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355 lines
9.3 KiB
355 lines
9.3 KiB
/*
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* Copyright (C) 2004-2006 Atmel Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#undef DEBUG
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/ptrace.h>
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#include <linux/errno.h>
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#include <linux/user.h>
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#include <linux/security.h>
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#include <linux/unistd.h>
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#include <linux/notifier.h>
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#include <asm/traps.h>
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#include <asm/uaccess.h>
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#include <asm/ocd.h>
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#include <asm/mmu_context.h>
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#include <linux/kdebug.h>
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static struct pt_regs *get_user_regs(struct task_struct *tsk)
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{
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return (struct pt_regs *)((unsigned long)task_stack_page(tsk) +
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THREAD_SIZE - sizeof(struct pt_regs));
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}
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static void user_enable_single_step(struct task_struct *tsk)
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{
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pr_debug("user_enable_single_step: pid=%u, PC=0x%08lx, SR=0x%08lx\n",
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tsk->pid, task_pt_regs(tsk)->pc, task_pt_regs(tsk)->sr);
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/*
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* We can't schedule in Debug mode, so when TIF_BREAKPOINT is
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* set, the system call or exception handler will do a
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* breakpoint to enter monitor mode before returning to
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* userspace.
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*
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* The monitor code will then notice that TIF_SINGLE_STEP is
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* set and return to userspace with single stepping enabled.
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* The CPU will then enter monitor mode again after exactly
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* one instruction has been executed, and the monitor code
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* will then send a SIGTRAP to the process.
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*/
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set_tsk_thread_flag(tsk, TIF_BREAKPOINT);
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set_tsk_thread_flag(tsk, TIF_SINGLE_STEP);
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}
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void user_disable_single_step(struct task_struct *child)
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{
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/* XXX(hch): a no-op here seems wrong.. */
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}
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/*
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* Called by kernel/ptrace.c when detaching
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*
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* Make sure any single step bits, etc. are not set
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*/
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void ptrace_disable(struct task_struct *child)
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{
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clear_tsk_thread_flag(child, TIF_SINGLE_STEP);
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clear_tsk_thread_flag(child, TIF_BREAKPOINT);
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ocd_disable(child);
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}
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/*
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* Read the word at offset "offset" into the task's "struct user". We
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* actually access the pt_regs struct stored on the kernel stack.
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*/
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static int ptrace_read_user(struct task_struct *tsk, unsigned long offset,
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unsigned long __user *data)
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{
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unsigned long *regs;
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unsigned long value;
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if (offset & 3 || offset >= sizeof(struct user)) {
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printk("ptrace_read_user: invalid offset 0x%08lx\n", offset);
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return -EIO;
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}
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regs = (unsigned long *)get_user_regs(tsk);
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value = 0;
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if (offset < sizeof(struct pt_regs))
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value = regs[offset / sizeof(regs[0])];
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pr_debug("ptrace_read_user(%s[%u], %#lx, %p) -> %#lx\n",
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tsk->comm, tsk->pid, offset, data, value);
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return put_user(value, data);
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}
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/*
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* Write the word "value" to offset "offset" into the task's "struct
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* user". We actually access the pt_regs struct stored on the kernel
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* stack.
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*/
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static int ptrace_write_user(struct task_struct *tsk, unsigned long offset,
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unsigned long value)
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{
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unsigned long *regs;
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pr_debug("ptrace_write_user(%s[%u], %#lx, %#lx)\n",
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tsk->comm, tsk->pid, offset, value);
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if (offset & 3 || offset >= sizeof(struct user)) {
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pr_debug(" invalid offset 0x%08lx\n", offset);
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return -EIO;
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}
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if (offset >= sizeof(struct pt_regs))
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return 0;
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regs = (unsigned long *)get_user_regs(tsk);
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regs[offset / sizeof(regs[0])] = value;
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return 0;
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}
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static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)
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{
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struct pt_regs *regs = get_user_regs(tsk);
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return copy_to_user(uregs, regs, sizeof(*regs)) ? -EFAULT : 0;
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}
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static int ptrace_setregs(struct task_struct *tsk, const void __user *uregs)
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{
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struct pt_regs newregs;
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int ret;
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ret = -EFAULT;
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if (copy_from_user(&newregs, uregs, sizeof(newregs)) == 0) {
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struct pt_regs *regs = get_user_regs(tsk);
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ret = -EINVAL;
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if (valid_user_regs(&newregs)) {
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*regs = newregs;
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ret = 0;
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}
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}
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return ret;
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}
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long arch_ptrace(struct task_struct *child, long request, long addr, long data)
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{
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int ret;
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switch (request) {
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/* Read the word at location addr in the child process */
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case PTRACE_PEEKTEXT:
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case PTRACE_PEEKDATA:
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ret = generic_ptrace_peekdata(child, addr, data);
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break;
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case PTRACE_PEEKUSR:
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ret = ptrace_read_user(child, addr,
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(unsigned long __user *)data);
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break;
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/* Write the word in data at location addr */
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case PTRACE_POKETEXT:
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case PTRACE_POKEDATA:
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ret = generic_ptrace_pokedata(child, addr, data);
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break;
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case PTRACE_POKEUSR:
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ret = ptrace_write_user(child, addr, data);
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break;
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case PTRACE_GETREGS:
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ret = ptrace_getregs(child, (void __user *)data);
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break;
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case PTRACE_SETREGS:
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ret = ptrace_setregs(child, (const void __user *)data);
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break;
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default:
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ret = ptrace_request(child, request, addr, data);
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break;
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}
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return ret;
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}
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asmlinkage void syscall_trace(void)
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{
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if (!test_thread_flag(TIF_SYSCALL_TRACE))
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return;
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if (!(current->ptrace & PT_PTRACED))
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return;
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/* The 0x80 provides a way for the tracing parent to
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* distinguish between a syscall stop and SIGTRAP delivery */
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ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
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? 0x80 : 0));
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/*
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* this isn't the same as continuing with a signal, but it
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* will do for normal use. strace only continues with a
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* signal if the stopping signal is not SIGTRAP. -brl
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*/
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if (current->exit_code) {
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pr_debug("syscall_trace: sending signal %d to PID %u\n",
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current->exit_code, current->pid);
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send_sig(current->exit_code, current, 1);
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current->exit_code = 0;
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}
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}
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/*
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* debug_trampoline() is an assembly stub which will store all user
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* registers on the stack and execute a breakpoint instruction.
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*
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* If we single-step into an exception handler which runs with
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* interrupts disabled the whole time so it doesn't have to check for
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* pending work, its return address will be modified so that it ends
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* up returning to debug_trampoline.
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*
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* If the exception handler decides to store the user context and
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* enable interrupts after all, it will restore the original return
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* address and status register value. Before it returns, it will
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* notice that TIF_BREAKPOINT is set and execute a breakpoint
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* instruction.
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*/
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extern void debug_trampoline(void);
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asmlinkage struct pt_regs *do_debug(struct pt_regs *regs)
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{
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struct thread_info *ti;
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unsigned long trampoline_addr;
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u32 status;
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u32 ctrl;
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int code;
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status = ocd_read(DS);
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ti = current_thread_info();
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code = TRAP_BRKPT;
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pr_debug("do_debug: status=0x%08x PC=0x%08lx SR=0x%08lx tif=0x%08lx\n",
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status, regs->pc, regs->sr, ti->flags);
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if (!user_mode(regs)) {
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unsigned long die_val = DIE_BREAKPOINT;
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if (status & (1 << OCD_DS_SSS_BIT))
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die_val = DIE_SSTEP;
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if (notify_die(die_val, "ptrace", regs, 0, 0, SIGTRAP)
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== NOTIFY_STOP)
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return regs;
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if ((status & (1 << OCD_DS_SWB_BIT))
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&& test_and_clear_ti_thread_flag(
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ti, TIF_BREAKPOINT)) {
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/*
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* Explicit breakpoint from trampoline or
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* exception/syscall/interrupt handler.
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*
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* The real saved regs are on the stack right
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* after the ones we saved on entry.
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*/
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regs++;
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pr_debug(" -> TIF_BREAKPOINT done, adjusted regs:"
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"PC=0x%08lx SR=0x%08lx\n",
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regs->pc, regs->sr);
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BUG_ON(!user_mode(regs));
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if (test_thread_flag(TIF_SINGLE_STEP)) {
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pr_debug("Going to do single step...\n");
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return regs;
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}
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/*
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* No TIF_SINGLE_STEP means we're done
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* stepping over a syscall. Do the trap now.
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*/
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code = TRAP_TRACE;
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} else if ((status & (1 << OCD_DS_SSS_BIT))
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&& test_ti_thread_flag(ti, TIF_SINGLE_STEP)) {
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pr_debug("Stepped into something, "
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"setting TIF_BREAKPOINT...\n");
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set_ti_thread_flag(ti, TIF_BREAKPOINT);
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/*
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* We stepped into an exception, interrupt or
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* syscall handler. Some exception handlers
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* don't check for pending work, so we need to
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* set up a trampoline just in case.
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*
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* The exception entry code will undo the
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* trampoline stuff if it does a full context
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* save (which also means that it'll check for
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* pending work later.)
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*/
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if ((regs->sr & MODE_MASK) == MODE_EXCEPTION) {
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trampoline_addr
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= (unsigned long)&debug_trampoline;
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pr_debug("Setting up trampoline...\n");
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ti->rar_saved = sysreg_read(RAR_EX);
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ti->rsr_saved = sysreg_read(RSR_EX);
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sysreg_write(RAR_EX, trampoline_addr);
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sysreg_write(RSR_EX, (MODE_EXCEPTION
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| SR_EM | SR_GM));
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BUG_ON(ti->rsr_saved & MODE_MASK);
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}
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/*
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* If we stepped into a system call, we
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* shouldn't do a single step after we return
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* since the return address is right after the
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* "scall" instruction we were told to step
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* over.
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*/
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if ((regs->sr & MODE_MASK) == MODE_SUPERVISOR) {
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pr_debug("Supervisor; no single step\n");
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clear_ti_thread_flag(ti, TIF_SINGLE_STEP);
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}
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ctrl = ocd_read(DC);
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ctrl &= ~(1 << OCD_DC_SS_BIT);
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ocd_write(DC, ctrl);
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return regs;
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} else {
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printk(KERN_ERR "Unexpected OCD_DS value: 0x%08x\n",
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status);
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printk(KERN_ERR "Thread flags: 0x%08lx\n", ti->flags);
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die("Unhandled debug trap in kernel mode",
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regs, SIGTRAP);
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}
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} else if (status & (1 << OCD_DS_SSS_BIT)) {
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/* Single step in user mode */
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code = TRAP_TRACE;
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ctrl = ocd_read(DC);
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ctrl &= ~(1 << OCD_DC_SS_BIT);
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ocd_write(DC, ctrl);
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}
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pr_debug("Sending SIGTRAP: code=%d PC=0x%08lx SR=0x%08lx\n",
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code, regs->pc, regs->sr);
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clear_thread_flag(TIF_SINGLE_STEP);
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_exception(SIGTRAP, regs, code, instruction_pointer(regs));
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return regs;
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}
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