x86/mm: Replace compile-time checks for 5-level paging with runtime-time checks

This patch converts the of CONFIG_X86_5LEVEL check to runtime checks for
p4d folding.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180214182542.69302-9-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

7 files changed, 32 insertions, 28 deletions

diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 9efee6f464ab..0d6d67d18ad6 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -348,9 +348,7 @@ static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st,
 				void *pt)
 {
 	if (__pa(pt) == __pa(kasan_zero_pmd) ||
-#ifdef CONFIG_X86_5LEVEL
-	    __pa(pt) == __pa(kasan_zero_p4d) ||
-#endif
+	    (pgtable_l5_enabled && __pa(pt) == __pa(kasan_zero_p4d)) ||
 	    __pa(pt) == __pa(kasan_zero_pud)) {
 		pgprotval_t prot = pte_flags(kasan_zero_pte[0]);
 		note_page(m, st, __pgprot(prot), 5);
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 800de815519c..321b78060e93 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -439,7 +439,7 @@ static noinline int vmalloc_fault(unsigned long address)
 	if (pgd_none(*pgd_ref))
 		return -1;
 
-	if (CONFIG_PGTABLE_LEVELS > 4) {
+	if (pgtable_l5_enabled) {
 		if (pgd_none(*pgd)) {
 			set_pgd(pgd, *pgd_ref);
 			arch_flush_lazy_mmu_mode();
@@ -454,7 +454,7 @@ static noinline int vmalloc_fault(unsigned long address)
 	if (p4d_none(*p4d_ref))
 		return -1;
 
-	if (p4d_none(*p4d) && CONFIG_PGTABLE_LEVELS == 4) {
+	if (p4d_none(*p4d) && !pgtable_l5_enabled) {
 		set_p4d(p4d, *p4d_ref);
 		arch_flush_lazy_mmu_mode();
 	} else {
diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
index ab33a32df2a8..9aa22be8331e 100644
--- a/arch/x86/mm/ident_map.c
+++ b/arch/x86/mm/ident_map.c
@@ -120,7 +120,7 @@ int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
 		result = ident_p4d_init(info, p4d, addr, next);
 		if (result)
 			return result;
-		if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
+		if (pgtable_l5_enabled) {
 			set_pgd(pgd, __pgd(__pa(p4d) | info->kernpg_flag));
 		} else {
 			/*
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 6a4b20bc7527..3186e6836036 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -88,12 +88,7 @@ static int __init nonx32_setup(char *str)
 }
 __setup("noexec32=", nonx32_setup);
 
-/*
- * When memory was added make sure all the processes MM have
- * suitable PGD entries in the local PGD level page.
- */
-#ifdef CONFIG_X86_5LEVEL
-void sync_global_pgds(unsigned long start, unsigned long end)
+static void sync_global_pgds_l5(unsigned long start, unsigned long end)
 {
 	unsigned long addr;
 
@@ -129,8 +124,8 @@ void sync_global_pgds(unsigned long start, unsigned long end)
 		spin_unlock(&pgd_lock);
 	}
 }
-#else
-void sync_global_pgds(unsigned long start, unsigned long end)
+
+static void sync_global_pgds_l4(unsigned long start, unsigned long end)
 {
 	unsigned long addr;
 
@@ -173,7 +168,18 @@ void sync_global_pgds(unsigned long start, unsigned long end)
 		spin_unlock(&pgd_lock);
 	}
 }
-#endif
+
+/*
+ * When memory was added make sure all the processes MM have
+ * suitable PGD entries in the local PGD level page.
+ */
+void sync_global_pgds(unsigned long start, unsigned long end)
+{
+	if (pgtable_l5_enabled)
+		sync_global_pgds_l5(start, end);
+	else
+		sync_global_pgds_l4(start, end);
+}
 
 /*
  * NOTE: This function is marked __ref because it calls __init function
@@ -632,7 +638,7 @@ phys_p4d_init(p4d_t *p4d_page, unsigned long paddr, unsigned long paddr_end,
 	unsigned long vaddr = (unsigned long)__va(paddr);
 	int i = p4d_index(vaddr);
 
-	if (!IS_ENABLED(CONFIG_X86_5LEVEL))
+	if (!pgtable_l5_enabled)
 		return phys_pud_init((pud_t *) p4d_page, paddr, paddr_end, page_size_mask);
 
 	for (; i < PTRS_PER_P4D; i++, paddr = paddr_next) {
@@ -712,7 +718,7 @@ kernel_physical_mapping_init(unsigned long paddr_start,
 					   page_size_mask);
 
 		spin_lock(&init_mm.page_table_lock);
-		if (IS_ENABLED(CONFIG_X86_5LEVEL))
+		if (pgtable_l5_enabled)
 			pgd_populate(&init_mm, pgd, p4d);
 		else
 			p4d_populate(&init_mm, p4d_offset(pgd, vaddr), (pud_t *) p4d);
@@ -1093,7 +1099,7 @@ remove_p4d_table(p4d_t *p4d_start, unsigned long addr, unsigned long end,
 		 * 5-level case we should free them. This code will have to change
 		 * to adapt for boot-time switching between 4 and 5 level page tables.
 		 */
-		if (CONFIG_PGTABLE_LEVELS == 5)
+		if (pgtable_l5_enabled)
 			free_pud_table(pud_base, p4d, altmap);
 	}
 
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 12ec90f62457..0df0dd13a71d 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -176,10 +176,10 @@ static void __init clear_pgds(unsigned long start,
 		 * With folded p4d, pgd_clear() is nop, use p4d_clear()
 		 * instead.
 		 */
-		if (CONFIG_PGTABLE_LEVELS < 5)
-			p4d_clear(p4d_offset(pgd, start));
-		else
+		if (pgtable_l5_enabled)
 			pgd_clear(pgd);
+		else
+			p4d_clear(p4d_offset(pgd, start));
 	}
 
 	pgd = pgd_offset_k(start);
@@ -191,7 +191,7 @@ static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr)
 {
 	unsigned long p4d;
 
-	if (!IS_ENABLED(CONFIG_X86_5LEVEL))
+	if (!pgtable_l5_enabled)
 		return (p4d_t *)pgd;
 
 	p4d = __pa_nodebug(pgd_val(*pgd)) & PTE_PFN_MASK;
@@ -272,7 +272,7 @@ void __init kasan_early_init(void)
 	for (i = 0; i < PTRS_PER_PUD; i++)
 		kasan_zero_pud[i] = __pud(pud_val);
 
-	for (i = 0; IS_ENABLED(CONFIG_X86_5LEVEL) && i < PTRS_PER_P4D; i++)
+	for (i = 0; pgtable_l5_enabled && i < PTRS_PER_P4D; i++)
 		kasan_zero_p4d[i] = __p4d(p4d_val);
 
 	kasan_map_early_shadow(early_top_pgt);
@@ -303,7 +303,7 @@ void __init kasan_init(void)
 	 * bunch of things like kernel code, modules, EFI mapping, etc.
 	 * We need to take extra steps to not overwrite them.
 	 */
-	if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
+	if (pgtable_l5_enabled) {
 		void *ptr;
 
 		ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
index 641169d38184..615cc03ced84 100644
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -124,7 +124,7 @@ void __init kernel_randomize_memory(void)
 		 */
 		entropy = remain_entropy / (ARRAY_SIZE(kaslr_regions) - i);
 		prandom_bytes_state(&rand_state, &rand, sizeof(rand));
-		if (IS_ENABLED(CONFIG_X86_5LEVEL))
+		if (pgtable_l5_enabled)
 			entropy = (rand % (entropy + 1)) & P4D_MASK;
 		else
 			entropy = (rand % (entropy + 1)) & PUD_MASK;
@@ -136,7 +136,7 @@ void __init kernel_randomize_memory(void)
 		 * randomization alignment.
 		 */
 		vaddr += get_padding(&kaslr_regions[i]);
-		if (IS_ENABLED(CONFIG_X86_5LEVEL))
+		if (pgtable_l5_enabled)
 			vaddr = round_up(vaddr + 1, P4D_SIZE);
 		else
 			vaddr = round_up(vaddr + 1, PUD_SIZE);
@@ -212,7 +212,7 @@ void __meminit init_trampoline(void)
 		return;
 	}
 
-	if (IS_ENABLED(CONFIG_X86_5LEVEL))
+	if (pgtable_l5_enabled)
 		init_trampoline_p4d();
 	else
 		init_trampoline_pud();
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 6550d37d0f06..92cb8a901c36 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -157,7 +157,7 @@ static void sync_current_stack_to_mm(struct mm_struct *mm)
 	unsigned long sp = current_stack_pointer;
 	pgd_t *pgd = pgd_offset(mm, sp);
 
-	if (CONFIG_PGTABLE_LEVELS > 4) {
+	if (pgtable_l5_enabled) {
 		if (unlikely(pgd_none(*pgd))) {
 			pgd_t *pgd_ref = pgd_offset_k(sp);