linux-kernel - Re: [PATCH 07/16] powerpc: mm: Support MAP_BELOW

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Message-ID: <a43c52c6-c1ac-4ef3-b511-08f0459bddad@csgroup.eu>
Date: Wed, 28 Aug 2024 08:34:49 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Charlie Jenkins <charlie@...osinc.com>, Arnd Bergmann <arnd@...db.de>,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt
 <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
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 Naveen N Rao <naveen@...nel.org>, Muchun Song <muchun.song@...ux.dev>,
 Andrew Morton <akpm@...ux-foundation.org>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, Vlastimil Babka
 <vbabka@...e.cz>, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
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Cc: linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
 Palmer Dabbelt <palmer@...osinc.com>, linux-riscv@...ts.infradead.org,
 linux-arm-kernel@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
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 linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 07/16] powerpc: mm: Support MAP_BELOW_HINT

Hi Charlie,

Le 28/08/2024 à 07:49, Charlie Jenkins a écrit :
> Add support for MAP_BELOW_HINT to arch_get_mmap_base() and
> arch_get_mmap_end().
> 
> Signed-off-by: Charlie Jenkins <charlie@...osinc.com>
> ---
>   arch/powerpc/include/asm/task_size_64.h | 36 +++++++++++++++++++++++++++------
>   1 file changed, 30 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/task_size_64.h b/arch/powerpc/include/asm/task_size_64.h
> index 239b363841aa..a37a5a81365d 100644
> --- a/arch/powerpc/include/asm/task_size_64.h
> +++ b/arch/powerpc/include/asm/task_size_64.h
> @@ -72,12 +72,36 @@
>   #define STACK_TOP_MAX TASK_SIZE_USER64
>   #define STACK_TOP (is_32bit_task() ? STACK_TOP_USER32 : STACK_TOP_USER64)
>   
> -#define arch_get_mmap_base(addr, len, base, flags) \
> -	(((addr) > DEFAULT_MAP_WINDOW) ? (base) + TASK_SIZE - DEFAULT_MAP_WINDOW : (base))
> +#define arch_get_mmap_base(addr, len, base, flags)					\

This macro looks quite big for a macro, can it be a static inline 
function instead ? Same for the other macro below.

> +({											\
> +	unsigned long mmap_base;							\
> +	typeof(flags) _flags = (flags);							\
> +	typeof(addr) _addr = (addr);							\
> +	typeof(base) _base = (base);							\
> +	typeof(len) _len = (len);							\
> +	unsigned long rnd_gap = DEFAULT_MAP_WINDOW - (_base);				\
> +	if (_flags & MAP_BELOW_HINT && _addr != 0 && ((_addr + _len) > BIT(VA_BITS - 1)))\
> +		mmap_base = (_addr + _len) - rnd_gap;					\
> +	else										\
> +		mmap_end = ((_addr > DEFAULT_MAP_WINDOW) ?				\
> +				_base + TASK_SIZE - DEFAULT_MAP_WINDOW :		\
> +				_base);							\
> +	mmap_end;									\

mmap_end doesn't exist, did you mean mmap_base ?

> +})
>   
> -#define arch_get_mmap_end(addr, len, flags) \
> -	(((addr) > DEFAULT_MAP_WINDOW) || \
> -	 (((flags) & MAP_FIXED) && ((addr) + (len) > DEFAULT_MAP_WINDOW)) ? TASK_SIZE : \
> -									    DEFAULT_MAP_WINDOW)
> +#define arch_get_mmap_end(addr, len, flags)							\
> +({												\
> +	unsigned long mmap_end;									\
> +	typeof(flags) _flags = (flags);								\
> +	typeof(addr) _addr = (addr);								\
> +	typeof(len) _len = (len);								\
> +	if (_flags & MAP_BELOW_HINT && _addr != 0 && ((_addr + _len) > BIT(VA_BITS - 1)))	\
> +		mmap_end = (_addr + _len);							\
> +	else											\
> +		mmap_end = (((_addr) > DEFAULT_MAP_WINDOW) ||					\
> +				(((_flags) & MAP_FIXED) && ((_addr) + (_len) > DEFAULT_MAP_WINDOW))\
> +				? TASK_SIZE : DEFAULT_MAP_WINDOW)				\
> +	mmap_end;										\
> +})
>   
>   #endif /* _ASM_POWERPC_TASK_SIZE_64_H */
>