| Message ID | 20181205164145.24568-3-steve.capper@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | 52-bit userspace VAs | expand |
On Wed, Dec 05, 2018 at 04:41:41PM +0000, Steve Capper wrote: > 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: Steve Capper <steve.capper@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
On Wed, Dec 05, 2018 at 05:36:52PM +0000, Catalin Marinas wrote: > On Wed, Dec 05, 2018 at 04:41:41PM +0000, Steve Capper wrote: > > 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: Steve Capper <steve.capper@arm.com> > > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Thanks!
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index 433b9554c6a1..bc9bd9e77d9d 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -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__ diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index 3e2091708b8e..50586ca6bacb 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -45,19 +45,25 @@ * 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) ? \ diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 9d9582cac6c4..7239c103be06 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -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 diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c index 922cfb813109..952cec5b611a 100644 --- a/drivers/firmware/efi/arm-runtime.c +++ b/drivers/firmware/efi/arm-runtime.c @@ -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, }; diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c index 30ac0c975f8a..d1ec7136e3e1 100644 --- a/drivers/firmware/efi/libstub/arm-stub.c +++ b/drivers/firmware/efi/libstub/arm-stub.c @@ -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
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: Steve Capper <steve.capper@arm.com> --- Changed in V3: corrections to allow COMPAT 32-bit EL0 mode to work --- arch/arm64/include/asm/elf.h | 2 +- arch/arm64/include/asm/processor.h | 10 ++++++++-- arch/arm64/mm/init.c | 2 +- drivers/firmware/efi/arm-runtime.c | 2 +- drivers/firmware/efi/libstub/arm-stub.c | 2 +- 5 files changed, 12 insertions(+), 6 deletions(-)