linux-kernel - Re: [PATCH -fixes 3/3] riscv: Optimize kernel virtual address conversion macro

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Message-ID: <mhng-163d949e-5efc-46d4-a5b7-c90e4745a7a3@palmerdabbelt-glaptop>
Date:   Sat, 07 Aug 2021 09:36:41 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     alex@...ti.fr
CC:     Paul Walmsley <paul.walmsley@...ive.com>, aou@...s.berkeley.edu,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        alex@...ti.fr
Subject:     Re: [PATCH -fixes 3/3] riscv: Optimize kernel virtual address conversion macro

On Wed, 21 Jul 2021 00:59:37 PDT (-0700), alex@...ti.fr wrote:
> The current test in kernel_mapping_va_to_pa only applies when
> CONFIG_XIP_KERNEL is set, so use IS_ENABLED to optimize this macro at
> compile-time in standard kernels that do not require this test.
>
> Signed-off-by: Alexandre Ghiti <alex@...ti.fr>
> ---
>  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 b0ca5058e7ae..10dc063868f6 100644
> --- a/arch/riscv/include/asm/page.h
> +++ b/arch/riscv/include/asm/page.h
> @@ -123,7 +123,7 @@ extern phys_addr_t phys_ram_base;
>  #define linear_mapping_va_to_pa(x)	((unsigned long)(x) - kernel_map.va_pa_offset)
>  #define kernel_mapping_va_to_pa(y) ({						\
>  	unsigned long _y = y;							\
> -	(_y < kernel_map.virt_addr + XIP_OFFSET) ?					\
> +	(IS_ENABLED(CONFIG_XIP_KERNEL) && _y < kernel_map.virt_addr + XIP_OFFSET) ?	\
>  		((unsigned long)(_y) - kernel_map.va_kernel_xip_pa_offset) :		\
>  		((unsigned long)(_y) - kernel_map.va_kernel_pa_offset - XIP_OFFSET);	\
>  	})

IIUC this isn't actually a fix?  The other two are, though, so 
they're on fixes.

Thanks!