[PATCH 1/3] x86/64/mm: Always use dynamic memory layout

From: Kirill A. Shutemov
Date: Fri Jun 21 2024 - 12:45:06 EST


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@xxxxxxxxxxxxxxx>
---
arch/x86/Kconfig | 8 --------
arch/x86/include/asm/page_64_types.h | 4 ----
arch/x86/include/asm/pgtable_64_types.h | 6 ------
arch/x86/kernel/head64.c | 2 --
scripts/gdb/linux/pgtable.py | 4 +---
5 files changed, 1 insertion(+), 23 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e30ea4129d2c..827928680ed6 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1501,7 +1501,6 @@ 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
@@ -2237,17 +2236,10 @@ 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
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 06ef25411d62..c2f3c50a2787 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -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)

diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h
index 9053dfe9fa03..09df8939b997 100644
--- a/arch/x86/include/asm/pgtable_64_types.h
+++ b/arch/x86/include/asm/pgtable_64_types.h
@@ -130,15 +130,9 @@ 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 */

/*
* End of the region for which vmalloc page tables are pre-allocated.
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index a817ed0724d1..ec36ad7117ae 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -60,14 +60,12 @@ 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

static inline bool check_la57_support(void)
{
diff --git a/scripts/gdb/linux/pgtable.py b/scripts/gdb/linux/pgtable.py
index 30d837f3dfae..09aac2421fb8 100644
--- a/scripts/gdb/linux/pgtable.py
+++ b/scripts/gdb/linux/pgtable.py
@@ -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)


--
2.43.0