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/* Target-dependent code for the VAX.
Copyright (C) 1986-2024 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 "defs.h"
#include "arch-utils.h"
#include "dis-asm.h"
#include "frame.h"
#include "frame-base.h"
#include "frame-unwind.h"
#include "gdbcore.h"
#include "gdbtypes.h"
#include "osabi.h"
#include "regcache.h"
#include "regset.h"
#include "trad-frame.h"
#include "value.h"
#include "vax-tdep.h"
/* Return the name of register REGNUM. */
static const char *
vax_register_name (struct gdbarch *gdbarch, int regnum)
{
static const char *register_names[] =
{
"r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
"r8", "r9", "r10", "r11", "ap", "fp", "sp", "pc",
"ps",
};
static_assert (VAX_NUM_REGS == ARRAY_SIZE (register_names));
return register_names[regnum];
}
/* Return the GDB type object for the "standard" data type of data in
register REGNUM. */
static struct type *
vax_register_type (struct gdbarch *gdbarch, int regnum)
{
return builtin_type (gdbarch)->builtin_int;
}
/* Core file support. */
/* Supply register REGNUM from the buffer specified by GREGS and LEN
in the general-purpose register set REGSET to register cache
REGCACHE. If REGNUM is -1, do this for all registers in REGSET. */
static void
vax_supply_gregset (const struct regset *regset, struct regcache *regcache,
int regnum, const void *gregs, size_t len)
{
const gdb_byte *regs = (const gdb_byte *) gregs;
int i;
for (i = 0; i < VAX_NUM_REGS; i++)
{
if (regnum == i || regnum == -1)
regcache->raw_supply (i, regs + i * 4);
}
}
/* VAX register set. */
static const struct regset vax_gregset =
{
NULL,
vax_supply_gregset
};
/* Iterate over core file register note sections. */
static void
vax_iterate_over_regset_sections (struct gdbarch *gdbarch,
iterate_over_regset_sections_cb *cb,
void *cb_data,
const struct regcache *regcache)
{
cb (".reg", VAX_NUM_REGS * 4, VAX_NUM_REGS * 4, &vax_gregset, NULL, cb_data);
}
/* The VAX UNIX calling convention uses R1 to pass a structure return
value address instead of passing it as a first (hidden) argument as
the VMS calling convention suggests. */
static CORE_ADDR
vax_store_arguments (struct regcache *regcache, int nargs,
struct value **args, CORE_ADDR sp)
{
struct gdbarch *gdbarch = regcache->arch ();
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
gdb_byte buf[4];
int count = 0;
int i;
/* We create an argument list on the stack, and make the argument
pointer to it. */
/* Push arguments in reverse order. */
for (i = nargs - 1; i >= 0; i--)
{
int len = args[i]->enclosing_type ()->length ();
sp -= (len + 3) & ~3;
count += (len + 3) / 4;
write_memory (sp, args[i]->contents_all ().data (), len);
}
/* Push argument count. */
sp -= 4;
store_unsigned_integer (buf, 4, byte_order, count);
write_memory (sp, buf, 4);
/* Update the argument pointer. */
store_unsigned_integer (buf, 4, byte_order, sp);
regcache->cooked_write (VAX_AP_REGNUM, buf);
return sp;
}
static CORE_ADDR
vax_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
struct regcache *regcache, CORE_ADDR bp_addr, int nargs,
struct value **args, CORE_ADDR sp,
function_call_return_method return_method,
CORE_ADDR struct_addr)
{
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
CORE_ADDR fp = sp;
gdb_byte buf[4];
/* Set up the function arguments. */
sp = vax_store_arguments (regcache, nargs, args, sp);
/* Store return value address. */
if (return_method == return_method_struct)
regcache_cooked_write_unsigned (regcache, VAX_R1_REGNUM, struct_addr);
/* Store return address in the PC slot. */
sp -= 4;
store_unsigned_integer (buf, 4, byte_order, bp_addr);
write_memory (sp, buf, 4);
/* Store the (fake) frame pointer in the FP slot. */
sp -= 4;
store_unsigned_integer (buf, 4, byte_order, fp);
write_memory (sp, buf, 4);
/* Skip the AP slot. */
sp -= 4;
/* Store register save mask and control bits. */
sp -= 4;
store_unsigned_integer (buf, 4, byte_order, 0);
write_memory (sp, buf, 4);
/* Store condition handler. */
sp -= 4;
store_unsigned_integer (buf, 4, byte_order, 0);
write_memory (sp, buf, 4);
/* Update the stack pointer and frame pointer. */
store_unsigned_integer (buf, 4, byte_order, sp);
regcache->cooked_write (VAX_SP_REGNUM, buf);
regcache->cooked_write (VAX_FP_REGNUM, buf);
/* Return the saved (fake) frame pointer. */
return fp;
}
static struct frame_id
vax_dummy_id (struct gdbarch *gdbarch, const frame_info_ptr &this_frame)
{
CORE_ADDR fp;
fp = get_frame_register_unsigned (this_frame, VAX_FP_REGNUM);
return frame_id_build (fp, get_frame_pc (this_frame));
}
static enum return_value_convention
vax_return_value (struct gdbarch *gdbarch, struct value *function,
struct type *type, struct regcache *regcache,
gdb_byte *readbuf, const gdb_byte *writebuf)
{
int len = type->length ();
gdb_byte buf[8];
if (type->code () == TYPE_CODE_STRUCT
|| type->code () == TYPE_CODE_UNION
|| type->code () == TYPE_CODE_ARRAY)
{
/* The default on VAX is to return structures in static memory.
Consequently a function must return the address where we can
find the return value. */
if (readbuf)
{
ULONGEST addr;
regcache_raw_read_unsigned (regcache, VAX_R0_REGNUM, &addr);
read_memory (addr, readbuf, len);
}
return RETURN_VALUE_ABI_RETURNS_ADDRESS;
}
if (readbuf)
{
/* Read the contents of R0 and (if necessary) R1. */
regcache->cooked_read (VAX_R0_REGNUM, buf);
if (len > 4)
regcache->cooked_read (VAX_R1_REGNUM, buf + 4);
memcpy (readbuf, buf, len);
}
if (writebuf)
{
/* Read the contents to R0 and (if necessary) R1. */
memcpy (buf, writebuf, len);
regcache->cooked_write (VAX_R0_REGNUM, buf);
if (len > 4)
regcache->cooked_write (VAX_R1_REGNUM, buf + 4);
}
return RETURN_VALUE_REGISTER_CONVENTION;
}
/* Use the program counter to determine the contents and size of a
breakpoint instruction. Return a pointer to a string of bytes that
encode a breakpoint instruction, store the length of the string in
*LEN and optionally adjust *PC to point to the correct memory
location for inserting the breakpoint. */
constexpr gdb_byte vax_break_insn[] = { 3 };
typedef BP_MANIPULATION (vax_break_insn) vax_breakpoint;
/* Advance PC across any function entry prologue instructions
to reach some "real" code. */
static CORE_ADDR
vax_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
{
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
gdb_byte op = read_memory_unsigned_integer (pc, 1, byte_order);
if (op == 0x11)
pc += 2; /* skip brb */
if (op == 0x31)
pc += 3; /* skip brw */
if (op == 0xC2
&& read_memory_unsigned_integer (pc + 2, 1, byte_order) == 0x5E)
pc += 3; /* skip subl2 */
if (op == 0x9E
&& read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xAE
&& read_memory_unsigned_integer (pc + 3, 1, byte_order) == 0x5E)
pc += 4; /* skip movab */
if (op == 0x9E
&& read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xCE
&& read_memory_unsigned_integer (pc + 4, 1, byte_order) == 0x5E)
pc += 5; /* skip movab */
if (op == 0x9E
&& read_memory_unsigned_integer (pc + 1, 1, byte_order) == 0xEE
&& read_memory_unsigned_integer (pc + 6, 1, byte_order) == 0x5E)
pc += 7; /* skip movab */
return pc;
}
/* Unwinding the stack is relatively easy since the VAX has a
dedicated frame pointer, and frames are set up automatically as the
result of a function call. Most of the relevant information can be
inferred from the documentation of the Procedure Call Instructions
in the VAX MACRO and Instruction Set Reference Manual. */
struct vax_frame_cache
{
/* Base address. */
CORE_ADDR base;
/* Table of saved registers. */
trad_frame_saved_reg *saved_regs;
};
static struct vax_frame_cache *
vax_frame_cache (const frame_info_ptr &this_frame, void **this_cache)
{
struct vax_frame_cache *cache;
CORE_ADDR addr;
ULONGEST mask;
int regnum;
if (*this_cache)
return (struct vax_frame_cache *) *this_cache;
/* Allocate a new cache. */
cache = FRAME_OBSTACK_ZALLOC (struct vax_frame_cache);
cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);
/* The frame pointer is used as the base for the frame. */
cache->base = get_frame_register_unsigned (this_frame, VAX_FP_REGNUM);
if (cache->base == 0)
return cache;
/* The register save mask and control bits determine the layout of
the stack frame. */
mask = get_frame_memory_unsigned (this_frame, cache->base + 4, 4) >> 16;
/* These are always saved. */
cache->saved_regs[VAX_PC_REGNUM].set_addr (cache->base + 16);
cache->saved_regs[VAX_FP_REGNUM].set_addr (cache->base + 12);
cache->saved_regs[VAX_AP_REGNUM].set_addr (cache->base + 8);
cache->saved_regs[VAX_PS_REGNUM].set_addr (cache->base + 4);
/* Scan the register save mask and record the location of the saved
registers. */
addr = cache->base + 20;
for (regnum = 0; regnum < VAX_AP_REGNUM; regnum++)
{
if (mask & (1 << regnum))
{
cache->saved_regs[regnum].set_addr (addr);
addr += 4;
}
}
/* The CALLS/CALLG flag determines whether this frame has a General
Argument List or a Stack Argument List. */
if (mask & (1 << 13))
{
ULONGEST numarg;
/* This is a procedure with Stack Argument List. Adjust the
stack address for the arguments that were pushed onto the
stack. The return instruction will automatically pop the
arguments from the stack. */
numarg = get_frame_memory_unsigned (this_frame, addr, 1);
addr += 4 + numarg * 4;
}
/* Bits 1:0 of the stack pointer were saved in the control bits. */
cache->saved_regs[VAX_SP_REGNUM].set_value (addr + (mask >> 14));
return cache;
}
static void
vax_frame_this_id (const frame_info_ptr &this_frame, void **this_cache,
struct frame_id *this_id)
{
struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);
/* This marks the outermost frame. */
if (cache->base == 0)
return;
(*this_id) = frame_id_build (cache->base, get_frame_func (this_frame));
}
static struct value *
vax_frame_prev_register (const frame_info_ptr &this_frame,
void **this_cache, int regnum)
{
struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);
return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum);
}
static const struct frame_unwind vax_frame_unwind =
{
"vax prologue",
NORMAL_FRAME,
default_frame_unwind_stop_reason,
vax_frame_this_id,
vax_frame_prev_register,
NULL,
default_frame_sniffer
};
static CORE_ADDR
vax_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
{
struct vax_frame_cache *cache = vax_frame_cache (this_frame, this_cache);
return cache->base;
}
static CORE_ADDR
vax_frame_args_address (const frame_info_ptr &this_frame, void **this_cache)
{
return get_frame_register_unsigned (this_frame, VAX_AP_REGNUM);
}
static const struct frame_base vax_frame_base =
{
&vax_frame_unwind,
vax_frame_base_address,
vax_frame_base_address,
vax_frame_args_address
};
/* Return number of arguments for FRAME. */
static int
vax_frame_num_args (const frame_info_ptr &frame)
{
CORE_ADDR args;
/* Assume that the argument pointer for the outermost frame is
hosed, as is the case on NetBSD/vax ELF. */
if (get_frame_base_address (frame) == 0)
return 0;
args = get_frame_register_unsigned (frame, VAX_AP_REGNUM);
return get_frame_memory_unsigned (frame, args, 1);
}
/* Initialize the current architecture based on INFO. If possible, re-use an
architecture from ARCHES, which is a list of architectures already created
during this debugging session.
Called e.g. at program startup, when reading a core file, and when reading
a binary file. */
static struct gdbarch *
vax_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
{
struct gdbarch *gdbarch;
/* If there is already a candidate, use it. */
arches = gdbarch_list_lookup_by_info (arches, &info);
if (arches != NULL)
return arches->gdbarch;
gdbarch = gdbarch_alloc (&info, NULL);
set_gdbarch_float_format (gdbarch, floatformats_vax_f);
set_gdbarch_double_format (gdbarch, floatformats_vax_d);
set_gdbarch_long_double_format (gdbarch, floatformats_vax_d);
set_gdbarch_long_double_bit (gdbarch, 64);
/* Register info */
set_gdbarch_num_regs (gdbarch, VAX_NUM_REGS);
set_gdbarch_register_name (gdbarch, vax_register_name);
set_gdbarch_register_type (gdbarch, vax_register_type);
set_gdbarch_sp_regnum (gdbarch, VAX_SP_REGNUM);
set_gdbarch_pc_regnum (gdbarch, VAX_PC_REGNUM);
set_gdbarch_ps_regnum (gdbarch, VAX_PS_REGNUM);
set_gdbarch_iterate_over_regset_sections
(gdbarch, vax_iterate_over_regset_sections);
/* Frame and stack info */
set_gdbarch_skip_prologue (gdbarch, vax_skip_prologue);
set_gdbarch_frame_num_args (gdbarch, vax_frame_num_args);
set_gdbarch_frame_args_skip (gdbarch, 4);
/* Stack grows downward. */
set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
/* Return value info */
set_gdbarch_return_value (gdbarch, vax_return_value);
/* Call dummy code. */
set_gdbarch_push_dummy_call (gdbarch, vax_push_dummy_call);
set_gdbarch_dummy_id (gdbarch, vax_dummy_id);
/* Breakpoint info */
set_gdbarch_breakpoint_kind_from_pc (gdbarch, vax_breakpoint::kind_from_pc);
set_gdbarch_sw_breakpoint_from_kind (gdbarch, vax_breakpoint::bp_from_kind);
/* Misc info */
set_gdbarch_deprecated_function_start_offset (gdbarch, 2);
set_gdbarch_believe_pcc_promotion (gdbarch, 1);
frame_base_set_default (gdbarch, &vax_frame_base);
/* Hook in ABI-specific overrides, if they have been registered. */
gdbarch_init_osabi (info, gdbarch);
frame_unwind_append_unwinder (gdbarch, &vax_frame_unwind);
return (gdbarch);
}
void _initialize_vax_tdep ();
void
_initialize_vax_tdep ()
{
gdbarch_register (bfd_arch_vax, vax_gdbarch_init, NULL);
}
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