arch/i386/kernel/ptrace.c - third_party/linux - Git at Google

 /* ptrace.c */
 /* By Ross Biro 1/23/92 */
 /*
  * Pentium III FXSR, SSE support
  *	Gareth Hughes <gareth@valinux.com>, May 2000
  */

 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
 #include <linux/smp_lock.h>
 #include <linux/errno.h>
 #include <linux/ptrace.h>
 #include <linux/user.h>
 #include <linux/security.h>
 #include <linux/audit.h>
 #include <linux/seccomp.h>
 #include <linux/signal.h>

 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 #include <asm/system.h>
 #include <asm/processor.h>
 #include <asm/i387.h>
 #include <asm/debugreg.h>
 #include <asm/ldt.h>
 #include <asm/desc.h>

 /*
  * does not yet catch signals sent when the child dies.
  * in exit.c or in signal.c.
  */

 /*
  * Determines which flags the user has access to [1 = access, 0 = no access].
  * Prohibits changing ID(21), VIP(20), VIF(19), VM(17), IOPL(12-13), IF(9).
  * Also masks reserved bits (31-22, 15, 5, 3, 1).
  */
 #define FLAG_MASK 0x00054dd5

 /* set's the trap flag. */
 #define TRAP_FLAG 0x100

 /*
  * Offset of eflags on child stack..
  */
 #define EFL_OFFSET ((EFL-2)*4-sizeof(struct pt_regs))

 static inline struct pt_regs *get_child_regs(struct task_struct *task)
 {
 	void *stack_top = (void *)task->thread.esp0;
 	return stack_top - sizeof(struct pt_regs);
 }

 /*
  * this routine will get a word off of the processes privileged stack.
  * the offset is how far from the base addr as stored in the TSS.
  * this routine assumes that all the privileged stacks are in our
  * data space.
  */
 static inline int get_stack_long(struct task_struct *task, int offset)
 {
 	unsigned char *stack;

 	stack = (unsigned char *)task->thread.esp0;
 	stack += offset;
 	return (*((int *)stack));
 }

 /*
  * this routine will put a word on the processes privileged stack.
  * the offset is how far from the base addr as stored in the TSS.
  * this routine assumes that all the privileged stacks are in our
  * data space.
  */
 static inline int put_stack_long(struct task_struct *task, int offset,
 	unsigned long data)
 {
 	unsigned char * stack;

 	stack = (unsigned char *) task->thread.esp0;
 	stack += offset;
 	*(unsigned long *) stack = data;
 	return 0;
 }

 static int putreg(struct task_struct *child,
 	unsigned long regno, unsigned long value)
 {
 	switch (regno >> 2) {
 		case FS:
 			if (value && (value & 3) != 3)
 				return -EIO;
 			child->thread.fs = value;
 			return 0;
 		case GS:
 			if (value && (value & 3) != 3)
 				return -EIO;
 			child->thread.gs = value;
 			return 0;
 		case DS:
 		case ES:
 			if (value && (value & 3) != 3)
 				return -EIO;
 			value &= 0xffff;
 			break;
 		case SS:
 		case CS:
 			if ((value & 3) != 3)
 				return -EIO;
 			value &= 0xffff;
 			break;
 		case EFL:
 			value &= FLAG_MASK;
 			value |= get_stack_long(child, EFL_OFFSET) & ~FLAG_MASK;
 			break;
 	}
 	if (regno > GS*4)
 		regno -= 2*4;
 	put_stack_long(child, regno - sizeof(struct pt_regs), value);
 	return 0;
 }

 static unsigned long getreg(struct task_struct *child,
 	unsigned long regno)
 {
 	unsigned long retval = ~0UL;

 	switch (regno >> 2) {
 		case FS:
 			retval = child->thread.fs;
 			break;
 		case GS:
 			retval = child->thread.gs;
 			break;
 		case DS:
 		case ES:
 		case SS:
 		case CS:
 			retval = 0xffff;
 			/* fall through */
 		default:
 			if (regno > GS*4)
 				regno -= 2*4;
 			regno = regno - sizeof(struct pt_regs);
 			retval &= get_stack_long(child, regno);
 	}
 	return retval;
 }

 #define LDT_SEGMENT 4

 static unsigned long convert_eip_to_linear(struct task_struct *child, struct pt_regs *regs)
 {
 	unsigned long addr, seg;

 	addr = regs->eip;
 	seg = regs->xcs & 0xffff;
 	if (regs->eflags & VM_MASK) {
 		addr = (addr & 0xffff) + (seg << 4);
 		return addr;
 	}

 	/*
 	 * We'll assume that the code segments in the GDT
 	 * are all zero-based. That is largely true: the
 	 * TLS segments are used for data, and the PNPBIOS
 	 * and APM bios ones we just ignore here.
 	 */
 	if (seg & LDT_SEGMENT) {
 		u32 *desc;
 		unsigned long base;

 		down(&child->mm->context.sem);
 		desc = child->mm->context.ldt + (seg & ~7);
 		base = (desc[0] >> 16) | ((desc[1] & 0xff) << 16) | (desc[1] & 0xff000000);

 		/* 16-bit code segment? */
 		if (!((desc[1] >> 22) & 1))
 			addr &= 0xffff;
 		addr += base;
 		up(&child->mm->context.sem);
 	}
 	return addr;
 }

 static inline int is_at_popf(struct task_struct *child, struct pt_regs *regs)
 {
 	int i, copied;
 	unsigned char opcode[16];
 	unsigned long addr = convert_eip_to_linear(child, regs);

 	copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
 	for (i = 0; i < copied; i++) {
 		switch (opcode[i]) {
 		/* popf */
 		case 0x9d:
 			return 1;
 		/* opcode and address size prefixes */
 		case 0x66: case 0x67:
 			continue;
 		/* irrelevant prefixes (segment overrides and repeats) */
 		case 0x26: case 0x2e:
 		case 0x36: case 0x3e:
 		case 0x64: case 0x65:
 		case 0xf0: case 0xf2: case 0xf3:
 			continue;

 		/*
 		 * pushf: NOTE! We should probably not let
 		 * the user see the TF bit being set. But
 		 * it's more pain than it's worth to avoid
 		 * it, and a debugger could emulate this
 		 * all in user space if it _really_ cares.
 		 */
 		case 0x9c:
 		default:
 			return 0;
 		}
 	}
 	return 0;
 }

 static void set_singlestep(struct task_struct *child)
 {
 	struct pt_regs *regs = get_child_regs(child);

 	/*
 	 * Always set TIF_SINGLESTEP - this guarantees that
 	 * we single-step system calls etc..  This will also
 	 * cause us to set TF when returning to user mode.
 	 */
 	set_tsk_thread_flag(child, TIF_SINGLESTEP);

 	/*
 	 * If TF was already set, don't do anything else
 	 */
 	if (regs->eflags & TRAP_FLAG)
 		return;

 	/* Set TF on the kernel stack.. */
 	regs->eflags |= TRAP_FLAG;

 	/*
 	 * ..but if TF is changed by the instruction we will trace,
 	 * don't mark it as being "us" that set it, so that we
 	 * won't clear it by hand later.
 	 */
 	if (is_at_popf(child, regs))
 		return;

 	child->ptrace |= PT_DTRACE;
 }

 static void clear_singlestep(struct task_struct *child)
 {
 	/* Always clear TIF_SINGLESTEP... */
 	clear_tsk_thread_flag(child, TIF_SINGLESTEP);

 	/* But touch TF only if it was set by us.. */
 	if (child->ptrace & PT_DTRACE) {
 		struct pt_regs *regs = get_child_regs(child);
 		regs->eflags &= ~TRAP_FLAG;
 		child->ptrace &= ~PT_DTRACE;
 	}
 }

 /*
  * Called by kernel/ptrace.c when detaching..
  *
  * Make sure the single step bit is not set.
  */
 void ptrace_disable(struct task_struct *child)
 {
 	clear_singlestep(child);
 	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 }

 /*
  * Perform get_thread_area on behalf of the traced child.
  */
 static int
 ptrace_get_thread_area(struct task_struct *child,
 		       int idx, struct user_desc __user *user_desc)
 {
 	struct user_desc info;
 	struct desc_struct *desc;

 /*
  * Get the current Thread-Local Storage area:
  */

 #define GET_BASE(desc) ( \
 	(((desc)->a >> 16) & 0x0000ffff) | \
 	(((desc)->b << 16) & 0x00ff0000) | \
 	( (desc)->b        & 0xff000000)   )

 #define GET_LIMIT(desc) ( \
 	((desc)->a & 0x0ffff) | \
 	 ((desc)->b & 0xf0000) )

 #define GET_32BIT(desc)		(((desc)->b >> 22) & 1)
 #define GET_CONTENTS(desc)	(((desc)->b >> 10) & 3)
 #define GET_WRITABLE(desc)	(((desc)->b >>  9) & 1)
 #define GET_LIMIT_PAGES(desc)	(((desc)->b >> 23) & 1)
 #define GET_PRESENT(desc)	(((desc)->b >> 15) & 1)
 #define GET_USEABLE(desc)	(((desc)->b >> 20) & 1)

 	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
 		return -EINVAL;

 	desc = child->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;

 	info.entry_number = idx;
 	info.base_addr = GET_BASE(desc);
 	info.limit = GET_LIMIT(desc);
 	info.seg_32bit = GET_32BIT(desc);
 	info.contents = GET_CONTENTS(desc);
 	info.read_exec_only = !GET_WRITABLE(desc);
 	info.limit_in_pages = GET_LIMIT_PAGES(desc);
 	info.seg_not_present = !GET_PRESENT(desc);
 	info.useable = GET_USEABLE(desc);

 	if (copy_to_user(user_desc, &info, sizeof(info)))
 		return -EFAULT;

 	return 0;
 }

 /*
  * Perform set_thread_area on behalf of the traced child.
  */
 static int
 ptrace_set_thread_area(struct task_struct *child,
 		       int idx, struct user_desc __user *user_desc)
 {
 	struct user_desc info;
 	struct desc_struct *desc;

 	if (copy_from_user(&info, user_desc, sizeof(info)))
 		return -EFAULT;

 	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
 		return -EINVAL;

 	desc = child->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
 	if (LDT_empty(&info)) {
 		desc->a = 0;
 		desc->b = 0;
 	} else {
 		desc->a = LDT_entry_a(&info);
 		desc->b = LDT_entry_b(&info);
 	}

 	return 0;
 }

 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 {
 	struct user * dummy = NULL;
 	int i, ret;
 	unsigned long __user *datap = (unsigned long __user *)data;

 	switch (request) {
 	/* when I and D space are separate, these will need to be fixed. */
 	case PTRACE_PEEKTEXT: /* read word at location addr. */
 	case PTRACE_PEEKDATA: {
 		unsigned long tmp;
 		int copied;

 		copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 		ret = -EIO;
 		if (copied != sizeof(tmp))
 			break;
 		ret = put_user(tmp, datap);
 		break;
 	}

 	/* read the word at location addr in the USER area. */
 	case PTRACE_PEEKUSR: {
 		unsigned long tmp;

 		ret = -EIO;
 		if ((addr & 3) || addr < 0 ||
 		    addr > sizeof(struct user) - 3)
 			break;

 		tmp = 0;  /* Default return condition */
 		if(addr < FRAME_SIZE*sizeof(long))
 			tmp = getreg(child, addr);
 		if(addr >= (long) &dummy->u_debugreg[0] &&
 		   addr <= (long) &dummy->u_debugreg[7]){
 			addr -= (long) &dummy->u_debugreg[0];
 			addr = addr >> 2;
 			tmp = child->thread.debugreg[addr];
 		}
 		ret = put_user(tmp, datap);
 		break;
 	}

 	/* when I and D space are separate, this will have to be fixed. */
 	case PTRACE_POKETEXT: /* write the word at location addr. */
 	case PTRACE_POKEDATA:
 		ret = 0;
 		if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 			break;
 		ret = -EIO;
 		break;

 	case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
 		ret = -EIO;
 		if ((addr & 3) || addr < 0 ||
 		    addr > sizeof(struct user) - 3)
 			break;

 		if (addr < FRAME_SIZE*sizeof(long)) {
 			ret = putreg(child, addr, data);
 			break;
 		}
 		/* We need to be very careful here.  We implicitly
 		   want to modify a portion of the task_struct, and we
 		   have to be selective about what portions we allow someone
 		   to modify. */

 		  ret = -EIO;
 		  if(addr >= (long) &dummy->u_debugreg[0] &&
 		     addr <= (long) &dummy->u_debugreg[7]){

 			  if(addr == (long) &dummy->u_debugreg[4]) break;
 			  if(addr == (long) &dummy->u_debugreg[5]) break;
 			  if(addr < (long) &dummy->u_debugreg[4] &&
 			     ((unsigned long) data) >= TASK_SIZE-3) break;

 			  /* Sanity-check data. Take one half-byte at once with
 			   * check = (val >> (16 + 4*i)) & 0xf. It contains the
 			   * R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits
 			   * 2 and 3 are LENi. Given a list of invalid values,
 			   * we do mask |= 1 << invalid_value, so that
 			   * (mask >> check) & 1 is a correct test for invalid
 			   * values.
 			   *
 			   * R/Wi contains the type of the breakpoint /
 			   * watchpoint, LENi contains the length of the watched
 			   * data in the watchpoint case.
 			   *
 			   * The invalid values are:
 			   * - LENi == 0x10 (undefined), so mask |= 0x0f00.
 			   * - R/Wi == 0x10 (break on I/O reads or writes), so
 			   *   mask |= 0x4444.
 			   * - R/Wi == 0x00 && LENi != 0x00, so we have mask |=
 			   *   0x1110.
 			   *
 			   * Finally, mask = 0x0f00 | 0x4444 | 0x1110 == 0x5f54.
 			   *
 			   * See the Intel Manual "System Programming Guide",
 			   * 15.2.4
 			   *
 			   * Note that LENi == 0x10 is defined on x86_64 in long
 			   * mode (i.e. even for 32-bit userspace software, but
 			   * 64-bit kernel), so the x86_64 mask value is 0x5454.
 			   * See the AMD manual no. 24593 (AMD64 System
 			   * Programming)*/

 			  if(addr == (long) &dummy->u_debugreg[7]) {
 				  data &= ~DR_CONTROL_RESERVED;
 				  for(i=0; i<4; i++)
 					  if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
 						  goto out_tsk;
 			  }

 			  addr -= (long) &dummy->u_debugreg;
 			  addr = addr >> 2;
 			  child->thread.debugreg[addr] = data;
 			  ret = 0;
 		  }
 		  break;

 	case PTRACE_SYSEMU: /* continue and stop at next syscall, which will not be executed */
 	case PTRACE_SYSCALL:	/* continue and stop at next (return from) syscall */
 	case PTRACE_CONT:	/* restart after signal. */
 		ret = -EIO;
 		if (!valid_signal(data))
 			break;
 		if (request == PTRACE_SYSEMU) {
 			set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 			clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 		} else if (request == PTRACE_SYSCALL) {
 			set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 			clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 		} else {
 			clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 			clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 		}
 		child->exit_code = data;
 		/* make sure the single step bit is not set. */
 		clear_singlestep(child);
 		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)	/* already dead */
 			break;
 		child->exit_code = SIGKILL;
 		/* make sure the single step bit is not set. */
 		clear_singlestep(child);
 		wake_up_process(child);
 		break;

 	case PTRACE_SYSEMU_SINGLESTEP: /* Same as SYSEMU, but singlestep if not syscall */
 	case PTRACE_SINGLESTEP:	/* set the trap flag. */
 		ret = -EIO;
 		if (!valid_signal(data))
 			break;

 		if (request == PTRACE_SYSEMU_SINGLESTEP)
 			set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 		else
 			clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);

 		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 		set_singlestep(child);
 		child->exit_code = data;
 		/* give it a chance to run. */
 		wake_up_process(child);
 		ret = 0;
 		break;

 	case PTRACE_DETACH:
 		/* detach a process that was attached. */
 		ret = ptrace_detach(child, data);
 		break;

 	case PTRACE_GETREGS: { /* Get all gp regs from the child. */
 	  	if (!access_ok(VERIFY_WRITE, datap, FRAME_SIZE*sizeof(long))) {
 			ret = -EIO;
 			break;
 		}
 		for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) {
 			__put_user(getreg(child, i), datap);
 			datap++;
 		}
 		ret = 0;
 		break;
 	}

 	case PTRACE_SETREGS: { /* Set all gp regs in the child. */
 		unsigned long tmp;
 	  	if (!access_ok(VERIFY_READ, datap, FRAME_SIZE*sizeof(long))) {
 			ret = -EIO;
 			break;
 		}
 		for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) {
 			__get_user(tmp, datap);
 			putreg(child, i, tmp);
 			datap++;
 		}
 		ret = 0;
 		break;
 	}

 	case PTRACE_GETFPREGS: { /* Get the child FPU state. */
 		if (!access_ok(VERIFY_WRITE, datap,
 			       sizeof(struct user_i387_struct))) {
 			ret = -EIO;
 			break;
 		}
 		ret = 0;
 		if (!tsk_used_math(child))
 			init_fpu(child);
 		get_fpregs((struct user_i387_struct __user *)data, child);
 		break;
 	}

 	case PTRACE_SETFPREGS: { /* Set the child FPU state. */
 		if (!access_ok(VERIFY_READ, datap,
 			       sizeof(struct user_i387_struct))) {
 			ret = -EIO;
 			break;
 		}
 		set_stopped_child_used_math(child);
 		set_fpregs(child, (struct user_i387_struct __user *)data);
 		ret = 0;
 		break;
 	}

 	case PTRACE_GETFPXREGS: { /* Get the child extended FPU state. */
 		if (!access_ok(VERIFY_WRITE, datap,
 			       sizeof(struct user_fxsr_struct))) {
 			ret = -EIO;
 			break;
 		}
 		if (!tsk_used_math(child))
 			init_fpu(child);
 		ret = get_fpxregs((struct user_fxsr_struct __user *)data, child);
 		break;
 	}

 	case PTRACE_SETFPXREGS: { /* Set the child extended FPU state. */
 		if (!access_ok(VERIFY_READ, datap,
 			       sizeof(struct user_fxsr_struct))) {
 			ret = -EIO;
 			break;
 		}
 		set_stopped_child_used_math(child);
 		ret = set_fpxregs(child, (struct user_fxsr_struct __user *)data);
 		break;
 	}

 	case PTRACE_GET_THREAD_AREA:
 		ret = ptrace_get_thread_area(child, addr,
 					(struct user_desc __user *) data);
 		break;

 	case PTRACE_SET_THREAD_AREA:
 		ret = ptrace_set_thread_area(child, addr,
 					(struct user_desc __user *) data);
 		break;

 	default:
 		ret = ptrace_request(child, request, addr, data);
 		break;
 	}
  out_tsk:
 	return ret;
 }

 void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
 {
 	struct siginfo info;

 	tsk->thread.trap_no = 1;
 	tsk->thread.error_code = error_code;

 	memset(&info, 0, sizeof(info));
 	info.si_signo = SIGTRAP;
 	info.si_code = TRAP_BRKPT;

 	/* User-mode eip? */
 	info.si_addr = user_mode_vm(regs) ? (void __user *) regs->eip : NULL;

 	/* Send us the fakey SIGTRAP */
 	force_sig_info(SIGTRAP, &info, tsk);
 }

 /* notification of system call entry/exit
  * - triggered by current->work.syscall_trace
  */
 __attribute__((regparm(3)))
 int do_syscall_trace(struct pt_regs *regs, int entryexit)
 {
 	int is_sysemu = test_thread_flag(TIF_SYSCALL_EMU);
 	/*
 	 * With TIF_SYSCALL_EMU set we want to ignore TIF_SINGLESTEP for syscall
 	 * interception
 	 */
 	int is_singlestep = !is_sysemu && test_thread_flag(TIF_SINGLESTEP);
 	int ret = 0;

 	/* do the secure computing check first */
 	if (!entryexit)
 		secure_computing(regs->orig_eax);

 	if (unlikely(current->audit_context)) {
 		if (entryexit)
 			audit_syscall_exit(current, AUDITSC_RESULT(regs->eax),
 						regs->eax);
 		/* Debug traps, when using PTRACE_SINGLESTEP, must be sent only
 		 * on the syscall exit path. Normally, when TIF_SYSCALL_AUDIT is
 		 * not used, entry.S will call us only on syscall exit, not
 		 * entry; so when TIF_SYSCALL_AUDIT is used we must avoid
 		 * calling send_sigtrap() on syscall entry.
 		 *
 		 * Note that when PTRACE_SYSEMU_SINGLESTEP is used,
 		 * is_singlestep is false, despite his name, so we will still do
 		 * the correct thing.
 		 */
 		else if (is_singlestep)
 			goto out;
 	}

 	if (!(current->ptrace & PT_PTRACED))
 		goto out;

 	/* If a process stops on the 1st tracepoint with SYSCALL_TRACE
 	 * and then is resumed with SYSEMU_SINGLESTEP, it will come in
 	 * here. We have to check this and return */
 	if (is_sysemu && entryexit)
 		return 0;

 	/* Fake a debug trap */
 	if (is_singlestep)
 		send_sigtrap(current, regs, 0);

  	if (!test_thread_flag(TIF_SYSCALL_TRACE) && !is_sysemu)
 		goto out;

 	/* the 0x80 provides a way for the tracing parent to distinguish
 	   between a syscall stop and SIGTRAP delivery */
 	/* Note that the debugger could change the result of test_thread_flag!*/
 	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;
 	}
 	ret = is_sysemu;
 out:
 	if (unlikely(current->audit_context) && !entryexit)
 		audit_syscall_entry(current, AUDIT_ARCH_I386, regs->orig_eax,
 				    regs->ebx, regs->ecx, regs->edx, regs->esi);
 	if (ret == 0)
 		return 0;

 	regs->orig_eax = -1; /* force skip of syscall restarting */
 	if (unlikely(current->audit_context))
 		audit_syscall_exit(current, AUDITSC_RESULT(regs->eax),
 				regs->eax);
 	return 1;
 }
	/* ptrace.c */
	/* By Ross Biro 1/23/92 */
	/*
	* Pentium III FXSR, SSE support
	* Gareth Hughes <gareth@valinux.com>, May 2000
	*/

	#include <linux/kernel.h>
	#include <linux/sched.h>
	#include <linux/mm.h>
	#include <linux/smp.h>
	#include <linux/smp_lock.h>
	#include <linux/errno.h>
	#include <linux/ptrace.h>
	#include <linux/user.h>
	#include <linux/security.h>
	#include <linux/audit.h>
	#include <linux/seccomp.h>
	#include <linux/signal.h>

	#include <asm/uaccess.h>
	#include <asm/pgtable.h>
	#include <asm/system.h>
	#include <asm/processor.h>
	#include <asm/i387.h>
	#include <asm/debugreg.h>
	#include <asm/ldt.h>
	#include <asm/desc.h>

	/*
	* does not yet catch signals sent when the child dies.
	* in exit.c or in signal.c.
	*/

	/*
	* Determines which flags the user has access to [1 = access, 0 = no access].
	* Prohibits changing ID(21), VIP(20), VIF(19), VM(17), IOPL(12-13), IF(9).
	* Also masks reserved bits (31-22, 15, 5, 3, 1).
	*/
	#define FLAG_MASK 0x00054dd5

	/* set's the trap flag. */
	#define TRAP_FLAG 0x100

	/*
	* Offset of eflags on child stack..
	*/
	#define EFL_OFFSET ((EFL-2)*4-sizeof(struct pt_regs))

	static inline struct pt_regs get_child_regs(struct task_struct task)
	{
	void stack_top = (void )task->thread.esp0;
	return stack_top - sizeof(struct pt_regs);
	}

	/*
	* this routine will get a word off of the processes privileged stack.
	* the offset is how far from the base addr as stored in the TSS.
	* this routine assumes that all the privileged stacks are in our
	* data space.
	*/
	static inline int get_stack_long(struct task_struct *task, int offset)
	{
	unsigned char *stack;

	stack = (unsigned char *)task->thread.esp0;
	stack += offset;
	return (((int )stack));
	}

	/*
	* this routine will put a word on the processes privileged stack.
	* the offset is how far from the base addr as stored in the TSS.
	* this routine assumes that all the privileged stacks are in our
	* data space.
	*/
	static inline int put_stack_long(struct task_struct *task, int offset,
	unsigned long data)
	{
	unsigned char * stack;

	stack = (unsigned char *) task->thread.esp0;
	stack += offset;
	(unsigned long ) stack = data;
	return 0;
	}

	static int putreg(struct task_struct *child,
	unsigned long regno, unsigned long value)
	{
	switch (regno >> 2) {
	case FS:
	if (value && (value & 3) != 3)
	return -EIO;
	child->thread.fs = value;
	return 0;
	case GS:
	if (value && (value & 3) != 3)
	return -EIO;
	child->thread.gs = value;
	return 0;
	case DS:
	case ES:
	if (value && (value & 3) != 3)
	return -EIO;
	value &= 0xffff;
	break;
	case SS:
	case CS:
	if ((value & 3) != 3)
	return -EIO;
	value &= 0xffff;
	break;
	case EFL:
	value &= FLAG_MASK;
	value \|= get_stack_long(child, EFL_OFFSET) & ~FLAG_MASK;
	break;
	}
	if (regno > GS*4)
	regno -= 2*4;
	put_stack_long(child, regno - sizeof(struct pt_regs), value);
	return 0;
	}

	static unsigned long getreg(struct task_struct *child,
	unsigned long regno)
	{
	unsigned long retval = ~0UL;

	switch (regno >> 2) {
	case FS:
	retval = child->thread.fs;
	break;
	case GS:
	retval = child->thread.gs;
	break;
	case DS:
	case ES:
	case SS:
	case CS:
	retval = 0xffff;
	/* fall through */
	default:
	if (regno > GS*4)
	regno -= 2*4;
	regno = regno - sizeof(struct pt_regs);
	retval &= get_stack_long(child, regno);
	}
	return retval;
	}

	#define LDT_SEGMENT 4

	static unsigned long convert_eip_to_linear(struct task_struct child, struct pt_regs regs)
	{
	unsigned long addr, seg;

	addr = regs->eip;
	seg = regs->xcs & 0xffff;
	if (regs->eflags & VM_MASK) {
	addr = (addr & 0xffff) + (seg << 4);
	return addr;
	}

	/*
	* We'll assume that the code segments in the GDT
	* are all zero-based. That is largely true: the
	* TLS segments are used for data, and the PNPBIOS
	* and APM bios ones we just ignore here.
	*/
	if (seg & LDT_SEGMENT) {
	u32 *desc;
	unsigned long base;

	down(&child->mm->context.sem);
	desc = child->mm->context.ldt + (seg & ~7);
	base = (desc[0] >> 16) \| ((desc[1] & 0xff) << 16) \| (desc[1] & 0xff000000);

	/* 16-bit code segment? */
	if (!((desc[1] >> 22) & 1))
	addr &= 0xffff;
	addr += base;
	up(&child->mm->context.sem);
	}
	return addr;
	}

	static inline int is_at_popf(struct task_struct child, struct pt_regs regs)
	{
	int i, copied;
	unsigned char opcode[16];
	unsigned long addr = convert_eip_to_linear(child, regs);

	copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
	for (i = 0; i < copied; i++) {
	switch (opcode[i]) {
	/* popf */
	case 0x9d:
	return 1;
	/* opcode and address size prefixes */
	case 0x66: case 0x67:
	continue;
	/* irrelevant prefixes (segment overrides and repeats) */
	case 0x26: case 0x2e:
	case 0x36: case 0x3e:
	case 0x64: case 0x65:
	case 0xf0: case 0xf2: case 0xf3:
	continue;

	/*
	* pushf: NOTE! We should probably not let
	* the user see the TF bit being set. But
	* it's more pain than it's worth to avoid
	* it, and a debugger could emulate this
	* all in user space if it _really_ cares.
	*/
	case 0x9c:
	default:
	return 0;
	}
	}
	return 0;
	}

	static void set_singlestep(struct task_struct *child)
	{
	struct pt_regs *regs = get_child_regs(child);

	/*
	* Always set TIF_SINGLESTEP - this guarantees that
	* we single-step system calls etc.. This will also
	* cause us to set TF when returning to user mode.
	*/
	set_tsk_thread_flag(child, TIF_SINGLESTEP);

	/*
	* If TF was already set, don't do anything else
	*/
	if (regs->eflags & TRAP_FLAG)
	return;

	/* Set TF on the kernel stack.. */
	regs->eflags \|= TRAP_FLAG;

	/*
	* ..but if TF is changed by the instruction we will trace,
	* don't mark it as being "us" that set it, so that we
	* won't clear it by hand later.
	*/
	if (is_at_popf(child, regs))
	return;

	child->ptrace \|= PT_DTRACE;
	}

	static void clear_singlestep(struct task_struct *child)
	{
	/* Always clear TIF_SINGLESTEP... */
	clear_tsk_thread_flag(child, TIF_SINGLESTEP);

	/* But touch TF only if it was set by us.. */
	if (child->ptrace & PT_DTRACE) {
	struct pt_regs *regs = get_child_regs(child);
	regs->eflags &= ~TRAP_FLAG;
	child->ptrace &= ~PT_DTRACE;
	}
	}

	/*
	* Called by kernel/ptrace.c when detaching..
	*
	* Make sure the single step bit is not set.
	*/
	void ptrace_disable(struct task_struct *child)
	{
	clear_singlestep(child);
	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
	}

	/*
	* Perform get_thread_area on behalf of the traced child.
	*/
	static int
	ptrace_get_thread_area(struct task_struct *child,
	int idx, struct user_desc __user *user_desc)
	{
	struct user_desc info;
	struct desc_struct *desc;

	/*
	* Get the current Thread-Local Storage area:
	*/

	#define GET_BASE(desc) ( \
	(((desc)->a >> 16) & 0x0000ffff) \| \
	(((desc)->b << 16) & 0x00ff0000) \| \
	( (desc)->b & 0xff000000) )

	#define GET_LIMIT(desc) ( \
	((desc)->a & 0x0ffff) \| \
	((desc)->b & 0xf0000) )

	#define GET_32BIT(desc) (((desc)->b >> 22) & 1)
	#define GET_CONTENTS(desc) (((desc)->b >> 10) & 3)
	#define GET_WRITABLE(desc) (((desc)->b >> 9) & 1)
	#define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1)
	#define GET_PRESENT(desc) (((desc)->b >> 15) & 1)
	#define GET_USEABLE(desc) (((desc)->b >> 20) & 1)

	if (idx < GDT_ENTRY_TLS_MIN \|\| idx > GDT_ENTRY_TLS_MAX)
	return -EINVAL;

	desc = child->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;

	info.entry_number = idx;
	info.base_addr = GET_BASE(desc);
	info.limit = GET_LIMIT(desc);
	info.seg_32bit = GET_32BIT(desc);
	info.contents = GET_CONTENTS(desc);
	info.read_exec_only = !GET_WRITABLE(desc);
	info.limit_in_pages = GET_LIMIT_PAGES(desc);
	info.seg_not_present = !GET_PRESENT(desc);
	info.useable = GET_USEABLE(desc);

	if (copy_to_user(user_desc, &info, sizeof(info)))
	return -EFAULT;

	return 0;
	}

	/*
	* Perform set_thread_area on behalf of the traced child.
	*/
	static int
	ptrace_set_thread_area(struct task_struct *child,
	int idx, struct user_desc __user *user_desc)
	{
	struct user_desc info;
	struct desc_struct *desc;

	if (copy_from_user(&info, user_desc, sizeof(info)))
	return -EFAULT;

	if (idx < GDT_ENTRY_TLS_MIN \|\| idx > GDT_ENTRY_TLS_MAX)
	return -EINVAL;

	desc = child->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
	if (LDT_empty(&info)) {
	desc->a = 0;
	desc->b = 0;
	} else {
	desc->a = LDT_entry_a(&info);
	desc->b = LDT_entry_b(&info);
	}

	return 0;
	}

	long arch_ptrace(struct task_struct *child, long request, long addr, long data)
	{
	struct user * dummy = NULL;
	int i, ret;
	unsigned long __user datap = (unsigned long __user )data;

	switch (request) {
	/* when I and D space are separate, these will need to be fixed. */
	case PTRACE_PEEKTEXT: /* read word at location addr. */
	case PTRACE_PEEKDATA: {
	unsigned long tmp;
	int copied;

	copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
	ret = -EIO;
	if (copied != sizeof(tmp))
	break;
	ret = put_user(tmp, datap);
	break;
	}

	/* read the word at location addr in the USER area. */
	case PTRACE_PEEKUSR: {
	unsigned long tmp;

	ret = -EIO;
	if ((addr & 3) \|\| addr < 0 \|\|
	addr > sizeof(struct user) - 3)
	break;

	tmp = 0; /* Default return condition */
	if(addr < FRAME_SIZE*sizeof(long))
	tmp = getreg(child, addr);
	if(addr >= (long) &dummy->u_debugreg[0] &&
	addr <= (long) &dummy->u_debugreg[7]){
	addr -= (long) &dummy->u_debugreg[0];
	addr = addr >> 2;
	tmp = child->thread.debugreg[addr];
	}
	ret = put_user(tmp, datap);
	break;
	}

	/* when I and D space are separate, this will have to be fixed. */
	case PTRACE_POKETEXT: /* write the word at location addr. */
	case PTRACE_POKEDATA:
	ret = 0;
	if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
	break;
	ret = -EIO;
	break;

	case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
	ret = -EIO;
	if ((addr & 3) \|\| addr < 0 \|\|
	addr > sizeof(struct user) - 3)
	break;

	if (addr < FRAME_SIZE*sizeof(long)) {
	ret = putreg(child, addr, data);
	break;
	}
	/* We need to be very careful here. We implicitly
	want to modify a portion of the task_struct, and we
	have to be selective about what portions we allow someone
	to modify. */

	ret = -EIO;
	if(addr >= (long) &dummy->u_debugreg[0] &&
	addr <= (long) &dummy->u_debugreg[7]){

	if(addr == (long) &dummy->u_debugreg[4]) break;
	if(addr == (long) &dummy->u_debugreg[5]) break;
	if(addr < (long) &dummy->u_debugreg[4] &&
	((unsigned long) data) >= TASK_SIZE-3) break;

	/* Sanity-check data. Take one half-byte at once with
	* check = (val >> (16 + 4*i)) & 0xf. It contains the
	* R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits
	* 2 and 3 are LENi. Given a list of invalid values,
	* we do mask \|= 1 << invalid_value, so that
	* (mask >> check) & 1 is a correct test for invalid
	* values.
	*
	* R/Wi contains the type of the breakpoint /
	* watchpoint, LENi contains the length of the watched
	* data in the watchpoint case.
	*
	* The invalid values are:
	* - LENi == 0x10 (undefined), so mask \|= 0x0f00.
	* - R/Wi == 0x10 (break on I/O reads or writes), so
	* mask \|= 0x4444.
	* - R/Wi == 0x00 && LENi != 0x00, so we have mask \|=
	* 0x1110.
	*
	* Finally, mask = 0x0f00 \| 0x4444 \| 0x1110 == 0x5f54.
	*
	* See the Intel Manual "System Programming Guide",
	* 15.2.4
	*
	* Note that LENi == 0x10 is defined on x86_64 in long
	* mode (i.e. even for 32-bit userspace software, but
	* 64-bit kernel), so the x86_64 mask value is 0x5454.
	* See the AMD manual no. 24593 (AMD64 System
	* Programming)*/

	if(addr == (long) &dummy->u_debugreg[7]) {
	data &= ~DR_CONTROL_RESERVED;
	for(i=0; i<4; i++)
	if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
	goto out_tsk;
	}

	addr -= (long) &dummy->u_debugreg;
	addr = addr >> 2;
	child->thread.debugreg[addr] = data;
	ret = 0;
	}
	break;

	case PTRACE_SYSEMU: /* continue and stop at next syscall, which will not be executed */
	case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
	case PTRACE_CONT: /* restart after signal. */
	ret = -EIO;
	if (!valid_signal(data))
	break;
	if (request == PTRACE_SYSEMU) {
	set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	} else if (request == PTRACE_SYSCALL) {
	set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
	} else {
	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	}
	child->exit_code = data;
	/* make sure the single step bit is not set. */
	clear_singlestep(child);
	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) /* already dead */
	break;
	child->exit_code = SIGKILL;
	/* make sure the single step bit is not set. */
	clear_singlestep(child);
	wake_up_process(child);
	break;

	case PTRACE_SYSEMU_SINGLESTEP: /* Same as SYSEMU, but singlestep if not syscall */
	case PTRACE_SINGLESTEP: /* set the trap flag. */
	ret = -EIO;
	if (!valid_signal(data))
	break;

	if (request == PTRACE_SYSEMU_SINGLESTEP)
	set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
	else
	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);

	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
	set_singlestep(child);
	child->exit_code = data;
	/* give it a chance to run. */
	wake_up_process(child);
	ret = 0;
	break;

	case PTRACE_DETACH:
	/* detach a process that was attached. */
	ret = ptrace_detach(child, data);
	break;

	case PTRACE_GETREGS: { /* Get all gp regs from the child. */
	if (!access_ok(VERIFY_WRITE, datap, FRAME_SIZE*sizeof(long))) {
	ret = -EIO;
	break;
	}
	for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) {
	__put_user(getreg(child, i), datap);
	datap++;
	}
	ret = 0;
	break;
	}

	case PTRACE_SETREGS: { /* Set all gp regs in the child. */
	unsigned long tmp;
	if (!access_ok(VERIFY_READ, datap, FRAME_SIZE*sizeof(long))) {
	ret = -EIO;
	break;
	}
	for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) {
	__get_user(tmp, datap);
	putreg(child, i, tmp);
	datap++;
	}
	ret = 0;
	break;
	}

	case PTRACE_GETFPREGS: { /* Get the child FPU state. */
	if (!access_ok(VERIFY_WRITE, datap,
	sizeof(struct user_i387_struct))) {
	ret = -EIO;
	break;
	}
	ret = 0;
	if (!tsk_used_math(child))
	init_fpu(child);
	get_fpregs((struct user_i387_struct __user *)data, child);
	break;
	}

	case PTRACE_SETFPREGS: { /* Set the child FPU state. */
	if (!access_ok(VERIFY_READ, datap,
	sizeof(struct user_i387_struct))) {
	ret = -EIO;
	break;
	}
	set_stopped_child_used_math(child);
	set_fpregs(child, (struct user_i387_struct __user *)data);
	ret = 0;
	break;
	}

	case PTRACE_GETFPXREGS: { /* Get the child extended FPU state. */
	if (!access_ok(VERIFY_WRITE, datap,
	sizeof(struct user_fxsr_struct))) {
	ret = -EIO;
	break;
	}
	if (!tsk_used_math(child))
	init_fpu(child);
	ret = get_fpxregs((struct user_fxsr_struct __user *)data, child);
	break;
	}

	case PTRACE_SETFPXREGS: { /* Set the child extended FPU state. */
	if (!access_ok(VERIFY_READ, datap,
	sizeof(struct user_fxsr_struct))) {
	ret = -EIO;
	break;
	}
	set_stopped_child_used_math(child);
	ret = set_fpxregs(child, (struct user_fxsr_struct __user *)data);
	break;
	}

	case PTRACE_GET_THREAD_AREA:
	ret = ptrace_get_thread_area(child, addr,
	(struct user_desc __user *) data);
	break;

	case PTRACE_SET_THREAD_AREA:
	ret = ptrace_set_thread_area(child, addr,
	(struct user_desc __user *) data);
	break;

	default:
	ret = ptrace_request(child, request, addr, data);
	break;
	}
	out_tsk:
	return ret;
	}

	void send_sigtrap(struct task_struct tsk, struct pt_regs regs, int error_code)
	{
	struct siginfo info;

	tsk->thread.trap_no = 1;
	tsk->thread.error_code = error_code;

	memset(&info, 0, sizeof(info));
	info.si_signo = SIGTRAP;
	info.si_code = TRAP_BRKPT;

	/* User-mode eip? */
	info.si_addr = user_mode_vm(regs) ? (void __user *) regs->eip : NULL;

	/* Send us the fakey SIGTRAP */
	force_sig_info(SIGTRAP, &info, tsk);
	}

	/* notification of system call entry/exit
	* - triggered by current->work.syscall_trace
	*/
	__attribute__((regparm(3)))
	int do_syscall_trace(struct pt_regs *regs, int entryexit)
	{
	int is_sysemu = test_thread_flag(TIF_SYSCALL_EMU);
	/*
	* With TIF_SYSCALL_EMU set we want to ignore TIF_SINGLESTEP for syscall
	* interception
	*/
	int is_singlestep = !is_sysemu && test_thread_flag(TIF_SINGLESTEP);
	int ret = 0;

	/* do the secure computing check first */
	if (!entryexit)
	secure_computing(regs->orig_eax);

	if (unlikely(current->audit_context)) {
	if (entryexit)
	audit_syscall_exit(current, AUDITSC_RESULT(regs->eax),
	regs->eax);
	/* Debug traps, when using PTRACE_SINGLESTEP, must be sent only
	* on the syscall exit path. Normally, when TIF_SYSCALL_AUDIT is
	* not used, entry.S will call us only on syscall exit, not
	* entry; so when TIF_SYSCALL_AUDIT is used we must avoid
	* calling send_sigtrap() on syscall entry.
	*
	* Note that when PTRACE_SYSEMU_SINGLESTEP is used,
	* is_singlestep is false, despite his name, so we will still do
	* the correct thing.
	*/
	else if (is_singlestep)
	goto out;
	}

	if (!(current->ptrace & PT_PTRACED))
	goto out;

	/* If a process stops on the 1st tracepoint with SYSCALL_TRACE
	* and then is resumed with SYSEMU_SINGLESTEP, it will come in
	* here. We have to check this and return */
	if (is_sysemu && entryexit)
	return 0;

	/* Fake a debug trap */
	if (is_singlestep)
	send_sigtrap(current, regs, 0);

	if (!test_thread_flag(TIF_SYSCALL_TRACE) && !is_sysemu)
	goto out;

	/* the 0x80 provides a way for the tracing parent to distinguish
	between a syscall stop and SIGTRAP delivery */
	/* Note that the debugger could change the result of test_thread_flag!*/
	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;
	}
	ret = is_sysemu;
	out:
	if (unlikely(current->audit_context) && !entryexit)
	audit_syscall_entry(current, AUDIT_ARCH_I386, regs->orig_eax,
	regs->ebx, regs->ecx, regs->edx, regs->esi);
	if (ret == 0)
	return 0;

	regs->orig_eax = -1; /* force skip of syscall restarting */
	if (unlikely(current->audit_context))
	audit_syscall_exit(current, AUDITSC_RESULT(regs->eax),
	regs->eax);
	return 1;
	}