lockdep: fix static memory detection even more

On the parisc architecture, lockdep reports for all static objects which
are in the __initdata section (e.g. "setup_done" in devtmpfs,
"kthreadd_done" in init/main.c) this warning:

INFO: trying to register non-static key.

The warning itself is wrong, because those objects are in the __initdata
section, but the section itself is on parisc outside of range from
_stext to _end, which is why the static_obj() functions returns a wrong
answer.

While fixing this issue, I noticed that the whole existing check can
be simplified a lot.
Instead of checking against the _stext and _end symbols (which include
code areas too) just check for the .data and .bss segments (since we check a
data object). This can be done with the existing is_kernel_core_data()
macro.

In addition objects in the __initdata section can be checked with
init_section_contains(), and is_kernel_rodata() allows keys to be in the
_ro_after_init section.

This partly reverts and simplifies commit bac59d18c701 ("x86/setup: Fix static
memory detection").

Link: https://lkml.kernel.org/r/ZNqrLRaOi/3wPAdp@p100
Fixes: bac59d18c701 ("x86/setup: Fix static memory detection")
Signed-off-by: Helge Deller <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Cc: Guenter Roeck <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: "Rafael J. Wysocki" <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

arch/x86/include/asm/sections.h

···
 #ifndef _ASM_X86_SECTIONS_H
 #define _ASM_X86_SECTIONS_H
 
-#define arch_is_kernel_initmem_freed arch_is_kernel_initmem_freed
-
 #include <asm-generic/sections.h>
 #include <asm/extable.h>
 
···
 extern char __end_of_kernel_reserve[];
 
 extern unsigned long _brk_start, _brk_end;
-
-static inline bool arch_is_kernel_initmem_freed(unsigned long addr)
-{
-	/*
-	 * If _brk_start has not been cleared, brk allocation is incomplete,
-	 * and we can not make assumptions about its use.
-	 */
-	if (_brk_start)
-		return 0;
-
-	/*
-	 * After brk allocation is complete, space between _brk_end and _end
-	 * is available for allocation.
-	 */
-	return addr >= _brk_end && addr < (unsigned long)&_end;
-}
 
 #endif	/* _ASM_X86_SECTIONS_H */

kernel/locking/lockdep.c

···
  * Is this the address of a static object:
  */
 #ifdef __KERNEL__
-/*
- * Check if an address is part of freed initmem. After initmem is freed,
- * memory can be allocated from it, and such allocations would then have
- * addresses within the range [_stext, _end].
- */
-#ifndef arch_is_kernel_initmem_freed
-static int arch_is_kernel_initmem_freed(unsigned long addr)
-{
-	if (system_state < SYSTEM_FREEING_INITMEM)
-		return 0;
-
-	return init_section_contains((void *)addr, 1);
-}
-#endif
-
 static int static_obj(const void *obj)
 {
-	unsigned long start = (unsigned long) &_stext,
-		      end   = (unsigned long) &_end,
-		      addr  = (unsigned long) obj;
+	unsigned long addr = (unsigned long) obj;
 
-	if (arch_is_kernel_initmem_freed(addr))
-		return 0;
+	if (is_kernel_core_data(addr))
+		return 1;
 
 	/*
-	 * static variable?
+	 * keys are allowed in the __ro_after_init section.
 	 */
-	if ((addr >= start) && (addr < end))
+	if (is_kernel_rodata(addr))
+		return 1;
+
+	/*
+	 * in initdata section and used during bootup only?
+	 * NOTE: On some platforms the initdata section is
+	 * outside of the _stext ... _end range.
+	 */
+	if (system_state < SYSTEM_FREEING_INITMEM &&
+		init_section_contains((void *)addr, 1))
 		return 1;
 
 	/*