Initial import

1 files changed, 1634 insertions, 0 deletions

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
new file mode 100644
index 000000000..a7bc79480
--- /dev/null
+++ b/arch/x86/kernel/ptrace.c
@@ -0,0 +1,1634 @@
+/* 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/errno.h>
+#include <linux/slab.h>
+#include <linux/ptrace.h>
+#include <linux/regset.h>
+#include <linux/tracehook.h>
+#include <linux/user.h>
+#include <linux/elf.h>
+#include <linux/security.h>
+#include <linux/audit.h>
+#include <linux/seccomp.h>
+#include <linux/signal.h>
+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>
+#include <linux/rcupdate.h>
+#include <linux/export.h>
+#include <linux/context_tracking.h>
+
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+#include <asm/processor.h>
+#include <asm/i387.h>
+#include <asm/fpu-internal.h>
+#include <asm/debugreg.h>
+#include <asm/ldt.h>
+#include <asm/desc.h>
+#include <asm/prctl.h>
+#include <asm/proto.h>
+#include <asm/hw_breakpoint.h>
+#include <asm/traps.h>
+
+#include "tls.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/syscalls.h>
+
+enum x86_regset {
+	REGSET_GENERAL,
+	REGSET_FP,
+	REGSET_XFP,
+	REGSET_IOPERM64 = REGSET_XFP,
+	REGSET_XSTATE,
+	REGSET_TLS,
+	REGSET_IOPERM32,
+};
+
+struct pt_regs_offset {
+	const char *name;
+	int offset;
+};
+
+#define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)}
+#define REG_OFFSET_END {.name = NULL, .offset = 0}
+
+static const struct pt_regs_offset regoffset_table[] = {
+#ifdef CONFIG_X86_64
+	REG_OFFSET_NAME(r15),
+	REG_OFFSET_NAME(r14),
+	REG_OFFSET_NAME(r13),
+	REG_OFFSET_NAME(r12),
+	REG_OFFSET_NAME(r11),
+	REG_OFFSET_NAME(r10),
+	REG_OFFSET_NAME(r9),
+	REG_OFFSET_NAME(r8),
+#endif
+	REG_OFFSET_NAME(bx),
+	REG_OFFSET_NAME(cx),
+	REG_OFFSET_NAME(dx),
+	REG_OFFSET_NAME(si),
+	REG_OFFSET_NAME(di),
+	REG_OFFSET_NAME(bp),
+	REG_OFFSET_NAME(ax),
+#ifdef CONFIG_X86_32
+	REG_OFFSET_NAME(ds),
+	REG_OFFSET_NAME(es),
+	REG_OFFSET_NAME(fs),
+	REG_OFFSET_NAME(gs),
+#endif
+	REG_OFFSET_NAME(orig_ax),
+	REG_OFFSET_NAME(ip),
+	REG_OFFSET_NAME(cs),
+	REG_OFFSET_NAME(flags),
+	REG_OFFSET_NAME(sp),
+	REG_OFFSET_NAME(ss),
+	REG_OFFSET_END,
+};
+
+/**
+ * regs_query_register_offset() - query register offset from its name
+ * @name:	the name of a register
+ *
+ * regs_query_register_offset() returns the offset of a register in struct
+ * pt_regs from its name. If the name is invalid, this returns -EINVAL;
+ */
+int regs_query_register_offset(const char *name)
+{
+	const struct pt_regs_offset *roff;
+	for (roff = regoffset_table; roff->name != NULL; roff++)
+		if (!strcmp(roff->name, name))
+			return roff->offset;
+	return -EINVAL;
+}
+
+/**
+ * regs_query_register_name() - query register name from its offset
+ * @offset:	the offset of a register in struct pt_regs.
+ *
+ * regs_query_register_name() returns the name of a register from its
+ * offset in struct pt_regs. If the @offset is invalid, this returns NULL;
+ */
+const char *regs_query_register_name(unsigned int offset)
+{
+	const struct pt_regs_offset *roff;
+	for (roff = regoffset_table; roff->name != NULL; roff++)
+		if (roff->offset == offset)
+			return roff->name;
+	return NULL;
+}
+
+static const int arg_offs_table[] = {
+#ifdef CONFIG_X86_32
+	[0] = offsetof(struct pt_regs, ax),
+	[1] = offsetof(struct pt_regs, dx),
+	[2] = offsetof(struct pt_regs, cx)
+#else /* CONFIG_X86_64 */
+	[0] = offsetof(struct pt_regs, di),
+	[1] = offsetof(struct pt_regs, si),
+	[2] = offsetof(struct pt_regs, dx),
+	[3] = offsetof(struct pt_regs, cx),
+	[4] = offsetof(struct pt_regs, r8),
+	[5] = offsetof(struct pt_regs, r9)
+#endif
+};
+
+/*
+ * 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
+
+/*
+ * X86_32 CPUs don't save ss and esp if the CPU is already in kernel mode
+ * when it traps.  The previous stack will be directly underneath the saved
+ * registers, and 'sp/ss' won't even have been saved. Thus the '&regs->sp'.
+ *
+ * Now, if the stack is empty, '&regs->sp' is out of range. In this
+ * case we try to take the previous stack. To always return a non-null
+ * stack pointer we fall back to regs as stack if no previous stack
+ * exists.
+ *
+ * This is valid only for kernel mode traps.
+ */
+unsigned long kernel_stack_pointer(struct pt_regs *regs)
+{
+	unsigned long context = (unsigned long)regs & ~(THREAD_SIZE - 1);
+	unsigned long sp = (unsigned long)&regs->sp;
+	u32 *prev_esp;
+
+	if (context == (sp & ~(THREAD_SIZE - 1)))
+		return sp;
+
+	prev_esp = (u32 *)(context);
+	if (prev_esp)
+		return (unsigned long)prev_esp;
+
+	return (unsigned long)regs;
+}
+EXPORT_SYMBOL_GPL(kernel_stack_pointer);
+
+static unsigned long *pt_regs_access(struct pt_regs *regs, unsigned long regno)
+{
+	BUILD_BUG_ON(offsetof(struct pt_regs, bx) != 0);
+	return &regs->bx + (regno >> 2);
+}
+
+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 {
+		if (task == current)
+			retval = get_user_gs(task_pt_regs(task));
+		else
+			retval = task_user_gs(task);
+	}
+	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;
+
+	/*
+	 * For %cs and %ss we cannot permit a null selector.
+	 * We can permit a bogus selector as long as it has USER_RPL.
+	 * Null selectors are fine for other segment registers, but
+	 * we will never get back to user mode with invalid %cs or %ss
+	 * and will take the trap in iret instead.  Much code relies
+	 * on user_mode() to distinguish a user trap frame (which can
+	 * safely use invalid selectors) from a kernel trap frame.
+	 */
+	switch (offset) {
+	case offsetof(struct user_regs_struct, cs):
+	case offsetof(struct user_regs_struct, ss):
+		if (unlikely(value == 0))
+			return -EIO;
+
+	default:
+		*pt_regs_access(task_pt_regs(task), offset) = value;
+		break;
+
+	case offsetof(struct user_regs_struct, gs):
+		if (task == current)
+			set_user_gs(task_pt_regs(task), value);
+		else
+			task_user_gs(task) = value;
+	}
+
+	return 0;
+}
+
+#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):
+		if (unlikely(value == 0))
+			return -EIO;
+		task_pt_regs(task)->cs = value;
+		break;
+	case offsetof(struct user_regs_struct,ss):
+		if (unlikely(value == 0))
+			return -EIO;
+		task_pt_regs(task)->ss = value;
+		break;
+	}
+
+	return 0;
+}
+
+#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 >= sizeof(*k)) {
+			*k++ = getreg(target, pos);
+			count -= sizeof(*k);
+			pos += sizeof(*k);
+		}
+	} else {
+		unsigned long __user *u = ubuf;
+		while (count >= sizeof(*u)) {
+			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 >= sizeof(*k) && !ret) {
+			ret = putreg(target, pos, *k++);
+			count -= sizeof(*k);
+			pos += sizeof(*k);
+		}
+	} else {
+		const unsigned long  __user *u = ubuf;
+		while (count >= sizeof(*u) && !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;
+}
+
+static void ptrace_triggered(struct perf_event *bp,
+			     struct perf_sample_data *data,
+			     struct pt_regs *regs)
+{
+	int i;
+	struct thread_struct *thread = &(current->thread);
+
+	/*
+	 * Store in the virtual DR6 register the fact that the breakpoint
+	 * was hit so the thread's debugger will see it.
+	 */
+	for (i = 0; i < HBP_NUM; i++) {
+		if (thread->ptrace_bps[i] == bp)
+			break;
+	}
+
+	thread->debugreg6 |= (DR_TRAP0 << i);
+}
+
+/*
+ * Walk through every ptrace breakpoints for this thread and
+ * build the dr7 value on top of their attributes.
+ *
+ */
+static unsigned long ptrace_get_dr7(struct perf_event *bp[])
+{
+	int i;
+	int dr7 = 0;
+	struct arch_hw_breakpoint *info;
+
+	for (i = 0; i < HBP_NUM; i++) {
+		if (bp[i] && !bp[i]->attr.disabled) {
+			info = counter_arch_bp(bp[i]);
+			dr7 |= encode_dr7(i, info->len, info->type);
+		}
+	}
+
+	return dr7;
+}
+
+static int ptrace_fill_bp_fields(struct perf_event_attr *attr,
+					int len, int type, bool disabled)
+{
+	int err, bp_len, bp_type;
+
+	err = arch_bp_generic_fields(len, type, &bp_len, &bp_type);
+	if (!err) {
+		attr->bp_len = bp_len;
+		attr->bp_type = bp_type;
+		attr->disabled = disabled;
+	}
+
+	return err;
+}
+
+static struct perf_event *
+ptrace_register_breakpoint(struct task_struct *tsk, int len, int type,
+				unsigned long addr, bool disabled)
+{
+	struct perf_event_attr attr;
+	int err;
+
+	ptrace_breakpoint_init(&attr);
+	attr.bp_addr = addr;
+
+	err = ptrace_fill_bp_fields(&attr, len, type, disabled);
+	if (err)
+		return ERR_PTR(err);
+
+	return register_user_hw_breakpoint(&attr, ptrace_triggered,
+						 NULL, tsk);
+}
+
+static int ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
+					int disabled)
+{
+	struct perf_event_attr attr = bp->attr;
+	int err;
+
+	err = ptrace_fill_bp_fields(&attr, len, type, disabled);
+	if (err)
+		return err;
+
+	return modify_user_hw_breakpoint(bp, &attr);
+}
+
+/*
+ * Handle ptrace writes to debug register 7.
+ */
+static int ptrace_write_dr7(struct task_struct *tsk, unsigned long data)
+{
+	struct thread_struct *thread = &tsk->thread;
+	unsigned long old_dr7;
+	bool second_pass = false;
+	int i, rc, ret = 0;
+
+	data &= ~DR_CONTROL_RESERVED;
+	old_dr7 = ptrace_get_dr7(thread->ptrace_bps);
+
+restore:
+	rc = 0;
+	for (i = 0; i < HBP_NUM; i++) {
+		unsigned len, type;
+		bool disabled = !decode_dr7(data, i, &len, &type);
+		struct perf_event *bp = thread->ptrace_bps[i];
+
+		if (!bp) {
+			if (disabled)
+				continue;
+
+			bp = ptrace_register_breakpoint(tsk,
+					len, type, 0, disabled);
+			if (IS_ERR(bp)) {
+				rc = PTR_ERR(bp);
+				break;
+			}
+
+			thread->ptrace_bps[i] = bp;
+			continue;
+		}
+
+		rc = ptrace_modify_breakpoint(bp, len, type, disabled);
+		if (rc)
+			break;
+	}
+
+	/* Restore if the first pass failed, second_pass shouldn't fail. */
+	if (rc && !WARN_ON(second_pass)) {
+		ret = rc;
+		data = old_dr7;
+		second_pass = true;
+		goto restore;
+	}
+
+	return ret;
+}
+
+/*
+ * Handle PTRACE_PEEKUSR calls for the debug register area.
+ */
+static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n)
+{
+	struct thread_struct *thread = &tsk->thread;
+	unsigned long val = 0;
+
+	if (n < HBP_NUM) {
+		struct perf_event *bp = thread->ptrace_bps[n];
+
+		if (bp)
+			val = bp->hw.info.address;
+	} else if (n == 6) {
+		val = thread->debugreg6;
+	} else if (n == 7) {
+		val = thread->ptrace_dr7;
+	}
+	return val;
+}
+
+static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
+				      unsigned long addr)
+{
+	struct thread_struct *t = &tsk->thread;
+	struct perf_event *bp = t->ptrace_bps[nr];
+	int err = 0;
+
+	if (!bp) {
+		/*
+		 * Put stub len and type to create an inactive but correct bp.
+		 *
+		 * CHECKME: the previous code returned -EIO if the addr wasn't
+		 * a valid task virtual addr. The new one will return -EINVAL in
+		 *  this case.
+		 * -EINVAL may be what we want for in-kernel breakpoints users,
+		 * but -EIO looks better for ptrace, since we refuse a register
+		 * writing for the user. And anyway this is the previous
+		 * behaviour.
+		 */
+		bp = ptrace_register_breakpoint(tsk,
+				X86_BREAKPOINT_LEN_1, X86_BREAKPOINT_WRITE,
+				addr, true);
+		if (IS_ERR(bp))
+			err = PTR_ERR(bp);
+		else
+			t->ptrace_bps[nr] = bp;
+	} else {
+		struct perf_event_attr attr = bp->attr;
+
+		attr.bp_addr = addr;
+		err = modify_user_hw_breakpoint(bp, &attr);
+	}
+
+	return err;
+}
+
+/*
+ * Handle PTRACE_POKEUSR calls for the debug register area.
+ */
+static int ptrace_set_debugreg(struct task_struct *tsk, int n,
+			       unsigned long val)
+{
+	struct thread_struct *thread = &tsk->thread;
+	/* There are no DR4 or DR5 registers */
+	int rc = -EIO;
+
+	if (n < HBP_NUM) {
+		rc = ptrace_set_breakpoint_addr(tsk, n, val);
+	} else if (n == 6) {
+		thread->debugreg6 = val;
+		rc = 0;
+	} else if (n == 7) {
+		rc = ptrace_write_dr7(tsk, val);
+		if (!rc)
+			thread->ptrace_dr7 = val;
+	}
+	return rc;
+}
+
+/*
+ * These access the current or another (stopped) task's io permission
+ * bitmap for debugging or core dump.
+ */
+static int ioperm_active(struct task_struct *target,
+			 const struct user_regset *regset)
+{
+	return target->thread.io_bitmap_max / regset->size;
+}
+
+static int ioperm_get(struct task_struct *target,
+		      const struct user_regset *regset,
+		      unsigned int pos, unsigned int count,
+		      void *kbuf, void __user *ubuf)
+{
+	if (!target->thread.io_bitmap_ptr)
+		return -ENXIO;
+
+	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				   target->thread.io_bitmap_ptr,
+				   0, IO_BITMAP_BYTES);
+}
+
+/*
+ * 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
+}
+
+#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
+static const struct user_regset_view user_x86_32_view; /* Initialized below. */
+#endif
+
+long arch_ptrace(struct task_struct *child, long request,
+		 unsigned long addr, unsigned long data)
+{
+	int ret;
+	unsigned long __user *datap = (unsigned long __user *)data;
+
+	switch (request) {
+	/* read the word at location addr in the USER area. */
+	case PTRACE_PEEKUSR: {
+		unsigned long tmp;
+
+		ret = -EIO;
+		if ((addr & (sizeof(data) - 1)) || 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;
+	}
+
+	case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
+		ret = -EIO;
+		if ((addr & (sizeof(data) - 1)) || 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. */
+		return copy_regset_to_user(child,
+					   task_user_regset_view(current),
+					   REGSET_GENERAL,
+					   0, sizeof(struct user_regs_struct),
+					   datap);
+
+	case PTRACE_SETREGS:	/* Set all gp regs in the child. */
+		return copy_regset_from_user(child,
+					     task_user_regset_view(current),
+					     REGSET_GENERAL,
+					     0, sizeof(struct user_regs_struct),
+					     datap);
+
+	case PTRACE_GETFPREGS:	/* Get the child FPU state. */
+		return copy_regset_to_user(child,
+					   task_user_regset_view(current),
+					   REGSET_FP,
+					   0, sizeof(struct user_i387_struct),
+					   datap);
+
+	case PTRACE_SETFPREGS:	/* Set the child FPU state. */
+		return copy_regset_from_user(child,
+					     task_user_regset_view(current),
+					     REGSET_FP,
+					     0, sizeof(struct user_i387_struct),
+					     datap);
+
+#ifdef CONFIG_X86_32
+	case PTRACE_GETFPXREGS:	/* Get the child extended FPU state. */
+		return copy_regset_to_user(child, &user_x86_32_view,
+					   REGSET_XFP,
+					   0, sizeof(struct user_fxsr_struct),
+					   datap) ? -EIO : 0;
+
+	case PTRACE_SETFPXREGS:	/* Set the child extended FPU state. */
+		return copy_regset_from_user(child, &user_x86_32_view,
+					     REGSET_XFP,
+					     0, sizeof(struct user_fxsr_struct),
+					     datap) ? -EIO : 0;
+#endif
+
+#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
+	case PTRACE_GET_THREAD_AREA:
+		if ((int) addr < 0)
+			return -EIO;
+		ret = do_get_thread_area(child, addr,
+					(struct user_desc __user *)data);
+		break;
+
+	case PTRACE_SET_THREAD_AREA:
+		if ((int) 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
+
+	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(eip, ip);
+	R32(esp, sp);
+
+	case offsetof(struct user32, regs.orig_eax):
+		/*
+		 * A 32-bit debugger setting orig_eax means to restore
+		 * the state of the task restarting a 32-bit syscall.
+		 * Make sure we interpret the -ERESTART* codes correctly
+		 * in case the task is not actually still sitting at the
+		 * exit from a 32-bit syscall with TS_COMPAT still set.
+		 */
+		regs->orig_ax = value;
+		if (syscall_get_nr(child, regs) >= 0)
+			task_thread_info(child)->status |= TS_COMPAT;
+		break;
+
+	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 >= sizeof(*k)) {
+			getreg32(target, pos, k++);
+			count -= sizeof(*k);
+			pos += sizeof(*k);
+		}
+	} else {
+		compat_ulong_t __user *u = ubuf;
+		while (count >= sizeof(*u)) {
+			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 >= sizeof(*k) && !ret) {
+			ret = putreg32(target, pos, *k++);
+			count -= sizeof(*k);
+			pos += sizeof(*k);
+		}
+	} else {
+		const compat_ulong_t __user *u = ubuf;
+		while (count >= sizeof(*u) && !ret) {
+			compat_ulong_t word;
+			ret = __get_user(word, u++);
+			if (ret)
+				break;
+			ret = putreg32(target, pos, word);
+			count -= sizeof(*u);
+			pos += sizeof(*u);
+		}
+	}
+	return ret;
+}
+
+#ifdef CONFIG_X86_X32_ABI
+static long x32_arch_ptrace(struct task_struct *child,
+			    compat_long_t request, compat_ulong_t caddr,
+			    compat_ulong_t cdata)
+{
+	unsigned long addr = caddr;
+	unsigned long data = cdata;
+	void __user *datap = compat_ptr(data);
+	int ret;
+
+	switch (request) {
+	/* Read 32bits at location addr in the USER area.  Only allow
+	   to return the lower 32bits of segment and debug registers.  */
+	case PTRACE_PEEKUSR: {
+		u32 tmp;
+
+		ret = -EIO;
+		if ((addr & (sizeof(data) - 1)) || addr >= sizeof(struct user) ||
+		    addr < offsetof(struct user_regs_struct, cs))
+			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, (__u32 __user *)datap);
+		break;
+	}
+
+	/* Write the word at location addr in the USER area.  Only allow
+	   to update segment and debug registers with the upper 32bits
+	   zero-extended. */
+	case PTRACE_POKEUSR:
+		ret = -EIO;
+		if ((addr & (sizeof(data) - 1)) || addr >= sizeof(struct user) ||
+		    addr < offsetof(struct user_regs_struct, cs))
+			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. */
+		return copy_regset_to_user(child,
+					   task_user_regset_view(current),
+					   REGSET_GENERAL,
+					   0, sizeof(struct user_regs_struct),
+					   datap);
+
+	case PTRACE_SETREGS:	/* Set all gp regs in the child. */
+		return copy_regset_from_user(child,
+					     task_user_regset_view(current),
+					     REGSET_GENERAL,
+					     0, sizeof(struct user_regs_struct),
+					     datap);
+
+	case PTRACE_GETFPREGS:	/* Get the child FPU state. */
+		return copy_regset_to_user(child,
+					   task_user_regset_view(current),
+					   REGSET_FP,
+					   0, sizeof(struct user_i387_struct),
+					   datap);
+
+	case PTRACE_SETFPREGS:	/* Set the child FPU state. */
+		return copy_regset_from_user(child,
+					     task_user_regset_view(current),
+					     REGSET_FP,
+					     0, sizeof(struct user_i387_struct),
+					     datap);
+
+	default:
+		return compat_ptrace_request(child, request, addr, data);
+	}
+
+	return ret;
+}
+#endif
+
+long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
+			compat_ulong_t caddr, compat_ulong_t cdata)
+{
+	unsigned long addr = caddr;
+	unsigned long data = cdata;
+	void __user *datap = compat_ptr(data);
+	int ret;
+	__u32 val;
+
+#ifdef CONFIG_X86_X32_ABI
+	if (!is_ia32_task())
+		return x32_arch_ptrace(child, request, caddr, cdata);
+#endif
+
+	switch (request) {
+	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. */
+		return copy_regset_to_user(child, &user_x86_32_view,
+					   REGSET_GENERAL,
+					   0, sizeof(struct user_regs_struct32),
+					   datap);
+
+	case PTRACE_SETREGS:	/* Set all gp regs in the child. */
+		return copy_regset_from_user(child, &user_x86_32_view,
+					     REGSET_GENERAL, 0,
+					     sizeof(struct user_regs_struct32),
+					     datap);
+
+	case PTRACE_GETFPREGS:	/* Get the child FPU state. */
+		return copy_regset_to_user(child, &user_x86_32_view,
+					   REGSET_FP, 0,
+					   sizeof(struct user_i387_ia32_struct),
+					   datap);
+
+	case PTRACE_SETFPREGS:	/* Set the child FPU state. */
+		return copy_regset_from_user(
+			child, &user_x86_32_view, REGSET_FP,
+			0, sizeof(struct user_i387_ia32_struct), datap);
+
+	case PTRACE_GETFPXREGS:	/* Get the child extended FPU state. */
+		return copy_regset_to_user(child, &user_x86_32_view,
+					   REGSET_XFP, 0,
+					   sizeof(struct user32_fxsr_struct),
+					   datap);
+
+	case PTRACE_SETFPXREGS:	/* Set the child extended FPU state. */
+		return copy_regset_from_user(child, &user_x86_32_view,
+					     REGSET_XFP, 0,
+					     sizeof(struct user32_fxsr_struct),
+					     datap);
+
+	case PTRACE_GET_THREAD_AREA:
+	case PTRACE_SET_THREAD_AREA:
+		return arch_ptrace(child, request, addr, data);
+
+	default:
+		return compat_ptrace_request(child, request, addr, data);
+	}
+
+	return ret;
+}
+
+#endif	/* CONFIG_IA32_EMULATION */
+
+#ifdef CONFIG_X86_64
+
+static struct user_regset x86_64_regsets[] __read_mostly = {
+	[REGSET_GENERAL] = {
+		.core_note_type = NT_PRSTATUS,
+		.n = sizeof(struct user_regs_struct) / sizeof(long),
+		.size = sizeof(long), .align = sizeof(long),
+		.get = genregs_get, .set = genregs_set
+	},
+	[REGSET_FP] = {
+		.core_note_type = NT_PRFPREG,
+		.n = sizeof(struct user_i387_struct) / sizeof(long),
+		.size = sizeof(long), .align = sizeof(long),
+		.active = xfpregs_active, .get = xfpregs_get, .set = xfpregs_set
+	},
+	[REGSET_XSTATE] = {
+		.core_note_type = NT_X86_XSTATE,
+		.size = sizeof(u64), .align = sizeof(u64),
+		.active = xstateregs_active, .get = xstateregs_get,
+		.set = xstateregs_set
+	},
+	[REGSET_IOPERM64] = {
+		.core_note_type = NT_386_IOPERM,
+		.n = IO_BITMAP_LONGS,
+		.size = sizeof(long), .align = sizeof(long),
+		.active = ioperm_active, .get = ioperm_get
+	},
+};
+
+static const struct user_regset_view user_x86_64_view = {
+	.name = "x86_64", .e_machine = EM_X86_64,
+	.regsets = x86_64_regsets, .n = ARRAY_SIZE(x86_64_regsets)
+};
+
+#else  /* CONFIG_X86_32 */
+
+#define user_regs_struct32	user_regs_struct
+#define genregs32_get		genregs_get
+#define genregs32_set		genregs_set
+
+#endif	/* CONFIG_X86_64 */
+
+#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
+static struct user_regset x86_32_regsets[] __read_mostly = {
+	[REGSET_GENERAL] = {
+		.core_note_type = NT_PRSTATUS,
+		.n = sizeof(struct user_regs_struct32) / sizeof(u32),
+		.size = sizeof(u32), .align = sizeof(u32),
+		.get = genregs32_get, .set = genregs32_set
+	},
+	[REGSET_FP] = {
+		.core_note_type = NT_PRFPREG,
+		.n = sizeof(struct user_i387_ia32_struct) / sizeof(u32),
+		.size = sizeof(u32), .align = sizeof(u32),
+		.active = fpregs_active, .get = fpregs_get, .set = fpregs_set
+	},
+	[REGSET_XFP] = {
+		.core_note_type = NT_PRXFPREG,
+		.n = sizeof(struct user32_fxsr_struct) / sizeof(u32),
+		.size = sizeof(u32), .align = sizeof(u32),
+		.active = xfpregs_active, .get = xfpregs_get, .set = xfpregs_set
+	},
+	[REGSET_XSTATE] = {
+		.core_note_type = NT_X86_XSTATE,
+		.size = sizeof(u64), .align = sizeof(u64),
+		.active = xstateregs_active, .get = xstateregs_get,
+		.set = xstateregs_set
+	},
+	[REGSET_TLS] = {
+		.core_note_type = NT_386_TLS,
+		.n = GDT_ENTRY_TLS_ENTRIES, .bias = GDT_ENTRY_TLS_MIN,
+		.size = sizeof(struct user_desc),
+		.align = sizeof(struct user_desc),
+		.active = regset_tls_active,
+		.get = regset_tls_get, .set = regset_tls_set
+	},
+	[REGSET_IOPERM32] = {
+		.core_note_type = NT_386_IOPERM,
+		.n = IO_BITMAP_BYTES / sizeof(u32),
+		.size = sizeof(u32), .align = sizeof(u32),
+		.active = ioperm_active, .get = ioperm_get
+	},
+};
+
+static const struct user_regset_view user_x86_32_view = {
+	.name = "i386", .e_machine = EM_386,
+	.regsets = x86_32_regsets, .n = ARRAY_SIZE(x86_32_regsets)
+};
+#endif
+
+/*
+ * This represents bytes 464..511 in the memory layout exported through
+ * the REGSET_XSTATE interface.
+ */
+u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
+
+void update_regset_xstate_info(unsigned int size, u64 xstate_mask)
+{
+#ifdef CONFIG_X86_64
+	x86_64_regsets[REGSET_XSTATE].n = size / sizeof(u64);
+#endif
+#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
+	x86_32_regsets[REGSET_XSTATE].n = size / sizeof(u64);
+#endif
+	xstate_fx_sw_bytes[USER_XSTATE_XCR0_WORD] = xstate_mask;
+}
+
+const struct user_regset_view *task_user_regset_view(struct task_struct *task)
+{
+#ifdef CONFIG_IA32_EMULATION
+	if (test_tsk_thread_flag(task, TIF_IA32))
+#endif
+#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
+		return &user_x86_32_view;
+#endif
+#ifdef CONFIG_X86_64
+	return &user_x86_64_view;
+#endif
+}
+
+static void fill_sigtrap_info(struct task_struct *tsk,
+				struct pt_regs *regs,
+				int error_code, int si_code,
+				struct siginfo *info)
+{
+	tsk->thread.trap_nr = X86_TRAP_DB;
+	tsk->thread.error_code = error_code;
+
+	memset(info, 0, sizeof(*info));
+	info->si_signo = SIGTRAP;
+	info->si_code = si_code;
+	info->si_addr = user_mode(regs) ? (void __user *)regs->ip : NULL;
+}
+
+void user_single_step_siginfo(struct task_struct *tsk,
+				struct pt_regs *regs,
+				struct siginfo *info)
+{
+	fill_sigtrap_info(tsk, regs, 0, TRAP_BRKPT, info);
+}
+
+void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
+					 int error_code, int si_code)
+{
+	struct siginfo info;
+
+	fill_sigtrap_info(tsk, regs, error_code, si_code, &info);
+	/* Send us the fake SIGTRAP */
+	force_sig_info(SIGTRAP, &info, tsk);
+}
+
+static void do_audit_syscall_entry(struct pt_regs *regs, u32 arch)
+{
+#ifdef CONFIG_X86_64
+	if (arch == AUDIT_ARCH_X86_64) {
+		audit_syscall_entry(regs->orig_ax, regs->di,
+				    regs->si, regs->dx, regs->r10);
+	} else
+#endif
+	{
+		audit_syscall_entry(regs->orig_ax, regs->bx,
+				    regs->cx, regs->dx, regs->si);
+	}
+}
+
+/*
+ * We can return 0 to resume the syscall or anything else to go to phase
+ * 2.  If we resume the syscall, we need to put something appropriate in
+ * regs->orig_ax.
+ *
+ * NB: We don't have full pt_regs here, but regs->orig_ax and regs->ax
+ * are fully functional.
+ *
+ * For phase 2's benefit, our return value is:
+ * 0:			resume the syscall
+ * 1:			go to phase 2; no seccomp phase 2 needed
+ * anything else:	go to phase 2; pass return value to seccomp
+ */
+unsigned long syscall_trace_enter_phase1(struct pt_regs *regs, u32 arch)
+{
+	unsigned long ret = 0;
+	u32 work;
+
+	BUG_ON(regs != task_pt_regs(current));
+
+	work = ACCESS_ONCE(current_thread_info()->flags) &
+		_TIF_WORK_SYSCALL_ENTRY;
+
+	/*
+	 * If TIF_NOHZ is set, we are required to call user_exit() before
+	 * doing anything that could touch RCU.
+	 */
+	if (work & _TIF_NOHZ) {
+		user_exit();
+		work &= ~_TIF_NOHZ;
+	}
+
+#ifdef CONFIG_SECCOMP
+	/*
+	 * Do seccomp first -- it should minimize exposure of other
+	 * code, and keeping seccomp fast is probably more valuable
+	 * than the rest of this.
+	 */
+	if (work & _TIF_SECCOMP) {
+		struct seccomp_data sd;
+
+		sd.arch = arch;
+		sd.nr = regs->orig_ax;
+		sd.instruction_pointer = regs->ip;
+#ifdef CONFIG_X86_64
+		if (arch == AUDIT_ARCH_X86_64) {
+			sd.args[0] = regs->di;
+			sd.args[1] = regs->si;
+			sd.args[2] = regs->dx;
+			sd.args[3] = regs->r10;
+			sd.args[4] = regs->r8;
+			sd.args[5] = regs->r9;
+		} else
+#endif
+		{
+			sd.args[0] = regs->bx;
+			sd.args[1] = regs->cx;
+			sd.args[2] = regs->dx;
+			sd.args[3] = regs->si;
+			sd.args[4] = regs->di;
+			sd.args[5] = regs->bp;
+		}
+
+		BUILD_BUG_ON(SECCOMP_PHASE1_OK != 0);
+		BUILD_BUG_ON(SECCOMP_PHASE1_SKIP != 1);
+
+		ret = seccomp_phase1(&sd);
+		if (ret == SECCOMP_PHASE1_SKIP) {
+			regs->orig_ax = -1;
+			ret = 0;
+		} else if (ret != SECCOMP_PHASE1_OK) {
+			return ret;  /* Go directly to phase 2 */
+		}
+
+		work &= ~_TIF_SECCOMP;
+	}
+#endif
+
+	/* Do our best to finish without phase 2. */
+	if (work == 0)
+		return ret;  /* seccomp and/or nohz only (ret == 0 here) */
+
+#ifdef CONFIG_AUDITSYSCALL
+	if (work == _TIF_SYSCALL_AUDIT) {
+		/*
+		 * If there is no more work to be done except auditing,
+		 * then audit in phase 1.  Phase 2 always audits, so, if
+		 * we audit here, then we can't go on to phase 2.
+		 */
+		do_audit_syscall_entry(regs, arch);
+		return 0;
+	}
+#endif
+
+	return 1;  /* Something is enabled that we can't handle in phase 1 */
+}
+
+/* Returns the syscall nr to run (which should match regs->orig_ax). */
+long syscall_trace_enter_phase2(struct pt_regs *regs, u32 arch,
+				unsigned long phase1_result)
+{
+	long ret = 0;
+	u32 work = ACCESS_ONCE(current_thread_info()->flags) &
+		_TIF_WORK_SYSCALL_ENTRY;
+
+	BUG_ON(regs != task_pt_regs(current));
+
+	/*
+	 * If we stepped into a sysenter/syscall insn, it trapped in
+	 * kernel mode; do_debug() cleared TF and set TIF_SINGLESTEP.
+	 * If user-mode had set TF itself, then it's still clear from
+	 * do_debug() and we need to set it again to restore the user
+	 * state.  If we entered on the slow path, TF was already set.
+	 */
+	if (work & _TIF_SINGLESTEP)
+		regs->flags |= X86_EFLAGS_TF;
+
+#ifdef CONFIG_SECCOMP
+	/*
+	 * Call seccomp_phase2 before running the other hooks so that
+	 * they can see any changes made by a seccomp tracer.
+	 */
+	if (phase1_result > 1 && seccomp_phase2(phase1_result)) {
+		/* seccomp failures shouldn't expose any additional code. */
+		return -1;
+	}
+#endif
+
+	if (unlikely(work & _TIF_SYSCALL_EMU))
+		ret = -1L;
+
+	if ((ret || test_thread_flag(TIF_SYSCALL_TRACE)) &&
+	    tracehook_report_syscall_entry(regs))
+		ret = -1L;
+
+	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
+		trace_sys_enter(regs, regs->orig_ax);
+
+	do_audit_syscall_entry(regs, arch);
+
+	return ret ?: regs->orig_ax;
+}
+
+long syscall_trace_enter(struct pt_regs *regs)
+{
+	u32 arch = is_ia32_task() ? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64;
+	unsigned long phase1_result = syscall_trace_enter_phase1(regs, arch);
+
+	if (phase1_result == 0)
+		return regs->orig_ax;
+	else
+		return syscall_trace_enter_phase2(regs, arch, phase1_result);
+}
+
+void syscall_trace_leave(struct pt_regs *regs)
+{
+	bool step;
+
+	/*
+	 * We may come here right after calling schedule_user()
+	 * or do_notify_resume(), in which case we can be in RCU
+	 * user mode.
+	 */
+	user_exit();
+
+	audit_syscall_exit(regs);
+
+	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
+		trace_sys_exit(regs, regs->ax);
+
+	/*
+	 * If TIF_SYSCALL_EMU is set, we only get here because of
+	 * TIF_SINGLESTEP (i.e. this is PTRACE_SYSEMU_SINGLESTEP).
+	 * We already reported this syscall instruction in
+	 * syscall_trace_enter().
+	 */
+	step = unlikely(test_thread_flag(TIF_SINGLESTEP)) &&
+			!test_thread_flag(TIF_SYSCALL_EMU);
+	if (step || test_thread_flag(TIF_SYSCALL_TRACE))
+		tracehook_report_syscall_exit(regs, step);
+
+	user_enter();
+}