Commit 0a6b58c5 authored by Helge Deller's avatar Helge Deller Committed by Andrew Morton
Browse files

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 bac59d18 ("x86/setup: Fix static
memory detection").

Link: https://lkml.kernel.org/r/ZNqrLRaOi/3wPAdp@p100


Fixes: bac59d18 ("x86/setup: Fix static memory detection")
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 66553609

arch/x86/include/asm/sections.h

+0 −18
Original line number Diff line number Diff line
@@ -2,8 +2,6 @@ 
#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>
@@ -18,20 +16,4 @@ 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

+14 −22
Original line number Diff line number Diff line
@@ -819,34 +819,26 @@ static int very_verbose(struct lock_class *class) 
 * 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;



	/*

	 * keys are allowed in the __ro_after_init section.

	 */

	if (is_kernel_rodata(addr))

		return 1;



	/*

	 * static variable?

	 * in initdata section and used during bootup only?

	 * NOTE: On some platforms the initdata section is

	 * outside of the _stext ... _end range.

	 */

	if ((addr >= start) && (addr < end))

	if (system_state < SYSTEM_FREEING_INITMEM &&

		init_section_contains((void *)addr, 1))

		return 1;



	/*