linux-kernel - Re: [PATCH 5/7] riscv: drop the use of XIP_OFFSET in kernel_mapping_va_to

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Message-ID: <187d7992-e2a7-446c-9f53-d0e7bf6a5843@ghiti.fr>
Date: Mon, 27 May 2024 14:49:57 +0200
From: Alexandre Ghiti <alex@...ti.fr>
To: Nam Cao <namcao@...utronix.de>, Paul Walmsley <paul.walmsley@...ive.com>,
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/7] riscv: drop the use of XIP_OFFSET in
 kernel_mapping_va_to_pa()


On 10/05/2024 08:28, Nam Cao wrote:
> XIP_OFFSET is the hard-coded offset of writable data section within the
> kernel.
>
> By hard-coding this value, the read-only section of the kernel (which is
> placed before the writable data section) is restricted in size.
>
> As a preparation to remove this hard-coded macro XIP_OFFSET entirely,
> remove the use of XIP_OFFSET in kernel_mapping_va_to_pa(). The macro
> XIP_OFFSET is used in this case to check if the virtual address is mapped
> to Flash or to RAM. The same check can be done with kernel_map.xiprom_sz.
>
> Signed-off-by: Nam Cao <namcao@...utronix.de>
> ---
>   arch/riscv/include/asm/page.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
> index 14d0de928f9b..bcd77df15835 100644
> --- a/arch/riscv/include/asm/page.h
> +++ b/arch/riscv/include/asm/page.h
> @@ -159,7 +159,7 @@ phys_addr_t linear_mapping_va_to_pa(unsigned long x);
>   #ifdef CONFIG_XIP_KERNEL
>   #define kernel_mapping_va_to_pa(y) ({						\
>   	unsigned long _y = (unsigned long)(y);					\
> -	(_y < kernel_map.virt_addr + XIP_OFFSET) ?				\
> +	(_y < kernel_map.virt_addr + kernel_map.xiprom_sz) ?			\
>   		(_y - kernel_map.va_kernel_xip_pa_offset) :			\
>   		(_y - kernel_map.va_kernel_data_pa_offset);			\
>   	})


Reviewed-by: Alexandre Ghiti <alexghiti@...osinc.com>

Thanks,

Alex