[PATCH V3 1/6] powerpc/mm/book3s: Update pmd_present to look at _PAGE_PRESENT bit
kbuild test robot
lkp at intel.com
Fri Aug 24 20:29:46 AEST 2018
Hi Aneesh,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on powerpc/next]
[also build test ERROR on v4.18 next-20180822]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Aneesh-Kumar-K-V/powerpc-mm-book3s-Update-pmd_present-to-look-at-_PAGE_PRESENT-bit/20180824-141837
base: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-allnoconfig (attached as .config)
compiler: powerpc-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.2.0 make.cross ARCH=powerpc
All errors (new ones prefixed by >>):
In file included from include/linux/kernel.h:15:0,
from arch/powerpc/mm/pgtable.c:24:
arch/powerpc/mm/pgtable.c: In function 'set_pte_at':
>> arch/powerpc/mm/pgtable.c:195:14: error: implicit declaration of function 'pte_raw'; did you mean 'pte_read'? [-Werror=implicit-function-declaration]
VM_WARN_ON((pte_raw(*ptep) & cpu_to_be64(_PAGE_PRESENT)) &&
^
include/linux/build_bug.h:36:63: note: in definition of macro 'BUILD_BUG_ON_INVALID'
#define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
^
arch/powerpc/mm/pgtable.c:195:2: note: in expansion of macro 'VM_WARN_ON'
VM_WARN_ON((pte_raw(*ptep) & cpu_to_be64(_PAGE_PRESENT)) &&
^~~~~~~~~~
cc1: all warnings being treated as errors
vim +195 arch/powerpc/mm/pgtable.c
> 24 #include <linux/kernel.h>
25 #include <linux/gfp.h>
26 #include <linux/mm.h>
27 #include <linux/percpu.h>
28 #include <linux/hardirq.h>
29 #include <linux/hugetlb.h>
30 #include <asm/pgalloc.h>
31 #include <asm/tlbflush.h>
32 #include <asm/tlb.h>
33
34 static inline int is_exec_fault(void)
35 {
36 return current->thread.regs && TRAP(current->thread.regs) == 0x400;
37 }
38
39 /* We only try to do i/d cache coherency on stuff that looks like
40 * reasonably "normal" PTEs. We currently require a PTE to be present
41 * and we avoid _PAGE_SPECIAL and cache inhibited pte. We also only do that
42 * on userspace PTEs
43 */
44 static inline int pte_looks_normal(pte_t pte)
45 {
46
47 #if defined(CONFIG_PPC_BOOK3S_64)
48 if ((pte_val(pte) & (_PAGE_PRESENT | _PAGE_SPECIAL)) == _PAGE_PRESENT) {
49 if (pte_ci(pte))
50 return 0;
51 if (pte_user(pte))
52 return 1;
53 }
54 return 0;
55 #else
56 return (pte_val(pte) &
57 (_PAGE_PRESENT | _PAGE_SPECIAL | _PAGE_NO_CACHE | _PAGE_USER |
58 _PAGE_PRIVILEGED)) ==
59 (_PAGE_PRESENT | _PAGE_USER);
60 #endif
61 }
62
63 static struct page *maybe_pte_to_page(pte_t pte)
64 {
65 unsigned long pfn = pte_pfn(pte);
66 struct page *page;
67
68 if (unlikely(!pfn_valid(pfn)))
69 return NULL;
70 page = pfn_to_page(pfn);
71 if (PageReserved(page))
72 return NULL;
73 return page;
74 }
75
76 #if defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0
77
78 /* Server-style MMU handles coherency when hashing if HW exec permission
79 * is supposed per page (currently 64-bit only). If not, then, we always
80 * flush the cache for valid PTEs in set_pte. Embedded CPU without HW exec
81 * support falls into the same category.
82 */
83
84 static pte_t set_pte_filter(pte_t pte)
85 {
86 if (radix_enabled())
87 return pte;
88
89 pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
90 if (pte_looks_normal(pte) && !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) ||
91 cpu_has_feature(CPU_FTR_NOEXECUTE))) {
92 struct page *pg = maybe_pte_to_page(pte);
93 if (!pg)
94 return pte;
95 if (!test_bit(PG_arch_1, &pg->flags)) {
96 flush_dcache_icache_page(pg);
97 set_bit(PG_arch_1, &pg->flags);
98 }
99 }
100 return pte;
101 }
102
103 static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
104 int dirty)
105 {
106 return pte;
107 }
108
109 #else /* defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0 */
110
111 /* Embedded type MMU with HW exec support. This is a bit more complicated
112 * as we don't have two bits to spare for _PAGE_EXEC and _PAGE_HWEXEC so
113 * instead we "filter out" the exec permission for non clean pages.
114 */
115 static pte_t set_pte_filter(pte_t pte)
116 {
117 struct page *pg;
118
119 /* No exec permission in the first place, move on */
120 if (!(pte_val(pte) & _PAGE_EXEC) || !pte_looks_normal(pte))
121 return pte;
122
123 /* If you set _PAGE_EXEC on weird pages you're on your own */
124 pg = maybe_pte_to_page(pte);
125 if (unlikely(!pg))
126 return pte;
127
128 /* If the page clean, we move on */
129 if (test_bit(PG_arch_1, &pg->flags))
130 return pte;
131
132 /* If it's an exec fault, we flush the cache and make it clean */
133 if (is_exec_fault()) {
134 flush_dcache_icache_page(pg);
135 set_bit(PG_arch_1, &pg->flags);
136 return pte;
137 }
138
139 /* Else, we filter out _PAGE_EXEC */
140 return __pte(pte_val(pte) & ~_PAGE_EXEC);
141 }
142
143 static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
144 int dirty)
145 {
146 struct page *pg;
147
148 /* So here, we only care about exec faults, as we use them
149 * to recover lost _PAGE_EXEC and perform I$/D$ coherency
150 * if necessary. Also if _PAGE_EXEC is already set, same deal,
151 * we just bail out
152 */
153 if (dirty || (pte_val(pte) & _PAGE_EXEC) || !is_exec_fault())
154 return pte;
155
156 #ifdef CONFIG_DEBUG_VM
157 /* So this is an exec fault, _PAGE_EXEC is not set. If it was
158 * an error we would have bailed out earlier in do_page_fault()
159 * but let's make sure of it
160 */
161 if (WARN_ON(!(vma->vm_flags & VM_EXEC)))
162 return pte;
163 #endif /* CONFIG_DEBUG_VM */
164
165 /* If you set _PAGE_EXEC on weird pages you're on your own */
166 pg = maybe_pte_to_page(pte);
167 if (unlikely(!pg))
168 goto bail;
169
170 /* If the page is already clean, we move on */
171 if (test_bit(PG_arch_1, &pg->flags))
172 goto bail;
173
174 /* Clean the page and set PG_arch_1 */
175 flush_dcache_icache_page(pg);
176 set_bit(PG_arch_1, &pg->flags);
177
178 bail:
179 return __pte(pte_val(pte) | _PAGE_EXEC);
180 }
181
182 #endif /* !(defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0) */
183
184 /*
185 * set_pte stores a linux PTE into the linux page table.
186 */
187 void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
188 pte_t pte)
189 {
190 /*
191 * When handling numa faults, we already have the pte marked
192 * _PAGE_PRESENT, but we can be sure that it is not in hpte.
193 * Hence we can use set_pte_at for them.
194 */
> 195 VM_WARN_ON((pte_raw(*ptep) & cpu_to_be64(_PAGE_PRESENT)) &&
196 !pte_protnone(*ptep));
197
198 /* Add the pte bit when trying to set a pte */
199 pte = __pte(pte_val(pte) | _PAGE_PTE);
200
201 /* Note: mm->context.id might not yet have been assigned as
202 * this context might not have been activated yet when this
203 * is called.
204 */
205 pte = set_pte_filter(pte);
206
207 /* Perform the setting of the PTE */
208 __set_pte_at(mm, addr, ptep, pte, 0);
209 }
210
---
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