powerpc/8xx: rework support for 8M pages using contiguous PTE entries

In order to fit better with standard Linux page tables layout, add support
for 8M pages using contiguous PTE entries in a standard page table.  Page
tables will then be populated with 1024 similar entries and two PMD
entries will point to that page table.

The PMD entries also get a flag to tell it is addressing an 8M page, this
is required for the HW tablewalk assistance.

Link: https://lkml.kernel.org/r/8693d9a0408371043ca63bf9e4a9c140667af63e.1719928057.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

5 files changed, 45 insertions, 58 deletions

diff --git a/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h b/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
index 92df40c6cc6b..014799557f60 100644
--- a/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
@@ -4,42 +4,12 @@
 
 #define PAGE_SHIFT_8M		23
 
-static inline pte_t *hugepd_page(hugepd_t hpd)
-{
-	BUG_ON(!hugepd_ok(hpd));
-
-	return (pte_t *)__va(hpd_val(hpd) & ~HUGEPD_SHIFT_MASK);
-}
-
-static inline unsigned int hugepd_shift(hugepd_t hpd)
-{
-	return PAGE_SHIFT_8M;
-}
-
-static inline pte_t *hugepte_offset(hugepd_t hpd, unsigned long addr,
-				    unsigned int pdshift)
-{
-	unsigned long idx = (addr & (SZ_4M - 1)) >> PAGE_SHIFT;
-
-	return hugepd_page(hpd) + idx;
-}
-
 static inline void flush_hugetlb_page(struct vm_area_struct *vma,
 				      unsigned long vmaddr)
 {
 	flush_tlb_page(vma, vmaddr);
 }
 
-static inline void hugepd_populate(hugepd_t *hpdp, pte_t *new, unsigned int pshift)
-{
-	*hpdp = __hugepd(__pa(new) | _PMD_USER | _PMD_PRESENT | _PMD_PAGE_8M);
-}
-
-static inline void hugepd_populate_kernel(hugepd_t *hpdp, pte_t *new, unsigned int pshift)
-{
-	*hpdp = __hugepd(__pa(new) | _PMD_PRESENT | _PMD_PAGE_8M);
-}
-
 static inline int check_and_get_huge_psize(int shift)
 {
 	return shift_to_mmu_psize(shift);
@@ -49,6 +19,14 @@ static inline int check_and_get_huge_psize(int shift)
 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
 		     pte_t pte, unsigned long sz);
 
+#define __HAVE_ARCH_HUGE_PTEP_GET
+static inline pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
+{
+	if (ptep_is_8m_pmdp(mm, addr, ptep))
+		ptep = pte_offset_kernel((pmd_t *)ptep, ALIGN_DOWN(addr, SZ_8M));
+	return ptep_get(ptep);
+}
+
 #define __HAVE_ARCH_HUGE_PTE_CLEAR
 static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
 				  pte_t *ptep, unsigned long sz)
diff --git a/arch/powerpc/include/asm/nohash/32/pte-8xx.h b/arch/powerpc/include/asm/nohash/32/pte-8xx.h
index 625c31d6ce5c..54ebb91dbdcf 100644
--- a/arch/powerpc/include/asm/nohash/32/pte-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/pte-8xx.h
@@ -119,7 +119,7 @@ static inline pte_t pte_mkhuge(pte_t pte)
 
 #define pte_mkhuge pte_mkhuge
 
-static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, pte_t *p,
+static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
 				     unsigned long clr, unsigned long set, int huge);
 
 static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
@@ -141,19 +141,12 @@ static inline void __ptep_set_access_flags(struct vm_area_struct *vma, pte_t *pt
 }
 #define __ptep_set_access_flags __ptep_set_access_flags
 
-static inline unsigned long pgd_leaf_size(pgd_t pgd)
-{
-	if (pgd_val(pgd) & _PMD_PAGE_8M)
-		return SZ_8M;
-	return SZ_4M;
-}
-
-#define pgd_leaf_size pgd_leaf_size
-
-static inline unsigned long pte_leaf_size(pte_t pte)
+static inline unsigned long __pte_leaf_size(pmd_t pmd, pte_t pte)
 {
 	pte_basic_t val = pte_val(pte);
 
+	if (pmd_val(pmd) & _PMD_PAGE_8M)
+		return SZ_8M;
 	if (val & _PAGE_HUGE)
 		return SZ_512K;
 	if (val & _PAGE_SPS)
@@ -161,31 +154,38 @@ static inline unsigned long pte_leaf_size(pte_t pte)
 	return SZ_4K;
 }
 
-#define pte_leaf_size pte_leaf_size
+#define __pte_leaf_size __pte_leaf_size
 
 /*
  * On the 8xx, the page tables are a bit special. For 16k pages, we have
  * 4 identical entries. For 512k pages, we have 128 entries as if it was
  * 4k pages, but they are flagged as 512k pages for the hardware.
- * For other page sizes, we have a single entry in the table.
+ * For 8M pages, we have 1024 entries as if it was 4M pages (PMD_SIZE)
+ * but they are flagged as 8M pages for the hardware.
+ * For 4k pages, we have a single entry in the table.
  */
 static pmd_t *pmd_off(struct mm_struct *mm, unsigned long addr);
-static int hugepd_ok(hugepd_t hpd);
+static inline pte_t *pte_offset_kernel(pmd_t *pmd, unsigned long address);
+
+static inline bool ptep_is_8m_pmdp(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
+{
+	return (pmd_t *)ptep == pmd_off(mm, ALIGN_DOWN(addr, SZ_8M));
+}
 
 static inline int number_of_cells_per_pte(pmd_t *pmd, pte_basic_t val, int huge)
 {
 	if (!huge)
 		return PAGE_SIZE / SZ_4K;
-	else if (hugepd_ok(*((hugepd_t *)pmd)))
-		return 1;
+	else if ((pmd_val(*pmd) & _PMD_PAGE_MASK) == _PMD_PAGE_8M)
+		return SZ_4M / SZ_4K;
 	else if (IS_ENABLED(CONFIG_PPC_4K_PAGES) && !(val & _PAGE_HUGE))
 		return SZ_16K / SZ_4K;
 	else
 		return SZ_512K / SZ_4K;
 }
 
-static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, pte_t *p,
-				     unsigned long clr, unsigned long set, int huge)
+static inline pte_basic_t __pte_update(struct mm_struct *mm, unsigned long addr, pte_t *p,
+				       unsigned long clr, unsigned long set, int huge)
 {
 	pte_basic_t *entry = (pte_basic_t *)p;
 	pte_basic_t old = pte_val(*p);
@@ -197,7 +197,7 @@ static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, p
 
 	for (i = 0; i < num; i += PAGE_SIZE / SZ_4K, new += PAGE_SIZE) {
 		*entry++ = new;
-		if (IS_ENABLED(CONFIG_PPC_16K_PAGES) && num != 1) {
+		if (IS_ENABLED(CONFIG_PPC_16K_PAGES)) {
 			*entry++ = new;
 			*entry++ = new;
 			*entry++ = new;
@@ -207,6 +207,21 @@ static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, p
 	return old;
 }
 
+static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
+				     unsigned long clr, unsigned long set, int huge)
+{
+	pte_basic_t old;
+
+	if (huge && ptep_is_8m_pmdp(mm, addr, ptep)) {
+		pmd_t *pmdp = (pmd_t *)ptep;
+
+		old = __pte_update(mm, addr, pte_offset_kernel(pmdp, 0), clr, set, huge);
+		__pte_update(mm, addr, pte_offset_kernel(pmdp + 1, 0), clr, set, huge);
+	} else {
+		old = __pte_update(mm, addr, ptep, clr, set, huge);
+	}
+	return old;
+}
 #define pte_update pte_update
 
 #ifdef CONFIG_PPC_16K_PAGES
diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h
index e7fc1314c23e..90d6a0943b35 100644
--- a/arch/powerpc/include/asm/nohash/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/pgtable.h
@@ -343,12 +343,8 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
 #ifdef CONFIG_ARCH_HAS_HUGEPD
 static inline int hugepd_ok(hugepd_t hpd)
 {
-#ifdef CONFIG_PPC_8xx
-	return ((hpd_val(hpd) & _PMD_PAGE_MASK) == _PMD_PAGE_8M);
-#else
 	/* We clear the top bit to indicate hugepd */
 	return (hpd_val(hpd) && (hpd_val(hpd) & PD_HUGE) == 0);
-#endif
 }
 
 #define is_hugepd(hpd)		(hugepd_ok(hpd))
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index e411e5a70ea3..018c3d55232c 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -293,13 +293,8 @@ static inline const void *pfn_to_kaddr(unsigned long pfn)
 /*
  * Some number of bits at the level of the page table that points to
  * a hugepte are used to encode the size.  This masks those bits.
- * On 8xx, HW assistance requires 4k alignment for the hugepte.
  */
-#ifdef CONFIG_PPC_8xx
-#define HUGEPD_SHIFT_MASK     0xfff
-#else
 #define HUGEPD_SHIFT_MASK     0x3f
-#endif
 
 #ifndef __ASSEMBLY__
 
diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index 239709a2f68e..264a6c09517a 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -106,6 +106,9 @@ unsigned long vmalloc_to_phys(void *vmalloc_addr);
 
 void pgtable_cache_add(unsigned int shift);
 
+#ifdef CONFIG_PPC32
+void __init *early_alloc_pgtable(unsigned long size);
+#endif
 pte_t *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va);
 
 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_PPC32)