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x86: user_regset helpers

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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: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Roland McGrath 2008-01-30 13:31:45 +01:00 committed by Ingo Molnar
parent 4206d3aa19
commit bae3f7c39d
1 changed files with 116 additions and 0 deletions
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116
include/linux/regset.h
View file

@ -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> */