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Date:   Mon, 5 Jun 2023 07:08:47 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Kefeng Wang <wangkefeng.wang@huawei.com>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        linux-arm-kernel@lists.infradead.org, anshuman.khandual@arm.com,
        egyszeregy@freemail.hu, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: mm: move _PAGE_IOREMAP into pgtable-prot.h
Message-ID: <ZH3sb1o8Q4lPFrU0@infradead.org>
References: <20230602073445.150273-1-wangkefeng.wang@huawei.com>
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On Fri, Jun 02, 2023 at 03:34:45PM +0800, Kefeng Wang wrote:
> Szőke Kálmán Benjamin reported to me a build issue on an out-of-tree
> module(from Xilinx[1]), which directly include <asm-generic/io.h>,

Err.  Not one should do that, and we certainly should not cater to such
crap.

NAK.

> 
>   "undefined reference" error for _PAGE_IOREMAP
> 
> In general, the module shouldn't include the low-level header file,
> it should be fixed, but _PAGE_IOREMAP definination is kind of pgtable
> prot, let's move it into pgtable-prot.h to put togethor with other prot.
> 
> [1] https://github.com/Xilinx/XilinxVirtualCable/blob/master/zynqMP/src/driver/xvc_driver.c
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  arch/arm64/include/asm/io.h           | 2 --
>  arch/arm64/include/asm/pgtable-prot.h | 1 +
>  2 files changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
> index 877495a0fd0c..0b0b12a95051 100644
> --- a/arch/arm64/include/asm/io.h
> +++ b/arch/arm64/include/asm/io.h
> @@ -142,8 +142,6 @@ extern void __memset_io(volatile void __iomem *, int, size_t);
>  bool ioremap_allowed(phys_addr_t phys_addr, size_t size, unsigned long prot);
>  #define ioremap_allowed ioremap_allowed
>  
> -#define _PAGE_IOREMAP PROT_DEVICE_nGnRE
> -
>  #define ioremap_wc(addr, size)	\
>  	ioremap_prot((addr), (size), PROT_NORMAL_NC)
>  #define ioremap_np(addr, size)	\
> diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
> index 9b165117a454..f79afbad26a0 100644
> --- a/arch/arm64/include/asm/pgtable-prot.h
> +++ b/arch/arm64/include/asm/pgtable-prot.h
> @@ -64,6 +64,7 @@ extern bool arm64_use_ng_mappings;
>  #define PROT_SECT_NORMAL_EXEC	(PROT_SECT_DEFAULT | PMD_SECT_UXN | PMD_ATTRINDX(MT_NORMAL))
>  
>  #define _PAGE_DEFAULT		(_PROT_DEFAULT | PTE_ATTRINDX(MT_NORMAL))
> +#define _PAGE_IOREMAP		PROT_DEVICE_nGnRE
>  
>  #define PAGE_KERNEL		__pgprot(PROT_NORMAL)
>  #define PAGE_KERNEL_RO		__pgprot((PROT_NORMAL & ~PTE_WRITE) | PTE_RDONLY)
> -- 
> 2.35.3
> 
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