/* Structure describing a frame state. */
+enum dwarf2_reg_rule
+{
+ /* Make certain that 0 maps onto the correct enum value; the
+ corresponding structure is being initialized using memset zero.
+ This indicates that CFI didn't provide any information at all
+ about a register, leaving how to obtain its value totally
+ unspecified. */
+ REG_UNSPECIFIED = 0,
+
+ /* The term "undefined" comes from the DWARF2 CFI spec which this
+ code is moddeling; it indicates that the register's value is
+ "undefined". GCC uses the less formal term "unsaved". Its
+ definition is a combination of REG_UNDEFINED and REG_UNSPECIFIED.
+ The failure to differentiate the two helps explain a few problems
+ with the CFI generated by GCC. */
+ REG_UNDEFINED,
+ REG_SAVED_OFFSET,
+ REG_SAVED_REG,
+ REG_SAVED_EXP,
+ REG_SAME_VALUE,
+
+ /* These aren't defined by the DWARF2 CFI specification, but are
+ used internally by GDB. */
+ REG_RA, /* Return Address. */
+ REG_CFA /* Call Frame Address. */
+};
+
struct dwarf2_frame_state
{
/* Each register save state can be described in terms of a CFA slot,
unsigned char *exp;
} loc;
ULONGEST exp_len;
- enum {
- REG_UNSAVED,
- REG_SAVED_OFFSET,
- REG_SAVED_REG,
- REG_SAVED_EXP,
- REG_UNMODIFIED
- } how;
+ enum dwarf2_reg_rule how;
} *reg;
int num_regs;
case DW_CFA_undefined:
insn_ptr = read_uleb128 (insn_ptr, insn_end, ®);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
- fs->regs.reg[reg].how = REG_UNSAVED;
+ fs->regs.reg[reg].how = REG_UNDEFINED;
break;
case DW_CFA_same_value:
insn_ptr = read_uleb128 (insn_ptr, insn_end, ®);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
- fs->regs.reg[reg].how = REG_UNMODIFIED;
+ fs->regs.reg[reg].how = REG_SAME_VALUE;
break;
case DW_CFA_register:
insn_ptr = read_uleb128 (insn_ptr, insn_end, ®);
insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
+ fs->regs.reg[reg].how = REG_SAVED_REG;
fs->regs.reg[reg].loc.reg = utmp;
break;
dwarf2_frame_cache (struct frame_info *next_frame, void **this_cache)
{
struct cleanup *old_chain;
- int num_regs = NUM_REGS + NUM_PSEUDO_REGS;
+ const int num_regs = NUM_REGS + NUM_PSEUDO_REGS;
struct dwarf2_frame_cache *cache;
struct dwarf2_frame_state *fs;
struct dwarf2_fde *fde;
- int reg;
if (*this_cache)
return *this_cache;
to abort), the compiler might optimize away the instruction at
NEXT_FRAME's return address. As a result the return address will
point at some random instruction, and the CFI for that
- instruction is probably wortless to us. GCC's unwinder solves
+ instruction is probably worthless to us. GCC's unwinder solves
this problem by substracting 1 from the return address to get an
address in the middle of a presumed call instruction (or the
instruction in the associated delay slot). This should only be
done for "normal" frames and not for resume-type frames (signal
- handlers, sentinel frames, dummy frames).
-
- frame_unwind_address_in_block does just this.
-
- It's not clear how reliable the method is though - there is the
- potential for the register state pre-call being different to that
- on return. */
+ handlers, sentinel frames, dummy frames). The function
+ frame_unwind_address_in_block does just this. It's not clear how
+ reliable the method is though; there is the potential for the
+ register state pre-call being different to that on return. */
fs->pc = frame_unwind_address_in_block (next_frame);
/* Find the correct FDE. */
internal_error (__FILE__, __LINE__, "Unknown CFA rule.");
}
- /* Save the register info in the cache. */
- for (reg = 0; reg < fs->regs.num_regs; reg++)
- {
- int regnum;
-
- /* Skip the return address column. */
- if (reg == fs->retaddr_column)
- /* NOTE: cagney/2003-06-07: Is this right? What if the
- RETADDR_COLUM corresponds to a real register (and, worse,
- that isn't the PC_REGNUM)? I'm guessing that the PC_REGNUM
- further down is trying to handle this. That can't be right
- though - PC_REGNUM may not be valid (it can be -ve). I
- think, instead when RETADDR_COLUM isn't a real register, it
- should map itself onto frame_pc_unwind. */
- continue;
+ /* Initialize the register rules. If we have a register that acts
+ as a program counter, mark it as a destination for the return
+ address. If we have a register that serves as the stack pointer,
+ arrange for it to be filled with the call frame address (CFA).
+ The other registers are marked as unspecified.
+
+ We copy the return address to the program counter, since many
+ parts in GDB assume that it is possible to get the return address
+ by unwind the program counter register. However, on ISA's with a
+ dedicated return address register, the CFI usually only contains
+ information to unwind that return address register.
+
+ The reason we're treating the stack pointer special here is
+ because in many cases GCC doesn't emit CFI for the stack pointer
+ and implicitly assumes that it is equal to the CFA. This makes
+ some sense since the DWARF specification (version 3, draft 8,
+ p. 102) says that:
+
+ "Typically, the CFA is defined to be the value of the stack
+ pointer at the call site in the previous frame (which may be
+ different from its value on entry to the current frame)."
+
+ However, this isn't true for all platforms supported by GCC
+ (e.g. IBM S/390 and zSeries). For those targets we should
+ override the defaults given here. */
+ {
+ int regnum;
+
+ for (regnum = 0; regnum < num_regs; regnum++)
+ {
+ if (regnum == PC_REGNUM)
+ cache->reg[regnum].how = REG_RA;
+ else if (regnum == SP_REGNUM)
+ cache->reg[regnum].how = REG_CFA;
+ else
+ cache->reg[regnum].how = REG_UNSPECIFIED;
+ }
+ }
+
+ /* Go through the DWARF2 CFI generated table and save its register
+ location information in the cache. Note that we don't skip the
+ return address column; it's perfectly all right for it to
+ correspond to a real register. If it doesn't correspond to a
+ real register, or if we shouldn't treat it as such,
+ DWARF2_REG_TO_REGNUM should be defined to return a number outside
+ the range [0, NUM_REGS). */
+ {
+ int column; /* CFI speak for "register number". */
- /* Use the GDB register number as index. */
- regnum = DWARF2_REG_TO_REGNUM (reg);
+ for (column = 0; column < fs->regs.num_regs; column++)
+ {
+ /* Use the GDB register number as the destination index. */
+ int regnum = DWARF2_REG_TO_REGNUM (column);
- if (regnum >= 0 && regnum < num_regs)
- cache->reg[regnum] = fs->regs.reg[reg];
- }
+ /* If there's no corresponding GDB register, ignore it. */
+ if (regnum < 0 || regnum >= num_regs)
+ continue;
- /* Store the location of the return addess. If the return address
- column (adjusted) is not the same as gdb's PC_REGNUM, then this
- implies a copy from the ra column register. */
- if (fs->retaddr_column < fs->regs.num_regs
- && fs->regs.reg[fs->retaddr_column].how != REG_UNSAVED)
- {
- /* See comment above about a possibly -ve PC_REGNUM. If this
- assertion fails, it's a problem with this code and not the
- architecture. */
- gdb_assert (PC_REGNUM >= 0);
- cache->reg[PC_REGNUM] = fs->regs.reg[fs->retaddr_column];
- }
- else
- {
- reg = DWARF2_REG_TO_REGNUM (fs->retaddr_column);
- if (reg != PC_REGNUM)
- {
- /* See comment above about PC_REGNUM being -ve. If this
- assertion fails, it's a problem with this code and not
- the architecture. */
- gdb_assert (PC_REGNUM >= 0);
- cache->reg[PC_REGNUM].loc.reg = reg;
- cache->reg[PC_REGNUM].how = REG_SAVED_REG;
- }
- }
+ /* NOTE: cagney/2003-09-05: CFI should specify the disposition
+ of all debug info registers. If it doesn't, complain (but
+ not too loudly). It turns out that GCC assumes that an
+ unspecified register implies "same value" when CFI (draft
+ 7) specifies nothing at all. Such a register could equally
+ be interpreted as "undefined". Also note that this check
+ isn't sufficient; it only checks that all registers in the
+ range [0 .. max column] are specified, and won't detect
+ problems when a debug info register falls outside of the
+ table. We need a way of iterating through all the valid
+ DWARF2 register numbers. */
+ if (fs->regs.reg[column].how == REG_UNSPECIFIED)
+ complaint (&symfile_complaints,
+ "Incomplete CFI data; unspecified registers at 0x%s",
+ paddr (fs->pc));
+ else
+ cache->reg[regnum] = fs->regs.reg[column];
+ }
+ }
+
+ /* Eliminate any REG_RA rules. */
+ {
+ int regnum;
+
+ for (regnum = 0; regnum < num_regs; regnum++)
+ {
+ if (cache->reg[regnum].how == REG_RA)
+ {
+ if (fs->retaddr_column < fs->regs.num_regs)
+ cache->reg[regnum] = fs->regs.reg[fs->retaddr_column];
+ else
+ {
+ /* It turns out that GCC assumes that if the return
+ address column is "empty" the return address can be
+ found in the register corresponding to the return
+ address column. */
+ cache->reg[regnum].loc.reg = fs->retaddr_column;
+ cache->reg[regnum].how = REG_SAVED_REG;
+ }
+ }
+ }
+ }
do_cleanups (old_chain);
switch (cache->reg[regnum].how)
{
- case REG_UNSAVED:
+ case REG_UNDEFINED:
+ /* If CFI explicitly specified that the value isn't defined,
+ mark it as optimized away; the value isn't available. */
*optimizedp = 1;
*lvalp = not_lval;
*addrp = 0;
*realnump = -1;
- if (regnum == SP_REGNUM)
- {
- /* GCC defines the CFA as the value of the stack pointer
- just before the call instruction is executed. Do other
- compilers use the same definition? */
- /* DWARF V3 Draft 7 p102: Typically, the CFA is defined to
- be the value of the stack pointer at the call site in the
- previous frame (which may be different from its value on
- entry to the current frame). */
- /* DWARF V3 Draft 7 p103: The first column of the rules
- defines the rule which computes the CFA value; it may be
- either a register and a signed offset that are added
- together or a DWARF expression that is evaluated. */
- /* FIXME: cagney/2003-07-07: I don't understand this. The
- CFI info should have provided unwind information for the
- SP register and then pointed ->cfa_reg at it, not the
- reverse. Assuming that SP_REGNUM is !-ve, there is a
- very real posibility that CFA is an offset from some
- other register, having nothing to do with the unwound SP
- value. */
- *optimizedp = 0;
- if (valuep)
- {
- /* Store the value. */
- store_typed_address (valuep, builtin_type_void_data_ptr,
- cache->cfa);
- }
- }
- else if (valuep)
+ if (valuep)
{
/* In some cases, for example %eflags on the i386, we have
to provide a sane value, even though this register wasn't
}
break;
- case REG_UNMODIFIED:
+ case REG_UNSPECIFIED:
+ /* GCC, in its infinite wisdom decided to not provide unwind
+ information for registers that are "same value". Since
+ DWARF2 (3 draft 7) doesn't define such behavior, said
+ registers are actually undefined (which is different to CFI
+ "undefined"). Code above issues a complaint about this.
+ Here just fudge the books, assume GCC, and that the value is
+ more inner on the stack. */
+ frame_register_unwind (next_frame, regnum,
+ optimizedp, lvalp, addrp, realnump, valuep);
+ break;
+
+ case REG_SAME_VALUE:
frame_register_unwind (next_frame, regnum,
optimizedp, lvalp, addrp, realnump, valuep);
break;
+ case REG_CFA:
+ *optimizedp = 0;
+ *lvalp = not_lval;
+ *addrp = 0;
+ *realnump = -1;
+ if (valuep)
+ {
+ /* Store the value. */
+ store_typed_address (valuep, builtin_type_void_data_ptr, cache->cfa);
+ }
+ break;
+
default:
internal_error (__FILE__, __LINE__, "Unknown register rule.");
}
/* Base for DW_EH_PE_datarel encodings. */
bfd_vma dbase;
+
+ /* Base for DW_EH_PE_textrel encodings. */
+ bfd_vma tbase;
};
const struct objfile_data *dwarf2_frame_data;
read_encoded_value (struct comp_unit *unit, unsigned char encoding,
char *buf, unsigned int *bytes_read_ptr)
{
+ int ptr_len = size_of_encoded_value (DW_EH_PE_absptr);
+ ptrdiff_t offset;
CORE_ADDR base;
/* GCC currently doesn't generate DW_EH_PE_indirect encodings for
internal_error (__FILE__, __LINE__,
"Unsupported encoding: DW_EH_PE_indirect");
+ *bytes_read_ptr = 0;
+
switch (encoding & 0x70)
{
case DW_EH_PE_absptr:
case DW_EH_PE_datarel:
base = unit->dbase;
break;
+ case DW_EH_PE_textrel:
+ base = unit->tbase;
+ break;
+ case DW_EH_PE_aligned:
+ base = 0;
+ offset = buf - unit->dwarf_frame_buffer;
+ if ((offset % ptr_len) != 0)
+ {
+ *bytes_read_ptr = ptr_len - (offset % ptr_len);
+ buf += *bytes_read_ptr;
+ }
+ break;
default:
internal_error (__FILE__, __LINE__, "Invalid or unsupported encoding");
}
if ((encoding & 0x0f) == 0x00)
- encoding |= encoding_for_size (TYPE_LENGTH(builtin_type_void_data_ptr));
+ encoding |= encoding_for_size (ptr_len);
switch (encoding & 0x0f)
{
case DW_EH_PE_udata2:
- *bytes_read_ptr = 2;
+ *bytes_read_ptr += 2;
return (base + bfd_get_16 (unit->abfd, (bfd_byte *) buf));
case DW_EH_PE_udata4:
- *bytes_read_ptr = 4;
+ *bytes_read_ptr += 4;
return (base + bfd_get_32 (unit->abfd, (bfd_byte *) buf));
case DW_EH_PE_udata8:
- *bytes_read_ptr = 8;
+ *bytes_read_ptr += 8;
return (base + bfd_get_64 (unit->abfd, (bfd_byte *) buf));
case DW_EH_PE_sdata2:
- *bytes_read_ptr = 2;
+ *bytes_read_ptr += 2;
return (base + bfd_get_signed_16 (unit->abfd, (bfd_byte *) buf));
case DW_EH_PE_sdata4:
- *bytes_read_ptr = 4;
+ *bytes_read_ptr += 4;
return (base + bfd_get_signed_32 (unit->abfd, (bfd_byte *) buf));
case DW_EH_PE_sdata8:
- *bytes_read_ptr = 8;
+ *bytes_read_ptr += 8;
return (base + bfd_get_signed_64 (unit->abfd, (bfd_byte *) buf));
default:
internal_error (__FILE__, __LINE__, "Invalid or unsupported encoding");
dwarf2read.c in a better way. */
/* Imported from dwarf2read.c. */
-extern file_ptr dwarf_frame_offset;
-extern unsigned int dwarf_frame_size;
extern asection *dwarf_frame_section;
-extern file_ptr dwarf_eh_frame_offset;
-extern unsigned int dwarf_eh_frame_size;
extern asection *dwarf_eh_frame_section;
/* Imported from dwarf2read.c. */
-extern char *dwarf2_read_section (struct objfile *objfile, file_ptr offset,
- unsigned int size, asection *sectp);
+extern char *dwarf2_read_section (struct objfile *objfile, asection *sectp);
void
dwarf2_build_frame_info (struct objfile *objfile)
unit.objfile = objfile;
unit.addr_size = objfile->obfd->arch_info->bits_per_address / 8;
unit.dbase = 0;
+ unit.tbase = 0;
/* First add the information from the .eh_frame section. That way,
the FDEs from that section are searched last. */
- if (dwarf_eh_frame_offset)
+ if (dwarf_eh_frame_section)
{
- asection *got;
+ asection *got, *txt;
unit.cie = NULL;
unit.dwarf_frame_buffer = dwarf2_read_section (objfile,
- dwarf_eh_frame_offset,
- dwarf_eh_frame_size,
dwarf_eh_frame_section);
- unit.dwarf_frame_size = dwarf_eh_frame_size;
+ unit.dwarf_frame_size
+ = bfd_get_section_size_before_reloc (dwarf_eh_frame_section);
unit.dwarf_frame_section = dwarf_eh_frame_section;
/* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
- that for the i386/amd64 target, which currently is the only
- target in GCC that supports/uses the DW_EH_PE_datarel
- encoding. */
+ that is used for the i386/amd64 target, which currently is
+ the only target in GCC that supports/uses the
+ DW_EH_PE_datarel encoding. */
got = bfd_get_section_by_name (unit.abfd, ".got");
if (got)
unit.dbase = got->vma;
+ /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64
+ so far. */
+ txt = bfd_get_section_by_name (unit.abfd, ".text");
+ if (txt)
+ unit.tbase = txt->vma;
+
frame_ptr = unit.dwarf_frame_buffer;
while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size)
frame_ptr = decode_frame_entry (&unit, frame_ptr, 1);
}
- if (dwarf_frame_offset)
+ if (dwarf_frame_section)
{
unit.cie = NULL;
unit.dwarf_frame_buffer = dwarf2_read_section (objfile,
- dwarf_frame_offset,
- dwarf_frame_size,
dwarf_frame_section);
- unit.dwarf_frame_size = dwarf_frame_size;
+ unit.dwarf_frame_size
+ = bfd_get_section_size_before_reloc (dwarf_frame_section);
unit.dwarf_frame_section = dwarf_frame_section;
frame_ptr = unit.dwarf_frame_buffer;
projects / deliverable / binutils-gdb.git / blobdiff