maccess,probe_kernel: Allow arch specific override probe_kernel_(read|write)

Some archs such as blackfin, would like to have an arch specific
probe_kernel_read() and probe_kernel_write() implementation which can
fall back to the generic implementation if no special operations are
needed.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

2 files changed, 12 insertions, 3 deletions

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 6b58367d145e..d512d98dfb7d 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -94,6 +94,7 @@ static inline unsigned long __copy_from_user_nocache(void *to,
  * happens, handle that and return -EFAULT.
  */
 extern long probe_kernel_read(void *dst, void *src, size_t size);
+extern long __probe_kernel_read(void *dst, void *src, size_t size);
 
 /*
  * probe_kernel_write(): safely attempt to write to a location
@@ -104,6 +105,7 @@ extern long probe_kernel_read(void *dst, void *src, size_t size);
  * Safely write to address @dst from the buffer at @src.  If a kernel fault
  * happens, handle that and return -EFAULT.
  */
-extern long probe_kernel_write(void *dst, void *src, size_t size);
+extern long notrace probe_kernel_write(void *dst, void *src, size_t size);
+extern long notrace __probe_kernel_write(void *dst, void *src, size_t size);
 
 #endif          /* __LINUX_UACCESS_H__ */
diff --git a/mm/maccess.c b/mm/maccess.c
index 9073695ff25f..4e348dbaecd7 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -14,7 +14,11 @@
  * Safely read from address @src to the buffer at @dst.  If a kernel fault
  * happens, handle that and return -EFAULT.
  */
-long probe_kernel_read(void *dst, void *src, size_t size)
+
+long __weak probe_kernel_read(void *dst, void *src, size_t size)
+    __attribute__((alias("__probe_kernel_read")));
+
+long __probe_kernel_read(void *dst, void *src, size_t size)
 {
         long ret;
         mm_segment_t old_fs = get_fs();
@@ -39,7 +43,10 @@ EXPORT_SYMBOL_GPL(probe_kernel_read);
  * Safely write to address @dst from the buffer at @src.  If a kernel fault
  * happens, handle that and return -EFAULT.
  */
-long notrace __weak probe_kernel_write(void *dst, void *src, size_t size)
+long __weak probe_kernel_write(void *dst, void *src, size_t size)
+    __attribute__((alias("__probe_kernel_write")));
+
+long __probe_kernel_write(void *dst, void *src, size_t size)
 {
         long ret;
         mm_segment_t old_fs = get_fs();