Re: [PATCH] RISC-V: Always define XIP_FIXUP

From: Palmer Dabbelt <palmer@dabbelt.com>
To: alex@ghiti.fr
Cc: linux-riscv@lists.infradead.org,
	Paul Walmsley <paul.walmsley@sifive.com>,
	aou@eecs.berkeley.edu, akpm@linux-foundation.org,
	Atish Patra <Atish.Patra@wdc.com>,
	Anup Patel <Anup.Patel@wdc.com>,
	wangkefeng.wang@huawei.com, rppt@kernel.org,
	vitaly.wool@konsulko.com, greentime.hu@sifive.com,
	0x7f454c46@gmail.com, chenhuang5@huawei.com,
	linux-kernel@vger.kernel.org, kernel-team@android.com,
	linux@roeck-us.net
Subject: Re: [PATCH] RISC-V: Always define XIP_FIXUP
Date: Wed, 28 Apr 2021 21:43:19 -0700 (PDT)	[thread overview]
Message-ID: <mhng-2e1a7543-84bc-4954-843a-b577fc132157@palmerdabbelt-glaptop> (raw)
In-Reply-To: <b674bc91-8228-9236-f3ec-8f65bb5620c8@ghiti.fr>

On Wed, 28 Apr 2021 01:25:55 PDT (-0700), alex@ghiti.fr wrote:
> Le 4/27/21 à 11:34 PM, Palmer Dabbelt a écrit :
>> From: Palmer Dabbelt <palmerdabbelt@google.com>
>>
>> XIP depends on MMU, but XIP_FIXUP is defined throughout the kernel in
>> order to avoid excessive ifdefs.  This just makes sure to always define
>> XIP_FIXIP, which will fix MMU=n builds.
>
> A small typo here.

Actually two: "defined" should have been "used".  Both are fixed.

>
>>
>> Fixes: 44c922572952 ("RISC-V: enable XIP")
>> Reported-by: Guenter Roeck <linux@roeck-us.net>
>> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
>> ---
>>   arch/riscv/include/asm/pgtable.h | 24 ++++++++++++------------
>>   1 file changed, 12 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
>> index 2f1384e14e31..fd749351f432 100644
>> --- a/arch/riscv/include/asm/pgtable.h
>> +++ b/arch/riscv/include/asm/pgtable.h
>> @@ -73,18 +73,6 @@
>>   #endif
>>   #define FIXADDR_START    (FIXADDR_TOP - FIXADDR_SIZE)
>>
>> -#ifdef CONFIG_XIP_KERNEL
>> -#define XIP_OFFSET		SZ_8M
>> -#define XIP_FIXUP(addr) ({							\
>> -	uintptr_t __a = (uintptr_t)(addr);					\
>> -	(__a >= CONFIG_XIP_PHYS_ADDR && __a < CONFIG_XIP_PHYS_ADDR + SZ_16M) ?	\
>> -		__a - CONFIG_XIP_PHYS_ADDR + CONFIG_PHYS_RAM_BASE - XIP_OFFSET :\
>> -		__a;								\
>> -	})
>> -#else
>> -#define XIP_FIXUP(addr)		(addr)
>> -#endif /* CONFIG_XIP_KERNEL */
>> -
>>   #endif
>>
>>   #ifndef __ASSEMBLY__
>> @@ -101,6 +89,18 @@
>>   #include <asm/pgtable-32.h>
>>   #endif /* CONFIG_64BIT */
>>
>> +#ifdef CONFIG_XIP_KERNEL
>> +#define XIP_OFFSET		SZ_8M
>
>
> XIP_OFFSET is used in head.S and then this breaks XIP_KERNEL. XIP_OFFSET
> must live outside the ifndef __ASSEMBLY__.

Thanks, I hadn't even seen XIP_OFFSET.  This is fixed in the v2.

Do you have an XIP config that will run on QEMU, and a way to run it?  
If so, can you post a defconfig and some instructions?  That'll make it 
easier to test on my end.

>> +#define XIP_FIXUP(addr) ({							\
>> +	uintptr_t __a = (uintptr_t)(addr);					\
>> +	(__a >= CONFIG_XIP_PHYS_ADDR && __a < CONFIG_XIP_PHYS_ADDR + SZ_16M) ?	\
>> +		__a - CONFIG_XIP_PHYS_ADDR + CONFIG_PHYS_RAM_BASE - XIP_OFFSET :\
>> +		__a;								\
>> +	})
>> +#else
>> +#define XIP_FIXUP(addr)		(addr)
>> +#endif /* CONFIG_XIP_KERNEL */
>> +
>>   #ifdef CONFIG_MMU
>>   /* Number of entries in the page global directory */
>>   #define PTRS_PER_PGD    (PAGE_SIZE / sizeof(pgd_t))
>>
>
> Thank you for doing that!
>
> Alex