From ddda785fb1d657f8a4375583bcefabd878c61e27 Mon Sep 17 00:00:00 2001
From: "venkatesh.pallipadi@intel.com" <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 <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
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 3a4baf95e24d5..caac7d5699a75 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 964ff3b1cff48..83495885ada0e 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 7b292d386713e..d5b11f60dbd07 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 509045f5fda29..6e73467a4fb13 100644
--- a/include/asm-x86/io_32.h
+++ b/include/asm-x86/io_32.h
@@ -48,12 +48,6 @@
#include <linux/vmalloc.h>
-/*
- * 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 c2f5eef47b888..0930bedf9e4d0 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