kernel.h: split out instruction pointer accessors

bottom_half.h needs _THIS_IP_ to be standalone, so split that and
_RET_IP_ out from kernel.h into the new instruction_pointer.h.  kernel.h
directly needs them, so include it there and replace the include of
kernel.h with this new file in bottom_half.h.

Link: https://lkml.kernel.org/r/20211028161248.45232-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/bottom_half.h

@@ -2,7 +2,7 @@
 #ifndef _LINUX_BH_H
 #define _LINUX_BH_H
 
-#include <linux/kernel.h>
+#include <linux/instruction_pointer.h>
 #include <linux/preempt.h>
 
 #if defined(CONFIG_PREEMPT_RT) || defined(CONFIG_TRACE_IRQFLAGS)

include/linux/instruction_pointer.h

@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_INSTRUCTION_POINTER_H
+#define _LINUX_INSTRUCTION_POINTER_H
+
+#define _RET_IP_		(unsigned long)__builtin_return_address(0)
+#define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
+
+#endif /* _LINUX_INSTRUCTION_POINTER_H */

include/linux/kernel.h

@@ -20,6 +20,7 @@
 #include <linux/printk.h>
 #include <linux/build_bug.h>
 #include <linux/static_call_types.h>
+#include <linux/instruction_pointer.h>
 #include <asm/byteorder.h>
 
 #include <uapi/linux/kernel.h>
@@ -53,9 +54,6 @@
 }					\
 )
 
-#define _RET_IP_		(unsigned long)__builtin_return_address(0)
-#define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
-
 /**
  * upper_32_bits - return bits 32-63 of a number
  * @n: the number we're accessing