/*
* Copyright (C) 2004-2006 Atmel Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#undef DEBUG
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/unistd.h>
#include <linux/notifier.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
#include <asm/ocd.h>
#include <asm/mmu_context.h>
#include <linux/kdebug.h>
static struct pt_regs *get_user_regs(struct task_struct *tsk)
{
return (struct pt_regs *)((unsigned long)task_stack_page(tsk) +
THREAD_SIZE - sizeof(struct pt_regs));
}
static void ptrace_single_step(struct task_struct *tsk)
{
pr_debug("ptrace_single_step: pid=%u, PC=0x%08lx, SR=0x%08lx\n",
tsk->pid, task_pt_regs(tsk)->pc, task_pt_regs(tsk)->sr);
/*
* We can't schedule in Debug mode, so when TIF_BREAKPOINT is
* set, the system call or exception handler will do a
* breakpoint to enter monitor mode before returning to
* userspace.
*
* The monitor code will then notice that TIF_SINGLE_STEP is
* set and return to userspace with single stepping enabled.
* The CPU will then enter monitor mode again after exactly
* one instruction has been executed, and the monitor code
* will then send a SIGTRAP to the process.
*/
set_tsk_thread_flag(tsk, TIF_BREAKPOINT);
set_tsk_thread_flag(tsk, TIF_SINGLE_STEP);
}
/*
* Called by kernel/ptrace.c when detaching
*
* Make sure any single step bits, etc. are not set
*/
void ptrace_disable(struct task_struct *child)
{
clear_tsk_thread_flag(child, TIF_SINGLE_STEP);
clear_tsk_thread_flag(child, TIF_BREAKPOINT);
ocd_disable(child);
}
/*
* Read the word at offset "offset" into the task's "struct user". We
* actually access the pt_regs struct stored on the kernel stack.
*/
static int ptrace_read_user(struct task_struct *tsk, unsigned long offset,
unsigned long __user *data)
{
unsigned long *regs;
unsigned long value;
if (offset & 3 || offset >= sizeof(struct user)) {
printk("ptrace_read_user: invalid offset 0x%08lx\n", offset);
return -EIO;
}
regs = (unsigned long *)get_user_regs(tsk);
value = 0;
if (offset < sizeof(struct pt_regs))
value = regs[offset / sizeof(regs[0])];
pr_debug("ptrace_read_user(%s[%u], %#lx, %p) -> %#lx\n",
tsk->comm, tsk->pid, offset, data, value);
return put_user(value, data);
}
/*
* Write the word "value" to offset "offset" into the task's "struct
* user". We actually access the pt_regs struct stored on the kernel
* stack.
*/
static int ptrace_write_user(struct task_struct *tsk, unsigned long offset,
unsigned long value)
{
unsigned long *regs;
pr_debug("ptrace_write_user(%s[%u], %#lx, %#lx)\n",
tsk->comm, tsk->pid, offset, value);
if (offset & 3 || offset >= sizeof(struct user)) {
pr_debug(" invalid offset 0x%08lx\n", offset);
return -EIO;
}
if (offset >= sizeof(struct pt_regs))
return 0;
regs = (unsigned long *)get_user_regs(tsk);
regs[offset / sizeof(regs[0])] = value;
return 0;
}
static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)
{
struct pt_regs *regs = get_user_regs(tsk);
return copy_to_user(uregs, regs, sizeof(*regs)) ? -EFAULT : 0;
}
static int ptrace_setregs(struct task_struct *tsk, const void __user *uregs)
{
struct pt_regs newregs;
int ret;
ret = -EFAULT;
if (copy_from_user(&newregs, uregs, sizeof(newregs)) == 0) {
struct pt_regs *regs = get_user_regs(tsk);
ret = -EINVAL;
if (valid_user_regs(&newregs)) {
*regs = newregs;
ret = 0;
}
}
return ret;
}
long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
int ret;
switch (request) {
/* Read the word at location addr in the child process */
case PTRACE_PEEKTEXT:
case PTRACE_PEEKDATA:
ret = generic_ptrace_peekdata(child, addr, data);
break;
case PTRACE_PEEKUSR:
ret = ptrace_read_user(child, addr,
(unsigned long __user *)data);
break;
/* Write the word in data at location addr */
case PTRACE_POKETEXT:
case PTRACE_POKEDATA:
ret = generic_ptrace_pokedata(child, addr, data);
break;
case PTRACE_POKEUSR:
ret = ptrace_write_user(child, addr, data);
break;
/* continue and stop at next (return from) syscall */
case PTRACE_SYSCALL:
/* restart after signal */
case PTRACE_CONT:
ret = -EIO;
if (!valid_signal(data))
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;
/* XXX: Are we sure no breakpoints are active here? */
wake_up_process(child);
ret = 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:
ret = 0;
if (child->exit_state == EXIT_ZOMBIE)
break;
child->exit_code = SIGKILL;
wake_up_process(child);
break;
/*
* execute single instruction.
*/
case PTRACE_SINGLESTEP:
ret = -EIO;
if (!valid_signal(data))
break;
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
ptrace_single_step(child);
child->exit_code = data;
wake_up_process(child);
ret = 0;
break;
case PTRACE_GETREGS:
ret = ptrace_getregs(child, (void __user *)data);
break;
case PTRACE_SETREGS:
ret = ptrace_setregs(child, (const void __user *)data);
break;
default:
ret = ptrace_request(child, request, addr, data);
break;
}
return ret;
}
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) {
pr_debug("syscall_trace: sending signal %d to PID %u\n",
current->exit_code, current->pid);
send_sig(current->exit_code, current, 1);
current->exit_code = 0;
}
}
/*
* debug_trampoline() is an assembly stub which will store all user
* registers on the stack and execute a breakpoint instruction.
*
* If we single-step into an exception handler which runs with
* interrupts disabled the whole time so it doesn't have to check for
* pending work, its return address will be modified so that it ends
* up returning to debug_trampoline.
*
* If the exception handler decides to store the user context and
* enable interrupts after all, it will restore the original return
* address and status register value. Before it returns, it will
* notice that TIF_BREAKPOINT is set and execute a breakpoint
* instruction.
*/
extern void debug_trampoline(void);
asmlinkage struct pt_regs *do_debug(struct pt_regs *regs)
{
struct thread_info *ti;
unsigned long trampoline_addr;
u32 status;
u32 ctrl;
int code;
status = ocd_read(DS);
ti = current_thread_info();
code = TRAP_BRKPT;
pr_debug("do_debug: status=0x%08x PC=0x%08lx SR=0x%08lx tif=0x%08lx\n",
status, regs->pc, regs->sr, ti->flags);
if (!user_mode(regs)) {
unsigned long die_val = DIE_BREAKPOINT;
if (status & (1 << OCD_DS_SSS_BIT))
die_val = DIE_SSTEP;
if (notify_die(die_val, "ptrace", regs, 0, 0, SIGTRAP)
== NOTIFY_STOP)
return regs;
if ((status & (1 << OCD_DS_SWB_BIT))
&& test_and_clear_ti_thread_flag(
ti, TIF_BREAKPOINT)) {
/*
* Explicit breakpoint from trampoline or
* exception/syscall/interrupt handler.
*
* The real saved regs are on the stack right
* after the ones we saved on entry.
*/
regs++;
pr_debug(" -> TIF_BREAKPOINT done, adjusted regs:"
"PC=0x%08lx SR=0x%08lx\n",
regs->pc, regs->sr);
BUG_ON(!user_mode(regs));
if (test_thread_flag(TIF_SINGLE_STEP)) {
pr_debug("Going to do single step...\n");
return regs;
}
/*
* No TIF_SINGLE_STEP means we're done
* stepping over a syscall. Do the trap now.
*/
code = TRAP_TRACE;
} else if ((status & (1 << OCD_DS_SSS_BIT))
&& test_ti_thread_flag(ti, TIF_SINGLE_STEP)) {
pr_debug("Stepped into something, "
"setting TIF_BREAKPOINT...\n");
set_ti_thread_flag(ti, TIF_BREAKPOINT);
/*
* We stepped into an exception, interrupt or
* syscall handler. Some exception handlers
* don't check for pending work, so we need to
* set up a trampoline just in case.
*
* The exception entry code will undo the
* trampoline stuff if it does a full context
* save (which also means that it'll check for
* pending work later.)
*/
if ((regs->sr & MODE_MASK) == MODE_EXCEPTION) {
trampoline_addr
= (unsigned long)&debug_trampoline;
pr_debug("Setting up trampoline...\n");
ti->rar_saved = sysreg_read(RAR_EX);
ti->rsr_saved = sysreg_read(RSR_EX);
sysreg_write(RAR_EX, trampoline_addr);
sysreg_write(RSR_EX, (MODE_EXCEPTION
| SR_EM | SR_GM));
BUG_ON(ti->rsr_saved & MODE_MASK);
}
/*
* If we stepped into a system call, we
* shouldn't do a single step after we return
* since the return address is right after the
* "scall" instruction we were told to step
* over.
*/
if ((regs->sr & MODE_MASK) == MODE_SUPERVISOR) {
pr_debug("Supervisor; no single step\n");
clear_ti_thread_flag(ti, TIF_SINGLE_STEP);
}
ctrl = ocd_read(DC);
ctrl &= ~(1 << OCD_DC_SS_BIT);
ocd_write(DC, ctrl);
return regs;
} else {
printk(KERN_ERR "Unexpected OCD_DS value: 0x%08x\n",
status);
printk(KERN_ERR "Thread flags: 0x%08lx\n", ti->flags);
die("Unhandled debug trap in kernel mode",
regs, SIGTRAP);
}
} else if (status & (1 << OCD_DS_SSS_BIT)) {
/* Single step in user mode */
code = TRAP_TRACE;
ctrl = ocd_read(DC);
ctrl &= ~(1 << OCD_DC_SS_BIT);
ocd_write(DC, ctrl);
}
pr_debug("Sending SIGTRAP: code=%d PC=0x%08lx SR=0x%08lx\n",
code, regs->pc, regs->sr);
clear_thread_flag(TIF_SINGLE_STEP);
_exception(SIGTRAP, regs, code, instruction_pointer(regs));
return regs;
}
