src/Unix/vm_alloc.cpp

/*
 *  vm_alloc.cpp - Wrapper to various virtual memory allocation schemes
 *                 (supports mmap, vm_allocate or fallbacks to malloc)
 *
 *  Basilisk II (C) 1997-2005 Christian Bauer
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif

#ifdef HAVE_WIN32_VM
#define WIN32_LEAN_AND_MEAN /* avoid including junk */
#include <windows.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include "vm_alloc.h"

#ifdef HAVE_MACH_VM
#ifndef HAVE_MACH_TASK_SELF
#ifdef HAVE_TASK_SELF
#define mach_task_self task_self
#else
#error "No task_self(), you lose."
#endif
#endif
#endif

/* We want MAP_32BIT, if available, for SheepShaver and BasiliskII
   because the emulated target is 32-bit and this helps to allocate
   memory so that branches could be resolved more easily (32-bit
   displacement to code in .text), on AMD64 for example.  */
#ifndef MAP_32BIT
#define MAP_32BIT 0
#endif
#ifndef MAP_ANON
#define MAP_ANON 0
#endif
#ifndef MAP_ANONYMOUS
#define MAP_ANONYMOUS 0
#endif

#define MAP_EXTRA_FLAGS (MAP_32BIT)

#ifdef HAVE_MMAP_VM
#if defined(__linux__) && defined(__i386__)
/* Force a reasonnable address below 0x80000000 on x86 so that we
   don't get addresses above when the program is run on AMD64.
   NOTE: this is empirically determined on Linux/x86.  */
#define MAP_BASE        0x10000000
#else
#define MAP_BASE        0x00000000
#endif
static char * next_address = (char *)MAP_BASE;
#ifdef HAVE_MMAP_ANON
#define map_flags       (MAP_ANON | MAP_EXTRA_FLAGS)
#define zero_fd         -1
#else
#ifdef HAVE_MMAP_ANONYMOUS
#define map_flags       (MAP_ANONYMOUS | MAP_EXTRA_FLAGS)
#define zero_fd         -1
#else
#define map_flags       (MAP_EXTRA_FLAGS)
static int zero_fd      = -1;
#endif
#endif
#endif

/* Utility functions for POSIX SHM handling.  */

#ifdef USE_33BIT_ADDRESSING
struct shm_range_t {
        const char *file;
        void *base;
        unsigned int size;
        shm_range_t *next;
};

static shm_range_t *shm_ranges = NULL;

static bool add_shm_range(const char *file, void *base, unsigned int size)
{
        shm_range_t *r = (shm_range_t *)malloc(sizeof(shm_range_t));
        if (r) {
                r->file = file;
                r->base = base;
                r->size = size;
                r->next = shm_ranges ? shm_ranges : NULL;
                shm_ranges = r;
                return true;
        }
        return false;
}

static shm_range_t *find_shm_range(void *base, unsigned int size)
{
        for (shm_range_t *r = shm_ranges; r != NULL; r = r->next)
                if (r->base == base && r->size == size)
                        return r;
        return NULL;
}

static bool remove_shm_range(shm_range_t *r)
{
        if (r) {
                for (shm_range_t *p = shm_ranges; p != NULL; p = p->next) {
                        if (p->next == r) {
                                p->next = r->next;
                                free(r);
                                return true;
                        }
                }
        }
        return false;
}

static bool remove_shm_range(void *base, unsigned int size)
{
        remove_shm_range(find_shm_range(base, size));
}
#endif

/* Build a POSIX SHM memory segment file descriptor name.  */

#ifdef USE_33BIT_ADDRESSING
static const char *build_shm_filename(void)
{
        static int id = 0;
        static char filename[PATH_MAX];
        
        int ret = snprintf(filename, sizeof(filename), "/BasiliskII-%d-shm-%d", getpid(), id);
        if (ret == -1 || ret >= sizeof(filename))
                return NULL;

        id++;
        return filename;
}
#endif

/* Translate generic VM map flags to host values.  */

#ifdef HAVE_MMAP_VM
static int translate_map_flags(int vm_flags)
{
        int flags = 0;
        if (vm_flags & VM_MAP_SHARED)
                flags |= MAP_SHARED;
        if (vm_flags & VM_MAP_PRIVATE)
                flags |= MAP_PRIVATE;
        if (vm_flags & VM_MAP_FIXED)
                flags |= MAP_FIXED;
        if (vm_flags & VM_MAP_32BIT)
                flags |= MAP_32BIT;
        return flags;
}
#endif

/* Align ADDR and SIZE to 64K boundaries.  */

#ifdef HAVE_WIN32_VM
static inline LPVOID align_addr_segment(LPVOID addr)
{
        return (LPVOID)(((DWORD)addr) & -65536);
}

static inline DWORD align_size_segment(LPVOID addr, DWORD size)
{
        return size + ((DWORD)addr - (DWORD)align_addr_segment(addr));
}
#endif

/* Translate generic VM prot flags to host values.  */

#ifdef HAVE_WIN32_VM
static int translate_prot_flags(int prot_flags)
{
        int prot = PAGE_READWRITE;
        if (prot_flags == (VM_PAGE_EXECUTE | VM_PAGE_READ | VM_PAGE_WRITE))
                prot = PAGE_EXECUTE_READWRITE;
        else if (prot_flags == (VM_PAGE_EXECUTE | VM_PAGE_READ))
                prot = PAGE_EXECUTE_READ;
        else if (prot_flags == (VM_PAGE_READ | VM_PAGE_WRITE))
                prot = PAGE_READWRITE;
        else if (prot_flags == VM_PAGE_READ)
                prot = PAGE_READONLY;
        else if (prot_flags == 0)
                prot = PAGE_NOACCESS;
        return prot;
}
#endif

/* Initialize the VM system. Returns 0 if successful, -1 for errors.  */

int vm_init(void)
{
#ifdef HAVE_MMAP_VM
#ifndef zero_fd
        zero_fd = open("/dev/zero", O_RDWR);
        if (zero_fd < 0)
                return -1;
#endif
#endif
        return 0;
}

/* Deallocate all internal data used to wrap virtual memory allocators.  */

void vm_exit(void)
{
#ifdef HAVE_MMAP_VM
#ifndef zero_fd
        close(zero_fd);
#endif
#endif
}

/* Allocate zero-filled memory of SIZE bytes. The mapping is private
   and default protection bits are read / write. The return value
   is the actual mapping address chosen or VM_MAP_FAILED for errors.  */

void * vm_acquire(size_t size, int options)
{
        void * addr;

        // VM_MAP_FIXED are to be used with vm_acquire_fixed() only
        if (options & VM_MAP_FIXED)
                return VM_MAP_FAILED;

#ifdef HAVE_MACH_VM
        // vm_allocate() returns a zero-filled memory region
        if (vm_allocate(mach_task_self(), (vm_address_t *)&addr, size, TRUE) != KERN_SUCCESS)
                return VM_MAP_FAILED;
#else
#ifdef HAVE_MMAP_VM
        int fd = zero_fd;
        int the_map_flags = translate_map_flags(options) | map_flags;

#ifdef USE_33BIT_ADDRESSING
        const char *shm_file = NULL;
        if (sizeof(void *) == 8 && (options & VM_MAP_33BIT)) {
                the_map_flags &= ~(MAP_PRIVATE | MAP_ANON | MAP_ANONYMOUS);
                the_map_flags |= MAP_SHARED;

                if ((shm_file = build_shm_filename()) == NULL)
                        return VM_MAP_FAILED;

                if ((fd = shm_open(shm_file, O_RDWR | O_CREAT | O_EXCL, 0644)) < 0)
                        return VM_MAP_FAILED;

                if (ftruncate(fd, size) < 0)
                        return VM_MAP_FAILED;

                the_map_flags |= MAP_SHARED;
        }
#endif

        if ((addr = mmap((caddr_t)next_address, size, VM_PAGE_DEFAULT, the_map_flags, fd, 0)) == (void *)MAP_FAILED)
                return VM_MAP_FAILED;
        
        // Sanity checks for 64-bit platforms
        if (sizeof(void *) == 8 && (options & VM_MAP_32BIT) && !((char *)addr <= (char *)0xffffffff))
                return VM_MAP_FAILED;

        next_address = (char *)addr + size;
        
        // Since I don't know the standard behavior of mmap(), zero-fill here
        if (memset(addr, 0, size) != addr)
                return VM_MAP_FAILED;

        // Remap to 33-bit space
#ifdef USE_33BIT_ADDRESSING
        if (sizeof(void *) == 8 && (options & VM_MAP_33BIT)) {
                if (!add_shm_range(strdup(shm_file), addr, size))
                        return VM_MAP_FAILED;

                if (mmap((char *)addr + (1L << 32), size, VM_PAGE_DEFAULT, the_map_flags | MAP_FIXED, fd, 0) == (void *)MAP_FAILED)
                        return VM_MAP_FAILED;
                close(fd);
        }
#endif
#else
#ifdef HAVE_WIN32_VM
        if ((addr = VirtualAlloc(NULL, size, MEM_RESERVE | MEM_COMMIT, PAGE_EXECUTE_READWRITE)) == NULL)
                return VM_MAP_FAILED;

        // Zero newly allocated memory
        if (memset(addr, 0, size) != addr)
                return VM_MAP_FAILED;
#else
        if ((addr = calloc(size, 1)) == 0)
                return VM_MAP_FAILED;
        
        // Omit changes for protections because they are not supported in this mode
        return addr;
#endif
#endif
#endif

        // Explicitely protect the newly mapped region here because on some systems,
        // say MacOS X, mmap() doesn't honour the requested protection flags.
        if (vm_protect(addr, size, VM_PAGE_DEFAULT) != 0)
                return VM_MAP_FAILED;
        
        return addr;
}

/* Allocate zero-filled memory at exactly ADDR (which must be page-aligned).
   Retuns 0 if successful, -1 on errors.  */

int vm_acquire_fixed(void * addr, size_t size, int options)
{
        // Fixed mappings are required to be private
        if (options & VM_MAP_SHARED)
                return -1;

#ifdef HAVE_MACH_VM
        // vm_allocate() returns a zero-filled memory region
        if (vm_allocate(mach_task_self(), (vm_address_t *)&addr, size, 0) != KERN_SUCCESS)
                return -1;
#else
#ifdef HAVE_MMAP_VM
        const int extra_map_flags = translate_map_flags(options);

        if (mmap((caddr_t)addr, size, VM_PAGE_DEFAULT, extra_map_flags | map_flags | MAP_FIXED, zero_fd, 0) == (void *)MAP_FAILED)
                return -1;
        
        // Since I don't know the standard behavior of mmap(), zero-fill here
        if (memset(addr, 0, size) != addr)
                return -1;
#else
#ifdef HAVE_WIN32_VM
        // Windows cannot allocate Low Memory
        if (addr == NULL)
                return -1;

        // Allocate a possibly offset region to align on 64K boundaries
        LPVOID req_addr = align_addr_segment(addr);
        DWORD  req_size = align_size_segment(addr, size);
        LPVOID ret_addr = VirtualAlloc(req_addr, req_size, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);
        if (ret_addr != req_addr)
                return -1;

        // Zero newly allocated memory
        if (memset(addr, 0, size) != addr)
                return -1;
#else
        // Unsupported
        return -1;
#endif
#endif
#endif
        
        // Explicitely protect the newly mapped region here because on some systems,
        // say MacOS X, mmap() doesn't honour the requested protection flags.
        if (vm_protect(addr, size, VM_PAGE_DEFAULT) != 0)
                return -1;
        
        return 0;
}

/* Deallocate any mapping for the region starting at ADDR and extending
   LEN bytes. Returns 0 if successful, -1 on errors.  */

int vm_release(void * addr, size_t size)
{
        // Safety check: don't try to release memory that was not allocated
        if (addr == VM_MAP_FAILED)
                return 0;

#ifdef HAVE_MACH_VM
        if (vm_deallocate(mach_task_self(), (vm_address_t)addr, size) != KERN_SUCCESS)
                return -1;
#else
#ifdef HAVE_MMAP_VM
        if (munmap((caddr_t)addr, size) != 0)
                return -1;

#ifdef USE_33BIT_ADDRESSING
        shm_range_t *r = find_shm_range(addr, size);
        if (r) {
                if (munmap((char *)r->base + (1L << 32), size) != 0)
                        return -1;

                if (shm_unlink(r->file) < 0)
                        return -1;
                free((char *)r->file);

                if (!remove_shm_range(r))
                        return -1;
        }
#endif
#else
#ifdef HAVE_WIN32_VM
        if (VirtualFree(align_addr_segment(addr), 0, MEM_RELEASE) == 0)
                return -1;
#else
        free(addr);
#endif
#endif
#endif
        
        return 0;
}

/* Change the memory protection of the region starting at ADDR and
   extending LEN bytes to PROT. Returns 0 if successful, -1 for errors.  */

int vm_protect(void * addr, size_t size, int prot)
{
#ifdef HAVE_MACH_VM
        int ret_code = vm_protect(mach_task_self(), (vm_address_t)addr, size, 0, prot);
        return ret_code == KERN_SUCCESS ? 0 : -1;
#else
#ifdef HAVE_MMAP_VM
        int ret_code = mprotect((caddr_t)addr, size, prot);
        return ret_code == 0 ? 0 : -1;
#else
#ifdef HAVE_WIN32_VM
        DWORD old_prot;
        int ret_code = VirtualProtect(addr, size, translate_prot_flags(prot), &old_prot);
        return ret_code != 0 ? 0 : -1;
#else
        // Unsupported
        return -1;
#endif
#endif
#endif
}

/* Returns the size of a page.  */

int vm_get_page_size(void)
{
#ifdef _WIN32
    return 4096;
#else
    return getpagesize();
#endif
}

#ifdef CONFIGURE_TEST_VM_MAP
/* Tests covered here:
   - TEST_VM_PROT_* program slices actually succeeds when a crash occurs
   - TEST_VM_MAP_ANON* program slices succeeds when it could be compiled
*/
int main(void)
{
        vm_init();
        
#define page_align(address) ((char *)((unsigned long)(address) & -page_size))
        unsigned long page_size = vm_get_page_size();
        
        const int area_size = 6 * page_size;
        volatile char * area = (volatile char *) vm_acquire(area_size);
        volatile char * fault_address = area + (page_size * 7) / 2;

#if defined(TEST_VM_MMAP_ANON) || defined(TEST_VM_MMAP_ANONYMOUS)
        if (area == VM_MAP_FAILED)
                return 1;

        if (vm_release((char *)area, area_size) < 0)
                return 1;
        
        return 0;
#endif

#if defined(TEST_VM_PROT_NONE_READ) || defined(TEST_VM_PROT_NONE_WRITE)
        if (area == VM_MAP_FAILED)
                return 0;
        
        if (vm_protect(page_align(fault_address), page_size, VM_PAGE_NOACCESS) < 0)
                return 0;
#endif

#if defined(TEST_VM_PROT_RDWR_WRITE)
        if (area == VM_MAP_FAILED)
                return 1;
        
        if (vm_protect(page_align(fault_address), page_size, VM_PAGE_READ) < 0)
                return 1;
        
        if (vm_protect(page_align(fault_address), page_size, VM_PAGE_READ | VM_PAGE_WRITE) < 0)
                return 1;
#endif

#if defined(TEST_VM_PROT_READ_WRITE)
        if (vm_protect(page_align(fault_address), page_size, VM_PAGE_READ) < 0)
                return 0;
#endif

#if defined(TEST_VM_PROT_NONE_READ)
        // this should cause a core dump
        char foo = *fault_address;
        return 0;
#endif

#if defined(TEST_VM_PROT_NONE_WRITE) || defined(TEST_VM_PROT_READ_WRITE)
        // this should cause a core dump
        *fault_address = 'z';
        return 0;
#endif

#if defined(TEST_VM_PROT_RDWR_WRITE)
        // this should not cause a core dump
        *fault_address = 'z';
        return 0;
#endif
}
#endif
Revision:	1.17
Committed:	2005-01-30T21:42:14Z (19 years, 9 months ago) by gbeauche
Branch:	MAIN
Changes since 1.16:	+1 -1 lines
Log Message:	Happy New Year!
#	Content
1	/*
2	* vm_alloc.cpp - Wrapper to various virtual memory allocation schemes
3	* (supports mmap, vm_allocate or fallbacks to malloc)
4	*
5	* Basilisk II (C) 1997-2005 Christian Bauer
6	*
7	* This program is free software; you can redistribute it and/or modify
8	* it under the terms of the GNU General Public License as published by
9	* the Free Software Foundation; either version 2 of the License, or
10	* (at your option) any later version.
11	*
12	* This program is distributed in the hope that it will be useful,
13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15	* GNU General Public License for more details.
16	*
17	* You should have received a copy of the GNU General Public License
18	* along with this program; if not, write to the Free Software
19	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20	*/
21
22	#ifdef HAVE_CONFIG_H
23	#include "config.h"
24	#endif
25
26	#ifdef HAVE_FCNTL_H
27	#include <fcntl.h>
28	#endif
29
30	#ifdef HAVE_WIN32_VM
31	#define WIN32_LEAN_AND_MEAN /* avoid including junk */
32	#include <windows.h>
33	#endif
34
35	#include <stdio.h>
36	#include <stdlib.h>
37	#include <string.h>
38	#include <limits.h>
39	#include "vm_alloc.h"
40
41	#ifdef HAVE_MACH_VM
42	#ifndef HAVE_MACH_TASK_SELF
43	#ifdef HAVE_TASK_SELF
44	#define mach_task_self task_self
45	#else
46	#error "No task_self(), you lose."
47	#endif
48	#endif
49	#endif
50
51	/* We want MAP_32BIT, if available, for SheepShaver and BasiliskII
52	because the emulated target is 32-bit and this helps to allocate
53	memory so that branches could be resolved more easily (32-bit
54	displacement to code in .text), on AMD64 for example. */
55	#ifndef MAP_32BIT
56	#define MAP_32BIT 0
57	#endif
58	#ifndef MAP_ANON
59	#define MAP_ANON 0
60	#endif
61	#ifndef MAP_ANONYMOUS
62	#define MAP_ANONYMOUS 0
63	#endif
64
65	#define MAP_EXTRA_FLAGS (MAP_32BIT)
66
67	#ifdef HAVE_MMAP_VM
68	#if defined(__linux__) && defined(__i386__)
69	/* Force a reasonnable address below 0x80000000 on x86 so that we
70	don't get addresses above when the program is run on AMD64.
71	NOTE: this is empirically determined on Linux/x86. */
72	#define MAP_BASE 0x10000000
73	#else
74	#define MAP_BASE 0x00000000
75	#endif
76	static char * next_address = (char *)MAP_BASE;
77	#ifdef HAVE_MMAP_ANON
78	#define map_flags (MAP_ANON \| MAP_EXTRA_FLAGS)
79	#define zero_fd -1
80	#else
81	#ifdef HAVE_MMAP_ANONYMOUS
82	#define map_flags (MAP_ANONYMOUS \| MAP_EXTRA_FLAGS)
83	#define zero_fd -1
84	#else
85	#define map_flags (MAP_EXTRA_FLAGS)
86	static int zero_fd = -1;
87	#endif
88	#endif
89	#endif
90
91	/* Utility functions for POSIX SHM handling. */
92
93	#ifdef USE_33BIT_ADDRESSING
94	struct shm_range_t {
95	const char *file;
96	void *base;
97	unsigned int size;
98	shm_range_t *next;
99	};
100
101	static shm_range_t *shm_ranges = NULL;
102
103	static bool add_shm_range(const char file, void base, unsigned int size)
104	{
105	shm_range_t r = (shm_range_t )malloc(sizeof(shm_range_t));
106	if (r) {
107	r->file = file;
108	r->base = base;
109	r->size = size;
110	r->next = shm_ranges ? shm_ranges : NULL;
111	shm_ranges = r;
112	return true;
113	}
114	return false;
115	}
116
117	static shm_range_t find_shm_range(void base, unsigned int size)
118	{
119	for (shm_range_t *r = shm_ranges; r != NULL; r = r->next)
120	if (r->base == base && r->size == size)
121	return r;
122	return NULL;
123	}
124
125	static bool remove_shm_range(shm_range_t *r)
126	{
127	if (r) {
128	for (shm_range_t *p = shm_ranges; p != NULL; p = p->next) {
129	if (p->next == r) {
130	p->next = r->next;
131	free(r);
132	return true;
133	}
134	}
135	}
136	return false;
137	}
138
139	static bool remove_shm_range(void *base, unsigned int size)
140	{
141	remove_shm_range(find_shm_range(base, size));
142	}
143	#endif
144
145	/* Build a POSIX SHM memory segment file descriptor name. */
146
147	#ifdef USE_33BIT_ADDRESSING
148	static const char *build_shm_filename(void)
149	{
150	static int id = 0;
151	static char filename[PATH_MAX];
152
153	int ret = snprintf(filename, sizeof(filename), "/BasiliskII-%d-shm-%d", getpid(), id);
154	if (ret == -1 \|\| ret >= sizeof(filename))
155	return NULL;
156
157	id++;
158	return filename;
159	}
160	#endif
161
162	/* Translate generic VM map flags to host values. */
163
164	#ifdef HAVE_MMAP_VM
165	static int translate_map_flags(int vm_flags)
166	{
167	int flags = 0;
168	if (vm_flags & VM_MAP_SHARED)
169	flags \|= MAP_SHARED;
170	if (vm_flags & VM_MAP_PRIVATE)
171	flags \|= MAP_PRIVATE;
172	if (vm_flags & VM_MAP_FIXED)
173	flags \|= MAP_FIXED;
174	if (vm_flags & VM_MAP_32BIT)
175	flags \|= MAP_32BIT;
176	return flags;
177	}
178	#endif
179
180	/* Align ADDR and SIZE to 64K boundaries. */
181
182	#ifdef HAVE_WIN32_VM
183	static inline LPVOID align_addr_segment(LPVOID addr)
184	{
185	return (LPVOID)(((DWORD)addr) & -65536);
186	}
187
188	static inline DWORD align_size_segment(LPVOID addr, DWORD size)
189	{
190	return size + ((DWORD)addr - (DWORD)align_addr_segment(addr));
191	}
192	#endif
193
194	/* Translate generic VM prot flags to host values. */
195
196	#ifdef HAVE_WIN32_VM
197	static int translate_prot_flags(int prot_flags)
198	{
199	int prot = PAGE_READWRITE;
200	if (prot_flags == (VM_PAGE_EXECUTE \| VM_PAGE_READ \| VM_PAGE_WRITE))
201	prot = PAGE_EXECUTE_READWRITE;
202	else if (prot_flags == (VM_PAGE_EXECUTE \| VM_PAGE_READ))
203	prot = PAGE_EXECUTE_READ;
204	else if (prot_flags == (VM_PAGE_READ \| VM_PAGE_WRITE))
205	prot = PAGE_READWRITE;
206	else if (prot_flags == VM_PAGE_READ)
207	prot = PAGE_READONLY;
208	else if (prot_flags == 0)
209	prot = PAGE_NOACCESS;
210	return prot;
211	}
212	#endif
213
214	/* Initialize the VM system. Returns 0 if successful, -1 for errors. */
215
216	int vm_init(void)
217	{
218	#ifdef HAVE_MMAP_VM
219	#ifndef zero_fd
220	zero_fd = open("/dev/zero", O_RDWR);
221	if (zero_fd < 0)
222	return -1;
223	#endif
224	#endif
225	return 0;
226	}
227
228	/* Deallocate all internal data used to wrap virtual memory allocators. */
229
230	void vm_exit(void)
231	{
232	#ifdef HAVE_MMAP_VM
233	#ifndef zero_fd
234	close(zero_fd);
235	#endif
236	#endif
237	}
238
239	/* Allocate zero-filled memory of SIZE bytes. The mapping is private
240	and default protection bits are read / write. The return value
241	is the actual mapping address chosen or VM_MAP_FAILED for errors. */
242
243	void * vm_acquire(size_t size, int options)
244	{
245	void * addr;
246
247	// VM_MAP_FIXED are to be used with vm_acquire_fixed() only
248	if (options & VM_MAP_FIXED)
249	return VM_MAP_FAILED;
250
251	#ifdef HAVE_MACH_VM
252	// vm_allocate() returns a zero-filled memory region
253	if (vm_allocate(mach_task_self(), (vm_address_t *)&addr, size, TRUE) != KERN_SUCCESS)
254	return VM_MAP_FAILED;
255	#else
256	#ifdef HAVE_MMAP_VM
257	int fd = zero_fd;
258	int the_map_flags = translate_map_flags(options) \| map_flags;
259
260	#ifdef USE_33BIT_ADDRESSING
261	const char *shm_file = NULL;
262	if (sizeof(void *) == 8 && (options & VM_MAP_33BIT)) {
263	the_map_flags &= ~(MAP_PRIVATE \| MAP_ANON \| MAP_ANONYMOUS);
264	the_map_flags \|= MAP_SHARED;
265
266	if ((shm_file = build_shm_filename()) == NULL)
267	return VM_MAP_FAILED;
268
269	if ((fd = shm_open(shm_file, O_RDWR \| O_CREAT \| O_EXCL, 0644)) < 0)
270	return VM_MAP_FAILED;
271
272	if (ftruncate(fd, size) < 0)
273	return VM_MAP_FAILED;
274
275	the_map_flags \|= MAP_SHARED;
276	}
277	#endif
278
279	if ((addr = mmap((caddr_t)next_address, size, VM_PAGE_DEFAULT, the_map_flags, fd, 0)) == (void *)MAP_FAILED)
280	return VM_MAP_FAILED;
281
282	// Sanity checks for 64-bit platforms
283	if (sizeof(void ) == 8 && (options & VM_MAP_32BIT) && !((char )addr <= (char *)0xffffffff))
284	return VM_MAP_FAILED;
285
286	next_address = (char *)addr + size;
287
288	// Since I don't know the standard behavior of mmap(), zero-fill here
289	if (memset(addr, 0, size) != addr)
290	return VM_MAP_FAILED;
291
292	// Remap to 33-bit space
293	#ifdef USE_33BIT_ADDRESSING
294	if (sizeof(void *) == 8 && (options & VM_MAP_33BIT)) {
295	if (!add_shm_range(strdup(shm_file), addr, size))
296	return VM_MAP_FAILED;
297
298	if (mmap((char )addr + (1L << 32), size, VM_PAGE_DEFAULT, the_map_flags \| MAP_FIXED, fd, 0) == (void )MAP_FAILED)
299	return VM_MAP_FAILED;
300	close(fd);
301	}
302	#endif
303	#else
304	#ifdef HAVE_WIN32_VM
305	if ((addr = VirtualAlloc(NULL, size, MEM_RESERVE \| MEM_COMMIT, PAGE_EXECUTE_READWRITE)) == NULL)
306	return VM_MAP_FAILED;
307
308	// Zero newly allocated memory
309	if (memset(addr, 0, size) != addr)
310	return VM_MAP_FAILED;
311	#else
312	if ((addr = calloc(size, 1)) == 0)
313	return VM_MAP_FAILED;
314
315	// Omit changes for protections because they are not supported in this mode
316	return addr;
317	#endif
318	#endif
319	#endif
320
321	// Explicitely protect the newly mapped region here because on some systems,
322	// say MacOS X, mmap() doesn't honour the requested protection flags.
323	if (vm_protect(addr, size, VM_PAGE_DEFAULT) != 0)
324	return VM_MAP_FAILED;
325
326	return addr;
327	}
328
329	/* Allocate zero-filled memory at exactly ADDR (which must be page-aligned).
330	Retuns 0 if successful, -1 on errors. */
331
332	int vm_acquire_fixed(void * addr, size_t size, int options)
333	{
334	// Fixed mappings are required to be private
335	if (options & VM_MAP_SHARED)
336	return -1;
337
338	#ifdef HAVE_MACH_VM
339	// vm_allocate() returns a zero-filled memory region
340	if (vm_allocate(mach_task_self(), (vm_address_t *)&addr, size, 0) != KERN_SUCCESS)
341	return -1;
342	#else
343	#ifdef HAVE_MMAP_VM
344	const int extra_map_flags = translate_map_flags(options);
345
346	if (mmap((caddr_t)addr, size, VM_PAGE_DEFAULT, extra_map_flags \| map_flags \| MAP_FIXED, zero_fd, 0) == (void *)MAP_FAILED)
347	return -1;
348
349	// Since I don't know the standard behavior of mmap(), zero-fill here
350	if (memset(addr, 0, size) != addr)
351	return -1;
352	#else
353	#ifdef HAVE_WIN32_VM
354	// Windows cannot allocate Low Memory
355	if (addr == NULL)
356	return -1;
357
358	// Allocate a possibly offset region to align on 64K boundaries
359	LPVOID req_addr = align_addr_segment(addr);
360	DWORD req_size = align_size_segment(addr, size);
361	LPVOID ret_addr = VirtualAlloc(req_addr, req_size, MEM_COMMIT \| MEM_RESERVE, PAGE_EXECUTE_READWRITE);
362	if (ret_addr != req_addr)
363	return -1;
364
365	// Zero newly allocated memory
366	if (memset(addr, 0, size) != addr)
367	return -1;
368	#else
369	// Unsupported
370	return -1;
371	#endif
372	#endif
373	#endif
374
375	// Explicitely protect the newly mapped region here because on some systems,
376	// say MacOS X, mmap() doesn't honour the requested protection flags.
377	if (vm_protect(addr, size, VM_PAGE_DEFAULT) != 0)
378	return -1;
379
380	return 0;
381	}
382
383	/* Deallocate any mapping for the region starting at ADDR and extending
384	LEN bytes. Returns 0 if successful, -1 on errors. */
385
386	int vm_release(void * addr, size_t size)
387	{
388	// Safety check: don't try to release memory that was not allocated
389	if (addr == VM_MAP_FAILED)
390	return 0;
391
392	#ifdef HAVE_MACH_VM
393	if (vm_deallocate(mach_task_self(), (vm_address_t)addr, size) != KERN_SUCCESS)
394	return -1;
395	#else
396	#ifdef HAVE_MMAP_VM
397	if (munmap((caddr_t)addr, size) != 0)
398	return -1;
399
400	#ifdef USE_33BIT_ADDRESSING
401	shm_range_t *r = find_shm_range(addr, size);
402	if (r) {
403	if (munmap((char *)r->base + (1L << 32), size) != 0)
404	return -1;
405
406	if (shm_unlink(r->file) < 0)
407	return -1;
408	free((char *)r->file);
409
410	if (!remove_shm_range(r))
411	return -1;
412	}
413	#endif
414	#else
415	#ifdef HAVE_WIN32_VM
416	if (VirtualFree(align_addr_segment(addr), 0, MEM_RELEASE) == 0)
417	return -1;
418	#else
419	free(addr);
420	#endif
421	#endif
422	#endif
423
424	return 0;
425	}
426
427	/* Change the memory protection of the region starting at ADDR and
428	extending LEN bytes to PROT. Returns 0 if successful, -1 for errors. */
429
430	int vm_protect(void * addr, size_t size, int prot)
431	{
432	#ifdef HAVE_MACH_VM
433	int ret_code = vm_protect(mach_task_self(), (vm_address_t)addr, size, 0, prot);
434	return ret_code == KERN_SUCCESS ? 0 : -1;
435	#else
436	#ifdef HAVE_MMAP_VM
437	int ret_code = mprotect((caddr_t)addr, size, prot);
438	return ret_code == 0 ? 0 : -1;
439	#else
440	#ifdef HAVE_WIN32_VM
441	DWORD old_prot;
442	int ret_code = VirtualProtect(addr, size, translate_prot_flags(prot), &old_prot);
443	return ret_code != 0 ? 0 : -1;
444	#else
445	// Unsupported
446	return -1;
447	#endif
448	#endif
449	#endif
450	}
451
452	/* Returns the size of a page. */
453
454	int vm_get_page_size(void)
455	{
456	#ifdef _WIN32
457	return 4096;
458	#else
459	return getpagesize();
460	#endif
461	}
462
463	#ifdef CONFIGURE_TEST_VM_MAP
464	/* Tests covered here:
465	- TEST_VM_PROT_* program slices actually succeeds when a crash occurs
466	- TEST_VM_MAP_ANON* program slices succeeds when it could be compiled
467	*/
468	int main(void)
469	{
470	vm_init();
471
472	#define page_align(address) ((char *)((unsigned long)(address) & -page_size))
473	unsigned long page_size = vm_get_page_size();
474
475	const int area_size = 6 * page_size;
476	volatile char * area = (volatile char *) vm_acquire(area_size);
477	volatile char * fault_address = area + (page_size * 7) / 2;
478
479	#if defined(TEST_VM_MMAP_ANON) \|\| defined(TEST_VM_MMAP_ANONYMOUS)
480	if (area == VM_MAP_FAILED)
481	return 1;
482
483	if (vm_release((char *)area, area_size) < 0)
484	return 1;
485
486	return 0;
487	#endif
488
489	#if defined(TEST_VM_PROT_NONE_READ) \|\| defined(TEST_VM_PROT_NONE_WRITE)
490	if (area == VM_MAP_FAILED)
491	return 0;
492
493	if (vm_protect(page_align(fault_address), page_size, VM_PAGE_NOACCESS) < 0)
494	return 0;
495	#endif
496
497	#if defined(TEST_VM_PROT_RDWR_WRITE)
498	if (area == VM_MAP_FAILED)
499	return 1;
500
501	if (vm_protect(page_align(fault_address), page_size, VM_PAGE_READ) < 0)
502	return 1;
503
504	if (vm_protect(page_align(fault_address), page_size, VM_PAGE_READ \| VM_PAGE_WRITE) < 0)
505	return 1;
506	#endif
507
508	#if defined(TEST_VM_PROT_READ_WRITE)
509	if (vm_protect(page_align(fault_address), page_size, VM_PAGE_READ) < 0)
510	return 0;
511	#endif
512
513	#if defined(TEST_VM_PROT_NONE_READ)
514	// this should cause a core dump
515	char foo = *fault_address;
516	return 0;
517	#endif
518
519	#if defined(TEST_VM_PROT_NONE_WRITE) \|\| defined(TEST_VM_PROT_READ_WRITE)
520	// this should cause a core dump
521	*fault_address = 'z';
522	return 0;
523	#endif
524
525	#if defined(TEST_VM_PROT_RDWR_WRITE)
526	// this should not cause a core dump
527	*fault_address = 'z';
528	return 0;
529	#endif
530	}
531	#endif