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x86/mm/64: Always use dynamic memory layout

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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: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Borislav 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
This commit is contained in:
Kirill A. Shutemov 2025-05-16 15:33:03 +03:00 committed by Ingo Molnar
parent a0f3fe547e
commit 1bffe6f689
5 changed files with 1 additions and 23 deletions
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8
arch/x86/Kconfig
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@ -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

4
arch/x86/include/asm/page_64_types.h
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@ -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)

6
arch/x86/include/asm/pgtable_64_types.h
View File

@ -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

2
arch/x86/kernel/head64.c
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@ -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)

4
scripts/gdb/linux/pgtable.py
View File

@ -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)