linux-kernel - [RFC V2 2/3] arm64/mm: Define arch_get_mappable

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Date:   Mon, 30 Nov 2020 08:59:51 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-mm@...ck.org, akpm@...ux-foundation.org, david@...hat.com
Cc:     linux-arm-kernel@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Anshuman Khandual <anshuman.khandual@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Mark Rutland <mark.rutland@....com>
Subject: [RFC V2 2/3] arm64/mm: Define arch_get_mappable_range()

This overrides arch_get_mappable_range() on arm64 platform which will be
used with recently added generic framework. It drops inside_linear_region()
and subsequent check in arch_add_memory() which are no longer required.

Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Cc: Ard Biesheuvel <ardb@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: David Hildenbrand <david@...hat.com>
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
 arch/arm64/mm/mmu.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index ca692a815731..49ec8f2838f2 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1444,16 +1444,19 @@ static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size)
 	free_empty_tables(start, end, PAGE_OFFSET, PAGE_END);
 }
 
-static bool inside_linear_region(u64 start, u64 size)
+struct range arch_get_mappable_range(void)
 {
+	struct range memhp_range;
+
 	/*
 	 * Linear mapping region is the range [PAGE_OFFSET..(PAGE_END - 1)]
 	 * accommodating both its ends but excluding PAGE_END. Max physical
 	 * range which can be mapped inside this linear mapping range, must
 	 * also be derived from its end points.
 	 */
-	return start >= __pa(_PAGE_OFFSET(vabits_actual)) &&
-	       (start + size - 1) <= __pa(PAGE_END - 1);
+	memhp_range.start = __pa(_PAGE_OFFSET(vabits_actual));
+	memhp_range.end =  __pa(PAGE_END - 1);
+	return memhp_range;
 }
 
 int arch_add_memory(int nid, u64 start, u64 size,
@@ -1461,11 +1464,6 @@ int arch_add_memory(int nid, u64 start, u64 size,
 {
 	int ret, flags = 0;
 
-	if (!inside_linear_region(start, size)) {
-		pr_err("[%llx %llx] is outside linear mapping region\n", start, start + size);
-		return -EINVAL;
-	}
-
 	if (rodata_full || debug_pagealloc_enabled())
 		flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
 
-- 
2.20.1