arm64: add support for folded p4d page tables

Implement primitives necessary for the 4th level folding, add walks of p4d
level where appropriate, replace 5level-fixup.h with pgtable-nop4d.h and
remove __ARCH_USE_5LEVEL_HACK.

[arnd@arndb.de: fix gcc-10 shift warning]
  Link: http://lkml.kernel.org/r/20200429185657.4085975-1-arnd@arndb.de
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: James Morse <james.morse@arm.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Julien Thierry <julien.thierry.kdev@gmail.com>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/20200414153455.21744-4-rppt@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 79 insertions, 30 deletions

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index dff2d72b0883..df8ae73d950b 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -145,6 +145,7 @@ static void show_pte(unsigned long addr)
 	pr_alert("[%016lx] pgd=%016llx", addr, pgd_val(pgd));
 
 	do {
+		p4d_t *p4dp, p4d;
 		pud_t *pudp, pud;
 		pmd_t *pmdp, pmd;
 		pte_t *ptep, pte;
@@ -152,7 +153,13 @@ static void show_pte(unsigned long addr)
 		if (pgd_none(pgd) || pgd_bad(pgd))
 			break;
 
-		pudp = pud_offset(pgdp, addr);
+		p4dp = p4d_offset(pgdp, addr);
+		p4d = READ_ONCE(*p4dp);
+		pr_cont(", p4d=%016llx", p4d_val(p4d));
+		if (p4d_none(p4d) || p4d_bad(p4d))
+			break;
+
+		pudp = pud_offset(p4dp, addr);
 		pud = READ_ONCE(*pudp);
 		pr_cont(", pud=%016llx", pud_val(pud));
 		if (pud_none(pud) || pud_bad(pud))
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 07f154b8b84a..0a52ce46f020 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -67,11 +67,13 @@ static int find_num_contig(struct mm_struct *mm, unsigned long addr,
 			   pte_t *ptep, size_t *pgsize)
 {
 	pgd_t *pgdp = pgd_offset(mm, addr);
+	p4d_t *p4dp;
 	pud_t *pudp;
 	pmd_t *pmdp;
 
 	*pgsize = PAGE_SIZE;
-	pudp = pud_offset(pgdp, addr);
+	p4dp = p4d_offset(pgdp, addr);
+	pudp = pud_offset(p4dp, addr);
 	pmdp = pmd_offset(pudp, addr);
 	if ((pte_t *)pmdp == ptep) {
 		*pgsize = PMD_SIZE;
@@ -217,12 +219,14 @@ pte_t *huge_pte_alloc(struct mm_struct *mm,
 		      unsigned long addr, unsigned long sz)
 {
 	pgd_t *pgdp;
+	p4d_t *p4dp;
 	pud_t *pudp;
 	pmd_t *pmdp;
 	pte_t *ptep = NULL;
 
 	pgdp = pgd_offset(mm, addr);
-	pudp = pud_alloc(mm, pgdp, addr);
+	p4dp = p4d_offset(pgdp, addr);
+	pudp = pud_alloc(mm, p4dp, addr);
 	if (!pudp)
 		return NULL;
 
@@ -261,6 +265,7 @@ pte_t *huge_pte_offset(struct mm_struct *mm,
 		       unsigned long addr, unsigned long sz)
 {
 	pgd_t *pgdp;
+	p4d_t *p4dp;
 	pud_t *pudp, pud;
 	pmd_t *pmdp, pmd;
 
@@ -268,7 +273,11 @@ pte_t *huge_pte_offset(struct mm_struct *mm,
 	if (!pgd_present(READ_ONCE(*pgdp)))
 		return NULL;
 
-	pudp = pud_offset(pgdp, addr);
+	p4dp = p4d_offset(pgdp, addr);
+	if (!p4d_present(READ_ONCE(*p4dp)))
+		return NULL;
+
+	pudp = pud_offset(p4dp, addr);
 	pud = READ_ONCE(*pudp);
 	if (sz != PUD_SIZE && pud_none(pud))
 		return NULL;
diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index f87a32484ea8..2339811f317b 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -84,17 +84,17 @@ static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,
 	return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr);
 }
 
-static pud_t *__init kasan_pud_offset(pgd_t *pgdp, unsigned long addr, int node,
+static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node,
 				      bool early)
 {
-	if (pgd_none(READ_ONCE(*pgdp))) {
+	if (p4d_none(READ_ONCE(*p4dp))) {
 		phys_addr_t pud_phys = early ?
 				__pa_symbol(kasan_early_shadow_pud)
 					: kasan_alloc_zeroed_page(node);
-		__pgd_populate(pgdp, pud_phys, PMD_TYPE_TABLE);
+		__p4d_populate(p4dp, pud_phys, PMD_TYPE_TABLE);
 	}
 
-	return early ? pud_offset_kimg(pgdp, addr) : pud_offset(pgdp, addr);
+	return early ? pud_offset_kimg(p4dp, addr) : pud_offset(p4dp, addr);
 }
 
 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
@@ -126,11 +126,11 @@ static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
 	} while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
 }
 
-static void __init kasan_pud_populate(pgd_t *pgdp, unsigned long addr,
+static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
 				      unsigned long end, int node, bool early)
 {
 	unsigned long next;
-	pud_t *pudp = kasan_pud_offset(pgdp, addr, node, early);
+	pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
 
 	do {
 		next = pud_addr_end(addr, end);
@@ -138,6 +138,18 @@ static void __init kasan_pud_populate(pgd_t *pgdp, unsigned long addr,
 	} while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp)));
 }
 
+static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
+				      unsigned long end, int node, bool early)
+{
+	unsigned long next;
+	p4d_t *p4dp = p4d_offset(pgdp, addr);
+
+	do {
+		next = p4d_addr_end(addr, end);
+		kasan_pud_populate(p4dp, addr, next, node, early);
+	} while (p4dp++, addr = next, addr != end);
+}
+
 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
 				      int node, bool early)
 {
@@ -147,7 +159,7 @@ static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
 	pgdp = pgd_offset_k(addr);
 	do {
 		next = pgd_addr_end(addr, end);
-		kasan_pud_populate(pgdp, addr, next, node, early);
+		kasan_p4d_populate(pgdp, addr, next, node, early);
 	} while (pgdp++, addr = next, addr != end);
 }
 
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index c299b73dd5e4..e7fbc6275329 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -290,18 +290,19 @@ static void alloc_init_pud(pgd_t *pgdp, unsigned long addr, unsigned long end,
 {
 	unsigned long next;
 	pud_t *pudp;
-	pgd_t pgd = READ_ONCE(*pgdp);
+	p4d_t *p4dp = p4d_offset(pgdp, addr);
+	p4d_t p4d = READ_ONCE(*p4dp);
 
-	if (pgd_none(pgd)) {
+	if (p4d_none(p4d)) {
 		phys_addr_t pud_phys;
 		BUG_ON(!pgtable_alloc);
 		pud_phys = pgtable_alloc(PUD_SHIFT);
-		__pgd_populate(pgdp, pud_phys, PUD_TYPE_TABLE);
-		pgd = READ_ONCE(*pgdp);
+		__p4d_populate(p4dp, pud_phys, PUD_TYPE_TABLE);
+		p4d = READ_ONCE(*p4dp);
 	}
-	BUG_ON(pgd_bad(pgd));
+	BUG_ON(p4d_bad(p4d));
 
-	pudp = pud_set_fixmap_offset(pgdp, addr);
+	pudp = pud_set_fixmap_offset(p4dp, addr);
 	do {
 		pud_t old_pud = READ_ONCE(*pudp);
 
@@ -672,6 +673,7 @@ static void __init map_kernel(pgd_t *pgdp)
 			READ_ONCE(*pgd_offset_k(FIXADDR_START)));
 	} else if (CONFIG_PGTABLE_LEVELS > 3) {
 		pgd_t *bm_pgdp;
+		p4d_t *bm_p4dp;
 		pud_t *bm_pudp;
 		/*
 		 * The fixmap shares its top level pgd entry with the kernel
@@ -681,7 +683,8 @@ static void __init map_kernel(pgd_t *pgdp)
 		 */
 		BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES));
 		bm_pgdp = pgd_offset_raw(pgdp, FIXADDR_START);
-		bm_pudp = pud_set_fixmap_offset(bm_pgdp, FIXADDR_START);
+		bm_p4dp = p4d_offset(bm_pgdp, FIXADDR_START);
+		bm_pudp = pud_set_fixmap_offset(bm_p4dp, FIXADDR_START);
 		pud_populate(&init_mm, bm_pudp, lm_alias(bm_pmd));
 		pud_clear_fixmap();
 	} else {
@@ -715,6 +718,7 @@ void __init paging_init(void)
 int kern_addr_valid(unsigned long addr)
 {
 	pgd_t *pgdp;
+	p4d_t *p4dp;
 	pud_t *pudp, pud;
 	pmd_t *pmdp, pmd;
 	pte_t *ptep, pte;
@@ -726,7 +730,11 @@ int kern_addr_valid(unsigned long addr)
 	if (pgd_none(READ_ONCE(*pgdp)))
 		return 0;
 
-	pudp = pud_offset(pgdp, addr);
+	p4dp = p4d_offset(pgdp, addr);
+	if (p4d_none(READ_ONCE(*p4dp)))
+		return 0;
+
+	pudp = pud_offset(p4dp, addr);
 	pud = READ_ONCE(*pudp);
 	if (pud_none(pud))
 		return 0;
@@ -1069,6 +1077,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 	unsigned long addr = start;
 	unsigned long next;
 	pgd_t *pgdp;
+	p4d_t *p4dp;
 	pud_t *pudp;
 	pmd_t *pmdp;
 
@@ -1079,7 +1088,11 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 		if (!pgdp)
 			return -ENOMEM;
 
-		pudp = vmemmap_pud_populate(pgdp, addr, node);
+		p4dp = vmemmap_p4d_populate(pgdp, addr, node);
+		if (!p4dp)
+			return -ENOMEM;
+
+		pudp = vmemmap_pud_populate(p4dp, addr, node);
 		if (!pudp)
 			return -ENOMEM;
 
@@ -1114,11 +1127,12 @@ void vmemmap_free(unsigned long start, unsigned long end,
 static inline pud_t * fixmap_pud(unsigned long addr)
 {
 	pgd_t *pgdp = pgd_offset_k(addr);
-	pgd_t pgd = READ_ONCE(*pgdp);
+	p4d_t *p4dp = p4d_offset(pgdp, addr);
+	p4d_t p4d = READ_ONCE(*p4dp);
 
-	BUG_ON(pgd_none(pgd) || pgd_bad(pgd));
+	BUG_ON(p4d_none(p4d) || p4d_bad(p4d));
 
-	return pud_offset_kimg(pgdp, addr);
+	return pud_offset_kimg(p4dp, addr);
 }
 
 static inline pmd_t * fixmap_pmd(unsigned long addr)
@@ -1144,25 +1158,27 @@ static inline pte_t * fixmap_pte(unsigned long addr)
  */
 void __init early_fixmap_init(void)
 {
-	pgd_t *pgdp, pgd;
+	pgd_t *pgdp;
+	p4d_t *p4dp, p4d;
 	pud_t *pudp;
 	pmd_t *pmdp;
 	unsigned long addr = FIXADDR_START;
 
 	pgdp = pgd_offset_k(addr);
-	pgd = READ_ONCE(*pgdp);
+	p4dp = p4d_offset(pgdp, addr);
+	p4d = READ_ONCE(*p4dp);
 	if (CONFIG_PGTABLE_LEVELS > 3 &&
-	    !(pgd_none(pgd) || pgd_page_paddr(pgd) == __pa_symbol(bm_pud))) {
+	    !(p4d_none(p4d) || p4d_page_paddr(p4d) == __pa_symbol(bm_pud))) {
 		/*
 		 * We only end up here if the kernel mapping and the fixmap
 		 * share the top level pgd entry, which should only happen on
 		 * 16k/4 levels configurations.
 		 */
 		BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES));
-		pudp = pud_offset_kimg(pgdp, addr);
+		pudp = pud_offset_kimg(p4dp, addr);
 	} else {
-		if (pgd_none(pgd))
-			__pgd_populate(pgdp, __pa_symbol(bm_pud), PUD_TYPE_TABLE);
+		if (p4d_none(p4d))
+			__p4d_populate(p4dp, __pa_symbol(bm_pud), PUD_TYPE_TABLE);
 		pudp = fixmap_pud(addr);
 	}
 	if (pud_none(READ_ONCE(*pudp)))
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index bde08090b838..4175bcb8ccb3 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -198,6 +198,7 @@ void __kernel_map_pages(struct page *page, int numpages, int enable)
 bool kernel_page_present(struct page *page)
 {
 	pgd_t *pgdp;
+	p4d_t *p4dp;
 	pud_t *pudp, pud;
 	pmd_t *pmdp, pmd;
 	pte_t *ptep;
@@ -210,7 +211,11 @@ bool kernel_page_present(struct page *page)
 	if (pgd_none(READ_ONCE(*pgdp)))
 		return false;
 
-	pudp = pud_offset(pgdp, addr);
+	p4dp = p4d_offset(pgdp, addr);
+	if (p4d_none(READ_ONCE(*p4dp)))
+		return false;
+
+	pudp = pud_offset(p4dp, addr);
 	pud = READ_ONCE(*pudp);
 	if (pud_none(pud))
 		return false;