lockdep: fix static memory detection even more

BugLink: https://bugs.launchpad.net/bugs/2039884
commit 0a6b58c5cd0dfd7961e725212f0fc8dfc5d96195 upstream.

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 <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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h
index a6e8373a5170f8d226350c7eb0459b2f8581bf2f..3fa87e5e11aba92e17737164894de5a299431d6d 100644 (file)
--- a/arch/x86/include/asm/sections.h
+++ b/arch/x86/include/asm/sections.h
@@ -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 */

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 50d4863974e7a218a3c4b855d3934712c80c614a..0224b0329d011a8168a4d71770b7fd94cf1d73e0 100644 (file)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -817,34 +817,26 @@ 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;
 
        /*