[PATCH] EFI, /dev/mem: simplify efi_mem_attribute_range()

Pass the size, not a pointer to the size, to efi_mem_attribute_range().

This function validates memory regions for the /dev/mem read/write/mmap paths.
The pointer allows arches to reduce the size of the range, but I think that's
unnecessary complexity.  Simplifying it will let me use
efi_mem_attribute_range() to improve the ia64 ioremap() implementation.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Matt Domsch <Matt_Domsch@dell.com>
Cc: "Tolentino, Matthew E" <matthew.e.tolentino@intel.com>
Cc: "Brown, Len" <len.brown@intel.com>
Cc: Andi Kleen <ak@muc.de>
Acked-by: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 30 insertions, 35 deletions

diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c
index 9990320b6f9a..2993748c13df 100644
--- a/arch/ia64/kernel/efi.c
+++ b/arch/ia64/kernel/efi.c
@@ -677,27 +677,34 @@ EXPORT_SYMBOL(efi_mem_attributes);
 /*
  * Determines whether the memory at phys_addr supports the desired
  * attribute (WB, UC, etc).  If this returns 1, the caller can safely
- * access *size bytes at phys_addr with the specified attribute.
+ * access size bytes at phys_addr with the specified attribute.
  */
-static int
-efi_mem_attribute_range (unsigned long phys_addr, unsigned long *size, u64 attr)
+int
+efi_mem_attribute_range (unsigned long phys_addr, unsigned long size, u64 attr)
 {
+        unsigned long end = phys_addr + size;
         efi_memory_desc_t *md = efi_memory_descriptor(phys_addr);
-        unsigned long md_end;
 
-        if (!md || (md->attribute & attr) != attr)
+        /*
+         * Some firmware doesn't report MMIO regions in the EFI memory
+         * map.  The Intel BigSur (a.k.a. HP i2000) has this problem.
+         * On those platforms, we have to assume UC is valid everywhere.
+         */
+        if (!md || (md->attribute & attr) != attr) {
+                if (attr == EFI_MEMORY_UC && !efi_memmap_has_mmio())
+                        return 1;
                 return 0;
+        }
 
         do {
-                md_end = efi_md_end(md);
-                if (phys_addr + *size <= md_end)
+                unsigned long md_end = efi_md_end(md);
+
+                if (end <= md_end)
                         return 1;
 
                 md = efi_memory_descriptor(md_end);
-                if (!md || (md->attribute & attr) != attr) {
-                        *size = md_end - phys_addr;
-                        return 1;
-                }
+                if (!md || (md->attribute & attr) != attr)
+                        return 0;
         } while (md);
         return 0;
 }
@@ -708,7 +715,7 @@ efi_mem_attribute_range (unsigned long phys_addr, unsigned long *size, u64 attr)
  * control access size.
  */
 int
-valid_phys_addr_range (unsigned long phys_addr, unsigned long *size)
+valid_phys_addr_range (unsigned long phys_addr, unsigned long size)
 {
         return efi_mem_attribute_range(phys_addr, size, EFI_MEMORY_WB);
 }
@@ -723,7 +730,7 @@ valid_phys_addr_range (unsigned long phys_addr, unsigned long *size)
  * because that doesn't appear in the boot-time EFI memory map.
  */
 int
-valid_mmap_phys_addr_range (unsigned long phys_addr, unsigned long *size)
+valid_mmap_phys_addr_range (unsigned long phys_addr, unsigned long size)
 {
         if (efi_mem_attribute_range(phys_addr, size, EFI_MEMORY_WB))
                 return 1;
@@ -731,14 +738,6 @@ valid_mmap_phys_addr_range (unsigned long phys_addr, unsigned long *size)
         if (efi_mem_attribute_range(phys_addr, size, EFI_MEMORY_UC))
                 return 1;
 
-        /*
-         * Some firmware doesn't report MMIO regions in the EFI memory map.
-         * The Intel BigSur (a.k.a. HP i2000) has this problem.  In this
-         * case, we can't use the EFI memory map to validate mmap requests.
-         */
-        if (!efi_memmap_has_mmio())
-                return 1;
-
         return 0;
 }
 
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 26d0116b48d4..5245ba1649ed 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -88,21 +88,15 @@ static inline int uncached_access(struct file *file, unsigned long addr)
 }
 
 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
-static inline int valid_phys_addr_range(unsigned long addr, size_t *count)
+static inline int valid_phys_addr_range(unsigned long addr, size_t count)
 {
-        unsigned long end_mem;
-
-        end_mem = __pa(high_memory);
-        if (addr >= end_mem)
+        if (addr + count > __pa(high_memory))
                 return 0;
 
-        if (*count > end_mem - addr)
-                *count = end_mem - addr;
-
         return 1;
 }
 
-static inline int valid_mmap_phys_addr_range(unsigned long addr, size_t *size)
+static inline int valid_mmap_phys_addr_range(unsigned long addr, size_t size)
 {
         return 1;
 }
@@ -119,7 +113,7 @@ static ssize_t read_mem(struct file * file, char __user * buf,
         ssize_t read, sz;
         char *ptr;
 
-        if (!valid_phys_addr_range(p, &count))
+        if (!valid_phys_addr_range(p, count))
                 return -EFAULT;
         read = 0;
 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
@@ -177,7 +171,7 @@ static ssize_t write_mem(struct file * file, const char __user * buf,
         unsigned long copied;
         void *ptr;
 
-        if (!valid_phys_addr_range(p, &count))
+        if (!valid_phys_addr_range(p, count))
                 return -EFAULT;
 
         written = 0;
@@ -249,7 +243,7 @@ static int mmap_mem(struct file * file, struct vm_area_struct * vma)
 {
         size_t size = vma->vm_end - vma->vm_start;
 
-        if (!valid_mmap_phys_addr_range(vma->vm_pgoff << PAGE_SHIFT, &size))
+        if (!valid_mmap_phys_addr_range(vma->vm_pgoff << PAGE_SHIFT, size))
                 return -EINVAL;
 
         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
diff --git a/include/asm-ia64/io.h b/include/asm-ia64/io.h
index 0d9bcc36f2a9..acba019b08e9 100644
--- a/include/asm-ia64/io.h
+++ b/include/asm-ia64/io.h
@@ -88,8 +88,8 @@ phys_to_virt (unsigned long address)
 }
 
 #define ARCH_HAS_VALID_PHYS_ADDR_RANGE
-extern int valid_phys_addr_range (unsigned long addr, size_t *count); /* efi.c */
-extern int valid_mmap_phys_addr_range (unsigned long addr, size_t *count);
+extern int valid_phys_addr_range (unsigned long addr, size_t count); /* efi.c */
+extern int valid_mmap_phys_addr_range (unsigned long addr, size_t count);
 
 /*
  * The following two macros are deprecated and scheduled for removal.
diff --git a/include/linux/efi.h b/include/linux/efi.h
index c7c5dd316182..d15725470aa4 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -292,6 +292,8 @@ extern void efi_enter_virtual_mode (void);	/* switch EFI to virtual mode, if pos
 extern u64 efi_get_iobase (void);
 extern u32 efi_mem_type (unsigned long phys_addr);
 extern u64 efi_mem_attributes (unsigned long phys_addr);
+extern int efi_mem_attribute_range (unsigned long phys_addr, unsigned long size,
+                                    u64 attr);
 extern int __init efi_uart_console_only (void);
 extern void efi_initialize_iomem_resources(struct resource *code_resource,
                                         struct resource *data_resource);