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dwarf2-frame.c
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/* Frame unwinder for frames with DWARF Call Frame Information.
Copyright (C) 2003-2015 Free Software Foundation, Inc.
Contributed by Mark Kettenis.
This file is part of GDB.
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 3 of the License, 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, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "dwarf2expr.h"
#include "dwarf2.h"
#include "frame.h"
#include "frame-base.h"
#include "frame-unwind.h"
#include "gdbcore.h"
#include "gdbtypes.h"
#include "symtab.h"
#include "objfiles.h"
#include "regcache.h"
#include "value.h"
#include "record.h"
#include "complaints.h"
#include "dwarf2-frame.h"
#include "ax.h"
#include "dwarf2loc.h"
#include "dwarf2-frame-tailcall.h"
struct comp_unit;
/* Call Frame Information (CFI). */
/* Common Information Entry (CIE). */
struct dwarf2_cie
{
/* Computation Unit for this CIE. */
struct comp_unit *unit;
/* Offset into the .debug_frame section where this CIE was found.
Used to identify this CIE. */
ULONGEST cie_pointer;
/* Constant that is factored out of all advance location
instructions. */
ULONGEST code_alignment_factor;
/* Constants that is factored out of all offset instructions. */
LONGEST data_alignment_factor;
/* Return address column. */
ULONGEST return_address_register;
/* Instruction sequence to initialize a register set. */
const gdb_byte *initial_instructions;
const gdb_byte *end;
/* Saved augmentation, in case it's needed later. */
char *augmentation;
/* Encoding of addresses. */
gdb_byte encoding;
/* Target address size in bytes. */
int addr_size;
/* Target pointer size in bytes. */
int ptr_size;
/* True if a 'z' augmentation existed. */
unsigned char saw_z_augmentation;
/* True if an 'S' augmentation existed. */
unsigned char signal_frame;
/* The version recorded in the CIE. */
unsigned char version;
/* The segment size. */
unsigned char segment_size;
};
struct dwarf2_cie_table
{
int num_entries;
struct dwarf2_cie **entries;
};
/* Frame Description Entry (FDE). */
struct dwarf2_fde
{
/* CIE for this FDE. */
struct dwarf2_cie *cie;
/* First location associated with this FDE. */
CORE_ADDR initial_location;
/* Number of bytes of program instructions described by this FDE. */
CORE_ADDR address_range;
/* Instruction sequence. */
const gdb_byte *instructions;
const 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_table
{
int num_entries;
struct dwarf2_fde **entries;
};
/* A minimal decoding of DWARF2 compilation units. We only decode
what's needed to get to the call frame information. */
struct comp_unit
{
/* Keep the bfd convenient. */
bfd *abfd;
struct objfile *objfile;
/* Pointer to the .debug_frame section loaded into memory. */
const gdb_byte *dwarf_frame_buffer;
/* Length of the loaded .debug_frame section. */
bfd_size_type dwarf_frame_size;
/* Pointer to the .debug_frame section. */
asection *dwarf_frame_section;
/* Base for DW_EH_PE_datarel encodings. */
bfd_vma dbase;
/* Base for DW_EH_PE_textrel encodings. */
bfd_vma tbase;
};
static struct dwarf2_fde *dwarf2_frame_find_fde (CORE_ADDR *pc,
CORE_ADDR *out_offset);
static int dwarf2_frame_adjust_regnum (struct gdbarch *gdbarch, int regnum,
int eh_frame_p);
static CORE_ADDR read_encoded_value (struct comp_unit *unit, gdb_byte encoding,
int ptr_len, const gdb_byte *buf,
unsigned int *bytes_read_ptr,
CORE_ADDR func_base);
enum cfa_how_kind
{
CFA_UNSET,
CFA_REG_OFFSET,
CFA_EXP
};
struct dwarf2_frame_state_reg_info
{
struct dwarf2_frame_state_reg *reg;
int num_regs;
LONGEST cfa_offset;
ULONGEST cfa_reg;
enum cfa_how_kind cfa_how;
const gdb_byte *cfa_exp;
/* Used to implement DW_CFA_remember_state. */
struct dwarf2_frame_state_reg_info *prev;
};
/* Structure describing a frame state. */
struct dwarf2_frame_state
{
/* Each register save state can be described in terms of a CFA slot,
another register, or a location expression. */
struct dwarf2_frame_state_reg_info regs;
/* The PC described by the current frame state. */
CORE_ADDR pc;
/* Initial register set from the CIE.
Used to implement DW_CFA_restore. */
struct dwarf2_frame_state_reg_info initial;
/* The information we care about from the CIE. */
LONGEST data_align;
ULONGEST code_align;
ULONGEST retaddr_column;
/* Flags for known producer quirks. */
/* The ARM compilers, in DWARF2 mode, assume that DW_CFA_def_cfa
and DW_CFA_def_cfa_offset takes a factored offset. */
int armcc_cfa_offsets_sf;
/* The ARM compilers, in DWARF2 or DWARF3 mode, may assume that
the CFA is defined as REG - OFFSET rather than REG + OFFSET. */
int armcc_cfa_offsets_reversed;
};
/* Store the length the expression for the CFA in the `cfa_reg' field,
which is unused in that case. */
#define cfa_exp_len cfa_reg
/* Assert that the register set RS is large enough to store gdbarch_num_regs
columns. If necessary, enlarge the register set. */
static void
dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info *rs,
int num_regs)
{
size_t size = sizeof (struct dwarf2_frame_state_reg);
if (num_regs <= rs->num_regs)
return;
rs->reg = (struct dwarf2_frame_state_reg *)
xrealloc (rs->reg, num_regs * size);
/* Initialize newly allocated registers. */
memset (rs->reg + rs->num_regs, 0, (num_regs - rs->num_regs) * size);
rs->num_regs = num_regs;
}
/* Copy the register columns in register set RS into newly allocated
memory and return a pointer to this newly created copy. */
static struct dwarf2_frame_state_reg *
dwarf2_frame_state_copy_regs (struct dwarf2_frame_state_reg_info *rs)
{
size_t size = rs->num_regs * sizeof (struct dwarf2_frame_state_reg);
struct dwarf2_frame_state_reg *reg;
reg = (struct dwarf2_frame_state_reg *) xmalloc (size);
memcpy (reg, rs->reg, size);
return reg;
}
/* Release the memory allocated to register set RS. */
static void
dwarf2_frame_state_free_regs (struct dwarf2_frame_state_reg_info *rs)
{
if (rs)
{
dwarf2_frame_state_free_regs (rs->prev);
xfree (rs->reg);
xfree (rs);
}
}
/* Release the memory allocated to the frame state FS. */
static void
dwarf2_frame_state_free (void *p)
{
struct dwarf2_frame_state *fs = p;
dwarf2_frame_state_free_regs (fs->initial.prev);
dwarf2_frame_state_free_regs (fs->regs.prev);
xfree (fs->initial.reg);
xfree (fs->regs.reg);
xfree (fs);
}
/* Helper functions for execute_stack_op. */
static CORE_ADDR
read_addr_from_reg (void *baton, int reg)
{
struct frame_info *this_frame = (struct frame_info *) baton;
struct gdbarch *gdbarch = get_frame_arch (this_frame);
int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, reg);
return address_from_register (regnum, this_frame);
}
/* Implement struct dwarf_expr_context_funcs' "get_reg_value" callback. */
static struct value *
get_reg_value (void *baton, struct type *type, int reg)
{
struct frame_info *this_frame = (struct frame_info *) baton;
struct gdbarch *gdbarch = get_frame_arch (this_frame);
int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, reg);
return value_from_register (type, regnum, this_frame);
}
static void
read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len)
{
read_memory (addr, buf, len);
}
/* Execute the required actions for both the DW_CFA_restore and
DW_CFA_restore_extended instructions. */
static void
dwarf2_restore_rule (struct gdbarch *gdbarch, ULONGEST reg_num,
struct dwarf2_frame_state *fs, int eh_frame_p)
{
ULONGEST reg;
gdb_assert (fs->initial.reg);
reg = dwarf2_frame_adjust_regnum (gdbarch, reg_num, eh_frame_p);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
/* Check if this register was explicitly initialized in the
CIE initial instructions. If not, default the rule to
UNSPECIFIED. */
if (reg < fs->initial.num_regs)
fs->regs.reg[reg] = fs->initial.reg[reg];
else
fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNSPECIFIED;
if (fs->regs.reg[reg].how == DWARF2_FRAME_REG_UNSPECIFIED)
complaint (&symfile_complaints, _("\
incomplete CFI data; DW_CFA_restore unspecified\n\
register %s (#%d) at %s"),
gdbarch_register_name
(gdbarch, gdbarch_dwarf2_reg_to_regnum (gdbarch, reg)),
gdbarch_dwarf2_reg_to_regnum (gdbarch, reg),
paddress (gdbarch, fs->pc));
}
/* Virtual method table for execute_stack_op below. */
static const struct dwarf_expr_context_funcs dwarf2_frame_ctx_funcs =
{
read_addr_from_reg,
get_reg_value,
read_mem,
ctx_no_get_frame_base,
ctx_no_get_frame_cfa,
ctx_no_get_frame_pc,
ctx_no_get_tls_address,
ctx_no_dwarf_call,
ctx_no_get_base_type,
ctx_no_push_dwarf_reg_entry_value,
ctx_no_get_addr_index
};
static CORE_ADDR
execute_stack_op (const gdb_byte *exp, ULONGEST len, int addr_size,
CORE_ADDR offset, struct frame_info *this_frame,
CORE_ADDR initial, int initial_in_stack_memory)
{
struct dwarf_expr_context *ctx;
CORE_ADDR result;
struct cleanup *old_chain;
ctx = new_dwarf_expr_context ();
old_chain = make_cleanup_free_dwarf_expr_context (ctx);
make_cleanup_value_free_to_mark (value_mark ());
ctx->gdbarch = get_frame_arch (this_frame);
ctx->addr_size = addr_size;
ctx->ref_addr_size = -1;
ctx->offset = offset;
ctx->baton = this_frame;
ctx->funcs = &dwarf2_frame_ctx_funcs;
dwarf_expr_push_address (ctx, initial, initial_in_stack_memory);
dwarf_expr_eval (ctx, exp, len);
if (ctx->location == DWARF_VALUE_MEMORY)
result = dwarf_expr_fetch_address (ctx, 0);
else if (ctx->location == DWARF_VALUE_REGISTER)
result = read_addr_from_reg (this_frame,
value_as_long (dwarf_expr_fetch (ctx, 0)));
else
{
/* This is actually invalid DWARF, but if we ever do run across
it somehow, we might as well support it. So, instead, report
it as unimplemented. */
error (_("\
Not implemented: computing unwound register using explicit value operator"));
}
do_cleanups (old_chain);
return result;
}
/* Execute FDE program from INSN_PTR possibly up to INSN_END or up to inferior
PC. Modify FS state accordingly. Return current INSN_PTR where the
execution has stopped, one can resume it on the next call. */
static const gdb_byte *
execute_cfa_program (struct dwarf2_fde *fde, const gdb_byte *insn_ptr,
const gdb_byte *insn_end, struct gdbarch *gdbarch,
CORE_ADDR pc, struct dwarf2_frame_state *fs)
{
int eh_frame_p = fde->eh_frame_p;
unsigned int bytes_read;
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
while (insn_ptr < insn_end && fs->pc <= pc)
{
gdb_byte insn = *insn_ptr++;
uint64_t utmp, reg;
int64_t offset;
if ((insn & 0xc0) == DW_CFA_advance_loc)
fs->pc += (insn & 0x3f) * fs->code_align;
else if ((insn & 0xc0) == DW_CFA_offset)
{
reg = insn & 0x3f;
reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
offset = utmp * fs->data_align;
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
}
else if ((insn & 0xc0) == DW_CFA_restore)
{
reg = insn & 0x3f;
dwarf2_restore_rule (gdbarch, reg, fs, eh_frame_p);
}
else
{
switch (insn)
{
case DW_CFA_set_loc:
fs->pc = read_encoded_value (fde->cie->unit, fde->cie->encoding,
fde->cie->ptr_size, insn_ptr,
&bytes_read, fde->initial_location);
/* Apply the objfile offset for relocatable objects. */
fs->pc += ANOFFSET (fde->cie->unit->objfile->section_offsets,
SECT_OFF_TEXT (fde->cie->unit->objfile));
insn_ptr += bytes_read;
break;
case DW_CFA_advance_loc1:
utmp = extract_unsigned_integer (insn_ptr, 1, byte_order);
fs->pc += utmp * fs->code_align;
insn_ptr++;
break;
case DW_CFA_advance_loc2:
utmp = extract_unsigned_integer (insn_ptr, 2, byte_order);
fs->pc += utmp * fs->code_align;
insn_ptr += 2;
break;
case DW_CFA_advance_loc4:
utmp = extract_unsigned_integer (insn_ptr, 4, byte_order);
fs->pc += utmp * fs->code_align;
insn_ptr += 4;
break;
case DW_CFA_offset_extended:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
offset = utmp * fs->data_align;
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
break;
case DW_CFA_restore_extended:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
dwarf2_restore_rule (gdbarch, reg, fs, eh_frame_p);
break;
case DW_CFA_undefined:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
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 = safe_read_uleb128 (insn_ptr, insn_end, ®);
reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
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 = safe_read_uleb128 (insn_ptr, insn_end, ®);
reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
utmp = dwarf2_frame_adjust_regnum (gdbarch, utmp, eh_frame_p);
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;
break;
case DW_CFA_remember_state:
{
struct dwarf2_frame_state_reg_info *new_rs;
new_rs = XNEW (struct dwarf2_frame_state_reg_info);
*new_rs = fs->regs;
fs->regs.reg = dwarf2_frame_state_copy_regs (&fs->regs);
fs->regs.prev = new_rs;
}
break;
case DW_CFA_restore_state:
{
struct dwarf2_frame_state_reg_info *old_rs = fs->regs.prev;
if (old_rs == NULL)
{
complaint (&symfile_complaints, _("\
bad CFI data; mismatched DW_CFA_restore_state at %s"),
paddress (gdbarch, fs->pc));
}
else
{
xfree (fs->regs.reg);
fs->regs = *old_rs;
xfree (old_rs);
}
}
break;
case DW_CFA_def_cfa:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
fs->regs.cfa_reg = reg;
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
if (fs->armcc_cfa_offsets_sf)
utmp *= fs->data_align;
fs->regs.cfa_offset = utmp;
fs->regs.cfa_how = CFA_REG_OFFSET;
break;
case DW_CFA_def_cfa_register:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
fs->regs.cfa_reg = dwarf2_frame_adjust_regnum (gdbarch, reg,
eh_frame_p);
fs->regs.cfa_how = CFA_REG_OFFSET;
break;
case DW_CFA_def_cfa_offset:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
if (fs->armcc_cfa_offsets_sf)
utmp *= fs->data_align;
fs->regs.cfa_offset = utmp;
/* cfa_how deliberately not set. */
break;
case DW_CFA_nop:
break;
case DW_CFA_def_cfa_expression:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
fs->regs.cfa_exp_len = utmp;
fs->regs.cfa_exp = insn_ptr;
fs->regs.cfa_how = CFA_EXP;
insn_ptr += fs->regs.cfa_exp_len;
break;
case DW_CFA_expression:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
fs->regs.reg[reg].loc.exp = insn_ptr;
fs->regs.reg[reg].exp_len = utmp;
fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_EXP;
insn_ptr += utmp;
break;
case DW_CFA_offset_extended_sf:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset);
offset *= fs->data_align;
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
break;
case DW_CFA_val_offset:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
offset = utmp * fs->data_align;
fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
break;
case DW_CFA_val_offset_sf:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset);
offset *= fs->data_align;
fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
break;
case DW_CFA_val_expression:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
fs->regs.reg[reg].loc.exp = insn_ptr;
fs->regs.reg[reg].exp_len = utmp;
fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_EXP;
insn_ptr += utmp;
break;
case DW_CFA_def_cfa_sf:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
fs->regs.cfa_reg = dwarf2_frame_adjust_regnum (gdbarch, reg,
eh_frame_p);
insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset);
fs->regs.cfa_offset = offset * fs->data_align;
fs->regs.cfa_how = CFA_REG_OFFSET;
break;
case DW_CFA_def_cfa_offset_sf:
insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset);
fs->regs.cfa_offset = offset * fs->data_align;
/* cfa_how deliberately not set. */
break;
case DW_CFA_GNU_window_save:
/* This is SPARC-specific code, and contains hard-coded
constants for the register numbering scheme used by
GCC. Rather than having a architecture-specific
operation that's only ever used by a single
architecture, we provide the implementation here.
Incidentally that's what GCC does too in its
unwinder. */
{
int size = register_size (gdbarch, 0);
dwarf2_frame_state_alloc_regs (&fs->regs, 32);
for (reg = 8; reg < 16; reg++)
{
fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG;
fs->regs.reg[reg].loc.reg = reg + 16;
}
for (reg = 16; reg < 32; reg++)
{
fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = (reg - 16) * size;
}
}
break;
case DW_CFA_GNU_args_size:
/* Ignored. */
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
break;
case DW_CFA_GNU_negative_offset_extended:
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
offset = utmp * fs->data_align;
dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = -offset;
break;
default:
internal_error (__FILE__, __LINE__,
_("Unknown CFI encountered."));
}
}
}
if (fs->initial.reg == NULL)
{
/* Don't allow remember/restore between CIE and FDE programs. */
dwarf2_frame_state_free_regs (fs->regs.prev);
fs->regs.prev = NULL;
}
return insn_ptr;
}
/* Architecture-specific operations. */
/* Per-architecture data key. */
static struct gdbarch_data *dwarf2_frame_data;
struct dwarf2_frame_ops
{
/* Pre-initialize the register state REG for register REGNUM. */
void (*init_reg) (struct gdbarch *, int, struct dwarf2_frame_state_reg *,
struct frame_info *);
/* Check whether the THIS_FRAME is a signal trampoline. */
int (*signal_frame_p) (struct gdbarch *, struct frame_info *);
/* Convert .eh_frame register number to DWARF register number, or
adjust .debug_frame register number. */
int (*adjust_regnum) (struct gdbarch *, int, int);
};
/* Default architecture-specific register state initialization
function. */
static void
dwarf2_frame_default_init_reg (struct gdbarch *gdbarch, int regnum,
struct dwarf2_frame_state_reg *reg,
struct frame_info *this_frame)
{
/* 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 unwinding 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). Those architectures should provide
their own architecture-specific initialization function. */
if (regnum == gdbarch_pc_regnum (gdbarch))
reg->how = DWARF2_FRAME_REG_RA;
else if (regnum == gdbarch_sp_regnum (gdbarch))
reg->how = DWARF2_FRAME_REG_CFA;
}
/* Return a default for the architecture-specific operations. */
static void *
dwarf2_frame_init (struct obstack *obstack)
{
struct dwarf2_frame_ops *ops;
ops = OBSTACK_ZALLOC (obstack, struct dwarf2_frame_ops);
ops->init_reg = dwarf2_frame_default_init_reg;
return ops;
}
/* Set the architecture-specific register state initialization
function for GDBARCH to INIT_REG. */
void
dwarf2_frame_set_init_reg (struct gdbarch *gdbarch,
void (*init_reg) (struct gdbarch *, int,
struct dwarf2_frame_state_reg *,
struct frame_info *))
{
struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
ops->init_reg = init_reg;
}
/* Pre-initialize the register state REG for register REGNUM. */
static void
dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
struct dwarf2_frame_state_reg *reg,
struct frame_info *this_frame)
{
struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
ops->init_reg (gdbarch, regnum, reg, this_frame);
}
/* Set the architecture-specific signal trampoline recognition
function for GDBARCH to SIGNAL_FRAME_P. */
void
dwarf2_frame_set_signal_frame_p (struct gdbarch *gdbarch,
int (*signal_frame_p) (struct gdbarch *,
struct frame_info *))
{
struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
ops->signal_frame_p = signal_frame_p;
}
/* Query the architecture-specific signal frame recognizer for
THIS_FRAME. */
static int
dwarf2_frame_signal_frame_p (struct gdbarch *gdbarch,
struct frame_info *this_frame)
{
struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
if (ops->signal_frame_p == NULL)
return 0;
return ops->signal_frame_p (gdbarch, this_frame);
}
/* Set the architecture-specific adjustment of .eh_frame and .debug_frame
register numbers. */
void
dwarf2_frame_set_adjust_regnum (struct gdbarch *gdbarch,
int (*adjust_regnum) (struct gdbarch *,
int, int))
{
struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
ops->adjust_regnum = adjust_regnum;
}
/* Translate a .eh_frame register to DWARF register, or adjust a .debug_frame
register. */
static int
dwarf2_frame_adjust_regnum (struct gdbarch *gdbarch,
int regnum, int eh_frame_p)
{
struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
if (ops->adjust_regnum == NULL)
return regnum;
return ops->adjust_regnum (gdbarch, regnum, eh_frame_p);
}
static void
dwarf2_frame_find_quirks (struct dwarf2_frame_state *fs,
struct dwarf2_fde *fde)
{
struct compunit_symtab *cust;
cust = find_pc_compunit_symtab (fs->pc);
if (cust == NULL)
return;
if (producer_is_realview (COMPUNIT_PRODUCER (cust)))
{
if (fde->cie->version == 1)
fs->armcc_cfa_offsets_sf = 1;
if (fde->cie->version == 1)
fs->armcc_cfa_offsets_reversed = 1;
/* The reversed offset problem is present in some compilers
using DWARF3, but it was eventually fixed. Check the ARM
defined augmentations, which are in the format "armcc" followed
by a list of one-character options. The "+" option means
this problem is fixed (no quirk needed). If the armcc
augmentation is missing, the quirk is needed. */
if (fde->cie->version == 3
&& (!startswith (fde->cie->augmentation, "armcc")
|| strchr (fde->cie->augmentation + 5, '+') == NULL))
fs->armcc_cfa_offsets_reversed = 1;
return;
}
}
/* See dwarf2-frame.h. */
int
dwarf2_fetch_cfa_info (struct gdbarch *gdbarch, CORE_ADDR pc,
struct dwarf2_per_cu_data *data,
int *regnum_out, LONGEST *offset_out,
CORE_ADDR *text_offset_out,
const gdb_byte **cfa_start_out,
const gdb_byte **cfa_end_out)
{
struct dwarf2_fde *fde;
CORE_ADDR text_offset;
struct dwarf2_frame_state fs;
int addr_size;
memset (&fs, 0, sizeof (struct dwarf2_frame_state));
fs.pc = pc;
/* Find the correct FDE. */
fde = dwarf2_frame_find_fde (&fs.pc, &text_offset);
if (fde == NULL)
error (_("Could not compute CFA; needed to translate this expression"));
/* Extract any interesting information from the CIE. */
fs.data_align = fde->cie->data_alignment_factor;
fs.code_align = fde->cie->code_alignment_factor;
fs.retaddr_column = fde->cie->return_address_register;
addr_size = fde->cie->addr_size;
/* Check for "quirks" - known bugs in producers. */
dwarf2_frame_find_quirks (&fs, fde);
/* First decode all the insns in the CIE. */
execute_cfa_program (fde, fde->cie->initial_instructions,
fde->cie->end, gdbarch, pc, &fs);
/* 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, fde->instructions, fde->end, gdbarch, pc, &fs);
/* Calculate the CFA. */
switch (fs.regs.cfa_how)
{
case CFA_REG_OFFSET:
{
int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, fs.regs.cfa_reg);
if (regnum == -1)
error (_("Unable to access DWARF register number %d"),
(int) fs.regs.cfa_reg); /* FIXME */
*regnum_out = regnum;
if (fs.armcc_cfa_offsets_reversed)
*offset_out = -fs.regs.cfa_offset;
else
*offset_out = fs.regs.cfa_offset;
return 1;
}
case CFA_EXP:
*text_offset_out = text_offset;
*cfa_start_out = fs.regs.cfa_exp;
*cfa_end_out = fs.regs.cfa_exp + fs.regs.cfa_exp_len;
return 0;
default:
internal_error (__FILE__, __LINE__, _("Unknown CFA rule."));
}
}
struct dwarf2_frame_cache
{
/* DWARF Call Frame Address. */
CORE_ADDR cfa;
/* Set if the return address column was marked as unavailable
(required non-collected memory or registers to compute). */
int unavailable_retaddr;
/* Set if the return address column was marked as undefined. */
int undefined_retaddr;
/* Saved registers, indexed by GDB register number, not by DWARF
register number. */
struct dwarf2_frame_state_reg *reg;
/* Return address register. */
struct dwarf2_frame_state_reg retaddr_reg;
/* Target address size in bytes. */
int addr_size;
/* The .text offset. */
CORE_ADDR text_offset;
/* True if we already checked whether this frame is the bottom frame
of a virtual tail call frame chain. */
int checked_tailcall_bottom;
/* If not NULL then this frame is the bottom frame of a TAILCALL_FRAME
sequence. If NULL then it is a normal case with no TAILCALL_FRAME
involved. Non-bottom frames of a virtual tail call frames chain use
dwarf2_tailcall_frame_unwind unwinder so this field does not apply for
them. */
void *tailcall_cache;