Add xlate and unxlate around /dev/mem read/write. This sets up the mapping that can be used for /dev/mem read and write without aliasing worries. Signed-off-by: Venkatesh Pallipadi Signed-off-by: Suresh Siddha Index: linux-2.6-x86.git/arch/x86/mm/ioremap.c =================================================================== --- linux-2.6-x86.git.orig/arch/x86/mm/ioremap.c 2008-03-18 02:16:08.000000000 -0700 +++ linux-2.6-x86.git/arch/x86/mm/ioremap.c 2008-03-18 09:20:38.000000000 -0700 @@ -284,6 +284,35 @@ } EXPORT_SYMBOL(iounmap); +/* + * Convert a physical pointer to a virtual kernel pointer for /dev/mem + * access + */ +void *xlate_dev_mem_ptr(unsigned long phys) +{ + void *addr; + unsigned long start = phys & PAGE_MASK; + + /* If page is RAM, we can use __va. Otherwise ioremap and unmap. */ + if (page_is_ram(start >> PAGE_SHIFT)) + return __va(phys); + + addr = (void *)ioremap(start, PAGE_SIZE); + if (addr) + addr = (void *)((unsigned long)addr | (phys & ~PAGE_MASK)); + + return addr; +} + +void unxlate_dev_mem_ptr(unsigned long phys, void *addr) +{ + if (page_is_ram(phys >> PAGE_SHIFT)) + return; + + iounmap((void __iomem *)((unsigned long)addr & PAGE_MASK)); + return; +} + #ifdef CONFIG_X86_32 int __initdata early_ioremap_debug; Index: linux-2.6-x86.git/drivers/char/mem.c =================================================================== --- linux-2.6-x86.git.orig/drivers/char/mem.c 2008-03-18 02:16:08.000000000 -0700 +++ linux-2.6-x86.git/drivers/char/mem.c 2008-03-18 09:20:34.000000000 -0700 @@ -134,6 +134,10 @@ } #endif +void __attribute__((weak)) unxlate_dev_mem_ptr(unsigned long phys, void *addr) +{ +} + /* * This funcion reads the *physical* memory. The f_pos points directly to the * memory location. @@ -176,17 +180,25 @@ sz = min_t(unsigned long, sz, count); + if (!range_is_allowed(p >> PAGE_SHIFT, count)) + return -EPERM; + /* * On ia64 if a page has been mapped somewhere as * uncached, then it must also be accessed uncached * by the kernel or data corruption may occur */ ptr = xlate_dev_mem_ptr(p); + if (!ptr) + return -EFAULT; - if (!range_is_allowed(p >> PAGE_SHIFT, count)) - return -EPERM; - if (copy_to_user(buf, ptr, sz)) + if (copy_to_user(buf, ptr, sz)) { + unxlate_dev_mem_ptr(p, ptr); return -EFAULT; + } + + unxlate_dev_mem_ptr(p, ptr); + buf += sz; p += sz; count -= sz; @@ -235,22 +247,32 @@ sz = min_t(unsigned long, sz, count); + if (!range_is_allowed(p >> PAGE_SHIFT, sz)) + return -EPERM; + /* * On ia64 if a page has been mapped somewhere as * uncached, then it must also be accessed uncached * by the kernel or data corruption may occur */ ptr = xlate_dev_mem_ptr(p); + if (!ptr) { + if (written) + break; + return -EFAULT; + } - if (!range_is_allowed(p >> PAGE_SHIFT, sz)) - return -EPERM; copied = copy_from_user(ptr, buf, sz); if (copied) { written += sz - copied; + unxlate_dev_mem_ptr(p, ptr); if (written) break; return -EFAULT; } + + unxlate_dev_mem_ptr(p, ptr); + buf += sz; p += sz; count -= sz; Index: linux-2.6-x86.git/include/asm-x86/io_32.h =================================================================== --- linux-2.6-x86.git.orig/include/asm-x86/io_32.h 2008-03-18 02:16:08.000000000 -0700 +++ linux-2.6-x86.git/include/asm-x86/io_32.h 2008-03-18 03:11:12.000000000 -0700 @@ -49,12 +49,6 @@ #include /* - * Convert a physical pointer to a virtual kernel pointer for /dev/mem - * access - */ -#define xlate_dev_mem_ptr(p) __va(p) - -/* * Convert a virtual cached pointer to an uncached pointer */ #define xlate_dev_kmem_ptr(p) p Index: linux-2.6-x86.git/include/asm-x86/io_64.h =================================================================== --- linux-2.6-x86.git.orig/include/asm-x86/io_64.h 2008-03-18 02:16:08.000000000 -0700 +++ linux-2.6-x86.git/include/asm-x86/io_64.h 2008-03-18 03:11:12.000000000 -0700 @@ -282,12 +282,6 @@ #define BIO_VMERGE_BOUNDARY iommu_bio_merge /* - * Convert a physical pointer to a virtual kernel pointer for /dev/mem - * access - */ -#define xlate_dev_mem_ptr(p) __va(p) - -/* * Convert a virtual cached pointer to an uncached pointer */ #define xlate_dev_kmem_ptr(p) p Index: linux-2.6-x86.git/include/asm-x86/io.h =================================================================== --- linux-2.6-x86.git.orig/include/asm-x86/io.h 2008-03-18 02:16:08.000000000 -0700 +++ linux-2.6-x86.git/include/asm-x86/io.h 2008-03-18 09:20:38.000000000 -0700 @@ -1,5 +1,13 @@ +#ifndef _ASM_X86_IO_H +#define _ASM_X86_IO_H + #ifdef CONFIG_X86_32 # include "io_32.h" #else # include "io_64.h" #endif + +extern void *xlate_dev_mem_ptr(unsigned long phys); +extern void unxlate_dev_mem_ptr(unsigned long phys, void *addr); + +#endif /* _ASM_X86_IO_H */ -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/