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From: Christoph Hellwig <hch@infradead.org>
To: Alexandre Ghiti <alex@ghiti.fr>
Cc: Christoph Hellwig <hch@infradead.org>,
	Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Ralf Baechle <ralf@linux-mips.org>,
	Paul Burton <paul.burton@mips.com>,
	James Hogan <jhogan@kernel.org>,
	Palmer Dabbelt <palmer@sifive.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
	linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH 1/4] arm64, mm: Move generic mmap layout functions to mm
Date: Fri, 22 Mar 2019 06:21:27 -0700	[thread overview]
Message-ID: <20190322132127.GA18602@infradead.org> (raw)
In-Reply-To: <20190322074225.22282-2-alex@ghiti.fr>

> It then introduces a new define ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
> that can be defined by other architectures to benefit from those functions.

Can you make this a Kconfig option defined in arch/Kconfig or mm/Kconfig
and selected by the architectures?

> -#ifndef STACK_RND_MASK
> -#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))	/* 8MB of VA */
> -#endif
> -
> -static unsigned long randomize_stack_top(unsigned long stack_top)
> -{
> -	unsigned long random_variable = 0;
> -
> -	if (current->flags & PF_RANDOMIZE) {
> -		random_variable = get_random_long();
> -		random_variable &= STACK_RND_MASK;
> -		random_variable <<= PAGE_SHIFT;
> -	}
> -#ifdef CONFIG_STACK_GROWSUP
> -	return PAGE_ALIGN(stack_top) + random_variable;
> -#else
> -	return PAGE_ALIGN(stack_top) - random_variable;
> -#endif
> -}
> -

Maybe the move of this function can be split into another prep patch,
as it is only very lightly related?

> +#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
> +	defined(ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)

Not sure if it is wrіtten down somehwere or just convention, but I
general see cpp defined statements aligned with spaces to the
one on the previous line.

Except for these nitpicks this looks very nice to me, thanks for doing
this work!

  reply	other threads:[~2019-03-22 13:21 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-22  7:42 [PATCH 0/4] Provide generic top-down mmap layout functions Alexandre Ghiti
2019-03-22  7:42 ` [PATCH 1/4] arm64, mm: Move generic mmap layout functions to mm Alexandre Ghiti
2019-03-22 13:21   ` Christoph Hellwig [this message]
2019-03-23  8:18     ` Alex Ghiti
2019-03-22  7:42 ` [PATCH 2/4] arm: Use generic mmap top-down layout Alexandre Ghiti
2019-03-22  7:42 ` [PATCH 3/4] mips: " Alexandre Ghiti
2019-03-22  7:42 ` [PATCH 4/4] riscv: Make mmap allocation top-down by default Alexandre Ghiti
2019-03-22 13:22   ` Christoph Hellwig
2019-03-23  8:05     ` Alex Ghiti

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