On 2019-08-14 7:35 a.m., Greentime Hu wrote:
> Logan Gunthorpe <log...@deltatee.com> 於 2019年8月14日 週三 上午12:50寫道：
>>
>> On 2019-08-13 10:39 a.m., Paul Walmsley wrote:
>>> On Tue, 13 Aug 2019, Logan Gunthorpe wrote:
>>>
>>>> On 2019-08-13 12:04 a.m., Greentime Hu wrote:
>>>>
>>>>> Every architecture with mmu defines their own pfn_valid().
>>>>
>>>> Not true. Arm64, for example just uses the generic implementation in
>>>> mmzone.h.
>>>
>>> arm64 seems to define their own:
>>>
>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/Kconfig#n899
>>
>> Oh, yup. My mistake.
>>
>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/mm/init.c#n235
>>>
>>> While there are many architectures which have their own pfn_valid();
>>> oddly, almost none of them set HAVE_ARCH_PFN_VALID ?
>>
>> Yes, much of this is super confusing. Seems HAVE_ARCH_PFN_VALID only
>> matters if SPARSEMEM is set. So risc-v probably doesn't need to set it
>> and we just need a #ifdef !CONFIG_FLATMEM around the pfn_valid
>> definition like other arches.
>>
>
> Maybe this commit explains why it used HAVE_ARCH_PFN_VALID instead of
> SPARSEMEM.
> https://github.com/torvalds/linux/commit/7b7bf499f79de3f6c85a340c8453a78789523f85
>
> BTW, I found another issue here.
> #define FIXADDR_TOP (VMALLOC_START)
> #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
> #define VMEMMAP_END (VMALLOC_START - 1)
> #define VMEMMAP_START (VMALLOC_START - VMEMMAP_SIZE)
> These 2 regions are overlapped.
>
> How about this fix? Not sure if it is good for everyone.
Yes, this looks good to me. I can fold these changes into my patch and
send a v5 to the list.
Thanks!
Logan
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 3f12b069af1d..3c4d394679d0 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -115,9 +115,6 @@ config PGTABLE_LEVELS
> default 3 if 64BIT
> default 2
>
> -config HAVE_ARCH_PFN_VALID
> - def_bool y
> -
> menu "Platform type"
>
> choice
> diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
> index c207f6634b91..72e106b60bc5 100644
> --- a/arch/riscv/include/asm/fixmap.h
> +++ b/arch/riscv/include/asm/fixmap.h
> @@ -26,7 +26,7 @@ enum fixed_addresses {
> };
>
> #define FIXADDR_SIZE (__end_of_fixed_addresses * PAGE_SIZE)
> -#define FIXADDR_TOP (VMALLOC_START)
> +#define FIXADDR_TOP (VMEMMAP_START)
> #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
>
> #define FIXMAP_PAGE_IO PAGE_KERNEL
> diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
> index 8ddb6c7fedac..83830997dce6 100644
> --- a/arch/riscv/include/asm/page.h
> +++ b/arch/riscv/include/asm/page.h
> @@ -100,8 +100,10 @@ extern unsigned long min_low_pfn;
> #define page_to_bus(page) (page_to_phys(page))
> #define phys_to_page(paddr) (pfn_to_page(phys_to_pfn(paddr)))
>
> +#if defined(CONFIG_FLATMEM)
> #define pfn_valid(pfn) \
> (((pfn) >= pfn_base) && (((pfn)-pfn_base) < max_mapnr))
> +#endif
>
> #define ARCH_PFN_OFFSET (pfn_base)
