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 <ard.biesheuvel@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index c0e8789..2416578 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -101,7 +101,7 @@
#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 de46b50..fc5508e 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -224,6 +224,8 @@
{
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 @@
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 @@
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)
