1#define JEMALLOC_PAGES_C_
2#include "jemalloc/internal/jemalloc_internal.h"
3
4/******************************************************************************/
5
6void *
7pages_map(void *addr, size_t size)
8{
9 void *ret;
10
11 assert(size != 0);
12
13#ifdef _WIN32
14 /*
15 * If VirtualAlloc can't allocate at the given address when one is
16 * given, it fails and returns NULL.
17 */
18 ret = VirtualAlloc(addr, size, MEM_COMMIT | MEM_RESERVE,
19 PAGE_READWRITE);
20#else
21 /*
22 * We don't use MAP_FIXED here, because it can cause the *replacement*
23 * of existing mappings, and we only want to create new mappings.
24 */
25 ret = mmap(addr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON,
26 -1, 0);
27 assert(ret != NULL);
28
29 if (ret == MAP_FAILED)
30 ret = NULL;
31 else if (addr != NULL && ret != addr) {
32 /*
33 * We succeeded in mapping memory, but not in the right place.
34 */
35 pages_unmap(ret, size);
36 ret = NULL;
37 }
38#endif
39 assert(ret == NULL || (addr == NULL && ret != addr)
40 || (addr != NULL && ret == addr));
41 return (ret);
42}
43
44void
45pages_unmap(void *addr, size_t size)
46{
47
48#ifdef _WIN32
49 if (VirtualFree(addr, 0, MEM_RELEASE) == 0)
50#else
51 if (munmap(addr, size) == -1)
52#endif
53 {
54 char buf[BUFERROR_BUF];
55
56 buferror(get_errno(), buf, sizeof(buf));
57 malloc_printf("<jemalloc>: Error in "
58#ifdef _WIN32
59 "VirtualFree"
60#else
61 "munmap"
62#endif
63 "(): %s\n", buf);
64 if (opt_abort)
65 abort();
66 }
67}
68
69void *
70pages_trim(void *addr, size_t alloc_size, size_t leadsize, size_t size)
71{
72 void *ret = (void *)((uintptr_t)addr + leadsize);
73
74 assert(alloc_size >= leadsize + size);
75#ifdef _WIN32
76 {
77 void *new_addr;
78
79 pages_unmap(addr, alloc_size);
80 new_addr = pages_map(ret, size);
81 if (new_addr == ret)
82 return (ret);
83 if (new_addr)
84 pages_unmap(new_addr, size);
85 return (NULL);
86 }
87#else
88 {
89 size_t trailsize = alloc_size - leadsize - size;
90
91 if (leadsize != 0)
92 pages_unmap(addr, leadsize);
93 if (trailsize != 0)
94 pages_unmap((void *)((uintptr_t)ret + size), trailsize);
95 return (ret);
96 }
97#endif
98}
99
100static bool
101pages_commit_impl(void *addr, size_t size, bool commit)
102{
103
104#ifndef _WIN32
105 /*
106 * The following decommit/commit implementation is functional, but
107 * always disabled because it doesn't add value beyong improved
108 * debugging (at the cost of extra system calls) on systems that
109 * overcommit.
110 */
111 if (false) {
112 int prot = commit ? (PROT_READ | PROT_WRITE) : PROT_NONE;
113 void *result = mmap(addr, size, prot, MAP_PRIVATE | MAP_ANON |
114 MAP_FIXED, -1, 0);
115 if (result == MAP_FAILED)
116 return (true);
117 if (result != addr) {
118 /*
119 * We succeeded in mapping memory, but not in the right
120 * place.
121 */
122 pages_unmap(result, size);
123 return (true);
124 }
125 return (false);
126 }
127#endif
128 return (true);
129}
130
131bool
132pages_commit(void *addr, size_t size)
133{
134
135 return (pages_commit_impl(addr, size, true));
136}
137
138bool
139pages_decommit(void *addr, size_t size)
140{
141
142 return (pages_commit_impl(addr, size, false));
143}
144
145bool
146pages_purge(void *addr, size_t size)
147{
148 bool unzeroed;
149
150#ifdef _WIN32
151 VirtualAlloc(addr, size, MEM_RESET, PAGE_READWRITE);
152 unzeroed = true;
153#elif defined(JEMALLOC_HAVE_MADVISE)
154# ifdef JEMALLOC_PURGE_MADVISE_DONTNEED
155# define JEMALLOC_MADV_PURGE MADV_DONTNEED
156# define JEMALLOC_MADV_ZEROS true
157# elif defined(JEMALLOC_PURGE_MADVISE_FREE)
158# define JEMALLOC_MADV_PURGE MADV_FREE
159# define JEMALLOC_MADV_ZEROS false
160# else
161# error "No madvise(2) flag defined for purging unused dirty pages."
162# endif
163 int err = madvise(addr, size, JEMALLOC_MADV_PURGE);
164 unzeroed = (!JEMALLOC_MADV_ZEROS || err != 0);
165# undef JEMALLOC_MADV_PURGE
166# undef JEMALLOC_MADV_ZEROS
167#else
168 /* Last resort no-op. */
169 unzeroed = true;
170#endif
171 return (unzeroed);
172}
173