arch/x86/kernel/ptrace.c

/* By Ross Biro 1/23/92 */
/*
 * Pentium III FXSR, SSE support
 *	Gareth Hughes <gareth@valinux.com>, May 2000
 *
 * BTS tracing
 *	Markus Metzger <markus.t.metzger@intel.com>, Dec 2007
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/regset.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>
#include <asm/prctl.h>
#include <asm/proto.h>
#include <asm/ds.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].
 */
#define FLAG_MASK_32		((unsigned long)			\
				 (X86_EFLAGS_CF | X86_EFLAGS_PF |	\
				  X86_EFLAGS_AF | X86_EFLAGS_ZF |	\
				  X86_EFLAGS_SF | X86_EFLAGS_TF |	\
				  X86_EFLAGS_DF | X86_EFLAGS_OF |	\
				  X86_EFLAGS_RF | X86_EFLAGS_AC))

/*
 * Determines whether a value may be installed in a segment register.
 */
static inline bool invalid_selector(u16 value)
{
	return unlikely(value != 0 && (value & SEGMENT_RPL_MASK) != USER_RPL);
}

#ifdef CONFIG_X86_32

#define FLAG_MASK		FLAG_MASK_32

static long *pt_regs_access(struct pt_regs *regs, unsigned long regno)
{
	BUILD_BUG_ON(offsetof(struct pt_regs, bx) != 0);
	regno >>= 2;
	if (regno > FS)
		--regno;
	return &regs->bx + regno;
}

static u16 get_segment_reg(struct task_struct *task, unsigned long offset)
{
	/*
	 * Returning the value truncates it to 16 bits.
	 */
	unsigned int retval;
	if (offset != offsetof(struct user_regs_struct, gs))
		retval = *pt_regs_access(task_pt_regs(task), offset);
	else {
		retval = task->thread.gs;
		if (task == current)
			savesegment(gs, retval);
	}
	return retval;
}

static int set_segment_reg(struct task_struct *task,
			   unsigned long offset, u16 value)
{
	/*
	 * The value argument was already truncated to 16 bits.
	 */
	if (invalid_selector(value))
		return -EIO;

	if (offset != offsetof(struct user_regs_struct, gs))
		*pt_regs_access(task_pt_regs(task), offset) = value;
	else {
		task->thread.gs = value;
		if (task == current)
			/*
			 * The user-mode %gs is not affected by
			 * kernel entry, so we must update the CPU.
			 */
			loadsegment(gs, value);
	}

	return 0;
}

static unsigned long debugreg_addr_limit(struct task_struct *task)
{
	return TASK_SIZE - 3;
}

#else  /* CONFIG_X86_64 */

#define FLAG_MASK		(FLAG_MASK_32 | X86_EFLAGS_NT)

static unsigned long *pt_regs_access(struct pt_regs *regs, unsigned long offset)
{
	BUILD_BUG_ON(offsetof(struct pt_regs, r15) != 0);
	return &regs->r15 + (offset / sizeof(regs->r15));
}

static u16 get_segment_reg(struct task_struct *task, unsigned long offset)
{
	/*
	 * Returning the value truncates it to 16 bits.
	 */
	unsigned int seg;

	switch (offset) {
	case offsetof(struct user_regs_struct, fs):
		if (task == current) {
			/* Older gas can't assemble movq %?s,%r?? */
			asm("movl %%fs,%0" : "=r" (seg));
			return seg;
		}
		return task->thread.fsindex;
	case offsetof(struct user_regs_struct, gs):
		if (task == current) {
			asm("movl %%gs,%0" : "=r" (seg));
			return seg;
		}
		return task->thread.gsindex;
	case offsetof(struct user_regs_struct, ds):
		if (task == current) {
			asm("movl %%ds,%0" : "=r" (seg));
			return seg;
		}
		return task->thread.ds;
	case offsetof(struct user_regs_struct, es):
		if (task == current) {
			asm("movl %%es,%0" : "=r" (seg));
			return seg;
		}
		return task->thread.es;

	case offsetof(struct user_regs_struct, cs):
	case offsetof(struct user_regs_struct, ss):
		break;
	}
	return *pt_regs_access(task_pt_regs(task), offset);
}

static int set_segment_reg(struct task_struct *task,
			   unsigned long offset, u16 value)
{
	/*
	 * The value argument was already truncated to 16 bits.
	 */
	if (invalid_selector(value))
		return -EIO;

	switch (offset) {
	case offsetof(struct user_regs_struct,fs):
		/*
		 * If this is setting fs as for normal 64-bit use but
		 * setting fs_base has implicitly changed it, leave it.
		 */
		if ((value == FS_TLS_SEL && task->thread.fsindex == 0 &&
		     task->thread.fs != 0) ||
		    (value == 0 && task->thread.fsindex == FS_TLS_SEL &&
		     task->thread.fs == 0))
			break;
		task->thread.fsindex = value;
		if (task == current)
			loadsegment(fs, task->thread.fsindex);
		break;
	case offsetof(struct user_regs_struct,gs):
		/*
		 * If this is setting gs as for normal 64-bit use but
		 * setting gs_base has implicitly changed it, leave it.
		 */
		if ((value == GS_TLS_SEL && task->thread.gsindex == 0 &&
		     task->thread.gs != 0) ||
		    (value == 0 && task->thread.gsindex == GS_TLS_SEL &&
		     task->thread.gs == 0))
			break;
		task->thread.gsindex = value;
		if (task == current)
			load_gs_index(task->thread.gsindex);
		break;
	case offsetof(struct user_regs_struct,ds):
		task->thread.ds = value;
		if (task == current)
			loadsegment(ds, task->thread.ds);
		break;
	case offsetof(struct user_regs_struct,es):
		task->thread.es = value;
		if (task == current)
			loadsegment(es, task->thread.es);
		break;

		/*
		 * Can't actually change these in 64-bit mode.
		 */
	case offsetof(struct user_regs_struct,cs):
#ifdef CONFIG_IA32_EMULATION
		if (test_tsk_thread_flag(task, TIF_IA32))
			task_pt_regs(task)->cs = value;
#endif
		break;
	case offsetof(struct user_regs_struct,ss):
#ifdef CONFIG_IA32_EMULATION
		if (test_tsk_thread_flag(task, TIF_IA32))
			task_pt_regs(task)->ss = value;
#endif
		break;
	}

	return 0;
}

static unsigned long debugreg_addr_limit(struct task_struct *task)
{
#ifdef CONFIG_IA32_EMULATION
	if (test_tsk_thread_flag(task, TIF_IA32))
		return IA32_PAGE_OFFSET - 3;
#endif
	return TASK_SIZE64 - 7;
}

#endif	/* CONFIG_X86_32 */

static unsigned long get_flags(struct task_struct *task)
{
	unsigned long retval = task_pt_regs(task)->flags;

	/*
	 * If the debugger set TF, hide it from the readout.
	 */
	if (test_tsk_thread_flag(task, TIF_FORCED_TF))
		retval &= ~X86_EFLAGS_TF;

	return retval;
}

static int set_flags(struct task_struct *task, unsigned long value)
{
	struct pt_regs *regs = task_pt_regs(task);

	/*
	 * If the user value contains TF, mark that
	 * it was not "us" (the debugger) that set it.
	 * If not, make sure it stays set if we had.
	 */
	if (value & X86_EFLAGS_TF)
		clear_tsk_thread_flag(task, TIF_FORCED_TF);
	else if (test_tsk_thread_flag(task, TIF_FORCED_TF))
		value |= X86_EFLAGS_TF;

	regs->flags = (regs->flags & ~FLAG_MASK) | (value & FLAG_MASK);

	return 0;
}

static int putreg(struct task_struct *child,
		  unsigned long offset, unsigned long value)
{
	switch (offset) {
	case offsetof(struct user_regs_struct, cs):
	case offsetof(struct user_regs_struct, ds):
	case offsetof(struct user_regs_struct, es):
	case offsetof(struct user_regs_struct, fs):
	case offsetof(struct user_regs_struct, gs):
	case offsetof(struct user_regs_struct, ss):
		return set_segment_reg(child, offset, value);

	case offsetof(struct user_regs_struct, flags):
		return set_flags(child, value);

#ifdef CONFIG_X86_64
	case offsetof(struct user_regs_struct,fs_base):
		if (value >= TASK_SIZE_OF(child))
			return -EIO;
		/*
		 * When changing the segment base, use do_arch_prctl
		 * to set either thread.fs or thread.fsindex and the
		 * corresponding GDT slot.
		 */
		if (child->thread.fs != value)
			return do_arch_prctl(child, ARCH_SET_FS, value);
		return 0;
	case offsetof(struct user_regs_struct,gs_base):
		/*
		 * Exactly the same here as the %fs handling above.
		 */
		if (value >= TASK_SIZE_OF(child))
			return -EIO;
		if (child->thread.gs != value)
			return do_arch_prctl(child, ARCH_SET_GS, value);
		return 0;
#endif
	}

	*pt_regs_access(task_pt_regs(child), offset) = value;
	return 0;
}

static unsigned long getreg(struct task_struct *task, unsigned long offset)
{
	switch (offset) {
	case offsetof(struct user_regs_struct, cs):
	case offsetof(struct user_regs_struct, ds):
	case offsetof(struct user_regs_struct, es):
	case offsetof(struct user_regs_struct, fs):
	case offsetof(struct user_regs_struct, gs):
	case offsetof(struct user_regs_struct, ss):
		return get_segment_reg(task, offset);

	case offsetof(struct user_regs_struct, flags):
		return get_flags(task);

#ifdef CONFIG_X86_64
	case offsetof(struct user_regs_struct, fs_base): {
		/*
		 * do_arch_prctl may have used a GDT slot instead of
		 * the MSR.  To userland, it appears the same either
		 * way, except the %fs segment selector might not be 0.
		 */
		unsigned int seg = task->thread.fsindex;
		if (task->thread.fs != 0)
			return task->thread.fs;
		if (task == current)
			asm("movl %%fs,%0" : "=r" (seg));
		if (seg != FS_TLS_SEL)
			return 0;
		return get_desc_base(&task->thread.tls_array[FS_TLS]);
	}
	case offsetof(struct user_regs_struct, gs_base): {
		/*
		 * Exactly the same here as the %fs handling above.
		 */
		unsigned int seg = task->thread.gsindex;
		if (task->thread.gs != 0)
			return task->thread.gs;
		if (task == current)
			asm("movl %%gs,%0" : "=r" (seg));
		if (seg != GS_TLS_SEL)
			return 0;
		return get_desc_base(&task->thread.tls_array[GS_TLS]);
	}
#endif
	}

	return *pt_regs_access(task_pt_regs(task), offset);
}

static int genregs_get(struct task_struct *target,
		       const struct user_regset *regset,
		       unsigned int pos, unsigned int count,
		       void *kbuf, void __user *ubuf)
{
	if (kbuf) {
		unsigned long *k = kbuf;
		while (count > 0) {
			*k++ = getreg(target, pos);
			count -= sizeof(*k);
			pos += sizeof(*k);
		}
	} else {
		unsigned long __user *u = ubuf;
		while (count > 0) {
			if (__put_user(getreg(target, pos), u++))
				return -EFAULT;
			count -= sizeof(*u);
			pos += sizeof(*u);
		}
	}

	return 0;
}

static int genregs_set(struct task_struct *target,
		       const struct user_regset *regset,
		       unsigned int pos, unsigned int count,
		       const void *kbuf, const void __user *ubuf)
{
	int ret = 0;
	if (kbuf) {
		const unsigned long *k = kbuf;
		while (count > 0 && !ret) {
			ret = putreg(target, pos, *k++);
			count -= sizeof(*k);
			pos += sizeof(*k);
		}
	} else {
		const unsigned long  __user *u = ubuf;
		while (count > 0 && !ret) {
			unsigned long word;
			ret = __get_user(word, u++);
			if (ret)
				break;
			ret = putreg(target, pos, word);
			count -= sizeof(*u);
			pos += sizeof(*u);
		}
	}
	return ret;
}

/*
 * This function is trivial and will be inlined by the compiler.
 * Having it separates the implementation details of debug
 * registers from the interface details of ptrace.
 */
static unsigned long ptrace_get_debugreg(struct task_struct *child, int n)
{
	switch (n) {
	case 0:		return child->thread.debugreg0;
	case 1:		return child->thread.debugreg1;
	case 2:		return child->thread.debugreg2;
	case 3:		return child->thread.debugreg3;
	case 6:		return child->thread.debugreg6;
	case 7:		return child->thread.debugreg7;
	}
	return 0;
}

static int ptrace_set_debugreg(struct task_struct *child,
			       int n, unsigned long data)
{
	int i;

	if (unlikely(n == 4 || n == 5))
		return -EIO;

	if (n < 4 && unlikely(data >= debugreg_addr_limit(child)))
		return -EIO;

	switch (n) {
	case 0:		child->thread.debugreg0 = data; break;
	case 1:		child->thread.debugreg1 = data; break;
	case 2:		child->thread.debugreg2 = data; break;
	case 3:		child->thread.debugreg3 = data; break;

	case 6:
		if ((data & ~0xffffffffUL) != 0)
			return -EIO;
		child->thread.debugreg6 = data;
		break;

	case 7:
		/*
		 * 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.	[32-bit]
		 * - 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)
		 */
#ifdef CONFIG_X86_32
#define	DR7_MASK	0x5f54
#else
#define	DR7_MASK	0x5554
#endif
		data &= ~DR_CONTROL_RESERVED;
		for (i = 0; i < 4; i++)
			if ((DR7_MASK >> ((data >> (16 + 4*i)) & 0xf)) & 1)
				return -EIO;
		child->thread.debugreg7 = data;
		if (data)
			set_tsk_thread_flag(child, TIF_DEBUG);
		else
			clear_tsk_thread_flag(child, TIF_DEBUG);
		break;
	}

	return 0;
}

static int ptrace_bts_get_size(struct task_struct *child)
{
	if (!child->thread.ds_area_msr)
		return -ENXIO;

	return ds_get_bts_index((void *)child->thread.ds_area_msr);
}

static int ptrace_bts_read_record(struct task_struct *child,
				  long index,
				  struct bts_struct __user *out)
{
	struct bts_struct ret;
	int retval;
	int bts_end;
	int bts_index;

	if (!child->thread.ds_area_msr)
		return -ENXIO;

	if (index < 0)
		return -EINVAL;

	bts_end = ds_get_bts_end((void *)child->thread.ds_area_msr);
	if (bts_end <= index)
		return -EINVAL;

	/* translate the ptrace bts index into the ds bts index */
	bts_index = ds_get_bts_index((void *)child->thread.ds_area_msr);
	bts_index -= (index + 1);
	if (bts_index < 0)
		bts_index += bts_end;

	retval = ds_read_bts((void *)child->thread.ds_area_msr,
			     bts_index, &ret);
	if (retval)
		return retval;

	if (copy_to_user(out, &ret, sizeof(ret)))
		return -EFAULT;

	return sizeof(ret);
}

static int ptrace_bts_write_record(struct task_struct *child,
				   const struct bts_struct *in)
{
	int retval;

	if (!child->thread.ds_area_msr)
		return -ENXIO;

	retval = ds_write_bts((void *)child->thread.ds_area_msr, in);
	if (retval)
		return retval;

	return sizeof(*in);
}

static int ptrace_bts_clear(struct task_struct *child)
{
	if (!child->thread.ds_area_msr)
		return -ENXIO;

	return ds_clear((void *)child->thread.ds_area_msr);
}

static int ptrace_bts_drain(struct task_struct *child,
			    struct bts_struct __user *out)
{
	int end, i;
	void *ds = (void *)child->thread.ds_area_msr;

	if (!ds)
		return -ENXIO;

	end = ds_get_bts_index(ds);
	if (end <= 0)
		return end;

	for (i = 0; i < end; i++, out++) {
		struct bts_struct ret;
		int retval;

		retval = ds_read_bts(ds, i, &ret);
		if (retval < 0)
			return retval;

		if (copy_to_user(out, &ret, sizeof(ret)))
			return -EFAULT;
	}

	ds_clear(ds);

	return i;
}

static int ptrace_bts_config(struct task_struct *child,
			     const struct ptrace_bts_config __user *ucfg)
{
	struct ptrace_bts_config cfg;
	unsigned long debugctl_mask;
	int bts_size, ret;
	void *ds;

	if (copy_from_user(&cfg, ucfg, sizeof(cfg)))
		return -EFAULT;

	bts_size = 0;
	ds = (void *)child->thread.ds_area_msr;
	if (ds) {
		bts_size = ds_get_bts_size(ds);
		if (bts_size < 0)
			return bts_size;
	}

	if (bts_size != cfg.size) {
		ret = ds_free((void **)&child->thread.ds_area_msr);
		if (ret < 0)
			return ret;

		if (cfg.size > 0)
			ret = ds_allocate((void **)&child->thread.ds_area_msr,
					  cfg.size);
		ds = (void *)child->thread.ds_area_msr;
		if (ds)
			set_tsk_thread_flag(child, TIF_DS_AREA_MSR);
		else
			clear_tsk_thread_flag(child, TIF_DS_AREA_MSR);

		if (ret < 0)
			return ret;

		bts_size = ds_get_bts_size(ds);
		if (bts_size <= 0)
			return bts_size;
	}

	if (ds) {
		if (cfg.flags & PTRACE_BTS_O_SIGNAL) {
			ret = ds_set_overflow(ds, DS_O_SIGNAL);
		} else {
			ret = ds_set_overflow(ds, DS_O_WRAP);
		}
		if (ret < 0)
			return ret;
	}

	debugctl_mask = ds_debugctl_mask();
	if (ds && (cfg.flags & PTRACE_BTS_O_TRACE)) {
		child->thread.debugctlmsr |= debugctl_mask;
		set_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
	} else {
		/* there is no way for us to check whether we 'own'
		 * the respective bits in the DEBUGCTL MSR, we're
		 * about to clear */
		child->thread.debugctlmsr &= ~debugctl_mask;

		if (!child->thread.debugctlmsr)
			clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
	}

	if (ds && (cfg.flags & PTRACE_BTS_O_SCHED))
		set_tsk_thread_flag(child, TIF_BTS_TRACE_TS);
	else
		clear_tsk_thread_flag(child, TIF_BTS_TRACE_TS);

	return 0;
}

static int ptrace_bts_status(struct task_struct *child,
			     struct ptrace_bts_config __user *ucfg)
{
	void *ds = (void *)child->thread.ds_area_msr;
	struct ptrace_bts_config cfg;

	memset(&cfg, 0, sizeof(cfg));

	if (ds) {
		cfg.size = ds_get_bts_size(ds);

		if (ds_get_overflow(ds) == DS_O_SIGNAL)
			cfg.flags |= PTRACE_BTS_O_SIGNAL;

		if (test_tsk_thread_flag(child, TIF_DEBUGCTLMSR) &&
		    child->thread.debugctlmsr & ds_debugctl_mask())
			cfg.flags |= PTRACE_BTS_O_TRACE;

		if (test_tsk_thread_flag(child, TIF_BTS_TRACE_TS))
			cfg.flags |= PTRACE_BTS_O_SCHED;
	}

	if (copy_to_user(ucfg, &cfg, sizeof(cfg)))
		return -EFAULT;

	return sizeof(cfg);
}

void ptrace_bts_take_timestamp(struct task_struct *tsk,
			       enum bts_qualifier qualifier)
{
	struct bts_struct rec = {
		.qualifier = qualifier,
		.variant.jiffies = jiffies
	};

	ptrace_bts_write_record(tsk, &rec);
}

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure the single step bit is not set.
 */
void ptrace_disable(struct task_struct *child)
{
	user_disable_single_step(child);
#ifdef TIF_SYSCALL_EMU
	clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
#endif
	ptrace_bts_config(child, /* options = */ 0);
	if (child->thread.ds_area_msr) {
	    ds_free((void **)&child->thread.ds_area_msr);
	    clear_tsk_thread_flag(child, TIF_DS_AREA_MSR);
	}
}

long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
	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:
		ret = generic_ptrace_peekdata(child, addr, data);
		break;

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

		ret = -EIO;
		if ((addr & (sizeof(data) - 1)) || addr < 0 ||
		    addr >= sizeof(struct user))
			break;

		tmp = 0;  /* Default return condition */
		if (addr < sizeof(struct user_regs_struct))
			tmp = getreg(child, addr);
		else if (addr >= offsetof(struct user, u_debugreg[0]) &&
			 addr <= offsetof(struct user, u_debugreg[7])) {
			addr -= offsetof(struct user, u_debugreg[0]);
			tmp = ptrace_get_debugreg(child, addr / sizeof(data));
		}
		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 = generic_ptrace_pokedata(child, addr, data);
		break;

	case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
		ret = -EIO;
		if ((addr & (sizeof(data) - 1)) || addr < 0 ||
		    addr >= sizeof(struct user))
			break;

		if (addr < sizeof(struct user_regs_struct))
			ret = putreg(child, addr, data);
		else if (addr >= offsetof(struct user, u_debugreg[0]) &&
			 addr <= offsetof(struct user, u_debugreg[7])) {
			addr -= offsetof(struct user, u_debugreg[0]);
			ret = ptrace_set_debugreg(child,
						  addr / sizeof(data), data);
		}
		break;

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

#ifdef CONFIG_X86_32
	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;
	}
#endif

#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
	case PTRACE_GET_THREAD_AREA:
		if (addr < 0)
			return -EIO;
		ret = do_get_thread_area(child, addr,
					 (struct user_desc __user *) data);
		break;

	case PTRACE_SET_THREAD_AREA:
		if (addr < 0)
			return -EIO;
		ret = do_set_thread_area(child, addr,
					 (struct user_desc __user *) data, 0);
		break;
#endif

#ifdef CONFIG_X86_64
		/* normal 64bit interface to access TLS data.
		   Works just like arch_prctl, except that the arguments
		   are reversed. */
	case PTRACE_ARCH_PRCTL:
		ret = do_arch_prctl(child, data, addr);
		break;
#endif

	case PTRACE_BTS_CONFIG:
		ret = ptrace_bts_config
			(child, (struct ptrace_bts_config __user *)addr);
		break;

	case PTRACE_BTS_STATUS:
		ret = ptrace_bts_status
			(child, (struct ptrace_bts_config __user *)addr);
		break;

	case PTRACE_BTS_SIZE:
		ret = ptrace_bts_get_size(child);
		break;

	case PTRACE_BTS_GET:
		ret = ptrace_bts_read_record
			(child, data, (struct bts_struct __user *) addr);
		break;

	case PTRACE_BTS_CLEAR:
		ret = ptrace_bts_clear(child);
		break;

	case PTRACE_BTS_DRAIN:
		ret = ptrace_bts_drain
			(child, (struct bts_struct __user *) addr);
		break;

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

	return ret;
}

#ifdef CONFIG_IA32_EMULATION

#include <linux/compat.h>
#include <linux/syscalls.h>
#include <asm/ia32.h>
#include <asm/user32.h>

#define R32(l,q)							\
	case offsetof(struct user32, regs.l):				\
		regs->q = value; break

#define SEG32(rs)							\
	case offsetof(struct user32, regs.rs):				\
		return set_segment_reg(child,				\
				       offsetof(struct user_regs_struct, rs), \
				       value);				\
		break

static int putreg32(struct task_struct *child, unsigned regno, u32 value)
{
	struct pt_regs *regs = task_pt_regs(child);

	switch (regno) {

	SEG32(cs);
	SEG32(ds);
	SEG32(es);
	SEG32(fs);
	SEG32(gs);
	SEG32(ss);

	R32(ebx, bx);
	R32(ecx, cx);
	R32(edx, dx);
	R32(edi, di);
	R32(esi, si);
	R32(ebp, bp);
	R32(eax, ax);
	R32(orig_eax, orig_ax);
	R32(eip, ip);
	R32(esp, sp);

	case offsetof(struct user32, regs.eflags):
		return set_flags(child, value);

	case offsetof(struct user32, u_debugreg[0]) ...
		offsetof(struct user32, u_debugreg[7]):
		regno -= offsetof(struct user32, u_debugreg[0]);
		return ptrace_set_debugreg(child, regno / 4, value);

	default:
		if (regno > sizeof(struct user32) || (regno & 3))
			return -EIO;

		/*
		 * Other dummy fields in the virtual user structure
		 * are ignored
		 */
		break;
	}
	return 0;
}

#undef R32
#undef SEG32

#define R32(l,q)							\
	case offsetof(struct user32, regs.l):				\
		*val = regs->q; break

#define SEG32(rs)							\
	case offsetof(struct user32, regs.rs):				\
		*val = get_segment_reg(child,				\
				       offsetof(struct user_regs_struct, rs)); \
		break

static int getreg32(struct task_struct *child, unsigned regno, u32 *val)
{
	struct pt_regs *regs = task_pt_regs(child);

	switch (regno) {

	SEG32(ds);
	SEG32(es);
	SEG32(fs);
	SEG32(gs);

	R32(cs, cs);
	R32(ss, ss);
	R32(ebx, bx);
	R32(ecx, cx);
	R32(edx, dx);
	R32(edi, di);
	R32(esi, si);
	R32(ebp, bp);
	R32(eax, ax);
	R32(orig_eax, orig_ax);
	R32(eip, ip);
	R32(esp, sp);

	case offsetof(struct user32, regs.eflags):
		*val = get_flags(child);
		break;

	case offsetof(struct user32, u_debugreg[0]) ...
		offsetof(struct user32, u_debugreg[7]):
		regno -= offsetof(struct user32, u_debugreg[0]);
		*val = ptrace_get_debugreg(child, regno / 4);
		break;

	default:
		if (regno > sizeof(struct user32) || (regno & 3))
			return -EIO;

		/*
		 * Other dummy fields in the virtual user structure
		 * are ignored
		 */
		*val = 0;
		break;
	}
	return 0;
}

#undef R32
#undef SEG32

static int genregs32_get(struct task_struct *target,
			 const struct user_regset *regset,
			 unsigned int pos, unsigned int count,
			 void *kbuf, void __user *ubuf)
{
	if (kbuf) {
		compat_ulong_t *k = kbuf;
		while (count > 0) {
			getreg32(target, pos, k++);
			count -= sizeof(*k);
			pos += sizeof(*k);
		}
	} else {
		compat_ulong_t __user *u = ubuf;
		while (count > 0) {
			compat_ulong_t word;
			getreg32(target, pos, &word);
			if (__put_user(word, u++))
				return -EFAULT;
			count -= sizeof(*u);
			pos += sizeof(*u);
		}
	}

	return 0;
}

static int genregs32_set(struct task_struct *target,
			 const struct user_regset *regset,
			 unsigned int pos, unsigned int count,
			 const void *kbuf, const void __user *ubuf)
{
	int ret = 0;
	if (kbuf) {
		const compat_ulong_t *k = kbuf;
		while (count > 0 && !ret) {
			ret = putreg(target, pos, *k++);
			count -= sizeof(*k);
			pos += sizeof(*k);
		}
	} else {
		const compat_ulong_t __user *u = ubuf;
		while (count > 0 && !ret) {
			compat_ulong_t word;
			ret = __get_user(word, u++);
			if (ret)
				break;
			ret = putreg(target, pos, word);
			count -= sizeof(*u);
			pos += sizeof(*u);
		}
	}
	return ret;
}

static long ptrace32_siginfo(unsigned request, u32 pid, u32 addr, u32 data)
{
	siginfo_t __user *si = compat_alloc_user_space(sizeof(siginfo_t));
	compat_siginfo_t __user *si32 = compat_ptr(data);
	siginfo_t ssi;
	int ret;

	if (request == PTRACE_SETSIGINFO) {
		memset(&ssi, 0, sizeof(siginfo_t));
		ret = copy_siginfo_from_user32(&ssi, si32);
		if (ret)
			return ret;
		if (copy_to_user(si, &ssi, sizeof(siginfo_t)))
			return -EFAULT;
	}
	ret = sys_ptrace(request, pid, addr, (unsigned long)si);
	if (ret)
		return ret;
	if (request == PTRACE_GETSIGINFO) {
		if (copy_from_user(&ssi, si, sizeof(siginfo_t)))
			return -EFAULT;
		ret = copy_siginfo_to_user32(si32, &ssi);
	}
	return ret;
}

asmlinkage long sys32_ptrace(long request, u32 pid, u32 addr, u32 data)
{
	struct task_struct *child;
	struct pt_regs *childregs;
	void __user *datap = compat_ptr(data);
	int ret;
	__u32 val;

	switch (request) {
	case PTRACE_TRACEME:
	case PTRACE_ATTACH:
	case PTRACE_KILL:
	case PTRACE_CONT:
	case PTRACE_SINGLESTEP:
	case PTRACE_SINGLEBLOCK:
	case PTRACE_DETACH:
	case PTRACE_SYSCALL:
	case PTRACE_OLDSETOPTIONS:
	case PTRACE_SETOPTIONS:
	case PTRACE_SET_THREAD_AREA:
	case PTRACE_GET_THREAD_AREA:
	case PTRACE_BTS_CONFIG:
	case PTRACE_BTS_STATUS:
	case PTRACE_BTS_SIZE:
	case PTRACE_BTS_GET:
	case PTRACE_BTS_CLEAR:
	case PTRACE_BTS_DRAIN:
		return sys_ptrace(request, pid, addr, data);

	default:
		return -EINVAL;

	case PTRACE_PEEKTEXT:
	case PTRACE_PEEKDATA:
	case PTRACE_POKEDATA:
	case PTRACE_POKETEXT:
	case PTRACE_POKEUSR:
	case PTRACE_PEEKUSR:
	case PTRACE_GETREGS:
	case PTRACE_SETREGS:
	case PTRACE_SETFPREGS:
	case PTRACE_GETFPREGS:
	case PTRACE_SETFPXREGS:
	case PTRACE_GETFPXREGS:
	case PTRACE_GETEVENTMSG:
		break;

	case PTRACE_SETSIGINFO:
	case PTRACE_GETSIGINFO:
		return ptrace32_siginfo(request, pid, addr, data);
	}

	child = ptrace_get_task_struct(pid);
	if (IS_ERR(child))
		return PTR_ERR(child);

	ret = ptrace_check_attach(child, request == PTRACE_KILL);
	if (ret < 0)
		goto out;

	childregs = task_pt_regs(child);

	switch (request) {
	case PTRACE_PEEKDATA:
	case PTRACE_PEEKTEXT:
		ret = 0;
		if (access_process_vm(child, addr, &val, sizeof(u32), 0) !=
		    sizeof(u32))
			ret = -EIO;
		else
			ret = put_user(val, (unsigned int __user *)datap);
		break;

	case PTRACE_POKEDATA:
	case PTRACE_POKETEXT:
		ret = 0;
		if (access_process_vm(child, addr, &data, sizeof(u32), 1) !=
		    sizeof(u32))
			ret = -EIO;
		break;

	case PTRACE_PEEKUSR:
		ret = getreg32(child, addr, &val);
		if (ret == 0)
			ret = put_user(val, (__u32 __user *)datap);
		break;

	case PTRACE_POKEUSR:
		ret = putreg32(child, addr, data);
		break;

	case PTRACE_GETREGS: { /* Get all gp regs from the child. */
		int i;

		if (!access_ok(VERIFY_WRITE, datap, 16*4)) {
			ret = -EIO;
			break;
		}
		ret = 0;
		for (i = 0; i < sizeof(struct user_regs_struct32); i += sizeof(__u32)) {
			getreg32(child, i, &val);
			ret |= __put_user(val, (u32 __user *)datap);
			datap += sizeof(u32);
		}
		break;
	}

	case PTRACE_SETREGS: { /* Set all gp regs in the child. */
		unsigned long tmp;
		int i;

		if (!access_ok(VERIFY_READ, datap, 16*4)) {
			ret = -EIO;
			break;
		}
		ret = 0;
		for (i = 0; i < sizeof(struct user_regs_struct32); i += sizeof(u32)) {
			ret |= __get_user(tmp, (u32 __user *)datap);
			putreg32(child, i, tmp);
			datap += sizeof(u32);
		}
		break;
	}

	case PTRACE_GETFPREGS:
		ret = -EIO;
		if (!access_ok(VERIFY_READ, compat_ptr(data),
			       sizeof(struct user_i387_struct)))
			break;
		save_i387_ia32(child, datap, childregs, 1);
		ret = 0;
			break;

	case PTRACE_SETFPREGS:
		ret = -EIO;
		if (!access_ok(VERIFY_WRITE, datap,
			       sizeof(struct user_i387_struct)))
			break;
		ret = 0;
		/* don't check EFAULT to be bug-to-bug compatible to i386 */
		restore_i387_ia32(child, datap, 1);
		break;

	case PTRACE_GETFPXREGS: {
		struct user32_fxsr_struct __user *u = datap;

		init_fpu(child);
		ret = -EIO;
		if (!access_ok(VERIFY_WRITE, u, sizeof(*u)))
			break;
			ret = -EFAULT;
		if (__copy_to_user(u, &child->thread.i387.fxsave, sizeof(*u)))
			break;
		ret = __put_user(childregs->cs, &u->fcs);
		ret |= __put_user(child->thread.ds, &u->fos);
		break;
	}
	case PTRACE_SETFPXREGS: {
		struct user32_fxsr_struct __user *u = datap;

		unlazy_fpu(child);
		ret = -EIO;
		if (!access_ok(VERIFY_READ, u, sizeof(*u)))
			break;
		/*
		 * no checking to be bug-to-bug compatible with i386.
		 * but silence warning
		 */
		if (__copy_from_user(&child->thread.i387.fxsave, u, sizeof(*u)))
			;
		set_stopped_child_used_math(child);
		child->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
		ret = 0;
		break;
	}

	case PTRACE_GETEVENTMSG:
		ret = put_user(child->ptrace_message,
			       (unsigned int __user *)compat_ptr(data));
		break;

	default:
		BUG();
	}

 out:
	put_task_struct(child);
	return ret;
}

#endif	/* CONFIG_IA32_EMULATION */

#ifdef CONFIG_X86_32

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

	/* Send us the fake 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_ax);

	if (unlikely(current->audit_context)) {
		if (entryexit)
			audit_syscall_exit(AUDITSC_RESULT(regs->ax),
						regs->ax);
		/* 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(AUDIT_ARCH_I386, regs->orig_ax,
				    regs->bx, regs->cx, regs->dx, regs->si);
	if (ret == 0)
		return 0;

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

#else  /* CONFIG_X86_64 */

static void syscall_trace(struct pt_regs *regs)
{

#if 0
	printk("trace %s ip %lx sp %lx ax %d origrax %d caller %lx tiflags %x ptrace %x\n",
	       current->comm,
	       regs->ip, regs->sp, regs->ax, regs->orig_ax, __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_ax);

	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_ax,
					    regs->bx, regs->cx,
					    regs->dx, regs->si);
		} else {
			audit_syscall_entry(AUDIT_ARCH_X86_64,
					    regs->orig_ax,
					    regs->di, regs->si,
					    regs->dx, regs->r10);
		}
	}
}

asmlinkage void syscall_trace_leave(struct pt_regs *regs)
{
	if (unlikely(current->audit_context))
		audit_syscall_exit(AUDITSC_RESULT(regs->ax), regs->ax);

	if ((test_thread_flag(TIF_SYSCALL_TRACE)
	     || test_thread_flag(TIF_SINGLESTEP))
	    && (current->ptrace & PT_PTRACED))
		syscall_trace(regs);
}

#endif	/* CONFIG_X86_32 */