Date:   Wed, 8 Feb 2023 19:10:26 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Arnd Bergmann <arnd@kernel.org>
Cc:     Josh Poimboeuf <jpoimboe@kernel.org>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        kasan-dev@googlegroups.com, Marco Elver <elver@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Alexander Potapenko <glider@google.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] kasan: mark addr_has_metadata __always_inline
Message-ID: <Y+Plku4Cf5Xkzq10@hirez.programming.kicks-ass.net>
References: <20230208164011.2287122-1-arnd@kernel.org>
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On Wed, Feb 08, 2023 at 05:39:55PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> When the compiler decides not to inline this function, objdump
> complains about incorrect UACCESS state:
> 
> mm/kasan/generic.o: warning: objtool: __asan_load2+0x11: call to addr_has_metadata() with UACCESS enabled
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

> ---
>  mm/kasan/kasan.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 3231314e071f..9377b0789edc 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -297,7 +297,7 @@ static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
>  		<< KASAN_SHADOW_SCALE_SHIFT);
>  }
>  
> -static inline bool addr_has_metadata(const void *addr)
> +static __always_inline bool addr_has_metadata(const void *addr)
>  {
>  	return (kasan_reset_tag(addr) >=
>  		kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
> @@ -316,7 +316,7 @@ bool kasan_check_range(unsigned long addr, size_t size, bool write,
>  
>  #else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
>  
> -static inline bool addr_has_metadata(const void *addr)
> +static __always_inline bool addr_has_metadata(const void *addr)
>  {
>  	return (is_vmalloc_addr(addr) || virt_addr_valid(addr));
>  }
> -- 
> 2.39.1
>