[RFC, PATCHv1 23/28] x86/mm: add support of additional page table level during early boot
From: Kirill A. Shutemov
Date: Thu Dec 08 2016 - 11:27:31 EST
This patch adds support for 5-level paging during early boot.
It generalizes boot for 4- and 5-level paging on 64-bit systems with
compile-time switch between them.
TODO: XEN support is missing
Not-yet-Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
arch/x86/boot/compressed/head_64.S | 23 ++++++++++--
arch/x86/include/asm/pgtable.h | 2 +-
arch/x86/include/asm/pgtable_64.h | 6 ++-
arch/x86/include/uapi/asm/processor-flags.h | 2 +
arch/x86/kernel/espfix_64.c | 2 +-
arch/x86/kernel/head64.c | 40 ++++++++++++++------
arch/x86/kernel/head_64.S | 58 ++++++++++++++++++++++-------
arch/x86/kernel/machine_kexec_64.c | 2 +-
arch/x86/mm/dump_pagetables.c | 2 +-
arch/x86/mm/kasan_init_64.c | 12 +++---
arch/x86/realmode/init.c | 2 +-
11 files changed, 110 insertions(+), 41 deletions(-)
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 0d80a7ad65cd..725c5ee939d1 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -123,9 +123,12 @@ ENTRY(startup_32)
movl %eax, gdt+2(%ebp)
lgdt gdt(%ebp)
- /* Enable PAE mode */
+ /* Enable PAE and LA57 mode */
movl %cr4, %eax
orl $X86_CR4_PAE, %eax
+#ifdef CONFIG_X86_5LEVEL
+ orl $X86_CR4_LA57, %eax
+#endif
movl %eax, %cr4
/*
@@ -137,13 +140,24 @@ ENTRY(startup_32)
movl $(BOOT_INIT_PGT_SIZE/4), %ecx
rep stosl
+ xorl %edx, %edx
+
+ /* Build Top Level */
+ leal pgtable(%ebx,%edx,1), %edi
+ leal 0x1007 (%edi), %eax
+ movl %eax, 0(%edi)
+
+#ifdef CONFIG_X86_5LEVEL
/* Build Level 4 */
- leal pgtable + 0(%ebx), %edi
+ addl $0x1000, %edx
+ leal pgtable(%ebx,%edx), %edi
leal 0x1007 (%edi), %eax
movl %eax, 0(%edi)
+#endif
/* Build Level 3 */
- leal pgtable + 0x1000(%ebx), %edi
+ addl $0x1000, %edx
+ leal pgtable(%ebx,%edx), %edi
leal 0x1007(%edi), %eax
movl $4, %ecx
1: movl %eax, 0x00(%edi)
@@ -153,7 +167,8 @@ ENTRY(startup_32)
jnz 1b
/* Build Level 2 */
- leal pgtable + 0x2000(%ebx), %edi
+ addl $0x1000, %edx
+ leal pgtable(%ebx,%edx), %edi
movl $0x00000183, %eax
movl $2048, %ecx
1: movl %eax, 0(%edi)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 398adab9a167..8992f0a9ea3a 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -813,7 +813,7 @@ extern pgd_t trampoline_pgd_entry;
static inline void __meminit init_trampoline_default(void)
{
/* Default trampoline pgd value */
- trampoline_pgd_entry = init_level4_pgt[pgd_index(__PAGE_OFFSET)];
+ trampoline_pgd_entry = init_top_pgt[pgd_index(__PAGE_OFFSET)];
}
# ifdef CONFIG_RANDOMIZE_MEMORY
void __meminit init_trampoline(void);
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index bfe276e9af1e..eab09641ef3f 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -14,15 +14,17 @@
#include <linux/bitops.h>
#include <linux/threads.h>
+extern p4d_t level4_kernel_pgt[512];
+extern p4d_t level4_ident_pgt[512];
extern pud_t level3_kernel_pgt[512];
extern pud_t level3_ident_pgt[512];
extern pmd_t level2_kernel_pgt[512];
extern pmd_t level2_fixmap_pgt[512];
extern pmd_t level2_ident_pgt[512];
extern pte_t level1_fixmap_pgt[512];
-extern pgd_t init_level4_pgt[];
+extern pgd_t init_top_pgt[];
-#define swapper_pg_dir init_level4_pgt
+#define swapper_pg_dir init_top_pgt
extern void paging_init(void);
diff --git a/arch/x86/include/uapi/asm/processor-flags.h b/arch/x86/include/uapi/asm/processor-flags.h
index 567de50a4c2a..185f3d10c194 100644
--- a/arch/x86/include/uapi/asm/processor-flags.h
+++ b/arch/x86/include/uapi/asm/processor-flags.h
@@ -104,6 +104,8 @@
#define X86_CR4_OSFXSR _BITUL(X86_CR4_OSFXSR_BIT)
#define X86_CR4_OSXMMEXCPT_BIT 10 /* enable unmasked SSE exceptions */
#define X86_CR4_OSXMMEXCPT _BITUL(X86_CR4_OSXMMEXCPT_BIT)
+#define X86_CR4_LA57_BIT 12 /* enable 5-level page tables */
+#define X86_CR4_LA57 _BITUL(X86_CR4_LA57_BIT)
#define X86_CR4_VMXE_BIT 13 /* enable VMX virtualization */
#define X86_CR4_VMXE _BITUL(X86_CR4_VMXE_BIT)
#define X86_CR4_SMXE_BIT 14 /* enable safer mode (TXT) */
diff --git a/arch/x86/kernel/espfix_64.c b/arch/x86/kernel/espfix_64.c
index f0afa0af4237..e6838b12414b 100644
--- a/arch/x86/kernel/espfix_64.c
+++ b/arch/x86/kernel/espfix_64.c
@@ -134,7 +134,7 @@ void __init init_espfix_bsp(void)
p4d_t *p4d;
/* Install the espfix pud into the kernel page directory */
- pgd_p = &init_level4_pgt[pgd_index(ESPFIX_BASE_ADDR)];
+ pgd_p = &init_top_pgt[pgd_index(ESPFIX_BASE_ADDR)];
switch (CONFIG_PGTABLE_LEVELS) {
case 4:
p4d = p4d_offset(pgd_p, ESPFIX_BASE_ADDR);
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 54a2372f5dbb..f32d22986f47 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -32,7 +32,7 @@
/*
* Manage page tables very early on.
*/
-extern pgd_t early_level4_pgt[PTRS_PER_PGD];
+extern pgd_t early_top_pgt[PTRS_PER_PGD];
extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
static unsigned int __initdata next_early_pgt = 2;
pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
@@ -40,9 +40,9 @@ pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
/* Wipe all early page tables except for the kernel symbol map */
static void __init reset_early_page_tables(void)
{
- memset(early_level4_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
+ memset(early_top_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
next_early_pgt = 0;
- write_cr3(__pa_nodebug(early_level4_pgt));
+ write_cr3(__pa_nodebug(early_top_pgt));
}
/* Create a new PMD entry */
@@ -50,15 +50,16 @@ int __init early_make_pgtable(unsigned long address)
{
unsigned long physaddr = address - __PAGE_OFFSET;
pgdval_t pgd, *pgd_p;
+ p4dval_t p4d, *p4d_p;
pudval_t pud, *pud_p;
pmdval_t pmd, *pmd_p;
/* Invalid address or early pgt is done ? */
- if (physaddr >= MAXMEM || read_cr3() != __pa_nodebug(early_level4_pgt))
+ if (physaddr >= MAXMEM || read_cr3() != __pa_nodebug(early_top_pgt))
return -1;
again:
- pgd_p = &early_level4_pgt[pgd_index(address)].pgd;
+ pgd_p = &early_top_pgt[pgd_index(address)].pgd;
pgd = *pgd_p;
/*
@@ -66,8 +67,25 @@ again:
* critical -- __PAGE_OFFSET would point us back into the dynamic
* range and we might end up looping forever...
*/
- if (pgd)
- pud_p = (pudval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
+ if (!IS_ENABLED(CONFIG_X86_5LEVEL))
+ p4d_p = pgd_p;
+ else if (pgd)
+ p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
+ else {
+ if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
+ reset_early_page_tables();
+ goto again;
+ }
+
+ p4d_p = (p4dval_t *)early_dynamic_pgts[next_early_pgt++];
+ memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
+ *pgd_p = (pgdval_t)p4d_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
+ }
+ p4d_p += p4d_index(address);
+ p4d = *p4d_p;
+
+ if (p4d)
+ pud_p = (pudval_t *)((p4d & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
else {
if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
reset_early_page_tables();
@@ -76,7 +94,7 @@ again:
pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
- *pgd_p = (pgdval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
+ *p4d_p = (p4dval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
}
pud_p += pud_index(address);
pud = *pud_p;
@@ -155,7 +173,7 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
clear_bss();
- clear_page(init_level4_pgt);
+ clear_page(init_top_pgt);
kasan_early_init();
@@ -170,8 +188,8 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
*/
load_ucode_bsp();
- /* set init_level4_pgt kernel high mapping*/
- init_level4_pgt[511] = early_level4_pgt[511];
+ /* set init_top_pgt kernel high mapping*/
+ init_top_pgt[511] = early_top_pgt[511];
x86_64_start_reservations(real_mode_data);
}
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 9f8efc9f0075..e1189003db50 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -36,10 +36,14 @@
*
*/
+#define p4d_index(x) (((x) >> P4D_SHIFT) & (PTRS_PER_P4D-1))
#define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
-L4_PAGE_OFFSET = pgd_index(__PAGE_OFFSET_BASE)
-L4_START_KERNEL = pgd_index(__START_KERNEL_map)
+PGD_PAGE_OFFSET = pgd_index(__PAGE_OFFSET_BASE)
+PGD_START_KERNEL = pgd_index(__START_KERNEL_map)
+#ifdef CONFIG_X86_5LEVEL
+L4_START_KERNEL = p4d_index(__START_KERNEL_map)
+#endif
L3_START_KERNEL = pud_index(__START_KERNEL_map)
.text
@@ -97,7 +101,11 @@ startup_64:
/*
* Fixup the physical addresses in the page table
*/
- addq %rbp, early_level4_pgt + (L4_START_KERNEL*8)(%rip)
+ addq %rbp, early_top_pgt + (PGD_START_KERNEL*8)(%rip)
+
+#ifdef CONFIG_X86_5LEVEL
+ addq %rbp, level4_kernel_pgt + (511*8)(%rip)
+#endif
addq %rbp, level3_kernel_pgt + (510*8)(%rip)
addq %rbp, level3_kernel_pgt + (511*8)(%rip)
@@ -111,7 +119,7 @@ startup_64:
* it avoids problems around wraparound.
*/
leaq _text(%rip), %rdi
- leaq early_level4_pgt(%rip), %rbx
+ leaq early_top_pgt(%rip), %rbx
movq %rdi, %rax
shrq $PGDIR_SHIFT, %rax
@@ -120,16 +128,26 @@ startup_64:
movq %rdx, 0(%rbx,%rax,8)
movq %rdx, 8(%rbx,%rax,8)
+#ifdef CONFIG_X86_5LEVEL
+ addq $4096, %rbx
+ addq $4096, %rdx
+ movq %rdi, %rax
+ shrq $P4D_SHIFT, %rax
+ andl $(PTRS_PER_P4D-1), %eax
+ movq %rdx, 0(%rbx,%rax,8)
+#endif
+
+ addq $4096, %rbx
addq $4096, %rdx
movq %rdi, %rax
shrq $PUD_SHIFT, %rax
andl $(PTRS_PER_PUD-1), %eax
- movq %rdx, 4096(%rbx,%rax,8)
+ movq %rdx, 0(%rbx,%rax,8)
incl %eax
andl $(PTRS_PER_PUD-1), %eax
- movq %rdx, 4096(%rbx,%rax,8)
+ movq %rdx, 0(%rbx,%rax,8)
- addq $8192, %rbx
+ addq $4096, %rbx
movq %rdi, %rax
shrq $PMD_SHIFT, %rdi
addq $(__PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL), %rax
@@ -166,7 +184,7 @@ startup_64:
/* Fixup phys_base */
addq %rbp, phys_base(%rip)
- movq $(early_level4_pgt - __START_KERNEL_map), %rax
+ movq $(early_top_pgt - __START_KERNEL_map), %rax
jmp 1f
ENTRY(secondary_startup_64)
/*
@@ -186,14 +204,17 @@ ENTRY(secondary_startup_64)
/* Sanitize CPU configuration */
call verify_cpu
- movq $(init_level4_pgt - __START_KERNEL_map), %rax
+ movq $(init_top_pgt - __START_KERNEL_map), %rax
1:
- /* Enable PAE mode and PGE */
+ /* Enable PAE mode, PGE and LA57 */
movl $(X86_CR4_PAE | X86_CR4_PGE), %ecx
+#ifdef CONFIG_X86_5LEVEL
+ orl $X86_CR4_LA57, %ecx
+#endif
movq %rcx, %cr4
- /* Setup early boot stage 4 level pagetables. */
+ /* Setup early boot stage 4-/5-level pagetables. */
addq phys_base(%rip), %rax
movq %rax, %cr3
@@ -415,9 +436,13 @@ GLOBAL(name)
.endr
__INITDATA
-NEXT_PAGE(early_level4_pgt)
+NEXT_PAGE(early_top_pgt)
.fill 511,8,0
+#ifdef CONFIG_X86_5LEVEL
+ .quad level4_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
+#else
.quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
+#endif
NEXT_PAGE(early_dynamic_pgts)
.fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0
@@ -425,9 +450,10 @@ NEXT_PAGE(early_dynamic_pgts)
.data
#ifndef CONFIG_XEN
-NEXT_PAGE(init_level4_pgt)
+NEXT_PAGE(init_top_pgt)
.fill 512,8,0
#else
+#error FIXME
NEXT_PAGE(init_level4_pgt)
.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
.org init_level4_pgt + L4_PAGE_OFFSET*8, 0
@@ -446,6 +472,12 @@ NEXT_PAGE(level2_ident_pgt)
PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
#endif
+#ifdef CONFIG_X86_5LEVEL
+NEXT_PAGE(level4_kernel_pgt)
+ .fill 511,8,0
+ .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
+#endif
+
NEXT_PAGE(level3_kernel_pgt)
.fill L3_START_KERNEL,8,0
/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 0a44cf20f939..f9bf209b826c 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -339,7 +339,7 @@ void machine_kexec(struct kimage *image)
void arch_crash_save_vmcoreinfo(void)
{
VMCOREINFO_SYMBOL(phys_base);
- VMCOREINFO_SYMBOL(init_level4_pgt);
+ VMCOREINFO_SYMBOL(init_top_pgt);
#ifdef CONFIG_NUMA
VMCOREINFO_SYMBOL(node_data);
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 15670b55861b..495ab353d576 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -411,7 +411,7 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
bool checkwx)
{
#ifdef CONFIG_X86_64
- pgd_t *start = (pgd_t *) &init_level4_pgt;
+ pgd_t *start = (pgd_t *) &init_top_pgt;
#else
pgd_t *start = swapper_pg_dir;
#endif
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index e37504e94e8f..2d754cc4e02f 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -9,7 +9,7 @@
#include <asm/tlbflush.h>
#include <asm/sections.h>
-extern pgd_t early_level4_pgt[PTRS_PER_PGD];
+extern pgd_t early_top_pgt[PTRS_PER_PGD];
extern struct range pfn_mapped[E820_X_MAX];
static int __init map_range(struct range *range)
@@ -103,8 +103,8 @@ void __init kasan_early_init(void)
for (i = 0; CONFIG_PGTABLE_LEVELS >= 5 && i < PTRS_PER_P4D; i++)
kasan_zero_p4d[i] = __p4d(p4d_val);
- kasan_map_early_shadow(early_level4_pgt);
- kasan_map_early_shadow(init_level4_pgt);
+ kasan_map_early_shadow(early_top_pgt);
+ kasan_map_early_shadow(init_top_pgt);
}
void __init kasan_init(void)
@@ -115,8 +115,8 @@ void __init kasan_init(void)
register_die_notifier(&kasan_die_notifier);
#endif
- memcpy(early_level4_pgt, init_level4_pgt, sizeof(early_level4_pgt));
- load_cr3(early_level4_pgt);
+ memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
+ load_cr3(early_top_pgt);
__flush_tlb_all();
clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
@@ -142,7 +142,7 @@ void __init kasan_init(void)
kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
(void *)KASAN_SHADOW_END);
- load_cr3(init_level4_pgt);
+ load_cr3(init_top_pgt);
__flush_tlb_all();
/*
diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index 5db706f14111..dc0836d5c5eb 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -102,7 +102,7 @@ static void __init setup_real_mode(void)
trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
trampoline_pgd[0] = trampoline_pgd_entry.pgd;
- trampoline_pgd[511] = init_level4_pgt[511].pgd;
+ trampoline_pgd[511] = init_top_pgt[511].pgd;
#endif
}
--
2.10.2