548 lines
15 KiB
C
548 lines
15 KiB
C
/* GNU/Linux on ARM native support.
|
|
Copyright 1999 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 2 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, write to the Free Software
|
|
Foundation, Inc., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
#include "defs.h"
|
|
#include "inferior.h"
|
|
#include "gdbcore.h"
|
|
#include "gdb_string.h"
|
|
|
|
#include <sys/user.h>
|
|
#include <sys/ptrace.h>
|
|
#include <sys/utsname.h>
|
|
|
|
extern int arm_apcs_32;
|
|
|
|
#define typeNone 0x00
|
|
#define typeSingle 0x01
|
|
#define typeDouble 0x02
|
|
#define typeExtended 0x03
|
|
#define FPWORDS 28
|
|
#define CPSR_REGNUM 16
|
|
|
|
typedef union tagFPREG
|
|
{
|
|
unsigned int fSingle;
|
|
unsigned int fDouble[2];
|
|
unsigned int fExtended[3];
|
|
}
|
|
FPREG;
|
|
|
|
typedef struct tagFPA11
|
|
{
|
|
FPREG fpreg[8]; /* 8 floating point registers */
|
|
unsigned int fpsr; /* floating point status register */
|
|
unsigned int fpcr; /* floating point control register */
|
|
unsigned char fType[8]; /* type of floating point value held in
|
|
floating point registers. */
|
|
int initflag; /* NWFPE initialization flag. */
|
|
}
|
|
FPA11;
|
|
|
|
/* The following variables are used to determine the version of the
|
|
underlying Linux operating system. Examples:
|
|
|
|
Linux 2.0.35 Linux 2.2.12
|
|
os_version = 0x00020023 os_version = 0x0002020c
|
|
os_major = 2 os_major = 2
|
|
os_minor = 0 os_minor = 2
|
|
os_release = 35 os_release = 12
|
|
|
|
Note: os_version = (os_major << 16) | (os_minor << 8) | os_release
|
|
|
|
These are initialized using get_linux_version() from
|
|
_initialize_arm_linux_nat(). */
|
|
|
|
static unsigned int os_version, os_major, os_minor, os_release;
|
|
|
|
static void
|
|
fetch_nw_fpe_single (unsigned int fn, FPA11 * fpa11, unsigned int *pmem)
|
|
{
|
|
unsigned int mem[3];
|
|
|
|
mem[0] = fpa11->fpreg[fn].fSingle;
|
|
mem[1] = 0;
|
|
mem[2] = 0;
|
|
supply_register (F0_REGNUM + fn, (char *) &mem[0]);
|
|
}
|
|
|
|
static void
|
|
fetch_nw_fpe_double (unsigned int fn, FPA11 * fpa11, unsigned int *pmem)
|
|
{
|
|
unsigned int mem[3];
|
|
|
|
mem[0] = fpa11->fpreg[fn].fDouble[1];
|
|
mem[1] = fpa11->fpreg[fn].fDouble[0];
|
|
mem[2] = 0;
|
|
supply_register (F0_REGNUM + fn, (char *) &mem[0]);
|
|
}
|
|
|
|
static void
|
|
fetch_nw_fpe_none (unsigned int fn, FPA11 * fpa11, unsigned int *pmem)
|
|
{
|
|
unsigned int mem[3] =
|
|
{0, 0, 0};
|
|
|
|
supply_register (F0_REGNUM + fn, (char *) &mem[0]);
|
|
}
|
|
|
|
static void
|
|
fetch_nw_fpe_extended (unsigned int fn, FPA11 * fpa11, unsigned int *pmem)
|
|
{
|
|
unsigned int mem[3];
|
|
|
|
mem[0] = fpa11->fpreg[fn].fExtended[0]; /* sign & exponent */
|
|
mem[1] = fpa11->fpreg[fn].fExtended[2]; /* ls bits */
|
|
mem[2] = fpa11->fpreg[fn].fExtended[1]; /* ms bits */
|
|
supply_register (F0_REGNUM + fn, (char *) &mem[0]);
|
|
}
|
|
|
|
static void
|
|
store_nw_fpe_single (unsigned int fn, FPA11 * fpa11)
|
|
{
|
|
unsigned int mem[3];
|
|
|
|
read_register_gen (F0_REGNUM + fn, (char *) &mem[0]);
|
|
fpa11->fpreg[fn].fSingle = mem[0];
|
|
fpa11->fType[fn] = typeSingle;
|
|
}
|
|
|
|
static void
|
|
store_nw_fpe_double (unsigned int fn, FPA11 * fpa11)
|
|
{
|
|
unsigned int mem[3];
|
|
|
|
read_register_gen (F0_REGNUM + fn, (char *) &mem[0]);
|
|
fpa11->fpreg[fn].fDouble[1] = mem[0];
|
|
fpa11->fpreg[fn].fDouble[0] = mem[1];
|
|
fpa11->fType[fn] = typeDouble;
|
|
}
|
|
|
|
void
|
|
store_nw_fpe_extended (unsigned int fn, FPA11 * fpa11)
|
|
{
|
|
unsigned int mem[3];
|
|
|
|
read_register_gen (F0_REGNUM + fn, (char *) &mem[0]);
|
|
fpa11->fpreg[fn].fExtended[0] = mem[0]; /* sign & exponent */
|
|
fpa11->fpreg[fn].fExtended[2] = mem[1]; /* ls bits */
|
|
fpa11->fpreg[fn].fExtended[1] = mem[2]; /* ms bits */
|
|
fpa11->fType[fn] = typeDouble;
|
|
}
|
|
|
|
/* Get the whole floating point state of the process and store the
|
|
floating point stack into registers[]. */
|
|
|
|
static void
|
|
fetch_fpregs (void)
|
|
{
|
|
int ret, regno;
|
|
FPA11 fp;
|
|
|
|
/* Read the floating point state. */
|
|
ret = ptrace (PT_GETFPREGS, inferior_pid, 0, &fp);
|
|
if (ret < 0)
|
|
{
|
|
warning ("Unable to fetch the floating point state.");
|
|
return;
|
|
}
|
|
|
|
/* Fetch fpsr. */
|
|
supply_register (FPS_REGNUM, (char *) &fp.fpsr);
|
|
|
|
/* Fetch the floating point registers. */
|
|
for (regno = F0_REGNUM; regno <= F7_REGNUM; regno++)
|
|
{
|
|
int fn = regno - F0_REGNUM;
|
|
unsigned int *p = (unsigned int *) ®isters[REGISTER_BYTE (regno)];
|
|
|
|
switch (fp.fType[fn])
|
|
{
|
|
case typeSingle:
|
|
fetch_nw_fpe_single (fn, &fp, p);
|
|
break;
|
|
|
|
case typeDouble:
|
|
fetch_nw_fpe_double (fn, &fp, p);
|
|
break;
|
|
|
|
case typeExtended:
|
|
fetch_nw_fpe_extended (fn, &fp, p);
|
|
break;
|
|
|
|
default:
|
|
fetch_nw_fpe_none (fn, &fp, p);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Save the whole floating point state of the process using
|
|
the contents from registers[]. */
|
|
|
|
static void
|
|
store_fpregs (void)
|
|
{
|
|
int ret, regno;
|
|
unsigned int mem[3];
|
|
FPA11 fp;
|
|
|
|
/* Store fpsr. */
|
|
if (register_valid[FPS_REGNUM])
|
|
read_register_gen (FPS_REGNUM, (char *) &fp.fpsr);
|
|
|
|
/* Store the floating point registers. */
|
|
for (regno = F0_REGNUM; regno <= F7_REGNUM; regno++)
|
|
{
|
|
if (register_valid[regno])
|
|
{
|
|
unsigned int fn = regno - F0_REGNUM;
|
|
switch (fp.fType[fn])
|
|
{
|
|
case typeSingle:
|
|
store_nw_fpe_single (fn, &fp);
|
|
break;
|
|
|
|
case typeDouble:
|
|
store_nw_fpe_double (fn, &fp);
|
|
break;
|
|
|
|
case typeExtended:
|
|
store_nw_fpe_extended (fn, &fp);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
ret = ptrace (PTRACE_SETFPREGS, inferior_pid, 0, &fp);
|
|
if (ret < 0)
|
|
{
|
|
warning ("Unable to store floating point state.");
|
|
return;
|
|
}
|
|
}
|
|
|
|
/* Fetch all general registers of the process and store into
|
|
registers[]. */
|
|
|
|
static void
|
|
fetch_regs (void)
|
|
{
|
|
int ret, regno;
|
|
struct pt_regs regs;
|
|
|
|
ret = ptrace (PTRACE_GETREGS, inferior_pid, 0, ®s);
|
|
if (ret < 0)
|
|
{
|
|
warning ("Unable to fetch general registers.");
|
|
return;
|
|
}
|
|
|
|
for (regno = A1_REGNUM; regno < PC_REGNUM; regno++)
|
|
supply_register (regno, (char *) ®s.uregs[regno]);
|
|
|
|
if (arm_apcs_32)
|
|
supply_register (PS_REGNUM, (char *) ®s.uregs[CPSR_REGNUM]);
|
|
else
|
|
supply_register (PS_REGNUM, (char *) ®s.uregs[PC_REGNUM]);
|
|
|
|
regs.uregs[PC_REGNUM] = ADDR_BITS_REMOVE (regs.uregs[PC_REGNUM]);
|
|
supply_register (PC_REGNUM, (char *) ®s.uregs[PC_REGNUM]);
|
|
}
|
|
|
|
/* Store all general registers of the process from the values in
|
|
registers[]. */
|
|
|
|
static void
|
|
store_regs (void)
|
|
{
|
|
int ret, regno;
|
|
struct pt_regs regs;
|
|
|
|
ret = ptrace (PTRACE_GETREGS, inferior_pid, 0, ®s);
|
|
if (ret < 0)
|
|
{
|
|
warning ("Unable to fetch general registers.");
|
|
return;
|
|
}
|
|
|
|
for (regno = A1_REGNUM; regno <= PC_REGNUM; regno++)
|
|
{
|
|
if (register_valid[regno])
|
|
read_register_gen (regno, (char *) ®s.uregs[regno]);
|
|
}
|
|
|
|
ret = ptrace (PTRACE_SETREGS, inferior_pid, 0, ®s);
|
|
|
|
if (ret < 0)
|
|
{
|
|
warning ("Unable to store general registers.");
|
|
return;
|
|
}
|
|
}
|
|
|
|
/* Fetch registers from the child process. Fetch all registers if
|
|
regno == -1, otherwise fetch all general registers or all floating
|
|
point registers depending upon the value of regno. */
|
|
|
|
void
|
|
fetch_inferior_registers (int regno)
|
|
{
|
|
if ((regno < F0_REGNUM) || (regno > FPS_REGNUM))
|
|
fetch_regs ();
|
|
|
|
if (((regno >= F0_REGNUM) && (regno <= FPS_REGNUM)) || (regno == -1))
|
|
fetch_fpregs ();
|
|
}
|
|
|
|
/* Store registers back into the inferior. Store all registers if
|
|
regno == -1, otherwise store all general registers or all floating
|
|
point registers depending upon the value of regno. */
|
|
|
|
void
|
|
store_inferior_registers (int regno)
|
|
{
|
|
if ((regno < F0_REGNUM) || (regno > FPS_REGNUM))
|
|
store_regs ();
|
|
|
|
if (((regno >= F0_REGNUM) && (regno <= FPS_REGNUM)) || (regno == -1))
|
|
store_fpregs ();
|
|
}
|
|
|
|
#ifdef GET_LONGJMP_TARGET
|
|
|
|
/* Figure out where the longjmp will land. We expect that we have
|
|
just entered longjmp and haven't yet altered r0, r1, so the
|
|
arguments are still in the registers. (A1_REGNUM) points at the
|
|
jmp_buf structure from which we extract the pc (JB_PC) that we will
|
|
land at. The pc is copied into ADDR. This routine returns true on
|
|
success. */
|
|
|
|
#define LONGJMP_TARGET_SIZE sizeof(int)
|
|
#define JB_ELEMENT_SIZE sizeof(int)
|
|
#define JB_SL 18
|
|
#define JB_FP 19
|
|
#define JB_SP 20
|
|
#define JB_PC 21
|
|
|
|
int
|
|
arm_get_longjmp_target (CORE_ADDR * pc)
|
|
{
|
|
CORE_ADDR jb_addr;
|
|
char buf[LONGJMP_TARGET_SIZE];
|
|
|
|
jb_addr = read_register (A1_REGNUM);
|
|
|
|
if (target_read_memory (jb_addr + JB_PC * JB_ELEMENT_SIZE, buf,
|
|
LONGJMP_TARGET_SIZE))
|
|
return 0;
|
|
|
|
*pc = extract_address (buf, LONGJMP_TARGET_SIZE);
|
|
return 1;
|
|
}
|
|
|
|
#endif /* GET_LONGJMP_TARGET */
|
|
|
|
/*
|
|
Dynamic Linking on ARM Linux
|
|
----------------------------
|
|
|
|
Note: PLT = procedure linkage table
|
|
GOT = global offset table
|
|
|
|
As much as possible, ELF dynamic linking defers the resolution of
|
|
jump/call addresses until the last minute. The technique used is
|
|
inspired by the i386 ELF design, and is based on the following
|
|
constraints.
|
|
|
|
1) The calling technique should not force a change in the assembly
|
|
code produced for apps; it MAY cause changes in the way assembly
|
|
code is produced for position independent code (i.e. shared
|
|
libraries).
|
|
|
|
2) The technique must be such that all executable areas must not be
|
|
modified; and any modified areas must not be executed.
|
|
|
|
To do this, there are three steps involved in a typical jump:
|
|
|
|
1) in the code
|
|
2) through the PLT
|
|
3) using a pointer from the GOT
|
|
|
|
When the executable or library is first loaded, each GOT entry is
|
|
initialized to point to the code which implements dynamic name
|
|
resolution and code finding. This is normally a function in the
|
|
program interpreter (on ARM Linux this is usually ld-linux.so.2,
|
|
but it does not have to be). On the first invocation, the function
|
|
is located and the GOT entry is replaced with the real function
|
|
address. Subsequent calls go through steps 1, 2 and 3 and end up
|
|
calling the real code.
|
|
|
|
1) In the code:
|
|
|
|
b function_call
|
|
bl function_call
|
|
|
|
This is typical ARM code using the 26 bit relative branch or branch
|
|
and link instructions. The target of the instruction
|
|
(function_call is usually the address of the function to be called.
|
|
In position independent code, the target of the instruction is
|
|
actually an entry in the PLT when calling functions in a shared
|
|
library. Note that this call is identical to a normal function
|
|
call, only the target differs.
|
|
|
|
2) In the PLT:
|
|
|
|
The PLT is a synthetic area, created by the linker. It exists in
|
|
both executables and libraries. It is an array of stubs, one per
|
|
imported function call. It looks like this:
|
|
|
|
PLT[0]:
|
|
str lr, [sp, #-4]! @push the return address (lr)
|
|
ldr lr, [pc, #16] @load from 6 words ahead
|
|
add lr, pc, lr @form an address for GOT[0]
|
|
ldr pc, [lr, #8]! @jump to the contents of that addr
|
|
|
|
The return address (lr) is pushed on the stack and used for
|
|
calculations. The load on the second line loads the lr with
|
|
&GOT[3] - . - 20. The addition on the third leaves:
|
|
|
|
lr = (&GOT[3] - . - 20) + (. + 8)
|
|
lr = (&GOT[3] - 12)
|
|
lr = &GOT[0]
|
|
|
|
On the fourth line, the pc and lr are both updated, so that:
|
|
|
|
pc = GOT[2]
|
|
lr = &GOT[0] + 8
|
|
= &GOT[2]
|
|
|
|
NOTE: PLT[0] borrows an offset .word from PLT[1]. This is a little
|
|
"tight", but allows us to keep all the PLT entries the same size.
|
|
|
|
PLT[n+1]:
|
|
ldr ip, [pc, #4] @load offset from gotoff
|
|
add ip, pc, ip @add the offset to the pc
|
|
ldr pc, [ip] @jump to that address
|
|
gotoff: .word GOT[n+3] - .
|
|
|
|
The load on the first line, gets an offset from the fourth word of
|
|
the PLT entry. The add on the second line makes ip = &GOT[n+3],
|
|
which contains either a pointer to PLT[0] (the fixup trampoline) or
|
|
a pointer to the actual code.
|
|
|
|
3) In the GOT:
|
|
|
|
The GOT contains helper pointers for both code (PLT) fixups and
|
|
data fixups. The first 3 entries of the GOT are special. The next
|
|
M entries (where M is the number of entries in the PLT) belong to
|
|
the PLT fixups. The next D (all remaining) entries belong to
|
|
various data fixups. The actual size of the GOT is 3 + M + D.
|
|
|
|
The GOT is also a synthetic area, created by the linker. It exists
|
|
in both executables and libraries. When the GOT is first
|
|
initialized , all the GOT entries relating to PLT fixups are
|
|
pointing to code back at PLT[0].
|
|
|
|
The special entries in the GOT are:
|
|
|
|
GOT[0] = linked list pointer used by the dynamic loader
|
|
GOT[1] = pointer to the reloc table for this module
|
|
GOT[2] = pointer to the fixup/resolver code
|
|
|
|
The first invocation of function call comes through and uses the
|
|
fixup/resolver code. On the entry to the fixup/resolver code:
|
|
|
|
ip = &GOT[n+3]
|
|
lr = &GOT[2]
|
|
stack[0] = return address (lr) of the function call
|
|
[r0, r1, r2, r3] are still the arguments to the function call
|
|
|
|
This is enough information for the fixup/resolver code to work
|
|
with. Before the fixup/resolver code returns, it actually calls
|
|
the requested function and repairs &GOT[n+3]. */
|
|
|
|
CORE_ADDR
|
|
arm_skip_solib_resolver (CORE_ADDR pc)
|
|
{
|
|
/* FIXME */
|
|
return 0;
|
|
}
|
|
|
|
int
|
|
arm_linux_register_u_addr (int blockend, int regnum)
|
|
{
|
|
return blockend + REGISTER_BYTE (regnum);
|
|
}
|
|
|
|
int
|
|
arm_linux_kernel_u_size (void)
|
|
{
|
|
return (sizeof (struct user));
|
|
}
|
|
|
|
/* Extract from an array REGBUF containing the (raw) register state
|
|
a function return value of type TYPE, and copy that, in virtual format,
|
|
into VALBUF. */
|
|
|
|
void
|
|
arm_linux_extract_return_value (struct type *type,
|
|
char regbuf[REGISTER_BYTES],
|
|
char *valbuf)
|
|
{
|
|
/* ScottB: This needs to be looked at to handle the different
|
|
floating point emulators on ARM Linux. Right now the code
|
|
assumes that fetch inferior registers does the right thing for
|
|
GDB. I suspect this won't handle NWFPE registers correctly, nor
|
|
will the default ARM version (arm_extract_return_value()). */
|
|
|
|
int regnum = (TYPE_CODE_FLT == TYPE_CODE (type)) ? F0_REGNUM : A1_REGNUM;
|
|
memcpy (valbuf, ®buf[REGISTER_BYTE (regnum)], TYPE_LENGTH (type));
|
|
}
|
|
|
|
static unsigned int
|
|
get_linux_version (unsigned int *vmajor,
|
|
unsigned int *vminor,
|
|
unsigned int *vrelease)
|
|
{
|
|
struct utsname info;
|
|
char *pmajor, *pminor, *prelease, *tail;
|
|
|
|
if (-1 == uname (&info))
|
|
{
|
|
warning ("Unable to determine Linux version.");
|
|
return -1;
|
|
}
|
|
|
|
pmajor = strtok (info.release, ".");
|
|
pminor = strtok (NULL, ".");
|
|
prelease = strtok (NULL, ".");
|
|
|
|
*vmajor = (unsigned int) strtoul (pmajor, &tail, 0);
|
|
*vminor = (unsigned int) strtoul (pminor, &tail, 0);
|
|
*vrelease = (unsigned int) strtoul (prelease, &tail, 0);
|
|
|
|
return ((*vmajor << 16) | (*vminor << 8) | *vrelease);
|
|
}
|
|
|
|
void
|
|
_initialize_arm_linux_nat (void)
|
|
{
|
|
os_version = get_linux_version (&os_major, &os_minor, &os_release);
|
|
}
|