[PATCH] mm/kasan: fix kasan_check_read() compiler warning

* [PATCH] mm/kasan: fix kasan_check_read() compiler warning
@ 2019-07-09 18:35 Arnd Bergmann
  2019-07-09 18:46 ` Marco Elver
  2019-07-09 18:51 ` Nick Desaulniers
  0 siblings, 2 replies; 4+ messages in thread
From: Arnd Bergmann @ 2019-07-09 18:35 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Arnd Bergmann, Marco Elver, Mark Rutland, Andrey Ryabinin,
	Dmitry Vyukov, Alexander Potapenko, Andrey Konovalov,
	Christoph Lameter, Pekka Enberg, David Rientjes, Joonsoo Kim,
	Kees Cook, Stephen Rothwell, Luc Van Oostenryck, ndesaulniers,
	Miguel Ojeda, Ingo Molnar, Josh Poimboeuf, linux-kernel

The kasan_check_read() is marked 'inline', which usually includes
the 'always_inline' attribute. In some configuration, gcc decides that
it cannot inline this, causing a build failure:

In file included from include/linux/compiler.h:257,
                 from arch/x86/include/asm/current.h:5,
                 from include/linux/sched.h:12,
                 from include/linux/ratelimit.h:6,
                 from fs/dcache.c:18:
include/linux/compiler.h: In function 'read_word_at_a_time':
include/linux/kasan-checks.h:31:20: error: inlining failed in call to always_inline 'kasan_check_read': function attribute mismatch
 static inline bool kasan_check_read(const volatile void *p, unsigned int size)
                    ^~~~~~~~~~~~~~~~
In file included from arch/x86/include/asm/current.h:5,
                 from include/linux/sched.h:12,
                 from include/linux/ratelimit.h:6,
                 from fs/dcache.c:18:
include/linux/compiler.h:280:2: note: called from here
  kasan_check_read(addr, 1);
  ^~~~~~~~~~~~~~~~~~~~~~~~~

While I have no idea why it does this, but changing the call to the
internal __kasan_check_read() fixes the issue.

Fixes: dc55b51f312c ("mm/kasan: introduce __kasan_check_{read,write}")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/linux/compiler.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index f0fd5636fddb..22909500ba1d 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -277,7 +277,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
 static __no_kasan_or_inline
 unsigned long read_word_at_a_time(const void *addr)
 {
-	kasan_check_read(addr, 1);
+	__kasan_check_read(addr, 1);
 	return *(unsigned long *)addr;
 }
 
-- 
2.20.0


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