[PATCH 16/18] ARC: mm: support 4 levels of page tables

From: Vineet Gupta
Date: Tue Aug 10 2021 - 20:43:58 EST

Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxx>
---
arch/arc/include/asm/page.h | 11 +++++++
arch/arc/include/asm/pgalloc.h | 22 +++++++++++++
arch/arc/include/asm/pgtable-levels.h | 45 ++++++++++++++++++++++++---
arch/arc/mm/fault.c | 2 ++
arch/arc/mm/tlbex.S | 9 ++++++
5 files changed, 84 insertions(+), 5 deletions(-)

diff --git a/arch/arc/include/asm/page.h b/arch/arc/include/asm/page.h
index df3cc154ae4a..883856f12afe 100644
--- a/arch/arc/include/asm/page.h
+++ b/arch/arc/include/asm/page.h
@@ -41,6 +41,17 @@ typedef struct {
#define pgd_val(x) ((x).pgd)
#define __pgd(x) ((pgd_t) { (x) })

+#if CONFIG_PGTABLE_LEVELS > 3
+
+typedef struct {
+ unsigned long pud;
+} pud_t;
+
+#define pud_val(x) ((x).pud)
+#define __pud(x) ((pud_t) { (x) })
+
+#endif
+
#if CONFIG_PGTABLE_LEVELS > 2

typedef struct {
diff --git a/arch/arc/include/asm/pgalloc.h b/arch/arc/include/asm/pgalloc.h
index 01c2d84418ed..e99c724d9235 100644
--- a/arch/arc/include/asm/pgalloc.h
+++ b/arch/arc/include/asm/pgalloc.h
@@ -86,6 +86,28 @@ static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
}


+#if CONFIG_PGTABLE_LEVELS > 3
+
+static inline void p4d_populate(struct mm_struct *mm, p4d_t *p4dp, pud_t *pudp)
+{
+ set_p4d(p4dp, __p4d((unsigned long)pudp));
+}
+
+static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
+{
+ return (pud_t *)__get_free_page(
+ GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_ZERO);
+}
+
+static inline void pud_free(struct mm_struct *mm, pud_t *pudp)
+{
+ free_page((unsigned long)pudp);
+}
+
+#define __pud_free_tlb(tlb, pmd, addr) pud_free((tlb)->mm, pmd)
+
+#endif
+
#if CONFIG_PGTABLE_LEVELS > 2

static inline void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmdp)
diff --git a/arch/arc/include/asm/pgtable-levels.h b/arch/arc/include/asm/pgtable-levels.h
index 1c2f022d4ad0..2da3c4e52a91 100644
--- a/arch/arc/include/asm/pgtable-levels.h
+++ b/arch/arc/include/asm/pgtable-levels.h
@@ -44,8 +44,13 @@
/*
* A default 3 level paging testing setup in software walked MMU
* MMUv4 (8K page): <4> : <7> : <8> : <13>
+ * A default 4 level paging testing setup in software walked MMU
+ * MMUv4 (8K page): <4> : <3> : <4> : <8> : <13>
*/
#define PGDIR_SHIFT 28
+#if CONFIG_PGTABLE_LEVELS > 3
+#define PUD_SHIFT 25
+#endif
#if CONFIG_PGTABLE_LEVELS > 2
#define PMD_SHIFT 21
#endif
@@ -56,17 +61,25 @@
#define PGDIR_MASK (~(PGDIR_SIZE - 1))
#define PTRS_PER_PGD BIT(32 - PGDIR_SHIFT)

+#if CONFIG_PGTABLE_LEVELS > 3
+#define PUD_SIZE BIT(PUD_SHIFT)
+#define PUD_MASK (~(PUD_SIZE - 1))
+#define PTRS_PER_PUD BIT(PGDIR_SHIFT - PUD_SHIFT)
+#endif
+
#if CONFIG_PGTABLE_LEVELS > 2
#define PMD_SIZE BIT(PMD_SHIFT)
#define PMD_MASK (~(PMD_SIZE - 1))
-#define PTRS_PER_PMD BIT(PGDIR_SHIFT - PMD_SHIFT)
+#define PTRS_PER_PMD BIT(PUD_SHIFT - PMD_SHIFT)
#endif

#define PTRS_PER_PTE BIT(PMD_SHIFT - PAGE_SHIFT)

#ifndef __ASSEMBLY__

-#if CONFIG_PGTABLE_LEVELS > 2
+#if CONFIG_PGTABLE_LEVELS > 3
+#include <asm-generic/pgtable-nop4d.h>
+#elif CONFIG_PGTABLE_LEVELS > 2
#include <asm-generic/pgtable-nopud.h>
#else
#include <asm-generic/pgtable-nopmd.h>
@@ -81,9 +94,31 @@
#define pgd_ERROR(e) \
pr_crit("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))

+#if CONFIG_PGTABLE_LEVELS > 3
+
+/* In 4 level paging, p4d_* macros work on pgd */
+#define p4d_none(x) (!p4d_val(x))
+#define p4d_bad(x) ((p4d_val(x) & ~PAGE_MASK))
+#define p4d_present(x) (p4d_val(x))
+#define p4d_clear(xp) do { p4d_val(*(xp)) = 0; } while (0)
+#define p4d_pgtable(p4d) ((pud_t *)(p4d_val(p4d) & PAGE_MASK))
+#define p4d_page(p4d) virt_to_page(p4d_pgtable(p4d))
+#define set_p4d(p4dp, p4d) (*(p4dp) = p4d)
+
+/*
+ * 2nd level paging: pud
+ */
+#define pud_ERROR(e) \
+ pr_crit("%s:%d: bad pud %08lx.\n", __FILE__, __LINE__, pud_val(e))
+
+#endif
+
#if CONFIG_PGTABLE_LEVELS > 2

-/* In 3 level paging, pud_* macros work on pgd */
+/*
+ * In 3 level paging, pud_* macros work on pgd
+ * In 4 level paging, pud_* macros work on pud
+ */
#define pud_none(x) (!pud_val(x))
#define pud_bad(x) ((pud_val(x) & ~PAGE_MASK))
#define pud_present(x) (pud_val(x))
@@ -93,7 +128,7 @@
#define set_pud(pudp, pud) (*(pudp) = pud)

/*
- * 2nd level paging: pmd
+ * 3rd level paging: pmd
*/
#define pmd_ERROR(e) \
pr_crit("%s:%d: bad pmd %08lx.\n", __FILE__, __LINE__, pmd_val(e))
@@ -121,7 +156,7 @@
#define pmd_pgtable(pmd) ((pgtable_t) pmd_page_vaddr(pmd))

/*
- * 3rd level paging: pte
+ * 4th level paging: pte
*/
#define pte_ERROR(e) \
pr_crit("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, pte_val(e))
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 8da2f0ad8c69..f8994164fa36 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -46,6 +46,8 @@ noinline static int handle_kernel_vaddr_fault(unsigned long address)
if (!p4d_present(*p4d_k))
goto bad_area;

+ set_p4d(p4d, *p4d_k);
+
pud = pud_offset(p4d, address);
pud_k = pud_offset(p4d_k, address);
if (!pud_present(*pud_k))
diff --git a/arch/arc/mm/tlbex.S b/arch/arc/mm/tlbex.S
index 5f6bfdfda1be..e1831b6fafa9 100644
--- a/arch/arc/mm/tlbex.S
+++ b/arch/arc/mm/tlbex.S
@@ -173,6 +173,15 @@ ex_saved_reg1:
tst r3, r3
bz do_slow_path_pf ; if no Page Table, do page fault

+#if CONFIG_PGTABLE_LEVELS > 3
+ lsr r0, r2, PUD_SHIFT ; Bits for indexing into PUD
+ and r0, r0, (PTRS_PER_PUD - 1)
+ ld.as r1, [r3, r0] ; PMD entry
+ tst r1, r1
+ bz do_slow_path_pf
+ mov r3, r1
+#endif
+
#if CONFIG_PGTABLE_LEVELS > 2
lsr r0, r2, PMD_SHIFT ; Bits for indexing into PMD
and r0, r0, (PTRS_PER_PMD - 1)
--
2.25.1