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__)) || HAVE_LINKER_SCRIPT
/* 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
        if (zero_fd != -1) {
                close(zero_fd);
                zero_fd = -1;
        }
#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;
        }
#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;

        // 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;
#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
        int fd = zero_fd;
        int the_map_flags = translate_map_flags(options) | map_flags | MAP_FIXED;

#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 -1;

                if ((fd = shm_open(shm_file, O_RDWR | O_CREAT | O_EXCL, 0644)) < 0)
                        return -1;

                if (ftruncate(fd, size) < 0)
                        return -1;
        }
#endif

        if (mmap((caddr_t)addr, size, VM_PAGE_DEFAULT, the_map_flags, fd, 0) == (void *)MAP_FAILED)
                return -1;

        // 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 -1;

                if (mmap((char *)addr + (1L << 32), size, VM_PAGE_DEFAULT, the_map_flags, fd, 0) == (void *)MAP_FAILED)
                        return -1;
                close(fd);
        }
#endif
#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;
                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 HAVE_WIN32_VM
        static unsigned long page_size = 0;
        if (page_size == 0) {
                SYSTEM_INFO si;
                GetSystemInfo(&si);
                page_size = si.dwAllocationGranularity;
        }
        return page_size;
#else
        return getpagesize();
#endif
}

#ifdef CONFIGURE_TEST_VM_MAP
#include <stdlib.h>
#include <signal.h>

static void fault_handler(int sig)
{
        exit(1);
}

/* 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();

        signal(SIGSEGV, fault_handler);
#ifdef SIGBUS
        signal(SIGBUS,  fault_handler);
#endif
        
#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:	1.23
Committed:	2006-02-27T07:16:40Z (18 years, 9 months ago) by gbeauche
Branch:	MAIN
Changes since 1.22:	+1 -1 lines
Log Message:	Start allocating memory from 0x10000000 with linker scripts since the system sometimes has a problem to make a decision when next_address == 0. NOTE: this makes it possible to allocate up to 1 GB with DIRECT_ADDRESSING
#	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__)) \|\| HAVE_LINKER_SCRIPT
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	if (zero_fd != -1) {
235	close(zero_fd);
236	zero_fd = -1;
237	}
238	#endif
239	#endif
240	}
241
242	/* Allocate zero-filled memory of SIZE bytes. The mapping is private
243	and default protection bits are read / write. The return value
244	is the actual mapping address chosen or VM_MAP_FAILED for errors. */
245
246	void * vm_acquire(size_t size, int options)
247	{
248	void * addr;
249
250	// VM_MAP_FIXED are to be used with vm_acquire_fixed() only
251	if (options & VM_MAP_FIXED)
252	return VM_MAP_FAILED;
253
254	#ifdef HAVE_MACH_VM
255	// vm_allocate() returns a zero-filled memory region
256	if (vm_allocate(mach_task_self(), (vm_address_t *)&addr, size, TRUE) != KERN_SUCCESS)
257	return VM_MAP_FAILED;
258	#else
259	#ifdef HAVE_MMAP_VM
260	int fd = zero_fd;
261	int the_map_flags = translate_map_flags(options) \| map_flags;
262
263	#ifdef USE_33BIT_ADDRESSING
264	const char *shm_file = NULL;
265	if (sizeof(void *) == 8 && (options & VM_MAP_33BIT)) {
266	the_map_flags &= ~(MAP_PRIVATE \| MAP_ANON \| MAP_ANONYMOUS);
267	the_map_flags \|= MAP_SHARED;
268
269	if ((shm_file = build_shm_filename()) == NULL)
270	return VM_MAP_FAILED;
271
272	if ((fd = shm_open(shm_file, O_RDWR \| O_CREAT \| O_EXCL, 0644)) < 0)
273	return VM_MAP_FAILED;
274
275	if (ftruncate(fd, size) < 0)
276	return VM_MAP_FAILED;
277	}
278	#endif
279
280	if ((addr = mmap((caddr_t)next_address, size, VM_PAGE_DEFAULT, the_map_flags, fd, 0)) == (void *)MAP_FAILED)
281	return VM_MAP_FAILED;
282
283	// Sanity checks for 64-bit platforms
284	if (sizeof(void ) == 8 && (options & VM_MAP_32BIT) && !((char )addr <= (char *)0xffffffff))
285	return VM_MAP_FAILED;
286
287	next_address = (char *)addr + size;
288
289	// Remap to 33-bit space
290	#ifdef USE_33BIT_ADDRESSING
291	if (sizeof(void *) == 8 && (options & VM_MAP_33BIT)) {
292	if (!add_shm_range(strdup(shm_file), addr, size))
293	return VM_MAP_FAILED;
294
295	if (mmap((char )addr + (1L << 32), size, VM_PAGE_DEFAULT, the_map_flags \| MAP_FIXED, fd, 0) == (void )MAP_FAILED)
296	return VM_MAP_FAILED;
297	close(fd);
298	}
299	#endif
300	#else
301	#ifdef HAVE_WIN32_VM
302	if ((addr = VirtualAlloc(NULL, size, MEM_RESERVE \| MEM_COMMIT, PAGE_EXECUTE_READWRITE)) == NULL)
303	return VM_MAP_FAILED;
304	#else
305	if ((addr = calloc(size, 1)) == 0)
306	return VM_MAP_FAILED;
307
308	// Omit changes for protections because they are not supported in this mode
309	return addr;
310	#endif
311	#endif
312	#endif
313
314	// Explicitely protect the newly mapped region here because on some systems,
315	// say MacOS X, mmap() doesn't honour the requested protection flags.
316	if (vm_protect(addr, size, VM_PAGE_DEFAULT) != 0)
317	return VM_MAP_FAILED;
318
319	return addr;
320	}
321
322	/* Allocate zero-filled memory at exactly ADDR (which must be page-aligned).
323	Retuns 0 if successful, -1 on errors. */
324
325	int vm_acquire_fixed(void * addr, size_t size, int options)
326	{
327	// Fixed mappings are required to be private
328	if (options & VM_MAP_SHARED)
329	return -1;
330
331	#ifdef HAVE_MACH_VM
332	// vm_allocate() returns a zero-filled memory region
333	if (vm_allocate(mach_task_self(), (vm_address_t *)&addr, size, 0) != KERN_SUCCESS)
334	return -1;
335	#else
336	#ifdef HAVE_MMAP_VM
337	int fd = zero_fd;
338	int the_map_flags = translate_map_flags(options) \| map_flags \| MAP_FIXED;
339
340	#ifdef USE_33BIT_ADDRESSING
341	const char *shm_file = NULL;
342	if (sizeof(void *) == 8 && (options & VM_MAP_33BIT)) {
343	the_map_flags &= ~(MAP_PRIVATE \| MAP_ANON \| MAP_ANONYMOUS);
344	the_map_flags \|= MAP_SHARED;
345
346	if ((shm_file = build_shm_filename()) == NULL)
347	return -1;
348
349	if ((fd = shm_open(shm_file, O_RDWR \| O_CREAT \| O_EXCL, 0644)) < 0)
350	return -1;
351
352	if (ftruncate(fd, size) < 0)
353	return -1;
354	}
355	#endif
356
357	if (mmap((caddr_t)addr, size, VM_PAGE_DEFAULT, the_map_flags, fd, 0) == (void *)MAP_FAILED)
358	return -1;
359
360	// Remap to 33-bit space
361	#ifdef USE_33BIT_ADDRESSING
362	if (sizeof(void *) == 8 && (options & VM_MAP_33BIT)) {
363	if (!add_shm_range(strdup(shm_file), addr, size))
364	return -1;
365
366	if (mmap((char )addr + (1L << 32), size, VM_PAGE_DEFAULT, the_map_flags, fd, 0) == (void )MAP_FAILED)
367	return -1;
368	close(fd);
369	}
370	#endif
371	#else
372	#ifdef HAVE_WIN32_VM
373	// Windows cannot allocate Low Memory
374	if (addr == NULL)
375	return -1;
376
377	// Allocate a possibly offset region to align on 64K boundaries
378	LPVOID req_addr = align_addr_segment(addr);
379	DWORD req_size = align_size_segment(addr, size);
380	LPVOID ret_addr = VirtualAlloc(req_addr, req_size, MEM_COMMIT \| MEM_RESERVE, PAGE_EXECUTE_READWRITE);
381	if (ret_addr != req_addr)
382	return -1;
383	return -1;
384	#else
385	// Unsupported
386	return -1;
387	#endif
388	#endif
389	#endif
390
391	// Explicitely protect the newly mapped region here because on some systems,
392	// say MacOS X, mmap() doesn't honour the requested protection flags.
393	if (vm_protect(addr, size, VM_PAGE_DEFAULT) != 0)
394	return -1;
395
396	return 0;
397	}
398
399	/* Deallocate any mapping for the region starting at ADDR and extending
400	LEN bytes. Returns 0 if successful, -1 on errors. */
401
402	int vm_release(void * addr, size_t size)
403	{
404	// Safety check: don't try to release memory that was not allocated
405	if (addr == VM_MAP_FAILED)
406	return 0;
407
408	#ifdef HAVE_MACH_VM
409	if (vm_deallocate(mach_task_self(), (vm_address_t)addr, size) != KERN_SUCCESS)
410	return -1;
411	#else
412	#ifdef HAVE_MMAP_VM
413	if (munmap((caddr_t)addr, size) != 0)
414	return -1;
415
416	#ifdef USE_33BIT_ADDRESSING
417	shm_range_t *r = find_shm_range(addr, size);
418	if (r) {
419	if (munmap((char *)r->base + (1L << 32), size) != 0)
420	return -1;
421
422	if (shm_unlink(r->file) < 0)
423	return -1;
424	free((char *)r->file);
425
426	if (!remove_shm_range(r))
427	return -1;
428	}
429	#endif
430	#else
431	#ifdef HAVE_WIN32_VM
432	if (VirtualFree(align_addr_segment(addr), 0, MEM_RELEASE) == 0)
433	return -1;
434	#else
435	free(addr);
436	#endif
437	#endif
438	#endif
439
440	return 0;
441	}
442
443	/* Change the memory protection of the region starting at ADDR and
444	extending LEN bytes to PROT. Returns 0 if successful, -1 for errors. */
445
446	int vm_protect(void * addr, size_t size, int prot)
447	{
448	#ifdef HAVE_MACH_VM
449	int ret_code = vm_protect(mach_task_self(), (vm_address_t)addr, size, 0, prot);
450	return ret_code == KERN_SUCCESS ? 0 : -1;
451	#else
452	#ifdef HAVE_MMAP_VM
453	int ret_code = mprotect((caddr_t)addr, size, prot);
454	return ret_code == 0 ? 0 : -1;
455	#else
456	#ifdef HAVE_WIN32_VM
457	DWORD old_prot;
458	int ret_code = VirtualProtect(addr, size, translate_prot_flags(prot), &old_prot);
459	return ret_code != 0 ? 0 : -1;
460	#else
461	// Unsupported
462	return -1;
463	#endif
464	#endif
465	#endif
466	}
467
468	/* Returns the size of a page. */
469
470	int vm_get_page_size(void)
471	{
472	#ifdef HAVE_WIN32_VM
473	static unsigned long page_size = 0;
474	if (page_size == 0) {
475	SYSTEM_INFO si;
476	GetSystemInfo(&si);
477	page_size = si.dwAllocationGranularity;
478	}
479	return page_size;
480	#else
481	return getpagesize();
482	#endif
483	}
484
485	#ifdef CONFIGURE_TEST_VM_MAP
486	#include <stdlib.h>
487	#include <signal.h>
488
489	static void fault_handler(int sig)
490	{
491	exit(1);
492	}
493
494	/* Tests covered here:
495	- TEST_VM_PROT_* program slices actually succeeds when a crash occurs
496	- TEST_VM_MAP_ANON* program slices succeeds when it could be compiled
497	*/
498	int main(void)
499	{
500	vm_init();
501
502	signal(SIGSEGV, fault_handler);
503	#ifdef SIGBUS
504	signal(SIGBUS, fault_handler);
505	#endif
506
507	#define page_align(address) ((char *)((unsigned long)(address) & -page_size))
508	unsigned long page_size = vm_get_page_size();
509
510	const int area_size = 6 * page_size;
511	volatile char * area = (volatile char *) vm_acquire(area_size);
512	volatile char * fault_address = area + (page_size * 7) / 2;
513
514	#if defined(TEST_VM_MMAP_ANON) \|\| defined(TEST_VM_MMAP_ANONYMOUS)
515	if (area == VM_MAP_FAILED)
516	return 1;
517
518	if (vm_release((char *)area, area_size) < 0)
519	return 1;
520
521	return 0;
522	#endif
523
524	#if defined(TEST_VM_PROT_NONE_READ) \|\| defined(TEST_VM_PROT_NONE_WRITE)
525	if (area == VM_MAP_FAILED)
526	return 0;
527
528	if (vm_protect(page_align(fault_address), page_size, VM_PAGE_NOACCESS) < 0)
529	return 0;
530	#endif
531
532	#if defined(TEST_VM_PROT_RDWR_WRITE)
533	if (area == VM_MAP_FAILED)
534	return 1;
535
536	if (vm_protect(page_align(fault_address), page_size, VM_PAGE_READ) < 0)
537	return 1;
538
539	if (vm_protect(page_align(fault_address), page_size, VM_PAGE_READ \| VM_PAGE_WRITE) < 0)
540	return 1;
541	#endif
542
543	#if defined(TEST_VM_PROT_READ_WRITE)
544	if (vm_protect(page_align(fault_address), page_size, VM_PAGE_READ) < 0)
545	return 0;
546	#endif
547
548	#if defined(TEST_VM_PROT_NONE_READ)
549	// this should cause a core dump
550	char foo = *fault_address;
551	return 0;
552	#endif
553
554	#if defined(TEST_VM_PROT_NONE_WRITE) \|\| defined(TEST_VM_PROT_READ_WRITE)
555	// this should cause a core dump
556	*fault_address = 'z';
557	return 0;
558	#endif
559
560	#if defined(TEST_VM_PROT_RDWR_WRITE)
561	// this should not cause a core dump
562	*fault_address = 'z';
563	return 0;
564	#endif
565	}
566	#endif