Commit 1bffe6f6 authored by Kiryl Shutsemau's avatar Kiryl Shutsemau Committed by Ingo Molnar
Browse files

x86/mm/64: Always use dynamic memory layout 



Dynamic memory layout is used by KASLR and 5-level paging.

CONFIG_X86_5LEVEL is going to be removed, making 5-level paging support
unconditional which requires unconditional support of dynamic memory
layout.

Remove CONFIG_DYNAMIC_MEMORY_LAYOUT.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarArd Biesheuvel <ardb@kernel.org>
Reviewed-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Kieran Bingham <kbingham@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250516123306.3812286-2-kirill.shutemov@linux.intel.com
parent a0f3fe54

arch/x86/Kconfig

+0 −8
Original line number Diff line number Diff line
@@ -1467,7 +1467,6 @@ config X86_PAE 
config X86_5LEVEL

	bool "Enable 5-level page tables support"

	default y

	select DYNAMIC_MEMORY_LAYOUT

	select SPARSEMEM_VMEMMAP

	depends on X86_64

	help
@@ -2168,17 +2167,10 @@ 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

arch/x86/include/asm/page_64_types.h

+0 −4
Original line number Diff line number Diff line
@@ -41,11 +41,7 @@ 
#define __PAGE_OFFSET_BASE_L5	_AC(0xff11000000000000, UL)

#define __PAGE_OFFSET_BASE_L4	_AC(0xffff888000000000, UL)



#ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT

#define __PAGE_OFFSET           page_offset_base

#else

#define __PAGE_OFFSET           __PAGE_OFFSET_BASE_L4

#endif /* CONFIG_DYNAMIC_MEMORY_LAYOUT */



#define __START_KERNEL_map	_AC(0xffffffff80000000, UL)

arch/x86/include/asm/pgtable_64_types.h

+0 −6
Original line number Diff line number Diff line
@@ -128,15 +128,9 @@ extern unsigned int ptrs_per_p4d; 
#define __VMEMMAP_BASE_L4	0xffffea0000000000UL

#define __VMEMMAP_BASE_L5	0xffd4000000000000UL



#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_L4

# define VMALLOC_SIZE_TB	VMALLOC_SIZE_TB_L4

# define VMEMMAP_START		__VMEMMAP_BASE_L4

#endif /* CONFIG_DYNAMIC_MEMORY_LAYOUT */



#ifdef CONFIG_RANDOMIZE_MEMORY

# define DIRECT_MAP_PHYSMEM_END	direct_map_physmem_end

arch/x86/kernel/head64.c

+0 −2
Original line number Diff line number Diff line
@@ -59,14 +59,12 @@ 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_L4;

EXPORT_SYMBOL(page_offset_base);

unsigned long vmalloc_base __ro_after_init = __VMALLOC_BASE_L4;

EXPORT_SYMBOL(vmalloc_base);

unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4;

EXPORT_SYMBOL(vmemmap_base);

#endif



/* Wipe all early page tables except for the kernel symbol map */

static void __init reset_early_page_tables(void)

scripts/gdb/linux/pgtable.py

+1 −3
Original line number Diff line number Diff line
@@ -29,11 +29,9 @@ def page_mask(level=1): 
        raise Exception(f'Unknown page level: {level}')





#page_offset_base in case CONFIG_DYNAMIC_MEMORY_LAYOUT is disabled

POB_NO_DYNAMIC_MEM_LAYOUT = '0xffff888000000000'

def _page_offset_base():

    pob_symbol = gdb.lookup_global_symbol('page_offset_base')

    pob = pob_symbol.name if pob_symbol else POB_NO_DYNAMIC_MEM_LAYOUT

    pob = pob_symbol.name

    return gdb.parse_and_eval(pob)