Commit 363524d2 authored by Steve Capper's avatar Steve Capper Committed by Will Deacon
Browse files

arm64: mm: Introduce DEFAULT_MAP_WINDOW 



We wish to introduce a 52-bit virtual address space for userspace but
maintain compatibility with software that assumes the maximum VA space
size is 48 bit.

In order to achieve this, on 52-bit VA systems, we make mmap behave as
if it were running on a 48-bit VA system (unless userspace explicitly
requests a VA where addr[51:48] != 0).

On a system running a 52-bit userspace we need TASK_SIZE to represent
the 52-bit limit as it is used in various places to distinguish between
kernelspace and userspace addresses.

Thus we need a new limit for mmap, stack, ELF loader and EFI (which uses
TTBR0) to represent the non-extended VA space.

This patch introduces DEFAULT_MAP_WINDOW and DEFAULT_MAP_WINDOW_64 and
switches the appropriate logic to use that instead of TASK_SIZE.

Signed-off-by: default avatarSteve Capper <steve.capper@arm.com>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent f6795053

arch/arm64/include/asm/elf.h

+1 −1
Original line number Diff line number Diff line
@@ -117,7 +117,7 @@ 
 * 64-bit, this is above 4GB to leave the entire 32-bit address

 * space open for things that want to use the area for 32-bit pointers.

 */

#define ELF_ET_DYN_BASE		(2 * TASK_SIZE_64 / 3)

#define ELF_ET_DYN_BASE		(2 * DEFAULT_MAP_WINDOW_64 / 3)



#ifndef __ASSEMBLY__

arch/arm64/include/asm/processor.h

+8 −2
Original line number Diff line number Diff line
@@ -53,19 +53,25 @@ 
 * TASK_SIZE - the maximum size of a user space task.

 * TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area.

 */



#define DEFAULT_MAP_WINDOW_64	(UL(1) << VA_BITS)



#ifdef CONFIG_COMPAT

#define TASK_SIZE_32		UL(0x100000000)

#define TASK_SIZE		(test_thread_flag(TIF_32BIT) ? \

				TASK_SIZE_32 : TASK_SIZE_64)

#define TASK_SIZE_OF(tsk)	(test_tsk_thread_flag(tsk, TIF_32BIT) ? \

				TASK_SIZE_32 : TASK_SIZE_64)

#define DEFAULT_MAP_WINDOW	(test_thread_flag(TIF_32BIT) ? \

				TASK_SIZE_32 : DEFAULT_MAP_WINDOW_64)

#else

#define TASK_SIZE		TASK_SIZE_64

#define DEFAULT_MAP_WINDOW	DEFAULT_MAP_WINDOW_64

#endif /* CONFIG_COMPAT */



#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE / 4))

#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(DEFAULT_MAP_WINDOW / 4))

#define STACK_TOP_MAX		DEFAULT_MAP_WINDOW_64



#define STACK_TOP_MAX		TASK_SIZE_64

#ifdef CONFIG_COMPAT

#define AARCH32_VECTORS_BASE	0xffff0000

#define STACK_TOP		(test_thread_flag(TIF_32BIT) ? \

arch/arm64/mm/init.c

+1 −1
Original line number Diff line number Diff line
@@ -609,7 +609,7 @@ void __init mem_init(void) 
	 * detected at build time already.

	 */

#ifdef CONFIG_COMPAT

	BUILD_BUG_ON(TASK_SIZE_32			> TASK_SIZE_64);

	BUILD_BUG_ON(TASK_SIZE_32 > DEFAULT_MAP_WINDOW_64);

#endif



#ifdef CONFIG_SPARSEMEM_VMEMMAP

drivers/firmware/efi/arm-runtime.c

+1 −1
Original line number Diff line number Diff line
@@ -38,7 +38,7 @@ static struct ptdump_info efi_ptdump_info = { 
	.mm		= &efi_mm,

	.markers	= (struct addr_marker[]){

		{ 0,		"UEFI runtime start" },

		{ TASK_SIZE_64,	"UEFI runtime end" }

		{ DEFAULT_MAP_WINDOW_64, "UEFI runtime end" }

	},

	.base_addr	= 0,

};

drivers/firmware/efi/libstub/arm-stub.c

+1 −1
Original line number Diff line number Diff line
@@ -33,7 +33,7 @@ 
#define EFI_RT_VIRTUAL_SIZE	SZ_512M



#ifdef CONFIG_ARM64

# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE_64

# define EFI_RT_VIRTUAL_LIMIT	DEFAULT_MAP_WINDOW_64

#else

# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE

#endif

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