![Chuck Ebbert](/assets/img/avatar_default.png)
The lock prefix will cause an exception when used with the popf instruction, so no need to continue searching after it's found. Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andi Kleen <ak@suse.de>
633 lines
16 KiB
C
633 lines
16 KiB
C
/* ptrace.c */
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/* By Ross Biro 1/23/92 */
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/*
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* Pentium III FXSR, SSE support
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* Gareth Hughes <gareth@valinux.com>, May 2000
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*
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* x86-64 port 2000-2002 Andi Kleen
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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/smp_lock.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/security.h>
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#include <linux/audit.h>
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#include <linux/seccomp.h>
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#include <linux/signal.h>
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#include <asm/uaccess.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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#include <asm/i387.h>
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#include <asm/debugreg.h>
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#include <asm/ldt.h>
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#include <asm/desc.h>
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#include <asm/proto.h>
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#include <asm/ia32.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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/*
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* Determines which flags the user has access to [1 = access, 0 = no access].
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* Prohibits changing ID(21), VIP(20), VIF(19), VM(17), IOPL(12-13), IF(9).
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* Also masks reserved bits (63-22, 15, 5, 3, 1).
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*/
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#define FLAG_MASK 0x54dd5UL
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/* set's the trap flag. */
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#define TRAP_FLAG 0x100UL
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/*
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* eflags and offset of eflags on child stack..
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*/
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#define EFLAGS offsetof(struct pt_regs, eflags)
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#define EFL_OFFSET ((int)(EFLAGS-sizeof(struct pt_regs)))
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/*
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* this routine will get a word off of the processes privileged stack.
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* the offset is how far from the base addr as stored in the TSS.
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* this routine assumes that all the privileged stacks are in our
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* data space.
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*/
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static inline unsigned long get_stack_long(struct task_struct *task, int offset)
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{
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unsigned char *stack;
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stack = (unsigned char *)task->thread.rsp0;
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stack += offset;
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return (*((unsigned long *)stack));
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}
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/*
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* this routine will put a word on the processes privileged stack.
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* the offset is how far from the base addr as stored in the TSS.
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* this routine assumes that all the privileged stacks are in our
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* data space.
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*/
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static inline long put_stack_long(struct task_struct *task, int offset,
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unsigned long data)
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{
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unsigned char * stack;
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stack = (unsigned char *) task->thread.rsp0;
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stack += offset;
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*(unsigned long *) stack = data;
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return 0;
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}
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#define LDT_SEGMENT 4
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unsigned long convert_rip_to_linear(struct task_struct *child, struct pt_regs *regs)
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{
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unsigned long addr, seg;
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addr = regs->rip;
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seg = regs->cs & 0xffff;
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/*
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* We'll assume that the code segments in the GDT
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* are all zero-based. That is largely true: the
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* TLS segments are used for data, and the PNPBIOS
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* and APM bios ones we just ignore here.
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*/
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if (seg & LDT_SEGMENT) {
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u32 *desc;
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unsigned long base;
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down(&child->mm->context.sem);
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desc = child->mm->context.ldt + (seg & ~7);
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base = (desc[0] >> 16) | ((desc[1] & 0xff) << 16) | (desc[1] & 0xff000000);
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/* 16-bit code segment? */
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if (!((desc[1] >> 22) & 1))
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addr &= 0xffff;
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addr += base;
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up(&child->mm->context.sem);
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}
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return addr;
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}
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static int is_at_popf(struct task_struct *child, struct pt_regs *regs)
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{
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int i, copied;
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unsigned char opcode[16];
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unsigned long addr = convert_rip_to_linear(child, regs);
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copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
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for (i = 0; i < copied; i++) {
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switch (opcode[i]) {
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/* popf */
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case 0x9d:
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return 1;
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/* CHECKME: 64 65 */
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/* opcode and address size prefixes */
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case 0x66: case 0x67:
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continue;
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/* irrelevant prefixes (segment overrides and repeats) */
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case 0x26: case 0x2e:
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case 0x36: case 0x3e:
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case 0x64: case 0x65:
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case 0xf2: case 0xf3:
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continue;
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case 0x40 ... 0x4f:
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if (regs->cs != __USER_CS)
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/* 32-bit mode: register increment */
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return 0;
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/* 64-bit mode: REX prefix */
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continue;
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/* CHECKME: f2, f3 */
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/*
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* pushf: NOTE! We should probably not let
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* the user see the TF bit being set. But
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* it's more pain than it's worth to avoid
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* it, and a debugger could emulate this
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* all in user space if it _really_ cares.
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*/
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case 0x9c:
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default:
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return 0;
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}
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}
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return 0;
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}
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static void set_singlestep(struct task_struct *child)
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{
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struct pt_regs *regs = task_pt_regs(child);
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/*
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* Always set TIF_SINGLESTEP - this guarantees that
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* we single-step system calls etc.. This will also
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* cause us to set TF when returning to user mode.
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*/
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set_tsk_thread_flag(child, TIF_SINGLESTEP);
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/*
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* If TF was already set, don't do anything else
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*/
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if (regs->eflags & TRAP_FLAG)
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return;
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/* Set TF on the kernel stack.. */
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regs->eflags |= TRAP_FLAG;
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/*
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* ..but if TF is changed by the instruction we will trace,
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* don't mark it as being "us" that set it, so that we
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* won't clear it by hand later.
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*
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* AK: this is not enough, LAHF and IRET can change TF in user space too.
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*/
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if (is_at_popf(child, regs))
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return;
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child->ptrace |= PT_DTRACE;
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}
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static void clear_singlestep(struct task_struct *child)
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{
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/* Always clear TIF_SINGLESTEP... */
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clear_tsk_thread_flag(child, TIF_SINGLESTEP);
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/* But touch TF only if it was set by us.. */
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if (child->ptrace & PT_DTRACE) {
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struct pt_regs *regs = task_pt_regs(child);
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regs->eflags &= ~TRAP_FLAG;
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child->ptrace &= ~PT_DTRACE;
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}
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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 the single step bit is 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_singlestep(child);
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}
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static int putreg(struct task_struct *child,
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unsigned long regno, unsigned long value)
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{
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unsigned long tmp;
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/* Some code in the 64bit emulation may not be 64bit clean.
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Don't take any chances. */
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if (test_tsk_thread_flag(child, TIF_IA32))
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value &= 0xffffffff;
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switch (regno) {
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case offsetof(struct user_regs_struct,fs):
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if (value && (value & 3) != 3)
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return -EIO;
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child->thread.fsindex = value & 0xffff;
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return 0;
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case offsetof(struct user_regs_struct,gs):
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if (value && (value & 3) != 3)
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return -EIO;
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child->thread.gsindex = value & 0xffff;
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return 0;
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case offsetof(struct user_regs_struct,ds):
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if (value && (value & 3) != 3)
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return -EIO;
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child->thread.ds = value & 0xffff;
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return 0;
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case offsetof(struct user_regs_struct,es):
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if (value && (value & 3) != 3)
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return -EIO;
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child->thread.es = value & 0xffff;
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return 0;
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case offsetof(struct user_regs_struct,ss):
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if ((value & 3) != 3)
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return -EIO;
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value &= 0xffff;
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return 0;
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case offsetof(struct user_regs_struct,fs_base):
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if (value >= TASK_SIZE_OF(child))
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return -EIO;
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child->thread.fs = value;
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return 0;
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case offsetof(struct user_regs_struct,gs_base):
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if (value >= TASK_SIZE_OF(child))
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return -EIO;
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child->thread.gs = value;
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return 0;
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case offsetof(struct user_regs_struct, eflags):
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value &= FLAG_MASK;
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tmp = get_stack_long(child, EFL_OFFSET);
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tmp &= ~FLAG_MASK;
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value |= tmp;
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break;
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case offsetof(struct user_regs_struct,cs):
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if ((value & 3) != 3)
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return -EIO;
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value &= 0xffff;
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break;
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}
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put_stack_long(child, regno - sizeof(struct pt_regs), value);
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return 0;
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}
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static unsigned long getreg(struct task_struct *child, unsigned long regno)
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{
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unsigned long val;
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switch (regno) {
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case offsetof(struct user_regs_struct, fs):
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return child->thread.fsindex;
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case offsetof(struct user_regs_struct, gs):
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return child->thread.gsindex;
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case offsetof(struct user_regs_struct, ds):
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return child->thread.ds;
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case offsetof(struct user_regs_struct, es):
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return child->thread.es;
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case offsetof(struct user_regs_struct, fs_base):
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return child->thread.fs;
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case offsetof(struct user_regs_struct, gs_base):
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return child->thread.gs;
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default:
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regno = regno - sizeof(struct pt_regs);
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val = get_stack_long(child, regno);
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if (test_tsk_thread_flag(child, TIF_IA32))
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val &= 0xffffffff;
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return val;
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}
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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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long i, ret;
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unsigned ui;
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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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unsigned long tmp;
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int copied;
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copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
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ret = -EIO;
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if (copied != sizeof(tmp))
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break;
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ret = put_user(tmp,(unsigned long __user *) data);
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break;
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}
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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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unsigned long tmp;
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ret = -EIO;
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if ((addr & 7) ||
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addr > sizeof(struct user) - 7)
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break;
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switch (addr) {
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case 0 ... sizeof(struct user_regs_struct) - sizeof(long):
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tmp = getreg(child, addr);
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break;
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case offsetof(struct user, u_debugreg[0]):
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tmp = child->thread.debugreg0;
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break;
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case offsetof(struct user, u_debugreg[1]):
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tmp = child->thread.debugreg1;
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break;
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case offsetof(struct user, u_debugreg[2]):
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tmp = child->thread.debugreg2;
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break;
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case offsetof(struct user, u_debugreg[3]):
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tmp = child->thread.debugreg3;
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break;
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case offsetof(struct user, u_debugreg[6]):
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tmp = child->thread.debugreg6;
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break;
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case offsetof(struct user, u_debugreg[7]):
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tmp = child->thread.debugreg7;
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break;
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default:
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tmp = 0;
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break;
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}
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ret = put_user(tmp,(unsigned long __user *) data);
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break;
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}
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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 = 0;
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if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
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break;
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ret = -EIO;
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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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{
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int dsize = test_tsk_thread_flag(child, TIF_IA32) ? 3 : 7;
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ret = -EIO;
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if ((addr & 7) ||
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addr > sizeof(struct user) - 7)
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break;
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switch (addr) {
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case 0 ... sizeof(struct user_regs_struct) - sizeof(long):
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ret = putreg(child, addr, data);
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break;
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/* Disallows to set a breakpoint into the vsyscall */
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case offsetof(struct user, u_debugreg[0]):
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if (data >= TASK_SIZE_OF(child) - dsize) break;
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child->thread.debugreg0 = data;
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ret = 0;
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break;
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case offsetof(struct user, u_debugreg[1]):
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if (data >= TASK_SIZE_OF(child) - dsize) break;
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child->thread.debugreg1 = data;
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ret = 0;
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break;
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case offsetof(struct user, u_debugreg[2]):
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if (data >= TASK_SIZE_OF(child) - dsize) break;
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child->thread.debugreg2 = data;
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ret = 0;
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break;
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case offsetof(struct user, u_debugreg[3]):
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if (data >= TASK_SIZE_OF(child) - dsize) break;
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child->thread.debugreg3 = data;
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ret = 0;
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break;
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case offsetof(struct user, u_debugreg[6]):
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if (data >> 32)
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break;
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child->thread.debugreg6 = data;
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ret = 0;
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break;
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case offsetof(struct user, u_debugreg[7]):
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/* See arch/i386/kernel/ptrace.c for an explanation of
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* this awkward check.*/
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data &= ~DR_CONTROL_RESERVED;
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for(i=0; i<4; i++)
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if ((0x5554 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
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break;
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if (i == 4) {
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child->thread.debugreg7 = data;
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if (data)
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set_tsk_thread_flag(child, TIF_DEBUG);
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else
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clear_tsk_thread_flag(child, TIF_DEBUG);
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ret = 0;
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}
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break;
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}
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break;
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}
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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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ret = -EIO;
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if (!valid_signal(data))
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break;
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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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clear_tsk_thread_flag(child, TIF_SINGLESTEP);
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child->exit_code = data;
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/* make sure the single step bit is not set. */
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clear_singlestep(child);
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wake_up_process(child);
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ret = 0;
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break;
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#ifdef CONFIG_IA32_EMULATION
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/* This makes only sense with 32bit programs. Allow a
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64bit debugger to fully examine them too. Better
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don't use it against 64bit processes, use
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PTRACE_ARCH_PRCTL instead. */
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case PTRACE_SET_THREAD_AREA: {
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struct user_desc __user *p;
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int old;
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p = (struct user_desc __user *)data;
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get_user(old, &p->entry_number);
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put_user(addr, &p->entry_number);
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ret = do_set_thread_area(&child->thread, p);
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put_user(old, &p->entry_number);
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break;
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case PTRACE_GET_THREAD_AREA:
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p = (struct user_desc __user *)data;
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get_user(old, &p->entry_number);
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put_user(addr, &p->entry_number);
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ret = do_get_thread_area(&child->thread, p);
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put_user(old, &p->entry_number);
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break;
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}
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#endif
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/* normal 64bit interface to access TLS data.
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Works just like arch_prctl, except that the arguments
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are reversed. */
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case PTRACE_ARCH_PRCTL:
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ret = do_arch_prctl(child, data, addr);
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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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ret = 0;
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if (child->exit_state == EXIT_ZOMBIE) /* already dead */
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break;
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clear_tsk_thread_flag(child, TIF_SINGLESTEP);
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child->exit_code = SIGKILL;
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/* make sure the single step bit is not set. */
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clear_singlestep(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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ret = -EIO;
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if (!valid_signal(data))
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break;
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clear_tsk_thread_flag(child,TIF_SYSCALL_TRACE);
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set_singlestep(child);
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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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ret = 0;
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break;
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case PTRACE_DETACH:
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/* 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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if (!access_ok(VERIFY_WRITE, (unsigned __user *)data,
|
|
sizeof(struct user_regs_struct))) {
|
|
ret = -EIO;
|
|
break;
|
|
}
|
|
ret = 0;
|
|
for (ui = 0; ui < sizeof(struct user_regs_struct); ui += sizeof(long)) {
|
|
ret |= __put_user(getreg(child, ui),(unsigned long __user *) data);
|
|
data += sizeof(long);
|
|
}
|
|
break;
|
|
}
|
|
|
|
case PTRACE_SETREGS: { /* Set all gp regs in the child. */
|
|
unsigned long tmp;
|
|
if (!access_ok(VERIFY_READ, (unsigned __user *)data,
|
|
sizeof(struct user_regs_struct))) {
|
|
ret = -EIO;
|
|
break;
|
|
}
|
|
ret = 0;
|
|
for (ui = 0; ui < sizeof(struct user_regs_struct); ui += sizeof(long)) {
|
|
ret |= __get_user(tmp, (unsigned long __user *) data);
|
|
putreg(child, ui, tmp);
|
|
data += sizeof(long);
|
|
}
|
|
break;
|
|
}
|
|
|
|
case PTRACE_GETFPREGS: { /* Get the child extended FPU state. */
|
|
if (!access_ok(VERIFY_WRITE, (unsigned __user *)data,
|
|
sizeof(struct user_i387_struct))) {
|
|
ret = -EIO;
|
|
break;
|
|
}
|
|
ret = get_fpregs((struct user_i387_struct __user *)data, child);
|
|
break;
|
|
}
|
|
|
|
case PTRACE_SETFPREGS: { /* Set the child extended FPU state. */
|
|
if (!access_ok(VERIFY_READ, (unsigned __user *)data,
|
|
sizeof(struct user_i387_struct))) {
|
|
ret = -EIO;
|
|
break;
|
|
}
|
|
set_stopped_child_used_math(child);
|
|
ret = set_fpregs(child, (struct user_i387_struct __user *)data);
|
|
break;
|
|
}
|
|
|
|
default:
|
|
ret = ptrace_request(child, request, addr, data);
|
|
break;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static void syscall_trace(struct pt_regs *regs)
|
|
{
|
|
|
|
#if 0
|
|
printk("trace %s rip %lx rsp %lx rax %d origrax %d caller %lx tiflags %x ptrace %x\n",
|
|
current->comm,
|
|
regs->rip, regs->rsp, regs->rax, regs->orig_rax, __builtin_return_address(0),
|
|
current_thread_info()->flags, current->ptrace);
|
|
#endif
|
|
|
|
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;
|
|
}
|
|
}
|
|
|
|
asmlinkage void syscall_trace_enter(struct pt_regs *regs)
|
|
{
|
|
/* do the secure computing check first */
|
|
secure_computing(regs->orig_rax);
|
|
|
|
if (test_thread_flag(TIF_SYSCALL_TRACE)
|
|
&& (current->ptrace & PT_PTRACED))
|
|
syscall_trace(regs);
|
|
|
|
if (unlikely(current->audit_context)) {
|
|
if (test_thread_flag(TIF_IA32)) {
|
|
audit_syscall_entry(AUDIT_ARCH_I386,
|
|
regs->orig_rax,
|
|
regs->rbx, regs->rcx,
|
|
regs->rdx, regs->rsi);
|
|
} else {
|
|
audit_syscall_entry(AUDIT_ARCH_X86_64,
|
|
regs->orig_rax,
|
|
regs->rdi, regs->rsi,
|
|
regs->rdx, regs->r10);
|
|
}
|
|
}
|
|
}
|
|
|
|
asmlinkage void syscall_trace_leave(struct pt_regs *regs)
|
|
{
|
|
if (unlikely(current->audit_context))
|
|
audit_syscall_exit(AUDITSC_RESULT(regs->rax), regs->rax);
|
|
|
|
if ((test_thread_flag(TIF_SYSCALL_TRACE)
|
|
|| test_thread_flag(TIF_SINGLESTEP))
|
|
&& (current->ptrace & PT_PTRACED))
|
|
syscall_trace(regs);
|
|
}
|