linux-kernel - [PATCH 1/4] m68k: mm: Convert get_pointer

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Message-ID: <20250611001255.527952-2-vishal.moola@gmail.com>
Date: Tue, 10 Jun 2025 17:12:52 -0700
From: "Vishal Moola (Oracle)" <vishal.moola@...il.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: linux-m68k@...ts.linux-m68k.org,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Vishal Moola (Oracle)" <vishal.moola@...il.com>
Subject: [PATCH 1/4] m68k: mm: Convert get_pointer_table() to use ptdescs

Motorola uses get_pointer_table() for page tables, so it should be using
struct ptdesc, not struct page.

This helps us prepare to allocate ptdescs as their own memory
descriptor, and prepares to remove a user of page->lru.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@...il.com>
---
 arch/m68k/mm/motorola.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/m68k/mm/motorola.c b/arch/m68k/mm/motorola.c
index 745bd575dcfa..35c3571ffbef 100644
--- a/arch/m68k/mm/motorola.c
+++ b/arch/m68k/mm/motorola.c
@@ -148,16 +148,18 @@ void *get_pointer_table(struct mm_struct *mm, int type)
 
 	/*
 	 * For a pointer table for a user process address space, a
-	 * table is taken from a page allocated for the purpose.  Each
-	 * page can hold 8 pointer tables.  The page is remapped in
+	 * table is taken from a ptdesc allocated for the purpose.  Each
+	 * ptdesc can hold 8 pointer tables.  The ptdesc is remapped in
 	 * virtual address space to be noncacheable.
 	 */
 	if (mask == 0) {
-		void *page;
+		struct ptdesc *ptdesc = pagetable_alloc(GFP_KERNEL | __GFP_ZERO, 0);
+		void *pt_addr;
 		ptable_desc *new;
 
-		if (!(page = (void *)get_zeroed_page(GFP_KERNEL)))
+		if (!ptdesc)
 			return NULL;
+		pt_addr = ptdesc_address(ptdesc);
 
 		switch (type) {
 		case TABLE_PTE:
@@ -165,23 +167,23 @@ void *get_pointer_table(struct mm_struct *mm, int type)
 			 * m68k doesn't have SPLIT_PTE_PTLOCKS for not having
 			 * SMP.
 			 */
-			pagetable_pte_ctor(mm, virt_to_ptdesc(page));
+			pagetable_pte_ctor(mm, ptdesc);
 			break;
 		case TABLE_PMD:
-			pagetable_pmd_ctor(mm, virt_to_ptdesc(page));
+			pagetable_pmd_ctor(mm, ptdesc);
 			break;
 		case TABLE_PGD:
-			pagetable_pgd_ctor(virt_to_ptdesc(page));
+			pagetable_pgd_ctor(ptdesc);
 			break;
 		}
 
-		mmu_page_ctor(page);
+		mmu_page_ctor(pt_addr);
 
-		new = PD_PTABLE(page);
+		new = PD_PTABLE(pt_addr);
 		PD_MARKBITS(new) = ptable_mask(type) - 1;
 		list_add_tail(new, dp);
 
-		return (pmd_t *)page;
+		return (pmd_t *)pt_addr;
 	}
 
 	for (tmp = 1, off = 0; (mask & tmp) == 0; tmp <<= 1, off += ptable_size(type))
@@ -191,7 +193,7 @@ void *get_pointer_table(struct mm_struct *mm, int type)
 		/* move to end of list */
 		list_move_tail(dp, &ptable_list[type]);
 	}
-	return page_address(PD_PAGE(dp)) + off;
+	return ptdesc_address(PD_PTDESC(dp)) + off;
 }
 
 int free_pointer_table(void *table, int type)
-- 
2.49.0