/*
* Given the state of the current frame as stored in REGS, execute the unwind
* operations in unwind_info until the location counter reaches POS. The result is
* stored back into REGS. OUT_CFA will receive the value of the CFA.
* If SAVE_LOCATIONS is non-NULL, it should point to an array of size SAVE_LOCATIONS_LEN.
* On return, the nth entry will point to the address of the stack slot where register
* N was saved, or NULL, if it was not saved by this frame.
* This function is signal safe.
*/
void
mono_unwind_frame (guint8 *unwind_info, guint32 unwind_info_len,
guint8 *start_ip, guint8 *end_ip, guint8 *ip, mgreg_t *regs, int nregs,
mgreg_t **save_locations, int save_locations_len,
guint8 **out_cfa)
{
Loc locations [NUM_REGS];
int i, pos, reg, cfa_reg, cfa_offset;
guint8 *p;
guint8 *cfa_val;
for (i = 0; i < NUM_REGS; ++i)
locations [i].loc_type = LOC_SAME;
p = unwind_info;
pos = 0;
cfa_reg = -1;
cfa_offset = -1;
while (pos <= ip - start_ip && p < unwind_info + unwind_info_len) {
int op = *p & 0xc0;
switch (op) {
case DW_CFA_advance_loc:
UNW_DEBUG (print_dwarf_state (cfa_reg, cfa_offset, pos, nregs, locations));
pos += *p & 0x3f;
p ++;
break;
case DW_CFA_offset:
reg = *p & 0x3f;
p ++;
locations [reg].loc_type = LOC_OFFSET;
locations [reg].offset = decode_uleb128 (p, &p) * DWARF_DATA_ALIGN;
break;
case 0: {
int ext_op = *p;
p ++;
switch (ext_op) {
case DW_CFA_def_cfa:
cfa_reg = decode_uleb128 (p, &p);
cfa_offset = decode_uleb128 (p, &p);
break;
case DW_CFA_def_cfa_offset:
cfa_offset = decode_uleb128 (p, &p);
break;
case DW_CFA_def_cfa_register:
cfa_reg = decode_uleb128 (p, &p);
break;
case DW_CFA_offset_extended_sf:
reg = decode_uleb128 (p, &p);
locations [reg].loc_type = LOC_OFFSET;
locations [reg].offset = decode_sleb128 (p, &p) * DWARF_DATA_ALIGN;
break;
case DW_CFA_advance_loc4:
pos += read32 (p);
p += 4;
break;
default:
g_assert_not_reached ();
}
break;
}
default:
g_assert_not_reached ();
}
}
if (save_locations)
memset (save_locations, 0, save_locations_len * sizeof (mgreg_t*));
cfa_val = (guint8*)regs [mono_dwarf_reg_to_hw_reg (cfa_reg)] + cfa_offset;
for (i = 0; i < NUM_REGS; ++i) {
if (locations [i].loc_type == LOC_OFFSET) {
int hreg = mono_dwarf_reg_to_hw_reg (i);
g_assert (hreg < nregs);
regs [hreg] = *(mgreg_t*)(cfa_val + locations [i].offset);
if (save_locations && hreg < save_locations_len)
save_locations [hreg] = (mgreg_t*)(cfa_val + locations [i].offset);
}
}
*out_cfa = cfa_val;
}
/*
* Given the state of the current frame as stored in REGS, execute the unwind
* operations in unwind_info until the location counter reaches POS. The result is
* stored back into REGS. OUT_CFA will receive the value of the CFA.
* If SAVE_LOCATIONS is non-NULL, it should point to an array of size SAVE_LOCATIONS_LEN.
* On return, the nth entry will point to the address of the stack slot where register
* N was saved, or NULL, if it was not saved by this frame.
* MARK_LOCATIONS should contain the locations marked by mono_emit_unwind_op_mark_loc (), if any.
* This function is signal safe.
*/
void
mono_unwind_frame (guint8 *unwind_info, guint32 unwind_info_len,
guint8 *start_ip, guint8 *end_ip, guint8 *ip, guint8 **mark_locations,
mono_unwind_reg_t *regs, int nregs,
mgreg_t **save_locations, int save_locations_len,
guint8 **out_cfa)
{
Loc locations [NUM_REGS];
guint8 reg_saved [NUM_REGS];
int i, pos, reg, cfa_reg = -1, cfa_offset = 0, offset;
guint8 *p;
guint8 *cfa_val;
UnwindState state_stack [1];
int state_stack_pos;
memset (reg_saved, 0, sizeof (reg_saved));
state_stack [0].cfa_reg = -1;
state_stack [0].cfa_offset = 0;
p = unwind_info;
pos = 0;
cfa_reg = -1;
cfa_offset = -1;
state_stack_pos = 0;
while (pos <= ip - start_ip && p < unwind_info + unwind_info_len) {
int op = *p & 0xc0;
switch (op) {
case DW_CFA_advance_loc:
UNW_DEBUG (print_dwarf_state (cfa_reg, cfa_offset, pos, nregs, locations));
pos += *p & 0x3f;
p ++;
break;
case DW_CFA_offset:
reg = *p & 0x3f;
p ++;
reg_saved [reg] = TRUE;
locations [reg].loc_type = LOC_OFFSET;
locations [reg].offset = decode_uleb128 (p, &p) * DWARF_DATA_ALIGN;
break;
case 0: {
int ext_op = *p;
p ++;
switch (ext_op) {
case DW_CFA_def_cfa:
cfa_reg = decode_uleb128 (p, &p);
cfa_offset = decode_uleb128 (p, &p);
break;
case DW_CFA_def_cfa_offset:
cfa_offset = decode_uleb128 (p, &p);
break;
case DW_CFA_def_cfa_register:
cfa_reg = decode_uleb128 (p, &p);
break;
case DW_CFA_offset_extended_sf:
reg = decode_uleb128 (p, &p);
offset = decode_sleb128 (p, &p);
g_assert (reg < NUM_REGS);
reg_saved [reg] = TRUE;
locations [reg].loc_type = LOC_OFFSET;
locations [reg].offset = offset * DWARF_DATA_ALIGN;
break;
case DW_CFA_offset_extended:
reg = decode_uleb128 (p, &p);
offset = decode_uleb128 (p, &p);
g_assert (reg < NUM_REGS);
reg_saved [reg] = TRUE;
locations [reg].loc_type = LOC_OFFSET;
locations [reg].offset = offset * DWARF_DATA_ALIGN;
break;
case DW_CFA_same_value:
reg = decode_uleb128 (p, &p);
locations [reg].loc_type = LOC_SAME;
break;
case DW_CFA_advance_loc1:
pos += *p;
p += 1;
break;
case DW_CFA_advance_loc2:
pos += read16 (p);
p += 2;
break;
case DW_CFA_advance_loc4:
pos += read32 (p);
p += 4;
break;
case DW_CFA_remember_state:
g_assert (state_stack_pos == 0);
memcpy (&state_stack [0].locations, &locations, sizeof (locations));
memcpy (&state_stack [0].reg_saved, ®_saved, sizeof (reg_saved));
state_stack [0].cfa_reg = cfa_reg;
state_stack [0].cfa_offset = cfa_offset;
state_stack_pos ++;
break;
case DW_CFA_restore_state:
g_assert (state_stack_pos == 1);
state_stack_pos --;
memcpy (&locations, &state_stack [0].locations, sizeof (locations));
memcpy (®_saved, &state_stack [0].reg_saved, sizeof (reg_saved));
cfa_reg = state_stack [0].cfa_reg;
cfa_offset = state_stack [0].cfa_offset;
break;
case DW_CFA_mono_advance_loc:
g_assert (mark_locations [0]);
pos = mark_locations [0] - start_ip;
break;
default:
g_assert_not_reached ();
}
break;
}
default:
g_assert_not_reached ();
}
}
if (save_locations)
memset (save_locations, 0, save_locations_len * sizeof (mgreg_t*));
g_assert (cfa_reg != -1);
cfa_val = (guint8*)regs [mono_dwarf_reg_to_hw_reg (cfa_reg)] + cfa_offset;
for (i = 0; i < NUM_REGS; ++i) {
if (reg_saved [i] && locations [i].loc_type == LOC_OFFSET) {
int hreg = mono_dwarf_reg_to_hw_reg (i);
g_assert (hreg < nregs);
if (IS_DOUBLE_REG (i))
regs [hreg] = *(guint64*)(cfa_val + locations [i].offset);
else
regs [hreg] = *(mgreg_t*)(cfa_val + locations [i].offset);
if (save_locations && hreg < save_locations_len)
save_locations [hreg] = (mgreg_t*)(cfa_val + locations [i].offset);
}
}
*out_cfa = cfa_val;
}