maccess: remove probe_read_common and probe_write_common

Each of the helpers has just two callers, which also different in
dealing with kernel or userspace pointers.  Just open code the logic
in the callers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200521152301.2587579-10-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: Christoph Hellwig

mm/maccess.c

@@ -6,30 +6,6 @@
 #include <linux/mm.h>
 #include <linux/uaccess.h>
 
-static __always_inline long
-probe_read_common(void *dst, const void __user *src, size_t size)
-{
-	long ret;
-
-	pagefault_disable();
-	ret = __copy_from_user_inatomic(dst, src, size);
-	pagefault_enable();
-
-	return ret ? -EFAULT : 0;
-}
-
-static __always_inline long
-probe_write_common(void __user *dst, const void *src, size_t size)
-{
-	long ret;
-
-	pagefault_disable();
-	ret = __copy_to_user_inatomic(dst, src, size);
-	pagefault_enable();
-
-	return ret ? -EFAULT : 0;
-}
-
 /**
  * probe_kernel_read(): safely attempt to read from any location
  * @dst: pointer to the buffer that shall take the data
@@ -70,10 +46,15 @@ long __probe_kernel_read(void *dst, const void *src, size_t size)
 	mm_segment_t old_fs = get_fs();
 
 	set_fs(KERNEL_DS);
-	ret = probe_read_common(dst, (__force const void __user *)src, size);
+	pagefault_disable();
+	ret = __copy_from_user_inatomic(dst, (__force const void __user *)src,
+			size);
+	pagefault_enable();
 	set_fs(old_fs);
 
-	return ret;
+	if (ret)
+		return -EFAULT;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(probe_kernel_read);
 
@@ -92,11 +73,16 @@ long probe_user_read(void *dst, const void __user *src, size_t size)
 	mm_segment_t old_fs = get_fs();
 
 	set_fs(USER_DS);
-	if (access_ok(src, size))
-		ret = probe_read_common(dst, src, size);
+	if (access_ok(src, size)) {
+		pagefault_disable();
+		ret = __copy_from_user_inatomic(dst, src, size);
+		pagefault_enable();
+	}
 	set_fs(old_fs);
 
-	return ret;
+	if (ret)
+		return -EFAULT;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(probe_user_read);
 
@@ -115,10 +101,14 @@ long probe_kernel_write(void *dst, const void *src, size_t size)
 	mm_segment_t old_fs = get_fs();
 
 	set_fs(KERNEL_DS);
-	ret = probe_write_common((__force void __user *)dst, src, size);
+	pagefault_disable();
+	ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
+	pagefault_enable();
 	set_fs(old_fs);
 
-	return ret;
+	if (ret)
+		return -EFAULT;
+	return 0;
 }
 
 /**
@@ -136,11 +126,16 @@ long probe_user_write(void __user *dst, const void *src, size_t size)
 	mm_segment_t old_fs = get_fs();
 
 	set_fs(USER_DS);
-	if (access_ok(dst, size))
-		ret = probe_write_common(dst, src, size);
+	if (access_ok(dst, size)) {
+		pagefault_disable();
+		ret = __copy_to_user_inatomic(dst, src, size);
+		pagefault_enable();
+	}
 	set_fs(old_fs);
 
-	return ret;
+	if (ret)
+		return -EFAULT;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(probe_user_write);