From e045fb2a988a9a1964059b0d33dbaf18d12f925f Mon Sep 17 00:00:00 2001 From: "venkatesh.pallipadi@intel.com" Date: Tue, 18 Mar 2008 17:00:15 -0700 Subject: [PATCH] x86: PAT avoid aliasing in /dev/mem read/write 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 Signed-off-by: Ingo Molnar --- arch/x86/mm/ioremap.c | 29 +++++++++++++++++++++++++++++ drivers/char/mem.c | 32 +++++++++++++++++++++++++++----- include/asm-x86/io.h | 8 ++++++++ include/asm-x86/io_32.h | 6 ------ include/asm-x86/io_64.h | 6 ------ 5 files changed, 64 insertions(+), 17 deletions(-) diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 3a4baf95e2..caac7d5699 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -336,6 +336,35 @@ void iounmap(volatile void __iomem *addr) } 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; diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 964ff3b1cf..83495885ad 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -134,6 +134,10 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size) } #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 @@ static ssize_t read_mem(struct file * file, char __user * buf, 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 @@ static ssize_t write_mem(struct file * file, const char __user * buf, 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; diff --git a/include/asm-x86/io.h b/include/asm-x86/io.h index 7b292d3867..d5b11f60db 100644 --- a/include/asm-x86/io.h +++ b/include/asm-x86/io.h @@ -1,3 +1,6 @@ +#ifndef _ASM_X86_IO_H +#define _ASM_X86_IO_H + #define ARCH_HAS_IOREMAP_WC #ifdef CONFIG_X86_32 @@ -5,7 +8,12 @@ #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); + extern int ioremap_change_attr(unsigned long vaddr, unsigned long size, unsigned long prot_val); extern void __iomem *ioremap_wc(unsigned long offset, unsigned long size); +#endif /* _ASM_X86_IO_H */ diff --git a/include/asm-x86/io_32.h b/include/asm-x86/io_32.h index 509045f5fd..6e73467a4f 100644 --- a/include/asm-x86/io_32.h +++ b/include/asm-x86/io_32.h @@ -48,12 +48,6 @@ #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 */ diff --git a/include/asm-x86/io_64.h b/include/asm-x86/io_64.h index c2f5eef47b..0930bedf9e 100644 --- a/include/asm-x86/io_64.h +++ b/include/asm-x86/io_64.h @@ -307,12 +307,6 @@ void memset_io(volatile void __iomem *a, int b, size_t c); extern int iommu_bio_merge; #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 */ -- 2.39.5