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Subject[PATCH 3/9] x86/mm: Make virtual memory layout movable for CONFIG_X86_5LEVEL
Date
We need to be able to adjust virtual memory layout at runtime to be able
to switch between 4- and 5-level paging at boot-time.

KASLR already has movable __VMALLOC_BASE, __VMEMMAP_BASE and __PAGE_OFFSET.
Let's re-use it.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/Kconfig | 8 ++++++++
arch/x86/include/asm/kaslr.h | 4 ----
arch/x86/include/asm/page_64.h | 4 ++++
arch/x86/include/asm/page_64_types.h | 4 ++--
arch/x86/include/asm/pgtable_64_types.h | 4 ++--
arch/x86/kernel/head64.c | 9 +++++++++
arch/x86/mm/kaslr.c | 8 --------
7 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a528c14d45a5..f925274ddf79 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1471,6 +1471,7 @@ config X86_PAE

config X86_5LEVEL
bool "Enable 5-level page tables support"
+ select DYNAMIC_MEMORY_LAYOUT
depends on X86_64
---help---
5-level paging enables access to larger address space:
@@ -2184,10 +2185,17 @@ config PHYSICAL_ALIGN

Don't change this unless you know what you are doing.

+config DYNAMIC_MEMORY_LAYOUT
+ bool
+ ---help---
+ This option makes base addresses of vmalloc and vmemmap as well as
+ __PAGE_OFFSET movable during boot.
+
config RANDOMIZE_MEMORY
bool "Randomize the kernel memory sections"
depends on X86_64
depends on RANDOMIZE_BASE
+ select DYNAMIC_MEMORY_LAYOUT
default RANDOMIZE_BASE
---help---
Randomizes the base virtual address of kernel memory sections
diff --git a/arch/x86/include/asm/kaslr.h b/arch/x86/include/asm/kaslr.h
index 460991e3b529..db7ba2feb947 100644
--- a/arch/x86/include/asm/kaslr.h
+++ b/arch/x86/include/asm/kaslr.h
@@ -5,10 +5,6 @@
unsigned long kaslr_get_random_long(const char *purpose);

#ifdef CONFIG_RANDOMIZE_MEMORY
-extern unsigned long page_offset_base;
-extern unsigned long vmalloc_base;
-extern unsigned long vmemmap_base;
-
void kernel_randomize_memory(void);
#else
static inline void kernel_randomize_memory(void) { }
diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h
index 9ca8dae9c716..939b1cff4a7b 100644
--- a/arch/x86/include/asm/page_64.h
+++ b/arch/x86/include/asm/page_64.h
@@ -11,6 +11,10 @@
extern unsigned long max_pfn;
extern unsigned long phys_base;

+extern unsigned long page_offset_base;
+extern unsigned long vmalloc_base;
+extern unsigned long vmemmap_base;
+
static inline unsigned long __phys_addr_nodebug(unsigned long x)
{
unsigned long y = x - __START_KERNEL_map;
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index f68e6526891d..d54a3d5b5b3b 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -43,11 +43,11 @@
#define __PAGE_OFFSET_BASE _AC(0xffff880000000000, UL)
#endif

-#ifdef CONFIG_RANDOMIZE_MEMORY
+#ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT
#define __PAGE_OFFSET page_offset_base
#else
#define __PAGE_OFFSET __PAGE_OFFSET_BASE
-#endif /* CONFIG_RANDOMIZE_MEMORY */
+#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 7168de7d34eb..a0db91ab63b8 100644
--- a/arch/x86/include/asm/pgtable_64_types.h
+++ b/arch/x86/include/asm/pgtable_64_types.h
@@ -100,13 +100,13 @@ typedef struct { pteval_t pte; } pte_t;
# define LDT_BASE_ADDR (LDT_PGD_ENTRY << PGDIR_SHIFT)
#endif

-#ifdef CONFIG_RANDOMIZE_MEMORY
+#ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT
# define VMALLOC_START vmalloc_base
# define VMEMMAP_START vmemmap_base
#else
# define VMALLOC_START __VMALLOC_BASE
# define VMEMMAP_START __VMEMMAP_BASE
-#endif /* CONFIG_RANDOMIZE_MEMORY */
+#endif /* CONFIG_DYNAMIC_MEMORY_LAYOUT */

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

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 7ba5d819ebe3..bf5c9ba63ba1 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -39,6 +39,15 @@ extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
static unsigned int __initdata next_early_pgt;
pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);

+#ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT
+unsigned long page_offset_base __ro_after_init = __PAGE_OFFSET_BASE;
+EXPORT_SYMBOL(page_offset_base);
+unsigned long vmalloc_base __ro_after_init = __VMALLOC_BASE;
+EXPORT_SYMBOL(vmalloc_base);
+unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE;
+EXPORT_SYMBOL(vmemmap_base);
+#endif
+
#define __head __section(.head.text)

static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
index aedebd2ebf1e..515b98a8ccee 100644
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -43,14 +43,6 @@
static const unsigned long vaddr_start = __PAGE_OFFSET_BASE;
static const unsigned long vaddr_end = CPU_ENTRY_AREA_BASE;

-/* Default values */
-unsigned long page_offset_base = __PAGE_OFFSET_BASE;
-EXPORT_SYMBOL(page_offset_base);
-unsigned long vmalloc_base = __VMALLOC_BASE;
-EXPORT_SYMBOL(vmalloc_base);
-unsigned long vmemmap_base = __VMEMMAP_BASE;
-EXPORT_SYMBOL(vmemmap_base);
-
/*
* Memory regions randomized by KASLR (except modules that use a separate logic
* earlier during boot). The list is ordered based on virtual addresses. This
--
2.15.1
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