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Date: Thu, 6 May 2010 16:38:33 -0500
From: "Steven J. Magnani" <steve@...idescorp.com>
To: microblaze-uclinux@...e.uq.edu.au
Cc: monstr@...str.eu, linux-kernel@...r.kernel.org,
"Steven J. Magnani" <steve@...idescorp.com>
Subject: [PATCH] microblaze: fix get_user/put_user side-effects
The Microblaze implementations of get_user() and (MMU) put_user() evaluate
the address argument more than once. This causes unexpected side-effects for
invocations that include increment operators, i.e. get_user(foo, bar++).
This patch also removes the distinction between MMU and noMMU put_user().
Without the patch:
$ echo 1234567890 > /proc/sys/kernel/core_pattern
$ cat /proc/sys/kernel/core_pattern
12345
Signed-off-by: Steven J. Magnani <steve@...idescorp.com>
---
diff -uprN a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
--- a/arch/microblaze/include/asm/uaccess.h 2010-04-27 10:14:33.000000000 -0500
+++ b/arch/microblaze/include/asm/uaccess.h 2010-05-06 16:21:02.000000000 -0500
@@ -182,6 +182,39 @@ extern long __user_bad(void);
* Returns zero on success, or -EFAULT on error.
* On error, the variable @x is set to zero.
*/
+#define get_user(x, ptr) \
+ __get_user_check((x), (ptr), sizeof(*(ptr)))
+
+#define __get_user_check(x, ptr, size) \
+({ \
+ unsigned long __gu_val = 0; \
+ const typeof(*(ptr)) __user *__gu_addr = (ptr); \
+ int __gu_err = 0; \
+ \
+ if (access_ok(VERIFY_READ, __gu_addr, size)) { \
+ switch (size) { \
+ case 1: \
+ __get_user_asm("lbu", __gu_addr, __gu_val, \
+ __gu_err); \
+ break; \
+ case 2: \
+ __get_user_asm("lhu", __gu_addr, __gu_val, \
+ __gu_err); \
+ break; \
+ case 4: \
+ __get_user_asm("lw", __gu_addr, __gu_val, \
+ __gu_err); \
+ break; \
+ default: \
+ __gu_err = __user_bad(); \
+ break; \
+ } \
+ } else { \
+ __gu_err = -EFAULT; \
+ } \
+ x = (typeof(*(ptr)))__gu_val; \
+ __gu_err; \
+})
#define __get_user(x, ptr) \
({ \
@@ -206,12 +239,6 @@ extern long __user_bad(void);
})
-#define get_user(x, ptr) \
-({ \
- access_ok(VERIFY_READ, (ptr), sizeof(*(ptr))) \
- ? __get_user((x), (ptr)) : -EFAULT; \
-})
-
#define __put_user_asm(insn, __gu_ptr, __gu_val, __gu_err) \
({ \
__asm__ __volatile__ ( \
@@ -266,6 +293,42 @@ extern long __user_bad(void);
*
* Returns zero on success, or -EFAULT on error.
*/
+#define put_user(x, ptr) \
+ __put_user_check((x), (ptr), sizeof(*(ptr)))
+
+#define __put_user_check(x, ptr, size) \
+({ \
+ typeof(*(ptr)) __pu_val; \
+ typeof(*(ptr)) __user *__pu_addr = (ptr); \
+ int __pu_err = 0; \
+ \
+ __pu_val = (x); \
+ if (access_ok(VERIFY_WRITE, __pu_addr, size)) { \
+ switch (size) { \
+ case 1: \
+ __put_user_asm("sb", __pu_addr, __pu_val, \
+ __pu_err); \
+ break; \
+ case 2: \
+ __put_user_asm("sh", __pu_addr, __pu_val, \
+ __pu_err); \
+ break; \
+ case 4: \
+ __put_user_asm("sw", __pu_addr, __pu_val, \
+ __pu_err); \
+ break; \
+ case 8: \
+ __put_user_asm_8(__pu_addr, __pu_val, __pu_err);\
+ break; \
+ default: \
+ __pu_err = __user_bad(); \
+ break; \
+ } \
+ } else { \
+ __pu_err = -EFAULT; \
+ } \
+ __pu_err; \
+})
#define __put_user(x, ptr) \
({ \
@@ -290,18 +353,6 @@ extern long __user_bad(void);
__gu_err; \
})
-#ifndef CONFIG_MMU
-
-#define put_user(x, ptr) __put_user((x), (ptr))
-
-#else /* CONFIG_MMU */
-
-#define put_user(x, ptr) \
-({ \
- access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) \
- ? __put_user((x), (ptr)) : -EFAULT; \
-})
-#endif /* CONFIG_MMU */
/* copy_to_from_user */
#define __copy_from_user(to, from, n) \
--
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