path: root/arch/x86/kernel/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/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 <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

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, l