-/* src/vm/jit/arm/md.c - machine dependent Arm functions
+/* src/vm/jit/arm/md.c - machine dependent ARM functions
- Copyright (C) 1996-2005, 2006, 2007 R. Grafl, A. Krall, C. Kruegel,
- C. Oates, R. Obermaisser, M. Platter, M. Probst, S. Ring,
- E. Steiner, C. Thalinger, D. Thuernbeck, P. Tomsich, C. Ullrich,
- J. Wenninger, Institut f. Computersprachen - TU Wien
+ Copyright (C) 1996-2005, 2006, 2007, 2008
+ CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO
This file is part of CACAO.
#include <assert.h>
#include <stdint.h>
+#include "vm/jit/arm/codegen.h"
#include "vm/jit/arm/md.h"
#include "vm/jit/arm/md-abi.h"
or
e590b000 ldr fp, [r0]
- e59bc000 ldr ip, [fp]
+ 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!)
{
uint32_t *pc;
uint32_t mcode;
- int32_t offset;
+ int32_t disp;
void *pa; /* patch address */
/* Go back to the actual load instruction. */
mcode = pc[0];
- /* sanity check: are we inside jit code? */
+ /* Sanity check: Are we inside jit code? */
assert(pc[1] == 0xe1a0e00f /*MOV LR,PC*/);
assert(pc[2] == 0xe1a0f00c /*MOV PC,IP*/);
- /* get the load instruction and offset */
-
- offset = (int32_t) (mcode & 0x0fff);
+ /* Sanity check: We unconditionally loaded a word into REG_PV? */
assert ((mcode & 0xff70f000) == 0xe510c000);
- if ((mcode & 0x000f0000) == 0x000b0000) {
- /* sanity check: offset was positive */
+ /* Get load displacement. */
+
+ disp = (int32_t) (mcode & 0x0fff);
- assert((mcode & 0x00800000) == 0x00800000);
+ /* 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)
/* we loaded from REG_METHODPTR */
- pa = ((uint8_t *) mptr) + offset;
+ pa = ((uint8_t *) mptr) + disp;
}
- else {
- /* sanity check: we loaded from REG_IP; offset was negative or zero */
- assert((mcode & 0x008f0000) == 0x000c0000 ||
- (mcode & 0x008f0fff) == 0x008c0000);
+ /* Case: We loaded from base REG_PV with positive offset. */
- /* we loaded from data segment; offset can be larger */
+ 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 "SUB IP, IP, #??, ROTL 12" */
+ /* check for "ADD IP, FP, #??, ROTL 12" */
- if ((mcode & 0xffffff00) == 0xe24cca00)
- offset += (int32_t) ((mcode & 0x00ff) << 12);
+ if ((mcode & 0xffffff00) == 0xe28bca00) {
+ /* We loaded from REG_METHODPTR with a larger displacement. */
- /* and get the final data segment address */
+ 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;
+ }
- pa = ((uint8_t *) pv) - offset;
+ /* 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;
}
+/**
+ * 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
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