Quelle  pgprot.c

// SPDX-License-Identifier: GPL-2.0

#include <linux/export.h>
#include <linux/mm.h>
#include <asm/pgtable.h>
#include <asm/mem_encrypt.h>

static pgprot_t protection_map[16] __ro_after_init = {
 [VM_NONE]     = PAGE_NONE,
 [VM_READ]     = PAGE_READONLY,
 [VM_WRITE]     = PAGE_COPY,
 [VM_WRITE | VM_READ]    = PAGE_COPY,
 [VM_EXEC]     = PAGE_READONLY_EXEC,
 [VM_EXEC | VM_READ]    = PAGE_READONLY_EXEC,
 [VM_EXEC | VM_WRITE]    = PAGE_COPY_EXEC,
 [VM_EXEC | VM_WRITE | VM_READ]   = PAGE_COPY_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,
 [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
};

void add_encrypt_protection_map(void)
{
 unsigned int i;

 for (i = 0; i < ARRAY_SIZE(protection_map); i++)
  protection_map[i] = pgprot_encrypted(protection_map[i]);
}

pgprot_t vm_get_page_prot(vm_flags_t vm_flags)
{
 unsigned long val = pgprot_val(protection_map[vm_flags &
          (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]);

#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
 /*
 * Take the 4 protection key bits out of the vma->vm_flags value and
 * turn them in to the bits that we can put in to a pte.
 *
 * Only override these if Protection Keys are available (which is only
 * on 64-bit).
 */
 if (vm_flags & VM_PKEY_BIT0)
  val |= _PAGE_PKEY_BIT0;
 if (vm_flags & VM_PKEY_BIT1)
  val |= _PAGE_PKEY_BIT1;
 if (vm_flags & VM_PKEY_BIT2)
  val |= _PAGE_PKEY_BIT2;
 if (vm_flags & VM_PKEY_BIT3)
  val |= _PAGE_PKEY_BIT3;
#endif

 val = __sme_set(val);
 if (val & _PAGE_PRESENT)
  val &= __supported_pte_mask;
 return __pgprot(val);
}
EXPORT_SYMBOL(vm_get_page_prot);