arch/riscv/include/asm/kfence.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2
   3 #ifndef _ASM_RISCV_KFENCE_H
   4 #define _ASM_RISCV_KFENCE_H
   5
   6 #include <linux/kfence.h>
   7 #include <linux/pfn.h>
   8 #include <asm-generic/pgalloc.h>
   9 #include <asm/pgtable.h>
  10
  11 static inline int split_pmd_page(unsigned long addr)
  12 {
  13         int i;
  14         unsigned long pfn = PFN_DOWN(__pa((addr & PMD_MASK)));
  15         pmd_t *pmd = pmd_off_k(addr);
  16         pte_t *pte = pte_alloc_one_kernel(&init_mm);
  17
  18         if (!pte)
  19                 return -ENOMEM;
  20
  21         for (i = 0; i < PTRS_PER_PTE; i++)
  22                 set_pte(pte + i, pfn_pte(pfn + i, PAGE_KERNEL));
  23         set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa(pte)), PAGE_TABLE));
  24
  25         flush_tlb_kernel_range(addr, addr + PMD_SIZE);
  26         return 0;
  27 }
  28
  29 static inline bool arch_kfence_init_pool(void)
  30 {
  31         int ret;
  32         unsigned long addr;
  33         pmd_t *pmd;
  34
  35         for (addr = (unsigned long)__kfence_pool; is_kfence_address((void *)addr);
  36              addr += PAGE_SIZE) {
  37                 pmd = pmd_off_k(addr);
  38
  39                 if (pmd_leaf(*pmd)) {
  40                         ret = split_pmd_page(addr);
  41                         if (ret)
  42                                 return false;
  43                 }
  44         }
  45
  46         return true;
  47 }
  48
  49 static inline bool kfence_protect_page(unsigned long addr, bool protect)
  50 {
  51         pte_t *pte = virt_to_kpte(addr);
  52
  53         if (protect)
  54                 set_pte(pte, __pte(pte_val(*pte) & ~_PAGE_PRESENT));
  55         else
  56                 set_pte(pte, __pte(pte_val(*pte) | _PAGE_PRESENT));
  57
  58         flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
  59
  60         return true;
  61 }
  62
  63 #endif /* _ASM_RISCV_KFENCE_H */