[PATCHv2 06/10] x86/mm: Handle boot-time paging mode switching at early boot
From: Kirill A. Shutemov
Date: Tue Jul 18 2017 - 10:20:13 EST
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@xxxxxxxxxxxxxxx>
---
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 | 35 +++++++++++--------
arch/x86/include/asm/processor.h | 2 +-
arch/x86/include/asm/sparsemem.h | 12 ++++---
arch/x86/kernel/head64.c | 62 +++++++++++++++++++++++++--------
arch/x86/kernel/head_64.S | 18 ++++++----
arch/x86/mm/dump_pagetables.c | 8 +++--
arch/x86/mm/kaslr.c | 13 ++++---
10 files changed, 132 insertions(+), 56 deletions(-)
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index b742b18cc10b..a0a8fefb6c0d 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);
@@ -635,6 +636,14 @@ 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 a9a8027a6c0e..66d7a4685e1f 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -268,8 +268,20 @@ 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..57718303805e 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
@@ -86,24 +86,31 @@ extern unsigned int ptrs_per_p4d;
#define PGDIR_MASK (~(PGDIR_SIZE - 1))
/* 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
+#define MAXMEM (1UL << (p4d_folded ? MAX_PHYSMEM_BITS48 : MAX_PHYSMEM_BITS57))
+
+#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 06d4dd8aca5d..2c331224e4b2 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -862,7 +862,7 @@ 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..719ac32f8eb5 100644
--- a/arch/x86/include/asm/sparsemem.h
+++ b/arch/x86/include/asm/sparsemem.h
@@ -26,12 +26,16 @@
# endif
#else /* CONFIG_X86_32 */
# define SECTION_SIZE_BITS 27 /* matt - 128 is convenient right now */
+# define MAX_PHYSADDR_BITS48 44
+# define MAX_PHYSADDR_BITS57 52
+# define MAX_PHYSMEM_BITS48 46
+# define MAX_PHYSMEM_BITS57 52
# ifdef CONFIG_X86_5LEVEL
-# define MAX_PHYSADDR_BITS 52
-# define MAX_PHYSMEM_BITS 52
+# define MAX_PHYSADDR_BITS MAX_PHYSADDR_BITS57
+# define MAX_PHYSMEM_BITS MAX_PHYSMEM_BITS57
# else
-# define MAX_PHYSADDR_BITS 44
-# define MAX_PHYSMEM_BITS 46
+# define MAX_PHYSADDR_BITS MAX_PHYSADDR_BITS48
+# define MAX_PHYSMEM_BITS MAX_PHYSMEM_BITS48
# endif
#endif
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index e432c5947459..4d06df5f317f 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
+
void __head __startup_64(unsigned long physaddr)
{
unsigned long load_delta, *p;
@@ -70,6 +98,8 @@ void __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 (;;);
@@ -87,9 +117,14 @@ void __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 - __START_KERNEL_map + load_delta;
+
+ if (!p4d_folded) {
p4d = fixup_pointer(&level4_kernel_pgt, physaddr);
p4d[511] += load_delta;
}
@@ -111,7 +146,7 @@ void __head __startup_64(unsigned long physaddr)
pud = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);
pmd = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);
- 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;
@@ -153,8 +188,7 @@ void __head __startup_64(unsigned long physaddr)
}
/* Fixup phys_base */
- p = fixup_pointer(&phys_base, physaddr);
- *p += load_delta;
+ *fixup_long(&phys_base, physaddr) += load_delta;
}
/* Wipe all early page tables except for the kernel symbol map */
@@ -187,7 +221,7 @@ int __init early_make_pgtable(unsigned long address)
* 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 979b388d5e37..5e046a0225d9 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)
@@ -105,7 +105,10 @@ 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
@@ -334,12 +337,7 @@ 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
-#else
- .quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
-#endif
+ .fill 512,8,0
NEXT_PAGE(early_dynamic_pgts)
.fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0
@@ -418,6 +416,12 @@ 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/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 36531c2b7a88..de83151ad689 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 },
@@ -497,6 +497,10 @@ 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).
--
2.11.0