[PATCH V4 2/4] arm64/mm: Define arch_get_mappable_range()

[Anshuman Khandual]

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. It
also adds a VM_BUG_ON() check that would ensure that mhp_range_allowed()
has already been called.

Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
 arch/arm64/mm/mmu.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index ae0c3d023824..b14fd1b6b1a0 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1442,16 +1442,19 @@ 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 mhp_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);
+	mhp_range.start = __pa(_PAGE_OFFSET(vabits_actual));
+	mhp_range.end =  __pa(PAGE_END - 1);
+	return mhp_range;
 }
 
 int arch_add_memory(int nid, u64 start, u64 size,
@@ -1459,11 +1462,7 @@ 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;
-	}
-
+	VM_BUG_ON(!mhp_range_allowed(start, size, true));
 	if (rodata_full || debug_pagealloc_enabled())
 		flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
 
-- 
2.20.1