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

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Message-ID: <39a1fa85-1885-effe-1670-ec9cf34099f5@ghiti.fr>
Date:   Sat, 7 Aug 2021 21:31:24 +0200
From:   Alex Ghiti <alex@...ti.fr>
To:     Palmer Dabbelt <palmer@...belt.com>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>, aou@...s.berkeley.edu,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -fixes 3/3] riscv: Optimize kernel virtual address
 conversion macro

Le 7/08/2021 à 18:36, Palmer Dabbelt a écrit :
> 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.

Indeed this is not a fix, this is symmetrical to what I have done in 
patch 1 so that seemed natural to land in the same patchset. Let me know 
if you want me to resend it on its own.

Thanks,

Alex

> 
> Thanks!
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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