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![Roland McGrath](/assets/img/avatar_default.png)
When PTRACE_SYSCALL was used and then PTRACE_DETACH is used, the TIF_SYSCALL_TRACE flag is left set on the formerly-traced task. This means that when a new tracer comes along and does PTRACE_ATTACH, it's possible he gets a syscall tracing stop even though he's never used PTRACE_SYSCALL. This happens if the task was in the middle of a system call when the second PTRACE_ATTACH was done. The symptom is an unexpected SIGTRAP when the tracer thinks that only SIGSTOP should have been provoked by his ptrace calls so far. A few machines already fixed this in ptrace_disable (i386, ia64, m68k). But all other machines do not, and still have this bug. On x86_64, this constitutes a regression in IA32 compatibility support. Since all machines now use TIF_SYSCALL_TRACE for this, I put the clearing of TIF_SYSCALL_TRACE in the generic ptrace_detach code rather than adding it to every other machine's ptrace_disable. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
295 lines
7.3 KiB
C
295 lines
7.3 KiB
C
/*
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* linux/arch/m68k/kernel/ptrace.c
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*
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* Copyright (C) 1994 by Hamish Macdonald
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* Taken from linux/kernel/ptrace.c and modified for M680x0.
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* linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
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*
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* This file is subject to the terms and conditions of the GNU General
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* Public License. See the file COPYING in the main directory of
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* this archive for more details.
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*/
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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/smp.h>
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#include <linux/errno.h>
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#include <linux/ptrace.h>
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#include <linux/user.h>
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#include <linux/signal.h>
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#include <asm/uaccess.h>
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include <asm/system.h>
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#include <asm/processor.h>
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/*
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* does not yet catch signals sent when the child dies.
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* in exit.c or in signal.c.
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*/
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/* determines which bits in the SR the user has access to. */
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/* 1 = access 0 = no access */
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#define SR_MASK 0x001f
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/* sets the trace bits. */
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#define TRACE_BITS 0x8000
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/* Find the stack offset for a register, relative to thread.esp0. */
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#define PT_REG(reg) ((long)&((struct pt_regs *)0)->reg)
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#define SW_REG(reg) ((long)&((struct switch_stack *)0)->reg \
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- sizeof(struct switch_stack))
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/* Mapping from PT_xxx to the stack offset at which the register is
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saved. Notice that usp has no stack-slot and needs to be treated
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specially (see get_reg/put_reg below). */
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static int regoff[] = {
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[0] = PT_REG(d1),
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[1] = PT_REG(d2),
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[2] = PT_REG(d3),
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[3] = PT_REG(d4),
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[4] = PT_REG(d5),
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[5] = SW_REG(d6),
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[6] = SW_REG(d7),
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[7] = PT_REG(a0),
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[8] = PT_REG(a1),
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[9] = PT_REG(a2),
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[10] = SW_REG(a3),
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[11] = SW_REG(a4),
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[12] = SW_REG(a5),
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[13] = SW_REG(a6),
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[14] = PT_REG(d0),
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[15] = -1,
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[16] = PT_REG(orig_d0),
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[17] = PT_REG(sr),
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[18] = PT_REG(pc),
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};
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/*
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* Get contents of register REGNO in task TASK.
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*/
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static inline long get_reg(struct task_struct *task, int regno)
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{
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unsigned long *addr;
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if (regno == PT_USP)
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addr = &task->thread.usp;
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else if (regno < ARRAY_SIZE(regoff))
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addr = (unsigned long *)(task->thread.esp0 + regoff[regno]);
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else
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return 0;
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return *addr;
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}
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/*
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* Write contents of register REGNO in task TASK.
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*/
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static inline int put_reg(struct task_struct *task, int regno,
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unsigned long data)
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{
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unsigned long *addr;
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if (regno == PT_USP)
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addr = &task->thread.usp;
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else if (regno < ARRAY_SIZE(regoff))
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addr = (unsigned long *)(task->thread.esp0 + regoff[regno]);
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else
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return -1;
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*addr = data;
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return 0;
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}
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/*
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* Make sure the single step bit is not set.
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*/
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static inline void singlestep_disable(struct task_struct *child)
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{
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unsigned long tmp = get_reg(child, PT_SR) & ~(TRACE_BITS << 16);
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put_reg(child, PT_SR, tmp);
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clear_tsk_thread_flag(child, TIF_DELAYED_TRACE);
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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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void ptrace_disable(struct task_struct *child)
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{
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singlestep_disable(child);
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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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unsigned long tmp;
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int i, ret = 0;
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switch (request) {
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/* when I and D space are separate, these will need to be fixed. */
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case PTRACE_PEEKTEXT: /* read word at location addr. */
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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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/* read the word at location addr in the USER area. */
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case PTRACE_PEEKUSR:
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if (addr & 3)
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goto out_eio;
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addr >>= 2; /* temporary hack. */
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if (addr >= 0 && addr < 19) {
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tmp = get_reg(child, addr);
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if (addr == PT_SR)
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tmp >>= 16;
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} else if (addr >= 21 && addr < 49) {
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tmp = child->thread.fp[addr - 21];
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/* Convert internal fpu reg representation
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* into long double format
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*/
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if (FPU_IS_EMU && (addr < 45) && !(addr % 3))
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tmp = ((tmp & 0xffff0000) << 15) |
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((tmp & 0x0000ffff) << 16);
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} else
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break;
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ret = put_user(tmp, (unsigned long *)data);
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break;
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/* when I and D space are separate, this will have to be fixed. */
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case PTRACE_POKETEXT: /* write the word at location addr. */
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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: /* write the word at location addr in the USER area */
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if (addr & 3)
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goto out_eio;
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addr >>= 2; /* temporary hack. */
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if (addr == PT_SR) {
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data &= SR_MASK;
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data <<= 16;
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data |= get_reg(child, PT_SR) & ~(SR_MASK << 16);
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} else if (addr >= 0 && addr < 19) {
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if (put_reg(child, addr, data))
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goto out_eio;
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} else if (addr >= 21 && addr < 48) {
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/* Convert long double format
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* into internal fpu reg representation
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*/
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if (FPU_IS_EMU && (addr < 45) && !(addr % 3)) {
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data = (unsigned long)data << 15;
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data = (data & 0xffff0000) |
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((data & 0x0000ffff) >> 1);
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}
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child->thread.fp[addr - 21] = data;
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} else
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goto out_eio;
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break;
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case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
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case PTRACE_CONT: /* restart after signal. */
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if (!valid_signal(data))
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goto out_eio;
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if (request == PTRACE_SYSCALL)
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set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
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else
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clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
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child->exit_code = data;
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singlestep_disable(child);
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wake_up_process(child);
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break;
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/*
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* make the child exit. Best I can do is send it a sigkill.
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* perhaps it should be put in the status that it wants to
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* exit.
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*/
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case PTRACE_KILL:
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if (child->exit_state == EXIT_ZOMBIE) /* already dead */
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break;
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child->exit_code = SIGKILL;
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singlestep_disable(child);
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wake_up_process(child);
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break;
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case PTRACE_SINGLESTEP: /* set the trap flag. */
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if (!valid_signal(data))
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goto out_eio;
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clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
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tmp = get_reg(child, PT_SR) | (TRACE_BITS << 16);
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put_reg(child, PT_SR, tmp);
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set_tsk_thread_flag(child, TIF_DELAYED_TRACE);
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child->exit_code = data;
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/* give it a chance to run. */
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wake_up_process(child);
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break;
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case PTRACE_DETACH: /* detach a process that was attached. */
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ret = ptrace_detach(child, data);
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break;
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case PTRACE_GETREGS: /* Get all gp regs from the child. */
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for (i = 0; i < 19; i++) {
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tmp = get_reg(child, i);
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if (i == PT_SR)
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tmp >>= 16;
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ret = put_user(tmp, (unsigned long *)data);
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if (ret)
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break;
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data += sizeof(long);
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}
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break;
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case PTRACE_SETREGS: /* Set all gp regs in the child. */
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for (i = 0; i < 19; i++) {
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ret = get_user(tmp, (unsigned long *)data);
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if (ret)
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break;
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if (i == PT_SR) {
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tmp &= SR_MASK;
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tmp <<= 16;
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tmp |= get_reg(child, PT_SR) & ~(SR_MASK << 16);
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}
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put_reg(child, i, tmp);
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data += sizeof(long);
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}
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break;
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case PTRACE_GETFPREGS: /* Get the child FPU state. */
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if (copy_to_user((void *)data, &child->thread.fp,
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sizeof(struct user_m68kfp_struct)))
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ret = -EFAULT;
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break;
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case PTRACE_SETFPREGS: /* Set the child FPU state. */
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if (copy_from_user(&child->thread.fp, (void *)data,
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sizeof(struct user_m68kfp_struct)))
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ret = -EFAULT;
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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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out_eio:
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return -EIO;
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}
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asmlinkage void syscall_trace(void)
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{
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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 will do
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* for normal use. strace only continues with a signal if the
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* stopping signal is not SIGTRAP. -brl
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*/
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if (current->exit_code) {
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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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