linux-kernel - Re: [PATCH 0/3] arm64: put objects into proper sections

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Date:	Wed, 10 Aug 2016 18:05:32 +0800
From:	Jisheng Zhang <jszhang@...vell.com>
To:	<catalin.marinas@....com>, <will.deacon@....com>,
	<lorenzo.pieralisi@....com>, Kees Cook <keescook@...omium.org>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3] arm64: put objects into proper sections

+ Kees,

On Wed, 10 Aug 2016 15:19:16 +0800 Jisheng Zhang wrote:

> This series tries to put objects into proper sections to avoid
> pontential unnecessary DDR traffics:
> 
> patch1 puts alloc_vectors_page() into .init section. This is a clean up
> patch.
> 
> patch2 puts vdso_pages, vdso_spec and vectors_page into read_mostly
> section, since they are read mostly in hot path.
> 
> patch3 puts cpu_ops into read_mostly section, since it's read mostly
> int hot path such as arm_cpuidle_suspend().

Is it better to mark them as __ro_after_init, suggestions are appreciated.

Thanks,
Jisheng

> 
> 
> Before this series:
> 
> ffff000008d660f0 b undef_lock
> ffff000008d660f8 b vectors_page
> ffff000008d66100 b vdso_pages
> ffff000008d66108 b vdso_spec
> ffff000008d66148 B cpu_ops
> ffff000008d66348 b patch_lock
> 
> After this series:
> 
> ffff000008ca5b08 D static_key_initialized
> ffff000008ca5b10 d vectors_page
> ffff000008ca5b18 d vdso_pages
> ffff000008ca5b20 d vdso_spec
> ffff000008ca5b60 D cpu_ops
> ffff000008ca5d60 D elf_hwcap
> ffff000008ca5d68 D compat_elf_hwcap
> ffff000008ca5d6c D compat_elf_hwcap2
> 
> Although there's no obvious issue with current code, because undef_lock and
> patch_lock is rarely used, but the situation may change in the future, so
> let's move them into proper sections now.
> 
> Jisheng Zhang (3):
>   arm64: vdso: add __init section marker to alloc_vectors_page
>   arm64: vdso: put read only/mostly objects into proper sections
>   arm64: kernel: declare cpu_ops __read_mostly
> 
>  arch/arm64/kernel/cpu_ops.c |  2 +-
>  arch/arm64/kernel/vdso.c    | 31 +++++++++++++++----------------
>  2 files changed, 16 insertions(+), 17 deletions(-)
>