tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1/*
2 * PPC64 Huge TLB Page Support for hash based MMUs (POWER4 and later)
3 *
4 * Copyright (C) 2003 David Gibson, IBM Corporation.
5 *
6 * Based on the IA-32 version:
7 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
8 */
9
10#include <linux/mm.h>
11#include <linux/hugetlb.h>
12#include <asm/pgtable.h>
13#include <asm/pgalloc.h>
14#include <asm/cacheflush.h>
15#include <asm/machdep.h>
16
17extern long hpte_insert_repeating(unsigned long hash, unsigned long vpn,
18 unsigned long pa, unsigned long rlags,
19 unsigned long vflags, int psize, int ssize);
20
21int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
22 pte_t *ptep, unsigned long trap, unsigned long flags,
23 int ssize, unsigned int shift, unsigned int mmu_psize)
24{
25 unsigned long vpn;
26 unsigned long old_pte, new_pte;
27 unsigned long rflags, pa, sz;
28 long slot;
29
30 BUG_ON(shift != mmu_psize_defs[mmu_psize].shift);
31
32 /* Search the Linux page table for a match with va */
33 vpn = hpt_vpn(ea, vsid, ssize);
34
35 /* At this point, we have a pte (old_pte) which can be used to build
36 * or update an HPTE. There are 2 cases:
37 *
38 * 1. There is a valid (present) pte with no associated HPTE (this is
39 * the most common case)
40 * 2. There is a valid (present) pte with an associated HPTE. The
41 * current values of the pp bits in the HPTE prevent access
42 * because we are doing software DIRTY bit management and the
43 * page is currently not DIRTY.
44 */
45
46
47 do {
48 old_pte = pte_val(*ptep);
49 /* If PTE busy, retry the access */
50 if (unlikely(old_pte & H_PAGE_BUSY))
51 return 0;
52 /* If PTE permissions don't match, take page fault */
53 if (unlikely(!check_pte_access(access, old_pte)))
54 return 1;
55
56 /* Try to lock the PTE, add ACCESSED and DIRTY if it was
57 * a write access */
58 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
59 if (access & _PAGE_WRITE)
60 new_pte |= _PAGE_DIRTY;
61 } while(!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
62
63 rflags = htab_convert_pte_flags(new_pte);
64
65 sz = ((1UL) << shift);
66 if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
67 /* No CPU has hugepages but lacks no execute, so we
68 * don't need to worry about that case */
69 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
70
71 /* Check if pte already has an hpte (case 2) */
72 if (unlikely(old_pte & H_PAGE_HASHPTE)) {
73 /* There MIGHT be an HPTE for this pte */
74 unsigned long hash, slot;
75
76 hash = hpt_hash(vpn, shift, ssize);
77 if (old_pte & H_PAGE_F_SECOND)
78 hash = ~hash;
79 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
80 slot += (old_pte & H_PAGE_F_GIX) >> H_PAGE_F_GIX_SHIFT;
81
82 if (mmu_hash_ops.hpte_updatepp(slot, rflags, vpn, mmu_psize,
83 mmu_psize, ssize, flags) == -1)
84 old_pte &= ~_PAGE_HPTEFLAGS;
85 }
86
87 if (likely(!(old_pte & H_PAGE_HASHPTE))) {
88 unsigned long hash = hpt_hash(vpn, shift, ssize);
89
90 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
91
92 /* clear HPTE slot informations in new PTE */
93 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
94
95 slot = hpte_insert_repeating(hash, vpn, pa, rflags, 0,
96 mmu_psize, ssize);
97
98 /*
99 * Hypervisor failure. Restore old pte and return -1
100 * similar to __hash_page_*
101 */
102 if (unlikely(slot == -2)) {
103 *ptep = __pte(old_pte);
104 hash_failure_debug(ea, access, vsid, trap, ssize,
105 mmu_psize, mmu_psize, old_pte);
106 return -1;
107 }
108
109 new_pte |= (slot << H_PAGE_F_GIX_SHIFT) &
110 (H_PAGE_F_SECOND | H_PAGE_F_GIX);
111 }
112
113 /*
114 * No need to use ldarx/stdcx here
115 */
116 *ptep = __pte(new_pte & ~H_PAGE_BUSY);
117 return 0;
118}
119
120#if defined(CONFIG_PPC_64K_PAGES) && defined(CONFIG_DEBUG_VM)
121/*
122 * This enables us to catch the wrong page directory format
123 * Moved here so that we can use WARN() in the call.
124 */
125int hugepd_ok(hugepd_t hpd)
126{
127 bool is_hugepd;
128
129 /*
130 * We should not find this format in page directory, warn otherwise.
131 */
132 is_hugepd = (((hpd.pd & 0x3) == 0x0) && ((hpd.pd & HUGEPD_SHIFT_MASK) != 0));
133 WARN(is_hugepd, "Found wrong page directory format\n");
134 return 0;
135}
136#endif