/*
* arch/v850/kernel/ptrace.c -- `ptrace' system call
*
* Copyright (C) 2002,03,04 NEC Electronics Corporation
* Copyright (C) 2002,03,04 Miles Bader <miles@gnu.org>
*
* Derived from arch/mips/kernel/ptrace.c:
*
* Copyright (C) 1992 Ross Biro
* Copyright (C) Linus Torvalds
* Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
* Copyright (C) 1996 David S. Miller
* Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
* Copyright (C) 1999 MIPS Technologies, Inc.
*
* This file is subject to the terms and conditions of the GNU General
* Public License. See the file COPYING in the main directory of this
* archive for more details.
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/smp_lock.h>
#include <linux/ptrace.h>
#include <linux/signal.h>
#include <asm/errno.h>
#include <asm/ptrace.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
/* Returns the address where the register at REG_OFFS in P is stashed away. */
static v850_reg_t *reg_save_addr (unsigned reg_offs, struct task_struct *t)
{
struct pt_regs *regs;
/* Three basic cases:
(1) A register normally saved before calling the scheduler, is
available in the kernel entry pt_regs structure at the top
of the kernel stack. The kernel trap/irq exit path takes
care to save/restore almost all registers for ptrace'd
processes.
(2) A call-clobbered register, where the process P entered the
kernel via [syscall] trap, is not stored anywhere; that's
OK, because such registers are not expected to be preserved
when the trap returns anyway (so we don't actually bother to
test for this case).
(3) A few registers not used at all by the kernel, and so
normally never saved except by context-switches, are in the
context switch state. */
if (reg_offs == PT_CTPC || reg_offs == PT_CTPSW || reg_offs == PT_CTBP)
/* Register saved during context switch. */
regs = thread_saved_regs (t);
else
/* Register saved during kernel entry (or not available). */
regs = task_regs (t);
return (v850_reg_t *)((char *)regs + reg_offs);
}
/* Set the bits SET and clear the bits CLEAR in the v850e DIR
(`debug information register'). Returns the new value of DIR. */
static inline v850_reg_t set_dir (v850_reg_t set, v850_reg_t clear)
{
register v850_reg_t rval asm ("r10");
register v850_reg_t arg0 asm ("r6") = set;
register v850_reg_t arg1 asm ("r7") = clear;
/* The dbtrap handler has exactly this functionality when called
from kernel mode. 0xf840 is a `dbtrap' insn. */
asm (".short 0xf840" : "=r" (rval) : "r" (arg0), "r" (arg1));
return rval;
}
/* Makes sure hardware single-stepping is (globally) enabled.
Returns true if successful. */
static inline int enable_single_stepping (void)
{
static int enabled = 0; /* Remember whether we already did it. */
if (! enabled) {
/* Turn on the SE (`single-step enable') bit, 0x100, in the
DIR (`debug information register'). This may fail if a
processor doesn't support it or something. We also try
to clear bit 0x40 (`INI'), which is necessary to use the
debug stuff on the v850e2; on the v850e, clearing 0x40
shouldn't cause any problem. */
v850_reg_t dir = set_dir (0x100, 0x40);
/* Make sure it really got set. */
if (dir & 0x100)
enabled = 1;
}
return enabled;
}
/* Try to set CHILD's single-step flag to VAL. Returns true if successful. */
static int set_single_step (struct task_struct *t, int val)
{
v850_reg_t *psw_addr = reg_save_addr(PT_PSW, t);
if (val) {
/* Make sure single-stepping is enabled. */
if (! enable_single_stepping ())
return 0;
/* Set T's single-step flag. */
*psw_addr |= 0x800;
} else
*psw_addr &= ~0x800;
return 1;
}
int sys_ptrace(long request, long pid, long addr, long data)
{
struct task_struct *child;
int rval;
lock_kernel();
if (request == PTRACE_TRACEME) {
/* are we already being traced? */
if (current->ptrace & PT_PTRACED) {
rval = -EPERM;
goto out;
}
/* set the ptrace bit in the process flags. */
current->ptrace |= PT_PTRACED;
rval = 0;
goto out;
}
rval = -ESRCH;
read_lock(&tasklist_lock);
child = find_task_by_pid(pid);
if (child)
get_task_struct(child);
read_unlock(&tasklist_lock);
if (!child)
goto out;
rval = -EPERM;
if (pid == 1) /* you may not mess with init */
goto out_tsk;
if (request == PTRACE_ATTACH) {
rval = ptrace_attach(child);
goto out_tsk;
}
rval = ptrace_check_attach(child, request == PTRACE_KILL);
if (rval < 0)
goto out_tsk;
switch (request) {
unsigned long val, copied;
case PTRACE_PEEKTEXT: /* read word at location addr. */
case PTRACE_PEEKDATA:
copied = access_process_vm(child, addr, &val, sizeof(val), 0);
rval = -EIO;
if (copied != sizeof(val))
break;
rval = put_user(val, (unsigned long *)data);
goto out;
case PTRACE_POKETEXT: /* write the word at location addr. */
case PTRACE_POKEDATA:
rval = 0;
if (access_process_vm(child, addr, &data, sizeof(data), 1)
== sizeof(data))
break;
rval = -EIO;
goto out;
/* Read/write the word at location ADDR in the registers. */
case PTRACE_PEEKUSR:
case PTRACE_POKEUSR:
rval = 0;
if (addr >= PT_SIZE && request == PTRACE_PEEKUSR) {
/* Special requests that don't actually correspond
to offsets in struct pt_regs. */
if (addr == PT_TEXT_ADDR)
val = child->mm->start_code;
else if (addr == PT_DATA_ADDR)
val = child->mm->start_data;
else if (addr == PT_TEXT_LEN)
val = child->mm->end_code
- child->mm->start_code;
else
rval = -EIO;
} else if (addr >= 0 && addr < PT_SIZE && (addr & 0x3) == 0) {
v850_reg_t *reg_addr = reg_save_addr(addr, child);
if (request == PTRACE_PEEKUSR)
val = *reg_addr;
else
*reg_addr = data;
} else
rval = -EIO;
if (rval == 0 && request == PTRACE_PEEKUSR)
rval = put_user (val, (unsigned long *)data);
goto out;
/* Continue and stop at next (return from) syscall */
case PTRACE_SYSCALL:
/* Restart after a signal. */
case PTRACE_CONT:
/* Execute a single instruction. */
case PTRACE_SINGLESTEP:
rval = -EIO;
if (!valid_signal(data))
break;
/* Turn CHILD's single-step flag on or off. */
if (! set_single_step (child, request == PTRACE_SINGLESTEP))
break;
if (request == PTRACE_SYSCALL)
set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
else
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
child->exit_code = data;
wake_up_process(child);
rval = 0;
break;
/*
* make the child exit. Best I can do is send it a sigkill.
* perhaps it should be put in the status that it wants to
* exit.
*/
case PTRACE_KILL:
rval = 0;
if (child->exit_state == EXIT_ZOMBIE) /* already dead */
break;
child->exit_code = SIGKILL;
wake_up_process(child);
break;
case PTRACE_DETACH: /* detach a process that was attached. */
set_single_step (child, 0); /* Clear single-step flag */
rval = ptrace_detach(child, data);
break;
default:
rval = -EIO;
goto out;
}
out_tsk:
put_task_struct(child);
out:
unlock_kernel();
return rval;
}
asmlinkage void syscall_trace(void)
{
if (!test_thread_flag(TIF_SYSCALL_TRACE))
return;
if (!(current->ptrace & PT_PTRACED))
return;
/* The 0x80 provides a way for the tracing parent to distinguish
between a syscall stop and SIGTRAP delivery */
ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
? 0x80 : 0));
/*
* this isn't the same as continuing with a signal, but it will do
* for normal use. strace only continues with a signal if the
* stopping signal is not SIGTRAP. -brl
*/
if (current->exit_code) {
send_sig(current->exit_code, current, 1);
current->exit_code = 0;
}
}
void ptrace_disable (struct task_struct *child)
{
/* nothing to do */
}
