[PATCH 9/9] x86/mm: Adjust virtual address space layout in early boot

From: Kirill A. Shutemov
Date: Wed Feb 14 2018 - 06:17:43 EST

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We need to adjust virtual address space to support switching between
paging modes.

The adjustment happens in __startup_64().

We also have to change KASLR code that doesn't expect variable
VMALLOC_SIZE_TB.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
arch/x86/boot/compressed/kaslr.c | 14 ++++++++--
arch/x86/include/asm/page_64_types.h | 9 ++----
arch/x86/include/asm/pgtable_64_types.h | 25 +++++++++--------
arch/x86/kernel/head64.c | 49 +++++++++++++++++++++++++++------
arch/x86/kernel/head_64.S | 2 +-
arch/x86/mm/dump_pagetables.c | 3 ++
arch/x86/mm/kaslr.c | 11 ++++----
7 files changed, 77 insertions(+), 36 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index b18e8f9512de..66e42a098d70 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -47,9 +47,9 @@
#include <linux/decompress/mm.h>

#ifdef CONFIG_X86_5LEVEL
-unsigned int pgtable_l5_enabled __ro_after_init = 1;
-unsigned int pgdir_shift __ro_after_init = 48;
-unsigned int ptrs_per_p4d __ro_after_init = 512;
+unsigned int pgtable_l5_enabled __ro_after_init;
+unsigned int pgdir_shift __ro_after_init = 39;
+unsigned int ptrs_per_p4d __ro_after_init = 1;
#endif

extern unsigned long get_cmd_line_ptr(void);
@@ -729,6 +729,14 @@ void choose_random_location(unsigned long input,
return;
}

+#ifdef CONFIG_X86_5LEVEL
+ if (__read_cr4() & X86_CR4_LA57) {
+ pgtable_l5_enabled = 1;
+ 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/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index fa7dc7cd8c19..2c5a966dc222 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -37,16 +37,13 @@
* 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_BASE_L5 _AC(0xff10000000000000, UL)
+#define __PAGE_OFFSET_BASE_L4 _AC(0xffff880000000000, UL)

#ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT
#define __PAGE_OFFSET page_offset_base
#else
-#define __PAGE_OFFSET __PAGE_OFFSET_BASE
+#define __PAGE_OFFSET __PAGE_OFFSET_BASE_L4
#endif /* CONFIG_DYNAMIC_MEMORY_LAYOUT */

#define __START_KERNEL_map _AC(0xffffffff80000000, UL)
diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h
index 59d971c85de5..68909a68e5b9 100644
--- a/arch/x86/include/asm/pgtable_64_types.h
+++ b/arch/x86/include/asm/pgtable_64_types.h
@@ -102,25 +102,26 @@ extern unsigned int ptrs_per_p4d;
#define LDT_PGD_ENTRY (pgtable_l5_enabled ? LDT_PGD_ENTRY_L5 : LDT_PGD_ENTRY_L4)
#define LDT_BASE_ADDR (LDT_PGD_ENTRY << PGDIR_SHIFT)

-#ifdef CONFIG_X86_5LEVEL
-# define VMALLOC_SIZE_TB _AC(12800, UL)
-# define __VMALLOC_BASE _AC(0xffa0000000000000, 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 __VMALLOC_BASE_L4 0xffffc90000000000
+#define __VMALLOC_BASE_L5 0xffa0000000000000
+
+#define VMALLOC_SIZE_TB_L4 32UL
+#define VMALLOC_SIZE_TB_L5 12800UL
+
+#define __VMEMMAP_BASE_L4 0xffffea0000000000
+#define __VMEMMAP_BASE_L5 0xffd4000000000000

#ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT
# define VMALLOC_START vmalloc_base
+# define VMALLOC_SIZE_TB (pgtable_l5_enabled ? VMALLOC_SIZE_TB_L5 : VMALLOC_SIZE_TB_L4)
# define VMEMMAP_START vmemmap_base
#else
-# define VMALLOC_START __VMALLOC_BASE
-# define VMEMMAP_START __VMEMMAP_BASE
+# define VMALLOC_START __VMALLOC_BASE_L4
+# define VMALLOC_SIZE_TB VMALLOC_SIZE_TB_L4
+# define VMEMMAP_START __VMEMMAP_BASE_L4
#endif /* CONFIG_DYNAMIC_MEMORY_LAYOUT */

-#define VMALLOC_END (VMALLOC_START + _AC((VMALLOC_SIZE_TB << 40) - 1, UL))
+#define VMALLOC_END (VMALLOC_START + (VMALLOC_SIZE_TB << 40) - 1)

#define MODULES_VADDR (__START_KERNEL_map + KERNEL_IMAGE_SIZE)
/* The module sections ends with the start of the fixmap */
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 98b0ff49b220..795e762f3c66 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -40,20 +40,20 @@ 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 pgtable_l5_enabled __ro_after_init = 1;
+unsigned int pgtable_l5_enabled __ro_after_init;
EXPORT_SYMBOL(pgtable_l5_enabled);
-unsigned int pgdir_shift __ro_after_init = 48;
+unsigned int pgdir_shift __ro_after_init = 39;
EXPORT_SYMBOL(pgdir_shift);
-unsigned int ptrs_per_p4d __ro_after_init = 512;
+unsigned int ptrs_per_p4d __ro_after_init = 1;
EXPORT_SYMBOL(ptrs_per_p4d);
#endif

#ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT
-unsigned long page_offset_base __ro_after_init = __PAGE_OFFSET_BASE;
+unsigned long page_offset_base __ro_after_init = __PAGE_OFFSET_BASE_L4;
EXPORT_SYMBOL(page_offset_base);
-unsigned long vmalloc_base __ro_after_init = __VMALLOC_BASE;
+unsigned long vmalloc_base __ro_after_init = __VMALLOC_BASE_L4;
EXPORT_SYMBOL(vmalloc_base);
-unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE;
+unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4;
EXPORT_SYMBOL(vmemmap_base);
#endif

@@ -64,10 +64,40 @@ 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(&pgtable_l5_enabled, physaddr) = 1;
+ *fixup_int(&pgdir_shift, physaddr) = 48;
+ *fixup_int(&ptrs_per_p4d, physaddr) = 512;
+ *fixup_long(&page_offset_base, physaddr) = __PAGE_OFFSET_BASE_L5;
+ *fixup_long(&vmalloc_base, physaddr) = __VMALLOC_BASE_L5;
+ *fixup_long(&vmemmap_base, physaddr) = __VMEMMAP_BASE_L5;
+}
+#else
+static void __head check_la57_support(unsigned long physaddr) {}
+#endif
+
unsigned long __head __startup_64(unsigned long physaddr,
struct boot_params *bp)
{
- unsigned long load_delta, *p;
+ unsigned long load_delta;
unsigned long pgtable_flags;
pgdval_t *pgd;
p4dval_t *p4d;
@@ -76,6 +106,8 @@ unsigned long __head __startup_64(unsigned long physaddr,
int i;
unsigned int *next_pgt_ptr;

+ check_la57_support(physaddr);
+
/* Is the address too large? */
if (physaddr >> MAX_PHYSMEM_BITS)
for (;;);
@@ -172,8 +204,7 @@ 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 and related (if SME is active) */
sme_encrypt_kernel(bp);
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 04a625f0fcda..d3f8b43d541a 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -41,7 +41,7 @@
#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_BASE_L4)
PGD_START_KERNEL = pgd_index(__START_KERNEL_map)
#endif
L3_START_KERNEL = pud_index(__START_KERNEL_map)
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 9efee6f464ab..a32f0621d664 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -579,6 +579,9 @@ static int __init pt_dump_init(void)
address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
#endif
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+ address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
+#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 d079878c6cbc..641169d38184 100644
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -34,13 +34,10 @@
#define TB_SHIFT 40

/*
- * Virtual address start and end range for randomization.
- *
* The end address could depend on more configuration options to make the
* highest amount of space for randomization available, but that's too hard
* to keep straight and caused issues already.
*/
-static const unsigned long vaddr_start = __PAGE_OFFSET_BASE;
static const unsigned long vaddr_end = CPU_ENTRY_AREA_BASE;

/*
@@ -53,7 +50,7 @@ static __initdata struct kaslr_memory_region {
unsigned long size_tb;
} kaslr_regions[] = {
{ &page_offset_base, 0 },
- { &vmalloc_base, VMALLOC_SIZE_TB },
+ { &vmalloc_base, 0 },
{ &vmemmap_base, 1 },
};

@@ -76,11 +73,14 @@ 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 = pgtable_l5_enabled ? __PAGE_OFFSET_BASE_L5 : __PAGE_OFFSET_BASE_L4;
+ vaddr = vaddr_start;
+
/*
* These BUILD_BUG_ON checks ensure the memory layout is consistent
* with the vaddr_start/vaddr_end variables. These checks are very
@@ -94,6 +94,7 @@ void __init kernel_randomize_memory(void)
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
--
2.15.1

Next message: Kirill A. Shutemov: "[PATCH 6/9] x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D variable"
Previous message: Kirill A. Shutemov: "[PATCH 8/9] x86/mm: Make __VIRTUAL_MASK_SHIFT dynamic"
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Next in thread: Ingo Molnar: "Re: [PATCH 9/9] x86/mm: Adjust virtual address space layout in early boot"
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