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[S390] Add real memory access functions

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Add access function for real memory needed by s390 kdump backend.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Michael Holzheu
2011-10-30 15:16:39 +01:00
committed by Martin Schwidefsky
parent 1943f53c9c
commit 7f0bf656c6
3 changed files with 60 additions and 18 deletions
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56
arch/s390/mm/maccess.c
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@ -11,6 +11,7 @@
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/gfp.h>
#include <asm/system.h>
/*
@ -60,6 +61,9 @@ long probe_kernel_write(void *dst, const void *src, size_t size)
return copied < 0 ? -EFAULT : 0;
}
/*
* Copy memory in real mode (kernel to kernel)
*/
int memcpy_real(void *dest, void *src, size_t count)
{
register unsigned long _dest asm("2") = (unsigned long) dest;
@ -101,3 +105,55 @@ void copy_to_absolute_zero(void *dest, void *src, size_t count)
__ctl_load(cr0, 0, 0);
preempt_enable();
}
/*
* Copy memory from kernel (real) to user (virtual)
*/
int copy_to_user_real(void __user *dest, void *src, size_t count)
{
int offs = 0, size, rc;
char *buf;
buf = (char *) __get_free_page(GFP_KERNEL);
if (!buf)
return -ENOMEM;
rc = -EFAULT;
while (offs < count) {
size = min(PAGE_SIZE, count - offs);
if (memcpy_real(buf, src + offs, size))
goto out;
if (copy_to_user(dest + offs, buf, size))
goto out;
offs += size;
}
rc = 0;
out:
free_page((unsigned long) buf);
return rc;
}
/*
* Copy memory from user (virtual) to kernel (real)
*/
int copy_from_user_real(void *dest, void __user *src, size_t count)
{
int offs = 0, size, rc;
char *buf;
buf = (char *) __get_free_page(GFP_KERNEL);
if (!buf)
return -ENOMEM;
rc = -EFAULT;
while (offs < count) {
size = min(PAGE_SIZE, count - offs);
if (copy_from_user(buf, src + offs, size))
goto out;
if (memcpy_real(dest + offs, buf, size))
goto out;
offs += size;
}
rc = 0;
out:
free_page((unsigned long) buf);
return rc;
}