| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Based on arch/arm/mm/mmap.c |
| * |
| * Copyright (C) 2012 ARM Ltd. |
| */ |
| |
| #include <linux/io.h> |
| #include <linux/memblock.h> |
| #include <linux/mm.h> |
| #include <linux/types.h> |
| |
| #include <asm/cpufeature.h> |
| #include <asm/page.h> |
| |
| /* |
| * You really shouldn't be using read() or write() on /dev/mem. This might go |
| * away in the future. |
| */ |
| int valid_phys_addr_range(phys_addr_t addr, size_t size) |
| { |
| /* |
| * Check whether addr is covered by a memory region without the |
| * MEMBLOCK_NOMAP attribute, and whether that region covers the |
| * entire range. In theory, this could lead to false negatives |
| * if the range is covered by distinct but adjacent memory regions |
| * that only differ in other attributes. However, few of such |
| * attributes have been defined, and it is debatable whether it |
| * follows that /dev/mem read() calls should be able traverse |
| * such boundaries. |
| */ |
| return memblock_is_region_memory(addr, size) && |
| memblock_is_map_memory(addr); |
| } |
| |
| /* |
| * Do not allow /dev/mem mappings beyond the supported physical range. |
| */ |
| int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) |
| { |
| return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK); |
| } |
| |
| static int __init adjust_protection_map(void) |
| { |
| /* |
| * With Enhanced PAN we can honour the execute-only permissions as |
| * there is no PAN override with such mappings. |
| */ |
| if (cpus_have_const_cap(ARM64_HAS_EPAN)) { |
| protection_map[VM_EXEC] = PAGE_EXECONLY; |
| protection_map[VM_EXEC | VM_SHARED] = PAGE_EXECONLY; |
| } |
| |
| return 0; |
| } |
| arch_initcall(adjust_protection_map); |
| |
| pgprot_t vm_get_page_prot(unsigned long vm_flags) |
| { |
| pteval_t prot = pgprot_val(protection_map[vm_flags & |
| (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]); |
| |
| if (vm_flags & VM_ARM64_BTI) |
| prot |= PTE_GP; |
| |
| /* |
| * There are two conditions required for returning a Normal Tagged |
| * memory type: (1) the user requested it via PROT_MTE passed to |
| * mmap() or mprotect() and (2) the corresponding vma supports MTE. We |
| * register (1) as VM_MTE in the vma->vm_flags and (2) as |
| * VM_MTE_ALLOWED. Note that the latter can only be set during the |
| * mmap() call since mprotect() does not accept MAP_* flags. |
| * Checking for VM_MTE only is sufficient since arch_validate_flags() |
| * does not permit (VM_MTE & !VM_MTE_ALLOWED). |
| */ |
| if (vm_flags & VM_MTE) |
| prot |= PTE_ATTRINDX(MT_NORMAL_TAGGED); |
| |
| return __pgprot(prot); |
| } |
| EXPORT_SYMBOL(vm_get_page_prot); |