From e045fb2a988a9a1964059b0d33dbaf18d12f925f Mon Sep 17 00:00:00 2001 From: "venkatesh.pallipadi@intel.com" Date: Tue, 18 Mar 2008 17:00:15 -0700 Subject: 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 --- drivers/char/mem.c | 32 +++++++++++++++++++++++++++----- 1 file changed, 27 insertions(+), 5 deletions(-) (limited to 'drivers/char/mem.c') diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 964ff3b1cff..83495885ada 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; -- cgit v1.2.3