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

From: tip-bot for Kirill A. Shutemov
Date: Fri Feb 16 2018 - 06:06:03 EST

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Commit-ID: 91f606a8fa68264224cbc76888fa8649cdbe9990
Gitweb: https://git.kernel.org/tip/91f606a8fa68264224cbc76888fa8649cdbe9990
Author: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
AuthorDate: Wed, 14 Feb 2018 21:25:41 +0300
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 16 Feb 2018 10:48:49 +0100

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@xxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Link: http://lkml.kernel.org/r/20180214182542.69302-9-kirill.shutemov@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/include/asm/pgtable_64.h | 23 ++++++++++-------------
arch/x86/mm/dump_pagetables.c | 4 +---
arch/x86/mm/fault.c | 4 ++--
arch/x86/mm/ident_map.c | 2 +-
arch/x86/mm/init_64.c | 30 ++++++++++++++++++------------
arch/x86/mm/kasan_init_64.c | 12 ++++++------
arch/x86/mm/kaslr.c | 6 +++---
arch/x86/mm/tlb.c | 2 +-
arch/x86/platform/efi/efi_64.c | 2 +-
arch/x86/power/hibernate_64.c | 6 +++---
10 files changed, 46 insertions(+), 45 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 81462e9..81dda8d 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -217,29 +217,26 @@ static inline pgd_t pti_set_user_pgd(pgd_t *pgdp, pgd_t pgd)

static inline void native_set_p4d(p4d_t *p4dp, p4d_t p4d)
{
-#if defined(CONFIG_PAGE_TABLE_ISOLATION) && !defined(CONFIG_X86_5LEVEL)
- p4dp->pgd = pti_set_user_pgd(&p4dp->pgd, p4d.pgd);
-#else
- *p4dp = p4d;
-#endif
+ pgd_t pgd;
+
+ if (pgtable_l5_enabled || !IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION)) {
+ *p4dp = p4d;
+ return;
+ }
+
+ pgd = native_make_pgd(p4d_val(p4d));
+ pgd = pti_set_user_pgd((pgd_t *)p4dp, pgd);
+ *p4dp = native_make_p4d(pgd_val(pgd));
}

static inline void native_p4d_clear(p4d_t *p4d)
{
-#ifdef CONFIG_X86_5LEVEL
native_set_p4d(p4d, native_make_p4d(0));
-#else
- native_set_p4d(p4d, (p4d_t) { .pgd = native_make_pgd(0)});
-#endif
}

static inline void native_set_pgd(pgd_t *pgdp, pgd_t pgd)
{
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
*pgdp = pti_set_user_pgd(pgdp, pgd);
-#else
- *pgdp = pgd;
-#endif
}

static inline void native_pgd_clear(pgd_t *pgd)
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 9efee6f..0d6d67d 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 800de81..321b780 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 ab33a32..9aa22be 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 6a4b20b..3186e68 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 12ec90f..0df0dd1 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 641169d..615cc03 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 6550d37..92cb8a9 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);

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index d52aaa7..4845871 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -227,7 +227,7 @@ int __init efi_alloc_page_tables(void)

pud = pud_alloc(&init_mm, p4d, EFI_VA_END);
if (!pud) {
- if (CONFIG_PGTABLE_LEVELS > 4)
+ if (pgtable_l5_enabled)
free_page((unsigned long) pgd_page_vaddr(*pgd));
free_page((unsigned long)efi_pgd);
return -ENOMEM;
diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c
index 0ef5e520..74a5329 100644
--- a/arch/x86/power/hibernate_64.c
+++ b/arch/x86/power/hibernate_64.c
@@ -50,7 +50,7 @@ static int set_up_temporary_text_mapping(pgd_t *pgd)
{
pmd_t *pmd;
pud_t *pud;
- p4d_t *p4d;
+ p4d_t *p4d = NULL;

/*
* The new mapping only has to cover the page containing the image
@@ -66,7 +66,7 @@ static int set_up_temporary_text_mapping(pgd_t *pgd)
* tables used by the image kernel.
*/

- if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
+ if (pgtable_l5_enabled) {
p4d = (p4d_t *)get_safe_page(GFP_ATOMIC);
if (!p4d)
return -ENOMEM;
@@ -84,7 +84,7 @@ static int set_up_temporary_text_mapping(pgd_t *pgd)
__pmd((jump_address_phys & PMD_MASK) | __PAGE_KERNEL_LARGE_EXEC));
set_pud(pud + pud_index(restore_jump_address),
__pud(__pa(pmd) | _KERNPG_TABLE));
- if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
+ if (p4d) {
set_p4d(p4d + p4d_index(restore_jump_address), __p4d(__pa(pud) | _KERNPG_TABLE));
set_pgd(pgd + pgd_index(restore_jump_address), __pgd(__pa(p4d) | _KERNPG_TABLE));
} else {

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