch_replacement_point: IMPLEMENT ME!"); } #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: */