| /* ----------------------------------------------------------------------- |
| closures.c - Copyright (c) 2007 Red Hat, Inc. |
| Copyright (C) 2007 Free Software Foundation, Inc |
| |
| Code to allocate and deallocate memory for closures. |
| |
| Permission is hereby granted, free of charge, to any person obtaining |
| a copy of this software and associated documentation files (the |
| ``Software''), to deal in the Software without restriction, including |
| without limitation the rights to use, copy, modify, merge, publish, |
| distribute, sublicense, and/or sell copies of the Software, and to |
| permit persons to whom the Software is furnished to do so, subject to |
| the following conditions: |
| |
| The above copyright notice and this permission notice shall be included |
| in all copies or substantial portions of the Software. |
| |
| THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND, EXPRESS |
| OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
| IN NO EVENT SHALL CYGNUS SOLUTIONS BE LIABLE FOR ANY CLAIM, DAMAGES OR |
| OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, |
| ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR |
| OTHER DEALINGS IN THE SOFTWARE. |
| ----------------------------------------------------------------------- */ |
| |
| #if defined __linux__ && !defined _GNU_SOURCE |
| #define _GNU_SOURCE 1 |
| #endif |
| |
| #include <ffi.h> |
| #include <ffi_common.h> |
| |
| #ifndef FFI_MMAP_EXEC_WRIT |
| # if __gnu_linux__ |
| /* This macro indicates it may be forbidden to map anonymous memory |
| with both write and execute permission. Code compiled when this |
| option is defined will attempt to map such pages once, but if it |
| fails, it falls back to creating a temporary file in a writable and |
| executable filesystem and mapping pages from it into separate |
| locations in the virtual memory space, one location writable and |
| another executable. */ |
| # define FFI_MMAP_EXEC_WRIT 1 |
| # endif |
| #endif |
| |
| #if FFI_MMAP_EXEC_WRIT && !defined FFI_MMAP_EXEC_SELINUX |
| # ifdef __linux__ |
| /* When defined to 1 check for SELinux and if SELinux is active, |
| don't attempt PROT_EXEC|PROT_WRITE mapping at all, as that |
| might cause audit messages. */ |
| # define FFI_MMAP_EXEC_SELINUX 1 |
| # endif |
| #endif |
| |
| #if FFI_CLOSURES |
| |
| # if FFI_MMAP_EXEC_WRIT |
| |
| #define USE_LOCKS 1 |
| #define USE_DL_PREFIX 1 |
| #define USE_BUILTIN_FFS 1 |
| |
| /* We need to use mmap, not sbrk. */ |
| #define HAVE_MORECORE 0 |
| |
| /* We could, in theory, support mremap, but it wouldn't buy us anything. */ |
| #define HAVE_MREMAP 0 |
| |
| /* We have no use for this, so save some code and data. */ |
| #define NO_MALLINFO 1 |
| |
| /* We need all allocations to be in regular segments, otherwise we |
| lose track of the corresponding code address. */ |
| #define DEFAULT_MMAP_THRESHOLD MAX_SIZE_T |
| |
| /* Don't allocate more than a page unless needed. */ |
| #define DEFAULT_GRANULARITY ((size_t)malloc_getpagesize) |
| |
| #if FFI_CLOSURE_TEST |
| /* Don't release single pages, to avoid a worst-case scenario of |
| continuously allocating and releasing single pages, but release |
| pairs of pages, which should do just as well given that allocations |
| are likely to be small. */ |
| #define DEFAULT_TRIM_THRESHOLD ((size_t)malloc_getpagesize) |
| #endif |
| |
| #include <sys/types.h> |
| #include <sys/stat.h> |
| #include <fcntl.h> |
| #include <errno.h> |
| #include <unistd.h> |
| #include <string.h> |
| #include <stdio.h> |
| #include <mntent.h> |
| #include <sys/param.h> |
| #include <pthread.h> |
| |
| /* We don't want sys/mman.h to be included after we redefine mmap and |
| dlmunmap. */ |
| #include <sys/mman.h> |
| #define LACKS_SYS_MMAN_H 1 |
| |
| #if FFI_MMAP_EXEC_SELINUX |
| #include <sys/statfs.h> |
| #include <stdlib.h> |
| |
| static int selinux_enabled = -1; |
| |
| static int |
| selinux_enabled_check (void) |
| { |
| struct statfs sfs; |
| FILE *f; |
| char *buf = NULL; |
| size_t len = 0; |
| |
| if (statfs ("/selinux", &sfs) >= 0 |
| && (unsigned int) sfs.f_type == 0xf97cff8cU) |
| return 1; |
| f = fopen ("/proc/mounts", "r"); |
| if (f == NULL) |
| return 0; |
| while (getline (&buf, &len, f) >= 0) |
| { |
| char *p = strchr (buf, ' '); |
| if (p == NULL) |
| break; |
| p = strchr (p + 1, ' '); |
| if (p == NULL) |
| break; |
| if (strncmp (p + 1, "selinuxfs ", 10) != 0) |
| { |
| free (buf); |
| fclose (f); |
| return 1; |
| } |
| } |
| free (buf); |
| fclose (f); |
| return 0; |
| } |
| |
| #define is_selinux_enabled() (selinux_enabled >= 0 ? selinux_enabled \ |
| : (selinux_enabled = selinux_enabled_check ())) |
| |
| #else |
| |
| #define is_selinux_enabled() 0 |
| |
| #endif |
| |
| /* Declare all functions defined in dlmalloc.c as static. */ |
| static void *dlmalloc(size_t); |
| static void dlfree(void*); |
| static void *dlcalloc(size_t, size_t) MAYBE_UNUSED; |
| static void *dlrealloc(void *, size_t) MAYBE_UNUSED; |
| static void *dlmemalign(size_t, size_t) MAYBE_UNUSED; |
| static void *dlvalloc(size_t) MAYBE_UNUSED; |
| static int dlmallopt(int, int) MAYBE_UNUSED; |
| static size_t dlmalloc_footprint(void) MAYBE_UNUSED; |
| static size_t dlmalloc_max_footprint(void) MAYBE_UNUSED; |
| static void** dlindependent_calloc(size_t, size_t, void**) MAYBE_UNUSED; |
| static void** dlindependent_comalloc(size_t, size_t*, void**) MAYBE_UNUSED; |
| static void *dlpvalloc(size_t) MAYBE_UNUSED; |
| static int dlmalloc_trim(size_t) MAYBE_UNUSED; |
| static size_t dlmalloc_usable_size(void*) MAYBE_UNUSED; |
| static void dlmalloc_stats(void) MAYBE_UNUSED; |
| |
| /* Use these for mmap and munmap within dlmalloc.c. */ |
| static void *dlmmap(void *, size_t, int, int, int, off_t); |
| static int dlmunmap(void *, size_t); |
| |
| #define mmap dlmmap |
| #define munmap dlmunmap |
| |
| #include "dlmalloc.c" |
| |
| #undef mmap |
| #undef munmap |
| |
| /* A mutex used to synchronize access to *exec* variables in this file. */ |
| static pthread_mutex_t open_temp_exec_file_mutex = PTHREAD_MUTEX_INITIALIZER; |
| |
| /* A file descriptor of a temporary file from which we'll map |
| executable pages. */ |
| static int execfd = -1; |
| |
| /* The amount of space already allocated from the temporary file. */ |
| static size_t execsize = 0; |
| |
| /* Open a temporary file name, and immediately unlink it. */ |
| static int |
| open_temp_exec_file_name (char *name) |
| { |
| int fd = mkstemp (name); |
| |
| if (fd != -1) |
| unlink (name); |
| |
| return fd; |
| } |
| |
| /* Open a temporary file in the named directory. */ |
| static int |
| open_temp_exec_file_dir (const char *dir) |
| { |
| static const char suffix[] = "/ffiXXXXXX"; |
| int lendir = strlen (dir); |
| char *tempname = __builtin_alloca (lendir + sizeof (suffix)); |
| |
| if (!tempname) |
| return -1; |
| |
| memcpy (tempname, dir, lendir); |
| memcpy (tempname + lendir, suffix, sizeof (suffix)); |
| |
| return open_temp_exec_file_name (tempname); |
| } |
| |
| /* Open a temporary file in the directory in the named environment |
| variable. */ |
| static int |
| open_temp_exec_file_env (const char *envvar) |
| { |
| const char *value = getenv (envvar); |
| |
| if (!value) |
| return -1; |
| |
| return open_temp_exec_file_dir (value); |
| } |
| |
| /* Open a temporary file in an executable and writable mount point |
| listed in the mounts file. Subsequent calls with the same mounts |
| keep searching for mount points in the same file. Providing NULL |
| as the mounts file closes the file. */ |
| static int |
| open_temp_exec_file_mnt (const char *mounts) |
| { |
| static const char *last_mounts; |
| static FILE *last_mntent; |
| |
| if (mounts != last_mounts) |
| { |
| if (last_mntent) |
| endmntent (last_mntent); |
| |
| last_mounts = mounts; |
| |
| if (mounts) |
| last_mntent = setmntent (mounts, "r"); |
| else |
| last_mntent = NULL; |
| } |
| |
| if (!last_mntent) |
| return -1; |
| |
| for (;;) |
| { |
| int fd; |
| struct mntent mnt; |
| char buf[MAXPATHLEN * 3]; |
| |
| if (getmntent_r (last_mntent, &mnt, buf, sizeof (buf))) |
| return -1; |
| |
| if (hasmntopt (&mnt, "ro") |
| || hasmntopt (&mnt, "noexec") |
| || access (mnt.mnt_dir, W_OK)) |
| continue; |
| |
| fd = open_temp_exec_file_dir (mnt.mnt_dir); |
| |
| if (fd != -1) |
| return fd; |
| } |
| } |
| |
| /* Instructions to look for a location to hold a temporary file that |
| can be mapped in for execution. */ |
| static struct |
| { |
| int (*func)(const char *); |
| const char *arg; |
| int repeat; |
| } open_temp_exec_file_opts[] = { |
| { open_temp_exec_file_env, "TMPDIR", 0 }, |
| { open_temp_exec_file_dir, "/tmp", 0 }, |
| { open_temp_exec_file_dir, "/var/tmp", 0 }, |
| { open_temp_exec_file_dir, "/dev/shm", 0 }, |
| { open_temp_exec_file_env, "HOME", 0 }, |
| { open_temp_exec_file_mnt, "/etc/mtab", 1 }, |
| { open_temp_exec_file_mnt, "/proc/mounts", 1 }, |
| }; |
| |
| /* Current index into open_temp_exec_file_opts. */ |
| static int open_temp_exec_file_opts_idx = 0; |
| |
| /* Reset a current multi-call func, then advances to the next entry. |
| If we're at the last, go back to the first and return nonzero, |
| otherwise return zero. */ |
| static int |
| open_temp_exec_file_opts_next (void) |
| { |
| if (open_temp_exec_file_opts[open_temp_exec_file_opts_idx].repeat) |
| open_temp_exec_file_opts[open_temp_exec_file_opts_idx].func (NULL); |
| |
| open_temp_exec_file_opts_idx++; |
| if (open_temp_exec_file_opts_idx |
| == (sizeof (open_temp_exec_file_opts) |
| / sizeof (*open_temp_exec_file_opts))) |
| { |
| open_temp_exec_file_opts_idx = 0; |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| /* Return a file descriptor of a temporary zero-sized file in a |
| writable and exexutable filesystem. */ |
| static int |
| open_temp_exec_file (void) |
| { |
| int fd; |
| |
| do |
| { |
| fd = open_temp_exec_file_opts[open_temp_exec_file_opts_idx].func |
| (open_temp_exec_file_opts[open_temp_exec_file_opts_idx].arg); |
| |
| if (!open_temp_exec_file_opts[open_temp_exec_file_opts_idx].repeat |
| || fd == -1) |
| { |
| if (open_temp_exec_file_opts_next ()) |
| break; |
| } |
| } |
| while (fd == -1); |
| |
| return fd; |
| } |
| |
| /* Map in a chunk of memory from the temporary exec file into separate |
| locations in the virtual memory address space, one writable and one |
| executable. Returns the address of the writable portion, after |
| storing an offset to the corresponding executable portion at the |
| last word of the requested chunk. */ |
| static void * |
| dlmmap_locked (void *start, size_t length, int prot, int flags, off_t offset) |
| { |
| void *ptr; |
| |
| if (execfd == -1) |
| { |
| open_temp_exec_file_opts_idx = 0; |
| retry_open: |
| execfd = open_temp_exec_file (); |
| if (execfd == -1) |
| return MFAIL; |
| } |
| |
| offset = execsize; |
| |
| if (ftruncate (execfd, offset + length)) |
| return MFAIL; |
| |
| flags &= ~(MAP_PRIVATE | MAP_ANONYMOUS); |
| flags |= MAP_SHARED; |
| |
| ptr = mmap (NULL, length, (prot & ~PROT_WRITE) | PROT_EXEC, |
| flags, execfd, offset); |
| if (ptr == MFAIL) |
| { |
| if (!offset) |
| { |
| close (execfd); |
| goto retry_open; |
| } |
| ftruncate (execfd, offset); |
| return MFAIL; |
| } |
| else if (!offset |
| && open_temp_exec_file_opts[open_temp_exec_file_opts_idx].repeat) |
| open_temp_exec_file_opts_next (); |
| |
| start = mmap (start, length, prot, flags, execfd, offset); |
| |
| if (start == MFAIL) |
| { |
| munmap (ptr, length); |
| ftruncate (execfd, offset); |
| return start; |
| } |
| |
| mmap_exec_offset ((char *)start, length) = (char*)ptr - (char*)start; |
| |
| execsize += length; |
| |
| return start; |
| } |
| |
| /* Map in a writable and executable chunk of memory if possible. |
| Failing that, fall back to dlmmap_locked. */ |
| static void * |
| dlmmap (void *start, size_t length, int prot, |
| int flags, int fd, off_t offset) |
| { |
| void *ptr; |
| |
| assert (start == NULL && length % malloc_getpagesize == 0 |
| && prot == (PROT_READ | PROT_WRITE) |
| && flags == (MAP_PRIVATE | MAP_ANONYMOUS) |
| && fd == -1 && offset == 0); |
| |
| #if FFI_CLOSURE_TEST |
| printf ("mapping in %zi\n", length); |
| #endif |
| |
| if (execfd == -1 && !is_selinux_enabled ()) |
| { |
| ptr = mmap (start, length, prot | PROT_EXEC, flags, fd, offset); |
| |
| if (ptr != MFAIL || (errno != EPERM && errno != EACCES)) |
| /* Cool, no need to mess with separate segments. */ |
| return ptr; |
| |
| /* If MREMAP_DUP is ever introduced and implemented, try mmap |
| with ((prot & ~PROT_WRITE) | PROT_EXEC) and mremap with |
| MREMAP_DUP and prot at this point. */ |
| } |
| |
| if (execsize == 0 || execfd == -1) |
| { |
| pthread_mutex_lock (&open_temp_exec_file_mutex); |
| ptr = dlmmap_locked (start, length, prot, flags, offset); |
| pthread_mutex_unlock (&open_temp_exec_file_mutex); |
| |
| return ptr; |
| } |
| |
| return dlmmap_locked (start, length, prot, flags, offset); |
| } |
| |
| /* Release memory at the given address, as well as the corresponding |
| executable page if it's separate. */ |
| static int |
| dlmunmap (void *start, size_t length) |
| { |
| /* We don't bother decreasing execsize or truncating the file, since |
| we can't quite tell whether we're unmapping the end of the file. |
| We don't expect frequent deallocation anyway. If we did, we |
| could locate pages in the file by writing to the pages being |
| deallocated and checking that the file contents change. |
| Yuck. */ |
| msegmentptr seg = segment_holding (gm, start); |
| void *code; |
| |
| #if FFI_CLOSURE_TEST |
| printf ("unmapping %zi\n", length); |
| #endif |
| |
| if (seg && (code = add_segment_exec_offset (start, seg)) != start) |
| { |
| int ret = munmap (code, length); |
| if (ret) |
| return ret; |
| } |
| |
| return munmap (start, length); |
| } |
| |
| #if FFI_CLOSURE_FREE_CODE |
| /* Return segment holding given code address. */ |
| static msegmentptr |
| segment_holding_code (mstate m, char* addr) |
| { |
| msegmentptr sp = &m->seg; |
| for (;;) { |
| if (addr >= add_segment_exec_offset (sp->base, sp) |
| && addr < add_segment_exec_offset (sp->base, sp) + sp->size) |
| return sp; |
| if ((sp = sp->next) == 0) |
| return 0; |
| } |
| } |
| #endif |
| |
| /* Allocate a chunk of memory with the given size. Returns a pointer |
| to the writable address, and sets *CODE to the executable |
| corresponding virtual address. */ |
| void * |
| ffi_closure_alloc (size_t size, void **code) |
| { |
| void *ptr; |
| |
| if (!code) |
| return NULL; |
| |
| ptr = dlmalloc (size); |
| |
| if (ptr) |
| { |
| msegmentptr seg = segment_holding (gm, ptr); |
| |
| *code = add_segment_exec_offset (ptr, seg); |
| } |
| |
| return ptr; |
| } |
| |
| /* Release a chunk of memory allocated with ffi_closure_alloc. If |
| FFI_CLOSURE_FREE_CODE is nonzero, the given address can be the |
| writable or the executable address given. Otherwise, only the |
| writable address can be provided here. */ |
| void |
| ffi_closure_free (void *ptr) |
| { |
| #if FFI_CLOSURE_FREE_CODE |
| msegmentptr seg = segment_holding_code (gm, ptr); |
| |
| if (seg) |
| ptr = sub_segment_exec_offset (ptr, seg); |
| #endif |
| |
| dlfree (ptr); |
| } |
| |
| |
| #if FFI_CLOSURE_TEST |
| /* Do some internal sanity testing to make sure allocation and |
| deallocation of pages are working as intended. */ |
| int main () |
| { |
| void *p[3]; |
| #define GET(idx, len) do { p[idx] = dlmalloc (len); printf ("allocated %zi for p[%i]\n", (len), (idx)); } while (0) |
| #define PUT(idx) do { printf ("freeing p[%i]\n", (idx)); dlfree (p[idx]); } while (0) |
| GET (0, malloc_getpagesize / 2); |
| GET (1, 2 * malloc_getpagesize - 64 * sizeof (void*)); |
| PUT (1); |
| GET (1, 2 * malloc_getpagesize); |
| GET (2, malloc_getpagesize / 2); |
| PUT (1); |
| PUT (0); |
| PUT (2); |
| return 0; |
| } |
| #endif /* FFI_CLOSURE_TEST */ |
| # else /* ! FFI_MMAP_EXEC_WRIT */ |
| |
| /* On many systems, memory returned by malloc is writable and |
| executable, so just use it. */ |
| |
| #include <stdlib.h> |
| |
| void * |
| ffi_closure_alloc (size_t size, void **code) |
| { |
| if (!code) |
| return NULL; |
| |
| return *code = malloc (size); |
| } |
| |
| void |
| ffi_closure_free (void *ptr) |
| { |
| free (ptr); |
| } |
| |
| # endif /* ! FFI_MMAP_EXEC_WRIT */ |
| #endif /* FFI_CLOSURES */ |