linux-kernel - Re: [PATCH v3 4/5] arm64: introduce pfn_valid

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Date:   Wed, 28 Mar 2018 17:38:30 +0800
From:   Wei Yang <richard.weiyang@...il.com>
To:     Jia He <hejianet@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Mel Gorman <mgorman@...e.de>,
        Will Deacon <will.deacon@....com>,
        Mark Rutland <mark.rutland@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Pavel Tatashin <pasha.tatashin@...cle.com>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        AKASHI Takahiro <takahiro.akashi@...aro.org>,
        Gioh Kim <gi-oh.kim@...fitbricks.com>,
        Steven Sistare <steven.sistare@...cle.com>,
        Daniel Vacek <neelx@...hat.com>,
        Eugeniu Rosca <erosca@...adit-jv.com>,
        Vlastimil Babka <vbabka@...e.cz>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, James Morse <james.morse@....com>,
        Steve Capper <steve.capper@....com>, x86@...nel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Kemi Wang <kemi.wang@...el.com>,
        Petr Tesarik <ptesarik@...e.com>,
        YASUAKI ISHIMATSU <yasu.isimatu@...il.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Nikolay Borisov <nborisov@...e.com>,
        Jia He <jia.he@...-semitech.com>
Subject: Re: [PATCH v3 4/5] arm64: introduce pfn_valid_region()

On Sun, Mar 25, 2018 at 08:02:18PM -0700, Jia He wrote:
>This is the preparation for further optimizing in early_pfn_valid
>on arm64.
>
>Signed-off-by: Jia He <jia.he@...-semitech.com>
>---
> arch/arm64/include/asm/page.h |  3 ++-
> arch/arm64/mm/init.c          | 25 ++++++++++++++++++++++++-
> 2 files changed, 26 insertions(+), 2 deletions(-)
>
>diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
>index 60d02c8..da2cba3 100644
>--- a/arch/arm64/include/asm/page.h
>+++ b/arch/arm64/include/asm/page.h
>@@ -38,7 +38,8 @@ extern void clear_page(void *to);
> typedef struct page *pgtable_t;
> 
> #ifdef CONFIG_HAVE_ARCH_PFN_VALID
>-extern int pfn_valid(unsigned long);
>+extern int pfn_valid(unsigned long pfn);
>+extern int pfn_valid_region(unsigned long pfn, int *last_idx);
> #endif
> 
> #include <asm/memory.h>
>diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>index 00e7b90..06433d5 100644
>--- a/arch/arm64/mm/init.c
>+++ b/arch/arm64/mm/init.c
>@@ -290,7 +290,30 @@ int pfn_valid(unsigned long pfn)
> 	return memblock_is_map_memory(pfn << PAGE_SHIFT);
> }
> EXPORT_SYMBOL(pfn_valid);
>-#endif
>+
>+int pfn_valid_region(unsigned long pfn, int *last_idx)
>+{
>+	unsigned long start_pfn, end_pfn;
>+	struct memblock_type *type = &memblock.memory;
>+
>+	if (*last_idx != -1) {
>+		start_pfn = PFN_DOWN(type->regions[*last_idx].base);

PFN_UP() should be used.

>+		end_pfn= PFN_DOWN(type->regions[*last_idx].base +
>+					type->regions[*last_idx].size);
>+
>+		if (pfn >= start_pfn && pfn < end_pfn)
>+			return !memblock_is_nomap(
>+				&memblock.memory.regions[*last_idx]);

Could use type->regions directly.

>+	}
>+
>+	*last_idx = memblock_search_pfn_regions(pfn);
>+	if (*last_idx == -1)
>+		return false;
>+
>+	return !memblock_is_nomap(&memblock.memory.regions[*last_idx]);

Could use type->regions directly.

Well, since your check memblock.memory.regions, how about use a variable
equals memblock.memory.regions directly instead of type->regions?

For example:

struct memblock_region *regions = memblock.memory.regions;

>+}
>+EXPORT_SYMBOL(pfn_valid_region);
>+#endif /*CONFIG_HAVE_ARCH_PFN_VALID*/
> 
> #ifndef CONFIG_SPARSEMEM
> static void __init arm64_memory_present(void)
>-- 
>2.7.4

-- 
Wei Yang
Help you, Help me