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-rw-r--r--arch/arm64/mm/mmap.c103
1 files changed, 103 insertions, 0 deletions
diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
new file mode 100644
index 000000000..8f5b7ce85
--- /dev/null
+++ b/arch/arm64/mm/mmap.c
@@ -0,0 +1,103 @@
+// 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>
+
+static pgprot_t protection_map[16] __ro_after_init = {
+ [VM_NONE] = PAGE_NONE,
+ [VM_READ] = PAGE_READONLY,
+ [VM_WRITE] = PAGE_READONLY,
+ [VM_WRITE | VM_READ] = PAGE_READONLY,
+ /* PAGE_EXECONLY if Enhanced PAN */
+ [VM_EXEC] = PAGE_READONLY_EXEC,
+ [VM_EXEC | VM_READ] = PAGE_READONLY_EXEC,
+ [VM_EXEC | VM_WRITE] = PAGE_READONLY_EXEC,
+ [VM_EXEC | VM_WRITE | VM_READ] = PAGE_READONLY_EXEC,
+ [VM_SHARED] = PAGE_NONE,
+ [VM_SHARED | VM_READ] = PAGE_READONLY,
+ [VM_SHARED | VM_WRITE] = PAGE_SHARED,
+ [VM_SHARED | VM_WRITE | VM_READ] = PAGE_SHARED,
+ /* PAGE_EXECONLY if Enhanced PAN */
+ [VM_SHARED | VM_EXEC] = PAGE_READONLY_EXEC,
+ [VM_SHARED | VM_EXEC | VM_READ] = PAGE_READONLY_EXEC,
+ [VM_SHARED | VM_EXEC | VM_WRITE] = PAGE_SHARED_EXEC,
+ [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED_EXEC
+};
+
+/*
+ * 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);