Commit bae3f7c3 authored by Roland McGrath's avatar Roland McGrath Committed by Ingo Molnar
Browse files

x86: user_regset helpers 



This adds some inlines to linux/regset.h intended for arch code to use in
its user_regset get and set functions.  These make it pretty easy to deal
with the interface's optional kernel-space or user-space pointers and its
generalized access to a part of the register data at a time.

In simple cases where the internal data structure matches the exported
layout (core dump format), a get function can be nothing but a call to
user_regset_copyout, and a set function a call to user_regset_copyin.

In other cases the exported layout is usually made up of a few pieces each
stored contiguously in a different internal data structure.  These helpers
make it straightforward to write a get or set function by processing each
contiguous chunk of the data in order.  The start_pos and end_pos arguments
are always constants, so these inlines collapse to a small amount of code.

Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 4206d3aa

include/linux/regset.h

+116 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 


#include <linux/compiler.h>

#include <linux/types.h>

#include <linux/uaccess.h>

struct task_struct;

struct user_regset;
@@ -203,4 +204,119 @@ struct user_regset_view { 
const struct user_regset_view *task_user_regset_view(struct task_struct *tsk);





/*

 * These are helpers for writing regset get/set functions in arch code.

 * Because @start_pos and @end_pos are always compile-time constants,

 * these are inlined into very little code though they look large.

 *

 * Use one or more calls sequentially for each chunk of regset data stored

 * contiguously in memory.  Call with constants for @start_pos and @end_pos,

 * giving the range of byte positions in the regset that data corresponds

 * to; @end_pos can be -1 if this chunk is at the end of the regset layout.

 * Each call updates the arguments to point past its chunk.

 */



static inline int user_regset_copyout(unsigned int *pos, unsigned int *count,

				      void **kbuf,

				      void __user **ubuf, const void *data,

				      const int start_pos, const int end_pos)

{

	if (*count == 0)

		return 0;

	BUG_ON(*pos < start_pos);

	if (end_pos < 0 || *pos < end_pos) {

		unsigned int copy = (end_pos < 0 ? *count

				     : min(*count, end_pos - *pos));

		data += *pos - start_pos;

		if (*kbuf) {

			memcpy(*kbuf, data, copy);

			*kbuf += copy;

		} else if (__copy_to_user(*ubuf, data, copy))

			return -EFAULT;

		else

			*ubuf += copy;

		*pos += copy;

		*count -= copy;

	}

	return 0;

}



static inline int user_regset_copyin(unsigned int *pos, unsigned int *count,

				     const void **kbuf,

				     const void __user **ubuf, void *data,

				     const int start_pos, const int end_pos)

{

	if (*count == 0)

		return 0;

	BUG_ON(*pos < start_pos);

	if (end_pos < 0 || *pos < end_pos) {

		unsigned int copy = (end_pos < 0 ? *count

				     : min(*count, end_pos - *pos));

		data += *pos - start_pos;

		if (*kbuf) {

			memcpy(data, *kbuf, copy);

			*kbuf += copy;

		} else if (__copy_from_user(data, *ubuf, copy))

			return -EFAULT;

		else

			*ubuf += copy;

		*pos += copy;

		*count -= copy;

	}

	return 0;

}



/*

 * These two parallel the two above, but for portions of a regset layout

 * that always read as all-zero or for which writes are ignored.

 */

static inline int user_regset_copyout_zero(unsigned int *pos,

					   unsigned int *count,

					   void **kbuf, void __user **ubuf,

					   const int start_pos,

					   const int end_pos)

{

	if (*count == 0)

		return 0;

	BUG_ON(*pos < start_pos);

	if (end_pos < 0 || *pos < end_pos) {

		unsigned int copy = (end_pos < 0 ? *count

				     : min(*count, end_pos - *pos));

		if (*kbuf) {

			memset(*kbuf, 0, copy);

			*kbuf += copy;

		} else if (__clear_user(*ubuf, copy))

			return -EFAULT;

		else

			*ubuf += copy;

		*pos += copy;

		*count -= copy;

	}

	return 0;

}



static inline int user_regset_copyin_ignore(unsigned int *pos,

					    unsigned int *count,

					    const void **kbuf,

					    const void __user **ubuf,

					    const int start_pos,

					    const int end_pos)

{

	if (*count == 0)

		return 0;

	BUG_ON(*pos < start_pos);

	if (end_pos < 0 || *pos < end_pos) {

		unsigned int copy = (end_pos < 0 ? *count

				     : min(*count, end_pos - *pos));

		if (*kbuf)

			*kbuf += copy;

		else

			*ubuf += copy;

		*pos += copy;

		*count -= copy;

	}

	return 0;

}





#endif	/* <linux/regset.h> */

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