Merge remote-tracking branch 'asoc/fix/cs4271' into asoc-linus

[mirror_ubuntu-eoan-kernel.git] / drivers / char / mem.c

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 6d9cc2d39d22306fd68f30bac6f4a60e6cfa5a87..7e4a9d1296bb7fb666f6b37ced2757a8585b7d75 100644 (file)
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -60,6 +60,10 @@ static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
 #endif
 
 #ifdef CONFIG_STRICT_DEVMEM
+static inline int page_is_allowed(unsigned long pfn)
+{
+       return devmem_is_allowed(pfn);
+}
 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
 {
        u64 from = ((u64)pfn) << PAGE_SHIFT;
@@ -75,6 +79,10 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size)
        return 1;
 }
 #else
+static inline int page_is_allowed(unsigned long pfn)
+{
+       return 1;
+}
 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
 {
        return 1;
@@ -122,23 +130,31 @@ static ssize_t read_mem(struct file *file, char __user *buf,
 
        while (count > 0) {
                unsigned long remaining;
+               int allowed;
 
                sz = size_inside_page(p, count);
 
-               if (!range_is_allowed(p >> PAGE_SHIFT, count))
+               allowed = page_is_allowed(p >> PAGE_SHIFT);
+               if (!allowed)
                        return -EPERM;
+               if (allowed == 2) {
+                       /* Show zeros for restricted memory. */
+                       remaining = clear_user(buf, sz);
+               } else {
+                       /*
+                        * 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;
 
-               /*
-                * 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;
+                       remaining = copy_to_user(buf, ptr, sz);
+
+                       unxlate_dev_mem_ptr(p, ptr);
+               }
 
-               remaining = copy_to_user(buf, ptr, sz);
-               unxlate_dev_mem_ptr(p, ptr);
                if (remaining)
                        return -EFAULT;
 
@@ -181,30 +197,36 @@ static ssize_t write_mem(struct file *file, const char __user *buf,
 #endif
 
        while (count > 0) {
+               int allowed;
+
                sz = size_inside_page(p, count);
 
-               if (!range_is_allowed(p >> PAGE_SHIFT, sz))
+               allowed = page_is_allowed(p >> PAGE_SHIFT);
+               if (!allowed)
                        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;
-               }
+               /* Skip actual writing when a page is marked as restricted. */
+               if (allowed == 1) {
+                       /*
+                        * 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;
+                       }
 
-               copied = copy_from_user(ptr, buf, sz);
-               unxlate_dev_mem_ptr(p, ptr);
-               if (copied) {
-                       written += sz - copied;
-                       if (written)
-                               break;
-                       return -EFAULT;
+                       copied = copy_from_user(ptr, buf, sz);
+                       unxlate_dev_mem_ptr(p, ptr);
+                       if (copied) {
+                               written += sz - copied;
+                               if (written)
+                                       break;
+                               return -EFAULT;
+                       }
                }
 
                buf += sz;