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Subject: Re: [RFC PATCH 03/10] powerpc: introduce kimage_vaddr to store the
 kernel base
To:     Jason Yan <yanaijie@huawei.com>, mpe@ellerman.id.au,
        linuxppc-dev@lists.ozlabs.org, diana.craciun@nxp.com,
        benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com,
        keescook@chromium.org, kernel-hardening@lists.openwall.com
Cc:     linux-kernel@vger.kernel.org, wangkefeng.wang@huawei.com,
        yebin10@huawei.com, thunder.leizhen@huawei.com,
        jingxiangfeng@huawei.com, fanchengyang@huawei.com
References: <20190717080621.40424-1-yanaijie@huawei.com>
 <20190717080621.40424-4-yanaijie@huawei.com>
From:   Christophe Leroy <christophe.leroy@c-s.fr>
Message-ID: <7e19ade3-cb1a-a633-aa2d-ef5f182ba80c@c-s.fr>
Date:   Mon, 29 Jul 2019 13:00:28 +0200
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Le 17/07/2019 à 10:06, Jason Yan a écrit :
> Now the kernel base is a fixed value - KERNELBASE. To support KASLR, we
> need a variable to store the kernel base.
> 
> Signed-off-by: Jason Yan <yanaijie@huawei.com>
> Cc: Diana Craciun <diana.craciun@nxp.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Christophe Leroy <christophe.leroy@c-s.fr>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Nicholas Piggin <npiggin@gmail.com>
> Cc: Kees Cook <keescook@chromium.org>

Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>


> ---
>   arch/powerpc/include/asm/page.h | 2 ++
>   arch/powerpc/mm/init-common.c   | 2 ++
>   2 files changed, 4 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
> index 0d52f57fca04..60a68d3a54b1 100644
> --- a/arch/powerpc/include/asm/page.h
> +++ b/arch/powerpc/include/asm/page.h
> @@ -315,6 +315,8 @@ void arch_free_page(struct page *page, int order);
>   
>   struct vm_area_struct;
>   
> +extern unsigned long kimage_vaddr;
> +
>   #include <asm-generic/memory_model.h>
>   #endif /* __ASSEMBLY__ */
>   #include <asm/slice.h>
> diff --git a/arch/powerpc/mm/init-common.c b/arch/powerpc/mm/init-common.c
> index 9273c38009cb..c7a98c73e5c1 100644
> --- a/arch/powerpc/mm/init-common.c
> +++ b/arch/powerpc/mm/init-common.c
> @@ -25,6 +25,8 @@ phys_addr_t memstart_addr = (phys_addr_t)~0ull;
>   EXPORT_SYMBOL(memstart_addr);
>   phys_addr_t kernstart_addr;
>   EXPORT_SYMBOL(kernstart_addr);
> +unsigned long kimage_vaddr = KERNELBASE;
> +EXPORT_SYMBOL(kimage_vaddr);
>   
>   static bool disable_kuep = !IS_ENABLED(CONFIG_PPC_KUEP);
>   static bool disable_kuap = !IS_ENABLED(CONFIG_PPC_KUAP);
>