diff options
| author | Steve Capper <steve.capper@arm.com> | 2018-12-06 22:50:42 +0000 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2018-12-10 18:42:18 +0000 |
| commit | b9567720a1b8e739380e0241413606c056c57859 (patch) | |
| tree | 760f658f0fbb3ec46f0cbdaa0314245f6f094fb7 | |
| parent | 67e7fdfcc6824a4f768d76d89377b33baad58fad (diff) | |
| download | linux-b9567720a1b8e739380e0241413606c056c57859.tar.bz2 | |
arm64: mm: Allow forcing all userspace addresses to 52-bit
On arm64 52-bit VAs are provided to userspace when a hint is supplied to
mmap. This helps maintain compatibility with software that expects at
most 48-bit VAs to be returned.
In order to help identify software that has 48-bit VA assumptions, this
patch allows one to compile a kernel where 52-bit VAs are returned by
default on HW that supports it.
This feature is intended to be for development systems only.
Signed-off-by: Steve Capper <steve.capper@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
| -rw-r--r-- | arch/arm64/Kconfig | 13 | ||||
| -rw-r--r-- | arch/arm64/include/asm/elf.h | 4 | ||||
| -rw-r--r-- | arch/arm64/include/asm/processor.h | 9 |
3 files changed, 25 insertions, 1 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 858e353b2f40..ca1f93233b22 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1186,6 +1186,19 @@ config ARM64_CNP at runtime, and does not affect PEs that do not implement this feature. +config ARM64_FORCE_52BIT + bool "Force 52-bit virtual addresses for userspace" + depends on ARM64_52BIT_VA && EXPERT + help + For systems with 52-bit userspace VAs enabled, the kernel will attempt + to maintain compatibility with older software by providing 48-bit VAs + unless a hint is supplied to mmap. + + This configuration option disables the 48-bit compatibility logic, and + forces all userspace addresses to be 52-bit on HW that supports it. One + should only enable this configuration option for stress testing userspace + memory management code. If unsure say N here. + endmenu config ARM64_SVE diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index bc9bd9e77d9d..6adc1a90e7e6 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -117,7 +117,11 @@ * 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. */ +#ifdef CONFIG_ARM64_FORCE_52BIT +#define ELF_ET_DYN_BASE (2 * TASK_SIZE_64 / 3) +#else #define ELF_ET_DYN_BASE (2 * DEFAULT_MAP_WINDOW_64 / 3) +#endif /* CONFIG_ARM64_FORCE_52BIT */ #ifndef __ASSEMBLY__ diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index 7ff75e52b762..efa0210cf927 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -74,8 +74,13 @@ extern u64 vabits_user; #define DEFAULT_MAP_WINDOW DEFAULT_MAP_WINDOW_64 #endif /* CONFIG_COMPAT */ -#define TASK_UNMAPPED_BASE (PAGE_ALIGN(DEFAULT_MAP_WINDOW / 4)) +#ifdef CONFIG_ARM64_FORCE_52BIT +#define STACK_TOP_MAX TASK_SIZE_64 +#define TASK_UNMAPPED_BASE (PAGE_ALIGN(TASK_SIZE / 4)) +#else #define STACK_TOP_MAX DEFAULT_MAP_WINDOW_64 +#define TASK_UNMAPPED_BASE (PAGE_ALIGN(DEFAULT_MAP_WINDOW / 4)) +#endif /* CONFIG_ARM64_FORCE_52BIT */ #ifdef CONFIG_COMPAT #define AARCH32_VECTORS_BASE 0xffff0000 @@ -85,12 +90,14 @@ extern u64 vabits_user; #define STACK_TOP STACK_TOP_MAX #endif /* CONFIG_COMPAT */ +#ifndef CONFIG_ARM64_FORCE_52BIT #define arch_get_mmap_end(addr) ((addr > DEFAULT_MAP_WINDOW) ? TASK_SIZE :\ DEFAULT_MAP_WINDOW) #define arch_get_mmap_base(addr, base) ((addr > DEFAULT_MAP_WINDOW) ? \ base + TASK_SIZE - DEFAULT_MAP_WINDOW :\ base) +#endif /* CONFIG_ARM64_FORCE_52BIT */ extern phys_addr_t arm64_dma_phys_limit; #define ARCH_LOW_ADDRESS_LIMIT (arm64_dma_phys_limit - 1) |