1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/hugetlb.h>
3 #include <asm-generic/tlb.h>
4 #include <asm/pgalloc.h>
5 
6 #include "internal.h"
7 
8 bool reclaim_pt_is_enabled(unsigned long start, unsigned long end,
9 			   struct zap_details *details)
10 {
11 	return details && details->reclaim_pt && (end - start >= PMD_SIZE);
12 }
13 
14 bool try_get_and_clear_pmd(struct mm_struct *mm, pmd_t *pmd, pmd_t *pmdval)
15 {
16 	spinlock_t *pml = pmd_lockptr(mm, pmd);
17 
18 	if (!spin_trylock(pml))
19 		return false;
20 
21 	*pmdval = pmdp_get_lockless(pmd);
22 	pmd_clear(pmd);
23 	spin_unlock(pml);
24 
25 	return true;
26 }
27 
28 void free_pte(struct mm_struct *mm, unsigned long addr, struct mmu_gather *tlb,
29 	      pmd_t pmdval)
30 {
31 	pte_free_tlb(tlb, pmd_pgtable(pmdval), addr);
32 	mm_dec_nr_ptes(mm);
33 }
34 
35 void try_to_free_pte(struct mm_struct *mm, pmd_t *pmd, unsigned long addr,
36 		     struct mmu_gather *tlb)
37 {
38 	pmd_t pmdval;
39 	spinlock_t *pml, *ptl = NULL;
40 	pte_t *start_pte, *pte;
41 	int i;
42 
43 	pml = pmd_lock(mm, pmd);
44 	start_pte = pte_offset_map_rw_nolock(mm, pmd, addr, &pmdval, &ptl);
45 	if (!start_pte)
46 		goto out_ptl;
47 	if (ptl != pml)
48 		spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
49 
50 	/* Check if it is empty PTE page */
51 	for (i = 0, pte = start_pte; i < PTRS_PER_PTE; i++, pte++) {
52 		if (!pte_none(ptep_get(pte)))
53 			goto out_ptl;
54 	}
55 	pte_unmap(start_pte);
56 
57 	pmd_clear(pmd);
58 
59 	if (ptl != pml)
60 		spin_unlock(ptl);
61 	spin_unlock(pml);
62 
63 	free_pte(mm, addr, tlb, pmdval);
64 
65 	return;
66 out_ptl:
67 	if (start_pte)
68 		pte_unmap_unlock(start_pte, ptl);
69 	if (ptl != pml)
70 		spin_unlock(pml);
71 }
72