From 3d9a18b92a7e3b48f6069f3f9fa1fb9230e84831 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 17 Nov 2015 09:53:31 +0100 Subject: [PATCH] arm64: use non-global mappings for UEFI runtime regions As pointed out by Russell King in response to the proposed ARM version of this code, the sequence to switch between the UEFI runtime mapping and current's actual userland mapping (and vice versa) is potentially unsafe, since it leaves a time window between the switch to the new page tables and the TLB flush where speculative accesses may hit on stale global TLB entries. So instead, use non-global mappings, and perform the switch via the ordinary ASID-aware context switch routines. Signed-off-by: Ard Biesheuvel Acked-by: Will Deacon Reviewed-by: Mark Rutland Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/mmu_context.h | 2 +- arch/arm64/kernel/efi.c | 14 +++++--------- 2 files changed, 6 insertions(+), 10 deletions(-) diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index c0e87898ba96b..24165784b8038 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -101,7 +101,7 @@ static inline void cpu_set_default_tcr_t0sz(void) #define destroy_context(mm) do { } while(0) void check_and_switch_context(struct mm_struct *mm, unsigned int cpu); -#define init_new_context(tsk,mm) ({ atomic64_set(&mm->context.id, 0); 0; }) +#define init_new_context(tsk,mm) ({ atomic64_set(&(mm)->context.id, 0); 0; }) /* * This is called when "tsk" is about to enter lazy TLB mode. diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c index de46b50f4cdf9..fc5508e0df57f 100644 --- a/arch/arm64/kernel/efi.c +++ b/arch/arm64/kernel/efi.c @@ -224,6 +224,8 @@ static bool __init efi_virtmap_init(void) { efi_memory_desc_t *md; + init_new_context(NULL, &efi_mm); + for_each_efi_memory_desc(&memmap, md) { u64 paddr, npages, size; pgprot_t prot; @@ -254,7 +256,8 @@ static bool __init efi_virtmap_init(void) else prot = PAGE_KERNEL; - create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, prot); + create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, + __pgprot(pgprot_val(prot) | PTE_NG)); } return true; } @@ -329,14 +332,7 @@ core_initcall(arm64_dmi_init); static void efi_set_pgd(struct mm_struct *mm) { - if (mm == &init_mm) - cpu_set_reserved_ttbr0(); - else - cpu_switch_mm(mm->pgd, mm); - - local_flush_tlb_all(); - if (icache_is_aivivt()) - __local_flush_icache_all(); + switch_mm(NULL, mm, NULL); } void efi_virtmap_load(void) -- 2.39.5