b2a68c2356
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>
51 lines
1 KiB
C
51 lines
1 KiB
C
/*
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* include/asm-s390/io.h
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*
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* S390 version
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* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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*
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* Derived from "include/asm-i386/io.h"
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*/
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#ifndef _S390_IO_H
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#define _S390_IO_H
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#ifdef __KERNEL__
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#include <asm/page.h>
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#define IO_SPACE_LIMIT 0xffffffff
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/*
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* Change virtual addresses to physical addresses and vv.
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* These are pretty trivial
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*/
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static inline unsigned long virt_to_phys(volatile void * address)
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{
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unsigned long real_address;
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asm volatile(
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" lra %0,0(%1)\n"
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" jz 0f\n"
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" la %0,0\n"
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"0:"
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: "=a" (real_address) : "a" (address) : "cc");
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return real_address;
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}
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static inline void * phys_to_virt(unsigned long address)
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{
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return (void *) address;
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}
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void *xlate_dev_mem_ptr(unsigned long phys);
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void unxlate_dev_mem_ptr(unsigned long phys, void *addr);
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/*
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* Convert a virtual cached pointer to an uncached pointer
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*/
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#define xlate_dev_kmem_ptr(p) p
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#endif /* __KERNEL__ */
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#endif
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