diff options
| author | Michael Holzheu <holzheu@linux.vnet.ibm.com> | 2012-05-09 16:27:36 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2012-05-16 14:42:38 +0200 |
| commit | b2a68c235663c65365c4b4424c6e6c5ee90ae3a1 (patch) | |
| tree | 2602a18a860e0dadd9a1332e6b9dd81f26ffb301 /arch/s390/include | |
| parent | 6022afc060425864c33f4ab62bbe41d20ac85362 (diff) | |
s390: allow absolute memory access for /dev/mem
Currently dev/mem for s390 provides only real memory access. This means
that the CPU prefix pages are swapped. The prefix swap for real memory
works as follows:
Each CPU owns a prefix register that points to a page aligned memory
location "P". If this CPU accesses the address range [0,0x1fff], it is
translated by the hardware to [P,P+0x1fff]. Accordingly if this CPU
accesses the address range [P,P+0x1fff], it is translated by the hardware
to [0,0x1fff]. Therefore, if [P,P+0x1fff] or [0,0x1fff] is read from
the current /dev/mem device, the incorrectly swapped memory content is
returned.
With this patch the /dev/mem architecture code is modified to provide
absolute memory access. This is done via the arch specific functions
xlate_dev_mem_ptr() and unxlate_dev_mem_ptr(). For swapped pages on
s390 the function xlate_dev_mem_ptr() now returns a new buffer with a
copy of the requested absolute memory. In case the buffer was allocated,
the unxlate_dev_mem_ptr() function frees it after /dev/mem code has
called copy_to_user().
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include')
| -rw-r--r-- | arch/s390/include/asm/io.h | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/arch/s390/include/asm/io.h b/arch/s390/include/asm/io.h index b7ff6afc3caa..27216d317991 100644 --- a/arch/s390/include/asm/io.h +++ b/arch/s390/include/asm/io.h @@ -38,11 +38,8 @@ static inline void * phys_to_virt(unsigned long address) return (void *) address; } -/* - * Convert a physical pointer to a virtual kernel pointer for /dev/mem - * access - */ -#define xlate_dev_mem_ptr(p) __va(p) +void *xlate_dev_mem_ptr(unsigned long phys); +void unxlate_dev_mem_ptr(unsigned long phys, void *addr); /* * Convert a virtual cached pointer to an uncached pointer |