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/* Target-dependent mdebug code for the ALPHA architecture.
Copyright (C) 1993-2024 Free Software Foundation, Inc.
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 "frame.h"
#include "frame-unwind.h"
#include "frame-base.h"
#include "symtab.h"
#include "gdbcore.h"
#include "block.h"
#include "trad-frame.h"
#include "alpha-tdep.h"
#include "mdebugread.h"
#include "gdbarch.h"
/* FIXME: Some of this code should perhaps be merged with mips. */
/* Layout of a stack frame on the alpha:
| |
pdr members: | 7th ... nth arg, |
| `pushed' by caller. |
| |
----------------|-------------------------------|<-- old_sp == vfp
^ ^ ^ ^ | |
| | | | | |
| |localoff | Copies of 1st .. 6th |
| | | | | argument if necessary. |
| | | v | |
| | | --- |-------------------------------|<-- LOCALS_ADDRESS
| | | | |
| | | | Locals and temporaries. |
| | | | |
| | | |-------------------------------|
| | | | |
|-fregoffset | Saved float registers. |
| | | | F9 |
| | | | . |
| | | | . |
| | | | F2 |
| | v | |
| | -------|-------------------------------|
| | | |
| | | Saved registers. |
| | | S6 |
|-regoffset | . |
| | | . |
| | | S0 |
| | | pdr.pcreg |
| v | |
| ----------|-------------------------------|
| | |
frameoffset | Argument build area, gets |
| | 7th ... nth arg for any |
| | called procedure. |
v | |
-------------|-------------------------------|<-- sp
| |
*/
#define PROC_LOW_ADDR(proc) ((proc)->pdr.adr)
#define PROC_FRAME_OFFSET(proc) ((proc)->pdr.frameoffset)
#define PROC_FRAME_REG(proc) ((proc)->pdr.framereg)
#define PROC_REG_MASK(proc) ((proc)->pdr.regmask)
#define PROC_FREG_MASK(proc) ((proc)->pdr.fregmask)
#define PROC_REG_OFFSET(proc) ((proc)->pdr.regoffset)
#define PROC_FREG_OFFSET(proc) ((proc)->pdr.fregoffset)
#define PROC_PC_REG(proc) ((proc)->pdr.pcreg)
#define PROC_LOCALOFF(proc) ((proc)->pdr.localoff)
/* Locate the mdebug PDR for the given PC. Return null if one can't
be found; you'll have to fall back to other methods in that case. */
static struct mdebug_extra_func_info *
find_proc_desc (CORE_ADDR pc)
{
const struct block *b = block_for_pc (pc);
struct mdebug_extra_func_info *proc_desc = NULL;
struct symbol *sym = NULL;
const char *sh_name = NULL;
if (b)
{
CORE_ADDR startaddr;
find_pc_partial_function (pc, &sh_name, &startaddr, NULL);
if (startaddr > b->start ())
/* This is the "pathological" case referred to in a comment in
print_frame_info. It might be better to move this check into
symbol reading. */
sym = NULL;
else
sym = lookup_symbol (MDEBUG_EFI_SYMBOL_NAME, b, SEARCH_LABEL_DOMAIN,
0).symbol;
}
if (sym)
{
proc_desc = (struct mdebug_extra_func_info *) sym->value_bytes ();
/* Correct incorrect setjmp procedure descriptor from the library
to make backtrace through setjmp work. */
if (proc_desc->pdr.pcreg == 0
&& strcmp (sh_name, "setjmp") == 0)
{
proc_desc->pdr.pcreg = ALPHA_RA_REGNUM;
proc_desc->pdr.regmask = 0x80000000;
proc_desc->pdr.regoffset = -4;
}
/* If we never found a PDR for this function in symbol reading,
then examine prologues to find the information. */
if (proc_desc->pdr.framereg == -1)
proc_desc = NULL;
}
return proc_desc;
}
/* Return a non-zero result if the function is frameless; zero otherwise. */
static int
alpha_mdebug_frameless (struct mdebug_extra_func_info *proc_desc)
{
return (PROC_FRAME_REG (proc_desc) == ALPHA_SP_REGNUM
&& PROC_FRAME_OFFSET (proc_desc) == 0);
}
/* This returns the PC of the first inst after the prologue. If we can't
find the prologue, then return 0. */
static CORE_ADDR
alpha_mdebug_after_prologue (CORE_ADDR pc,
struct mdebug_extra_func_info *proc_desc)
{
if (proc_desc)
{
/* If function is frameless, then we need to do it the hard way. I
strongly suspect that frameless always means prologueless... */
if (alpha_mdebug_frameless (proc_desc))
return 0;
}
return alpha_after_prologue (pc);
}
/* Return non-zero if we *might* be in a function prologue. Return zero
if we are definitively *not* in a function prologue. */
static int
alpha_mdebug_in_prologue (CORE_ADDR pc,
struct mdebug_extra_func_info *proc_desc)
{
CORE_ADDR after_prologue_pc = alpha_mdebug_after_prologue (pc, proc_desc);
return (after_prologue_pc == 0 || pc < after_prologue_pc);
}
/* Frame unwinder that reads mdebug PDRs. */
struct alpha_mdebug_unwind_cache
{
struct mdebug_extra_func_info *proc_desc;
CORE_ADDR vfp;
trad_frame_saved_reg *saved_regs;
};
/* Extract all of the information about the frame from PROC_DESC
and store the resulting register save locations in the structure. */
static struct alpha_mdebug_unwind_cache *
alpha_mdebug_frame_unwind_cache (const frame_info_ptr &this_frame,
void **this_prologue_cache)
{
struct alpha_mdebug_unwind_cache *info;
struct mdebug_extra_func_info *proc_desc;
ULONGEST vfp;
CORE_ADDR pc, reg_position;
unsigned long mask;
int ireg, returnreg;
if (*this_prologue_cache)
return (struct alpha_mdebug_unwind_cache *) *this_prologue_cache;
info = FRAME_OBSTACK_ZALLOC (struct alpha_mdebug_unwind_cache);
*this_prologue_cache = info;
pc = get_frame_address_in_block (this_frame);
/* ??? We don't seem to be able to cache the lookup of the PDR
from alpha_mdebug_frame_p. It'd be nice if we could change
the arguments to that function. Oh well. */
proc_desc = find_proc_desc (pc);
info->proc_desc = proc_desc;
gdb_assert (proc_desc != NULL);
info->saved_regs = trad_frame_alloc_saved_regs (this_frame);
/* The VFP of the frame is at FRAME_REG+FRAME_OFFSET. */
vfp = get_frame_register_unsigned (this_frame, PROC_FRAME_REG (proc_desc));
vfp += PROC_FRAME_OFFSET (info->proc_desc);
info->vfp = vfp;
/* Fill in the offsets for the registers which gen_mask says were saved. */
reg_position = vfp + PROC_REG_OFFSET (proc_desc);
mask = PROC_REG_MASK (proc_desc);
returnreg = PROC_PC_REG (proc_desc);
/* Note that RA is always saved first, regardless of its actual
register number. */
if (mask & (1 << returnreg))
{
/* Clear bit for RA so we don't save it again later. */
mask &= ~(1 << returnreg);
info->saved_regs[returnreg].set_addr (reg_position);
reg_position += 8;
}
for (ireg = 0; ireg <= 31; ++ireg)
if (mask & (1 << ireg))
{
info->saved_regs[ireg].set_addr (reg_position);
reg_position += 8;
}
reg_position = vfp + PROC_FREG_OFFSET (proc_desc);
mask = PROC_FREG_MASK (proc_desc);
for (ireg = 0; ireg <= 31; ++ireg)
if (mask & (1 << ireg))
{
info->saved_regs[ALPHA_FP0_REGNUM + ireg].set_addr (reg_position);
reg_position += 8;
}
/* The stack pointer of the previous frame is computed by popping
the current stack frame. */
if (!info->saved_regs[ALPHA_SP_REGNUM].is_addr ())
info->saved_regs[ALPHA_SP_REGNUM].set_value (vfp);
return info;
}
/* Given a GDB frame, determine the address of the calling function's
frame. This will be used to create a new GDB frame struct. */
static void
alpha_mdebug_frame_this_id (const frame_info_ptr &this_frame,
void **this_prologue_cache,
struct frame_id *this_id)
{
struct alpha_mdebug_unwind_cache *info
= alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
*this_id = frame_id_build (info->vfp, get_frame_func (this_frame));
}
/* Retrieve the value of REGNUM in FRAME. Don't give up! */
static struct value *
alpha_mdebug_frame_prev_register (const frame_info_ptr &this_frame,
void **this_prologue_cache, int regnum)
{
struct alpha_mdebug_unwind_cache *info
= alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
/* The PC of the previous frame is stored in the link register of
the current frame. Frob regnum so that we pull the value from
the correct place. */
if (regnum == ALPHA_PC_REGNUM)
regnum = PROC_PC_REG (info->proc_desc);
return trad_frame_get_prev_register (this_frame, info->saved_regs, regnum);
}
/* Return a non-zero result if the size of the stack frame exceeds the
maximum debuggable frame size (512 Kbytes); zero otherwise. */
static int
alpha_mdebug_max_frame_size_exceeded (struct mdebug_extra_func_info *proc_desc)
{
/* If frame offset is null, we can be in two cases: either the
function is frameless (the stack frame is null) or its
frame exceeds the maximum debuggable frame size (512 Kbytes). */
return (PROC_FRAME_OFFSET (proc_desc) == 0
&& !alpha_mdebug_frameless (proc_desc));
}
static int
alpha_mdebug_frame_sniffer (const struct frame_unwind *self,
const frame_info_ptr &this_frame,
void **this_cache)
{
CORE_ADDR pc = get_frame_address_in_block (this_frame);
struct mdebug_extra_func_info *proc_desc;
/* If this PC does not map to a PDR, then clearly this isn't an
mdebug frame. */
proc_desc = find_proc_desc (pc);
if (proc_desc == NULL)
return 0;
/* If we're in the prologue, the PDR for this frame is not yet valid.
Say no here and we'll fall back on the heuristic unwinder. */
if (alpha_mdebug_in_prologue (pc, proc_desc))
return 0;
/* If the maximum debuggable frame size has been exceeded, the
proc desc is bogus. Fall back on the heuristic unwinder. */
if (alpha_mdebug_max_frame_size_exceeded (proc_desc))
return 0;
return 1;
}
static const struct frame_unwind alpha_mdebug_frame_unwind =
{
"alpha mdebug",
NORMAL_FRAME,
default_frame_unwind_stop_reason,
alpha_mdebug_frame_this_id,
alpha_mdebug_frame_prev_register,
NULL,
alpha_mdebug_frame_sniffer
};
static CORE_ADDR
alpha_mdebug_frame_base_address (const frame_info_ptr &this_frame,
void **this_prologue_cache)
{
struct alpha_mdebug_unwind_cache *info
= alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
return info->vfp;
}
static CORE_ADDR
alpha_mdebug_frame_locals_address (const frame_info_ptr &this_frame,
void **this_prologue_cache)
{
struct alpha_mdebug_unwind_cache *info
= alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
return info->vfp - PROC_LOCALOFF (info->proc_desc);
}
static CORE_ADDR
alpha_mdebug_frame_args_address (const frame_info_ptr &this_frame,
void **this_prologue_cache)
{
struct alpha_mdebug_unwind_cache *info
= alpha_mdebug_frame_unwind_cache (this_frame, this_prologue_cache);
return info->vfp - ALPHA_NUM_ARG_REGS * 8;
}
static const struct frame_base alpha_mdebug_frame_base = {
&alpha_mdebug_frame_unwind,
alpha_mdebug_frame_base_address,
alpha_mdebug_frame_locals_address,
alpha_mdebug_frame_args_address
};
static const struct frame_base *
alpha_mdebug_frame_base_sniffer (const frame_info_ptr &this_frame)
{
CORE_ADDR pc = get_frame_address_in_block (this_frame);
struct mdebug_extra_func_info *proc_desc;
/* If this PC does not map to a PDR, then clearly this isn't an
mdebug frame. */
proc_desc = find_proc_desc (pc);
if (proc_desc == NULL)
return NULL;
/* If the maximum debuggable frame size has been exceeded, the
proc desc is bogus. Fall back on the heuristic unwinder. */
if (alpha_mdebug_max_frame_size_exceeded (proc_desc))
return 0;
return &alpha_mdebug_frame_base;
}
void
alpha_mdebug_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
frame_unwind_append_unwinder (gdbarch, &alpha_mdebug_frame_unwind);
frame_base_append_sniffer (gdbarch, alpha_mdebug_frame_base_sniffer);
}