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Subject[PATCHv3 08/13] x86/mm: Handle boot-time paging mode switching at early boot
Date
This patch adds detection of 5-level paging at boot-time and adjusts
virtual memory layout and folds p4d page table layer if needed.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/boot/compressed/kaslr.c | 13 +++++--
arch/x86/entry/entry_64.S | 12 +++++++
arch/x86/include/asm/page_64_types.h | 13 +++----
arch/x86/include/asm/pgtable_64_types.h | 33 +++++++++++-------
arch/x86/include/asm/processor.h | 2 +-
arch/x86/include/asm/sparsemem.h | 9 ++---
arch/x86/kernel/head64.c | 62 +++++++++++++++++++++++++--------
arch/x86/kernel/head_64.S | 18 ++++++----
arch/x86/kernel/setup.c | 5 ++-
arch/x86/mm/dump_pagetables.c | 8 +++--
arch/x86/mm/kaslr.c | 13 ++++---
11 files changed, 127 insertions(+), 61 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index afde5eb91358..6eb2fd1732c3 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -44,8 +44,9 @@
#include <linux/decompress/mm.h>

#ifdef CONFIG_X86_5LEVEL
-unsigned int pgdir_shift = 48;
-unsigned int ptrs_per_p4d = 512;
+unsigned int p4d_folded = 1;
+unsigned int pgdir_shift = 39;
+unsigned int ptrs_per_p4d = 1;
#endif

extern unsigned long get_cmd_line_ptr(void);
@@ -642,6 +643,14 @@ void choose_random_location(unsigned long input,
return;
}

+#ifdef CONFIG_X86_5LEVEL
+ if (__read_cr4() & X86_CR4_LA57) {
+ p4d_folded = 0;
+ pgdir_shift = 48;
+ ptrs_per_p4d = 512;
+ }
+#endif
+
boot_params->hdr.loadflags |= KASLR_FLAG;

/* Prepare to add new identity pagetables on demand. */
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index daf8936d0628..077e8b45784c 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -273,8 +273,20 @@ return_from_SYSCALL_64:
* Change top bits to match most significant bit (47th or 56th bit
* depending on paging mode) in the address.
*/
+#ifdef CONFIG_X86_5LEVEL
+ testl $1, p4d_folded(%rip)
+ jnz 1f
+ shl $(64 - 57), %rcx
+ sar $(64 - 57), %rcx
+ jmp 2f
+1:
+ shl $(64 - 48), %rcx
+ sar $(64 - 48), %rcx
+2:
+#else
shl $(64 - (__VIRTUAL_MASK_SHIFT+1)), %rcx
sar $(64 - (__VIRTUAL_MASK_SHIFT+1)), %rcx
+#endif

/* If this changed %rcx, it was not canonical */
cmpq %rcx, %r11
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 0126d6bc2eb1..26056ef366b8 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -36,24 +36,21 @@
* hypervisor to fit. Choosing 16 slots here is arbitrary, but it's
* what Xen requires.
*/
-#ifdef CONFIG_X86_5LEVEL
-#define __PAGE_OFFSET_BASE _AC(0xff10000000000000, UL)
-#else
-#define __PAGE_OFFSET_BASE _AC(0xffff880000000000, UL)
-#endif
+#define __PAGE_OFFSET_BASE57 _AC(0xff10000000000000, UL)
+#define __PAGE_OFFSET_BASE48 _AC(0xffff880000000000, UL)

#if defined(CONFIG_RANDOMIZE_MEMORY) || defined(CONFIG_X86_5LEVEL)
#define __PAGE_OFFSET page_offset_base
#else
-#define __PAGE_OFFSET __PAGE_OFFSET_BASE
+#define __PAGE_OFFSET __PAGE_OFFSET_BASE48
#endif /* CONFIG_RANDOMIZE_MEMORY */

#define __START_KERNEL_map _AC(0xffffffff80000000, UL)

/* See Documentation/x86/x86_64/mm.txt for a description of the memory map. */
#ifdef CONFIG_X86_5LEVEL
-#define __PHYSICAL_MASK_SHIFT 52
-#define __VIRTUAL_MASK_SHIFT 56
+#define __PHYSICAL_MASK_SHIFT (p4d_folded ? 52 : 46)
+#define __VIRTUAL_MASK_SHIFT (p4d_folded ? 47 : 56)
#else
#define __PHYSICAL_MASK_SHIFT 46
#define __VIRTUAL_MASK_SHIFT 47
diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h
index a5338b0936ad..a29cc23e96b8 100644
--- a/arch/x86/include/asm/pgtable_64_types.h
+++ b/arch/x86/include/asm/pgtable_64_types.h
@@ -20,7 +20,7 @@ typedef unsigned long pgprotval_t;
typedef struct { pteval_t pte; } pte_t;

#ifdef CONFIG_X86_5LEVEL
-#define p4d_folded 0
+extern unsigned int p4d_folded;
#else
#define p4d_folded 1
#endif
@@ -87,23 +87,30 @@ extern unsigned int ptrs_per_p4d;

/* See Documentation/x86/x86_64/mm.txt for a description of the memory map. */
#define MAXMEM _AC(__AC(1, UL) << MAX_PHYSMEM_BITS, UL)
-#ifdef CONFIG_X86_5LEVEL
-#define VMALLOC_SIZE_TB _AC(16384, UL)
-#define __VMALLOC_BASE _AC(0xff92000000000000, UL)
-#define __VMEMMAP_BASE _AC(0xffd4000000000000, UL)
-#else
-#define VMALLOC_SIZE_TB _AC(32, UL)
-#define __VMALLOC_BASE _AC(0xffffc90000000000, UL)
-#define __VMEMMAP_BASE _AC(0xffffea0000000000, UL)
-#endif
+
+#ifndef __ASSEMBLY__
+#define __VMALLOC_BASE48 0xffffc90000000000
+#define __VMALLOC_BASE57 0xff92000000000000
+
+#define VMALLOC_SIZE_TB48 32UL
+#define VMALLOC_SIZE_TB57 16384UL
+
+#define __VMEMMAP_BASE48 0xffffea0000000000
+#define __VMEMMAP_BASE57 0xffd4000000000000
+
#if defined(CONFIG_RANDOMIZE_MEMORY) || defined(CONFIG_X86_5LEVEL)
#define VMALLOC_START vmalloc_base
+#define VMALLOC_SIZE_TB (!p4d_folded ? VMALLOC_SIZE_TB57 : VMALLOC_SIZE_TB48)
#define VMEMMAP_START vmemmap_base
#else
-#define VMALLOC_START __VMALLOC_BASE
-#define VMEMMAP_START __VMEMMAP_BASE
+#define VMALLOC_START __VMALLOC_BASE48
+#define VMALLOC_SIZE_TB VMALLOC_SIZE_TB48
+#define VMEMMAP_START __VMEMMAP_BASE48
#endif /* CONFIG_RANDOMIZE_MEMORY */
-#define VMALLOC_END (VMALLOC_START + _AC((VMALLOC_SIZE_TB << 40) - 1, UL))
+
+#define VMALLOC_END (VMALLOC_START + (VMALLOC_SIZE_TB << 40) - 1)
+#endif
+
#define MODULES_VADDR (__START_KERNEL_map + KERNEL_IMAGE_SIZE)
/* The module sections ends with the start of the fixmap */
#define MODULES_END __fix_to_virt(__end_of_fixed_addresses + 1)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index c1352771b2f6..cb2958b88de5 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -871,7 +871,7 @@ static inline void spin_lock_prefetch(const void *x)
IA32_PAGE_OFFSET : TASK_SIZE_MAX)

#define STACK_TOP TASK_SIZE_LOW
-#define STACK_TOP_MAX TASK_SIZE_MAX
+#define STACK_TOP_MAX (!p4d_folded ? TASK_SIZE_MAX : DEFAULT_MAP_WINDOW)

#define INIT_THREAD { \
.sp0 = TOP_OF_INIT_STACK, \
diff --git a/arch/x86/include/asm/sparsemem.h b/arch/x86/include/asm/sparsemem.h
index 1f5bee2c202f..ba67afd870b7 100644
--- a/arch/x86/include/asm/sparsemem.h
+++ b/arch/x86/include/asm/sparsemem.h
@@ -26,13 +26,8 @@
# endif
#else /* CONFIG_X86_32 */
# define SECTION_SIZE_BITS 27 /* matt - 128 is convenient right now */
-# ifdef CONFIG_X86_5LEVEL
-# define MAX_PHYSADDR_BITS 52
-# define MAX_PHYSMEM_BITS 52
-# else
-# define MAX_PHYSADDR_BITS 44
-# define MAX_PHYSMEM_BITS 46
-# endif
+# define MAX_PHYSADDR_BITS (p4d_folded ? 44 : 52)
+# define MAX_PHYSMEM_BITS (p4d_folded ? 46 : 52)
#endif

#endif /* CONFIG_SPARSEMEM */
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index f81e61ee5e9d..4c9ffb58a3b5 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -39,20 +39,18 @@ static unsigned int __initdata next_early_pgt;
pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);

#ifdef CONFIG_X86_5LEVEL
-unsigned int pgdir_shift = 48;
+unsigned int pgdir_shift = 39;
EXPORT_SYMBOL(pgdir_shift);
-unsigned int ptrs_per_p4d = 512;
+unsigned int ptrs_per_p4d = 1;
EXPORT_SYMBOL(ptrs_per_p4d);
#endif

-#if defined(CONFIG_RANDOMIZE_MEMORY) || defined(CONFIG_X86_5LEVEL)
-unsigned long page_offset_base = __PAGE_OFFSET_BASE;
+unsigned long page_offset_base = __PAGE_OFFSET_BASE48;
EXPORT_SYMBOL(page_offset_base);
-unsigned long vmalloc_base = __VMALLOC_BASE;
+unsigned long vmalloc_base = __VMALLOC_BASE48;
EXPORT_SYMBOL(vmalloc_base);
-unsigned long vmemmap_base = __VMEMMAP_BASE;
+unsigned long vmemmap_base = __VMEMMAP_BASE48;
EXPORT_SYMBOL(vmemmap_base);
-#endif

#define __head __section(.head.text)

@@ -61,6 +59,36 @@ static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
return ptr - (void *)_text + (void *)physaddr;
}

+static unsigned long __head *fixup_long(void *ptr, unsigned long physaddr)
+{
+ return fixup_pointer(ptr, physaddr);
+}
+
+#ifdef CONFIG_X86_5LEVEL
+static unsigned int __head *fixup_int(void *ptr, unsigned long physaddr)
+{
+ return fixup_pointer(ptr, physaddr);
+}
+
+static void __head check_la57_support(unsigned long physaddr)
+{
+ if (native_cpuid_eax(0) < 7)
+ return;
+
+ if (!(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31))))
+ return;
+
+ *fixup_int(&p4d_folded, physaddr) = 0;
+ *fixup_int(&pgdir_shift, physaddr) = 48;
+ *fixup_int(&ptrs_per_p4d, physaddr) = 512;
+ *fixup_long(&page_offset_base, physaddr) = __PAGE_OFFSET_BASE57;
+ *fixup_long(&vmalloc_base, physaddr) = __VMALLOC_BASE57;
+ *fixup_long(&vmemmap_base, physaddr) = __VMEMMAP_BASE57;
+}
+#else
+static void __head check_la57_support(unsigned long physaddr) {}
+#endif
+
unsigned long __head __startup_64(unsigned long physaddr,
struct boot_params *bp)
{
@@ -72,6 +100,8 @@ unsigned long __head __startup_64(unsigned long physaddr,
pmdval_t *pmd, pmd_entry;
int i;

+ check_la57_support(physaddr);
+
/* Is the address too large? */
if (physaddr >> MAX_PHYSMEM_BITS)
for (;;);
@@ -95,9 +125,14 @@ unsigned long __head __startup_64(unsigned long physaddr,
/* Fixup the physical addresses in the page table */

pgd = fixup_pointer(&early_top_pgt, physaddr);
- pgd[pgd_index(__START_KERNEL_map)] += load_delta;
-
- if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
+ p = pgd + pgd_index(__START_KERNEL_map);
+ if (p4d_folded)
+ *p = (unsigned long)level3_kernel_pgt;
+ else
+ *p = (unsigned long)level4_kernel_pgt;
+ *p += _PAGE_TABLE_NOENC - __START_KERNEL_map + load_delta;
+
+ if (!p4d_folded) {
p4d = fixup_pointer(&level4_kernel_pgt, physaddr);
p4d[511] += load_delta;
}
@@ -120,7 +155,7 @@ unsigned long __head __startup_64(unsigned long physaddr,
pmd = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);
pgtable_flags = _KERNPG_TABLE_NOENC + sme_get_me_mask();

- if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
+ if (!p4d_folded) {
p4d = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);

i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
@@ -166,8 +201,7 @@ unsigned long __head __startup_64(unsigned long physaddr,
* Fixup phys_base - remove the memory encryption mask to obtain
* the true physical address.
*/
- p = fixup_pointer(&phys_base, physaddr);
- *p += load_delta - sme_get_me_mask();
+ *fixup_long(&phys_base, physaddr) += load_delta - sme_get_me_mask();

/* Encrypt the kernel (if SME is active) */
sme_encrypt_kernel();
@@ -218,7 +252,7 @@ int __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
* critical -- __PAGE_OFFSET would point us back into the dynamic
* range and we might end up looping forever...
*/
- if (!IS_ENABLED(CONFIG_X86_5LEVEL))
+ if (p4d_folded)
p4d_p = pgd_p;
else if (pgd)
p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 2be7d1e7fcf1..ebdcb08a91cb 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -40,7 +40,7 @@
#define pud_index(x) (((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))

#if defined(CONFIG_XEN_PV) || defined(CONFIG_XEN_PVH)
-PGD_PAGE_OFFSET = pgd_index(__PAGE_OFFSET_BASE)
+PGD_PAGE_OFFSET = pgd_index(__PAGE_OFFSET_BASE48)
PGD_START_KERNEL = pgd_index(__START_KERNEL_map)
#endif
L3_START_KERNEL = pud_index(__START_KERNEL_map)
@@ -121,7 +121,10 @@ ENTRY(secondary_startup_64)
/* Enable PAE mode, PGE and LA57 */
movl $(X86_CR4_PAE | X86_CR4_PGE), %ecx
#ifdef CONFIG_X86_5LEVEL
+ testl $1, p4d_folded(%rip)
+ jnz 1f
orl $X86_CR4_LA57, %ecx
+1:
#endif
movq %rcx, %cr4

@@ -350,12 +353,7 @@ GLOBAL(name)

__INITDATA
NEXT_PAGE(early_top_pgt)
- .fill 511,8,0
-#ifdef CONFIG_X86_5LEVEL
- .quad level4_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
-#else
- .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
-#endif
+ .fill 512,8,0

NEXT_PAGE(early_dynamic_pgts)
.fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0
@@ -434,6 +432,12 @@ ENTRY(phys_base)
.quad 0x0000000000000000
EXPORT_SYMBOL(phys_base)

+#ifdef CONFIG_X86_5LEVEL
+ENTRY(p4d_folded)
+ .word 1
+EXPORT_SYMBOL(p4d_folded)
+#endif
+
#include "../../x86/xen/xen-head.S"

__PAGE_ALIGNED_BSS
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 022ebddb3734..10e6dd1cb948 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -202,9 +202,7 @@ struct ist_info ist_info;
#endif

#else
-struct cpuinfo_x86 boot_cpu_data __read_mostly = {
- .x86_phys_bits = MAX_PHYSMEM_BITS,
-};
+struct cpuinfo_x86 boot_cpu_data __read_mostly;
EXPORT_SYMBOL(boot_cpu_data);
#endif

@@ -892,6 +890,7 @@ void __init setup_arch(char **cmdline_p)
__flush_tlb_all();
#else
printk(KERN_INFO "Command line: %s\n", boot_command_line);
+ boot_cpu_data.x86_phys_bits = MAX_PHYSMEM_BITS;
#endif

/*
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index bad178deffba..acf264ab02f3 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -82,8 +82,8 @@ static struct addr_marker address_markers[] = {
{ 0/* VMALLOC_START */, "vmalloc() Area" },
{ 0/* VMEMMAP_START */, "Vmemmap" },
#ifdef CONFIG_KASAN
- { KASAN_SHADOW_START, "KASAN shadow" },
- { KASAN_SHADOW_END, "KASAN shadow end" },
+ { 0/* KASAN_SHADOW_START */, "KASAN shadow" },
+ { 0/* KASAN_SHADOW_END */, "KASAN shadow end" },
#endif
# ifdef CONFIG_X86_ESPFIX64
{ ESPFIX_BASE_ADDR, "ESPfix Area", 16 },
@@ -515,6 +515,10 @@ static int __init pt_dump_init(void)
address_markers[LOW_KERNEL_NR].start_address = PAGE_OFFSET;
address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START;
+#ifdef CONFIG_KASAN
+ address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
+ address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
+#endif
#endif
#ifdef CONFIG_X86_32
address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
index e6420b18f6e0..2f6ba5c72905 100644
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -43,7 +43,6 @@
* before. You also need to add a BUILD_BUG_ON() in kernel_randomize_memory() to
* ensure that this order is correct and won't be changed.
*/
-static const unsigned long vaddr_start = __PAGE_OFFSET_BASE;

#if defined(CONFIG_X86_ESPFIX64)
static const unsigned long vaddr_end = ESPFIX_BASE_ADDR;
@@ -62,8 +61,8 @@ static __initdata struct kaslr_memory_region {
unsigned long *base;
unsigned long size_tb;
} kaslr_regions[] = {
- { &page_offset_base, 1 << (__PHYSICAL_MASK_SHIFT - TB_SHIFT) /* Maximum */ },
- { &vmalloc_base, VMALLOC_SIZE_TB },
+ { &page_offset_base, 0 },
+ { &vmalloc_base, 0 },
{ &vmemmap_base, 1 },
};

@@ -86,11 +85,14 @@ static inline bool kaslr_memory_enabled(void)
void __init kernel_randomize_memory(void)
{
size_t i;
- unsigned long vaddr = vaddr_start;
+ unsigned long vaddr_start, vaddr;
unsigned long rand, memory_tb;
struct rnd_state rand_state;
unsigned long remain_entropy;

+ vaddr_start = p4d_folded ? __PAGE_OFFSET_BASE48 : __PAGE_OFFSET_BASE57;
+ vaddr = vaddr_start;
+
/*
* All these BUILD_BUG_ON checks ensures the memory layout is
* consistent with the vaddr_start/vaddr_end variables.
@@ -106,6 +108,9 @@ void __init kernel_randomize_memory(void)
if (!kaslr_memory_enabled())
return;

+ kaslr_regions[0].size_tb = 1 << (__PHYSICAL_MASK_SHIFT - TB_SHIFT);
+ kaslr_regions[1].size_tb = VMALLOC_SIZE_TB;
+
/*
* Update Physical memory mapping to available and
* add padding if needed (especially for memory hotplug support).
--
2.13.2
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