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.eh_frame vs. .debug_frame register encoding
- From: Andreas Schwab <schwab at suse dot de>
- To: gdb-patches at sourceware dot org
- Date: Tue, 09 May 2006 16:06:22 +0200
- Subject: .eh_frame vs. .debug_frame register encoding
On powerpc the register encoding inside .eh_frame differs from the one in
.debug_frame. The former is using GCC internal numbering, whereas the
latter is (of course) using the DWARF numbering. So when gdb is reading
.eh_frame it needs to translate the register numbers (one important
difference is that the lr register has a different encoding). This is a
prerequisite for using the DWARF CFI unwinder on powerpc.
Andreas.
2006-05-09 Andreas Schwab <schwab@suse.de>
* dwarf2-frame.c (struct dwarf2_fde): Add eh_frame_p.
(execute_cfa_program): Add parameter eh_frame_p. Call
dwarf2_frame_eh_frame_regnum when true.
(dwarf2_frame_cache): Pass eh_frame_p from fde to
execute_cfa_program.
(decode_frame_entry_1): Call dwarf2_frame_eh_frame_regnum when
processing .eh_frame. Copy eh_frame_p to the new fde.
(struct dwarf2_frame_ops): Add eh_frame_regnum.
(dwarf2_frame_set_eh_frame_regnum): Define.
(dwarf2_frame_eh_frame_regnum): Define.
* dwarf2-frame.h (dwarf2_frame_set_eh_frame_regnum): Declare.
(dwarf2_frame_eh_frame_regnum): Declare.
Index: gdb/dwarf2-frame.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2-frame.c,v
retrieving revision 1.59
diff -u -a -p -u -p -a -r1.59 gdb/dwarf2-frame.c
--- gdb/dwarf2-frame.c 5 Apr 2006 20:01:19 -0000 1.59
+++ gdb/dwarf2-frame.c 9 May 2006 13:54:43 -0000
@@ -89,6 +89,10 @@ struct dwarf2_fde
gdb_byte *instructions;
gdb_byte *end;
+ /* True if this FDE is read from a .eh_frame instead of a .debug_frame
+ section. */
+ unsigned char eh_frame_p;
+
struct dwarf2_fde *next;
};
@@ -267,10 +271,11 @@ execute_stack_op (gdb_byte *exp, ULONGES
static void
execute_cfa_program (gdb_byte *insn_ptr, gdb_byte *insn_end,
struct frame_info *next_frame,
- struct dwarf2_frame_state *fs)
+ struct dwarf2_frame_state *fs, int eh_frame_p)
{
CORE_ADDR pc = frame_pc_unwind (next_frame);
int bytes_read;
+ struct gdbarch *gdbarch = get_frame_arch (next_frame);
while (insn_ptr < insn_end && fs->pc <= pc)
{
@@ -283,6 +288,8 @@ execute_cfa_program (gdb_byte *insn_ptr,
else if ((insn & 0xc0) == DW_CFA_offset)
{
reg = insn & 0x3f;
+ if (eh_frame_p)
+ reg = dwarf2_frame_eh_frame_regnum (gdbarch, reg);
insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
offset = utmp * fs->data_align;
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
@@ -293,6 +300,8 @@ execute_cfa_program (gdb_byte *insn_ptr,
{
gdb_assert (fs->initial.reg);
reg = insn & 0x3f;
+ if (eh_frame_p)
+ reg = dwarf2_frame_eh_frame_regnum (gdbarch, reg);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
if (reg < fs->initial.num_regs)
fs->regs.reg[reg] = fs->initial.reg[reg];
@@ -333,6 +342,8 @@ register %s (#%d) at 0x%s"),
case DW_CFA_offset_extended:
insn_ptr = read_uleb128 (insn_ptr, insn_end, ®);
+ if (eh_frame_p)
+ reg = dwarf2_frame_eh_frame_regnum (gdbarch, reg);
insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
offset = utmp * fs->data_align;
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
@@ -343,25 +354,35 @@ register %s (#%d) at 0x%s"),
case DW_CFA_restore_extended:
gdb_assert (fs->initial.reg);
insn_ptr = read_uleb128 (insn_ptr, insn_end, ®);
+ if (eh_frame_p)
+ reg = dwarf2_frame_eh_frame_regnum (gdbarch, reg);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
fs->regs.reg[reg] = fs->initial.reg[reg];
break;
case DW_CFA_undefined:
insn_ptr = read_uleb128 (insn_ptr, insn_end, ®);
+ if (eh_frame_p)
+ reg = dwarf2_frame_eh_frame_regnum (gdbarch, reg);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNDEFINED;
break;
case DW_CFA_same_value:
insn_ptr = read_uleb128 (insn_ptr, insn_end, ®);
+ if (eh_frame_p)
+ reg = dwarf2_frame_eh_frame_regnum (gdbarch, reg);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAME_VALUE;
break;
case DW_CFA_register:
insn_ptr = read_uleb128 (insn_ptr, insn_end, ®);
+ if (eh_frame_p)
+ reg = dwarf2_frame_eh_frame_regnum (gdbarch, reg);
insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
+ if (eh_frame_p)
+ utmp = dwarf2_frame_eh_frame_regnum (gdbarch, utmp);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG;
fs->regs.reg[reg].loc.reg = utmp;
@@ -405,6 +426,9 @@ bad CFI data; mismatched DW_CFA_restore_
case DW_CFA_def_cfa_register:
insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg);
+ if (eh_frame_p)
+ fs->cfa_reg = dwarf2_frame_eh_frame_regnum (gdbarch,
+ fs->cfa_reg);
fs->cfa_how = CFA_REG_OFFSET;
break;
@@ -426,6 +450,8 @@ bad CFI data; mismatched DW_CFA_restore_
case DW_CFA_expression:
insn_ptr = read_uleb128 (insn_ptr, insn_end, ®);
+ if (eh_frame_p)
+ reg = dwarf2_frame_eh_frame_regnum (gdbarch, reg);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
fs->regs.reg[reg].loc.exp = insn_ptr;
@@ -436,6 +462,8 @@ bad CFI data; mismatched DW_CFA_restore_
case DW_CFA_offset_extended_sf:
insn_ptr = read_uleb128 (insn_ptr, insn_end, ®);
+ if (eh_frame_p)
+ reg = dwarf2_frame_eh_frame_regnum (gdbarch, reg);
insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
offset *= fs->data_align;
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
@@ -445,6 +473,9 @@ bad CFI data; mismatched DW_CFA_restore_
case DW_CFA_def_cfa_sf:
insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg);
+ if (eh_frame_p)
+ fs->cfa_reg = dwarf2_frame_eh_frame_regnum (gdbarch,
+ fs->cfa_reg);
insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
fs->cfa_offset = offset * fs->data_align;
fs->cfa_how = CFA_REG_OFFSET;
@@ -512,6 +543,9 @@ struct dwarf2_frame_ops
/* Check whether the frame preceding NEXT_FRAME will be a signal
trampoline. */
int (*signal_frame_p) (struct gdbarch *, struct frame_info *);
+
+ /* Convert .eh_frame register number to DWARF register number. */
+ int (*eh_frame_regnum) (struct gdbarch *, int);
};
/* Default architecture-specific register state initialization
@@ -618,6 +652,31 @@ dwarf2_frame_signal_frame_p (struct gdba
return 0;
return ops->signal_frame_p (gdbarch, next_frame);
}
+
+/* Set the architecture-specific mapping of .eh_frame register numbers to
+ DWARF register numbers. */
+
+void
+dwarf2_frame_set_eh_frame_regnum (struct gdbarch *gdbarch,
+ int (*eh_frame_regnum) (struct gdbarch *,
+ int))
+{
+ struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
+
+ ops->eh_frame_regnum = eh_frame_regnum;
+}
+
+/* Translate a .eh_frame register to DWARF register. */
+
+int
+dwarf2_frame_eh_frame_regnum (struct gdbarch *gdbarch, int regnum)
+{
+ struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
+
+ if (ops->eh_frame_regnum == NULL)
+ return regnum;
+ return ops->eh_frame_regnum (gdbarch, regnum);
+}
struct dwarf2_frame_cache
@@ -686,14 +745,15 @@ dwarf2_frame_cache (struct frame_info *n
/* First decode all the insns in the CIE. */
execute_cfa_program (fde->cie->initial_instructions,
- fde->cie->end, next_frame, fs);
+ fde->cie->end, next_frame, fs, fde->eh_frame_p);
/* Save the initialized register set. */
fs->initial = fs->regs;
fs->initial.reg = dwarf2_frame_state_copy_regs (&fs->regs);
/* Then decode the insns in the FDE up to our target PC. */
- execute_cfa_program (fde->instructions, fde->end, next_frame, fs);
+ execute_cfa_program (fde->instructions, fde->end, next_frame, fs,
+ fde->eh_frame_p);
/* Caclulate the CFA. */
switch (fs->cfa_how)
@@ -1490,6 +1550,11 @@ decode_frame_entry_1 (struct comp_unit *
else
cie->return_address_register = read_unsigned_leb128 (unit->abfd, buf,
&bytes_read);
+ if (eh_frame_p)
+ cie->return_address_register
+ = dwarf2_frame_eh_frame_regnum (current_gdbarch,
+ cie->return_address_register);
+
buf += bytes_read;
cie->saw_z_augmentation = (*augmentation == 'z');
@@ -1607,6 +1672,8 @@ decode_frame_entry_1 (struct comp_unit *
fde->instructions = buf;
fde->end = end;
+ fde->eh_frame_p = eh_frame_p;
+
add_fde (unit, fde);
}
Index: gdb/dwarf2-frame.h
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2-frame.h,v
retrieving revision 1.11
diff -u -a -p -u -p -a -r1.11 gdb/dwarf2-frame.h
--- gdb/dwarf2-frame.h 5 Apr 2006 20:01:19 -0000 1.11
+++ gdb/dwarf2-frame.h 9 May 2006 13:55:07 -0000
@@ -90,6 +90,19 @@ extern void
int (*signal_frame_p) (struct gdbarch *,
struct frame_info *));
+/* Set the architecture-specific mapping of .eh_frame register numbers to
+ DWARF register numbers. */
+
+extern void
+ dwarf2_frame_set_eh_frame_regnum (struct gdbarch *gdbarch,
+ int (*eh_frame_regnum) (struct gdbarch *,
+ int));
+
+/* Translate a .eh_frame register to DWARF register. */
+
+extern int
+ dwarf2_frame_eh_frame_regnum (struct gdbarch *gdbarch, int regnum);
+
/* Return the frame unwind methods for the function that contains PC,
or NULL if it can't be handled by DWARF CFI frame unwinder. */
--
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."