From 67e7fdfcc6824a4f768d76d89377b33baad58fad Mon Sep 17 00:00:00 2001 From: Steve Capper Date: Thu, 6 Dec 2018 22:50:41 +0000 Subject: [PATCH] arm64: mm: introduce 52-bit userspace support On arm64 there is optional support for a 52-bit virtual address space. To exploit this one has to be running with a 64KB page size and be running on hardware that supports this. For an arm64 kernel supporting a 48 bit VA with a 64KB page size, some changes are needed to support a 52-bit userspace: * TCR_EL1.T0SZ needs to be 12 instead of 16, * TASK_SIZE needs to reflect the new size. This patch implements the above when the support for 52-bit VAs is detected at early boot time. On arm64 userspace addresses translation is controlled by TTBR0_EL1. As well as userspace, TTBR0_EL1 controls: * The identity mapping, * EFI runtime code. It is possible to run a kernel with an identity mapping that has a larger VA size than userspace (and for this case __cpu_set_tcr_t0sz() would set TCR_EL1.T0SZ as appropriate). However, when the conditions for 52-bit userspace are met; it is possible to keep TCR_EL1.T0SZ fixed at 12. Thus in this patch, the TCR_EL1.T0SZ size changing logic is disabled. Reviewed-by: Catalin Marinas Signed-off-by: Steve Capper Signed-off-by: Will Deacon --- arch/arm64/Kconfig | 4 ++++ arch/arm64/include/asm/assembler.h | 7 +++---- arch/arm64/include/asm/mmu_context.h | 3 +++ arch/arm64/include/asm/processor.h | 13 +++++++++---- arch/arm64/kernel/head.S | 13 +++++++++++++ arch/arm64/mm/fault.c | 2 +- arch/arm64/mm/mmu.c | 1 + arch/arm64/mm/proc.S | 10 +++++++++- 8 files changed, 43 insertions(+), 10 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 6d2b25f51bb3..858e353b2f40 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -716,6 +716,10 @@ config ARM64_PA_BITS_52 endchoice +config ARM64_52BIT_VA + def_bool y + depends on ARM64_VA_BITS_48 && ARM64_64K_PAGES && (ARM64_PAN || !ARM64_SW_TTBR0_PAN) + config ARM64_PA_BITS int default 48 if ARM64_PA_BITS_48 diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index ba609e0439e8..122d91d4097a 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -357,11 +357,10 @@ alternative_endif .endm /* - * tcr_set_idmap_t0sz - update TCR.T0SZ so that we can load the ID map + * tcr_set_t0sz - update TCR.T0SZ so that we can load the ID map */ - .macro tcr_set_idmap_t0sz, valreg, tmpreg - ldr_l \tmpreg, idmap_t0sz - bfi \valreg, \tmpreg, #TCR_T0SZ_OFFSET, #TCR_TxSZ_WIDTH + .macro tcr_set_t0sz, valreg, t0sz + bfi \valreg, \t0sz, #TCR_T0SZ_OFFSET, #TCR_TxSZ_WIDTH .endm /* diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index dfcfeffd2080..b0768502fa08 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -74,6 +74,9 @@ extern u64 idmap_ptrs_per_pgd; static inline bool __cpu_uses_extended_idmap(void) { + if (IS_ENABLED(CONFIG_ARM64_52BIT_VA)) + return false; + return unlikely(idmap_t0sz != TCR_T0SZ(VA_BITS)); } diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index 759927faf7f6..7ff75e52b762 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -19,10 +19,12 @@ #ifndef __ASM_PROCESSOR_H #define __ASM_PROCESSOR_H -#define TASK_SIZE_64 (UL(1) << VA_BITS) - -#define KERNEL_DS UL(-1) -#define USER_DS (TASK_SIZE_64 - 1) +#define KERNEL_DS UL(-1) +#ifdef CONFIG_ARM64_52BIT_VA +#define USER_DS ((UL(1) << 52) - 1) +#else +#define USER_DS ((UL(1) << VA_BITS) - 1) +#endif /* CONFIG_ARM64_52BIT_VA */ /* * On arm64 systems, unaligned accesses by the CPU are cheap, and so there is @@ -56,6 +58,9 @@ #define DEFAULT_MAP_WINDOW_64 (UL(1) << VA_BITS) +extern u64 vabits_user; +#define TASK_SIZE_64 (UL(1) << vabits_user) + #ifdef CONFIG_COMPAT #define TASK_SIZE_32 UL(0x100000000) #define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \ diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 58fcc1edd852..c229d9cfe9bf 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -318,6 +318,19 @@ __create_page_tables: adrp x0, idmap_pg_dir adrp x3, __idmap_text_start // __pa(__idmap_text_start) +#ifdef CONFIG_ARM64_52BIT_VA + mrs_s x6, SYS_ID_AA64MMFR2_EL1 + and x6, x6, #(0xf << ID_AA64MMFR2_LVA_SHIFT) + mov x5, #52 + cbnz x6, 1f +#endif + mov x5, #VA_BITS +1: + adr_l x6, vabits_user + str x5, [x6] + dmb sy + dc ivac, x6 // Invalidate potentially stale cache line + /* * VA_BITS may be too small to allow for an ID mapping to be created * that covers system RAM if that is located sufficiently high in the diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 7d9571f4ae3d..5fe6d2e40e9b 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -160,7 +160,7 @@ void show_pte(unsigned long addr) pr_alert("%s pgtable: %luk pages, %u-bit VAs, pgdp = %p\n", mm == &init_mm ? "swapper" : "user", PAGE_SIZE / SZ_1K, - VA_BITS, mm->pgd); + mm == &init_mm ? VA_BITS : (int) vabits_user, mm->pgd); pgdp = pgd_offset(mm, addr); pgd = READ_ONCE(*pgdp); pr_alert("[%016lx] pgd=%016llx", addr, pgd_val(pgd)); diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index e1b2d58a311a..0d3eacc4bfbb 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -52,6 +52,7 @@ u64 idmap_t0sz = TCR_T0SZ(VA_BITS); u64 idmap_ptrs_per_pgd = PTRS_PER_PGD; +u64 vabits_user __ro_after_init; u64 kimage_voffset __ro_after_init; EXPORT_SYMBOL(kimage_voffset); diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 2db1c491d45d..0cf86b17714c 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -450,7 +450,15 @@ ENTRY(__cpu_setup) ldr x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \ TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \ TCR_TBI0 | TCR_A1 - tcr_set_idmap_t0sz x10, x9 + +#ifdef CONFIG_ARM64_52BIT_VA + ldr_l x9, vabits_user + sub x9, xzr, x9 + add x9, x9, #64 +#else + ldr_l x9, idmap_t0sz +#endif + tcr_set_t0sz x10, x9 /* * Set the IPS bits in TCR_EL1. -- 2.30.2