Linker.c 220 KB
Newer Older
1 2
/* -----------------------------------------------------------------------------
 *
Gabor Greif's avatar
typo  
Gabor Greif committed
3
 * (c) The GHC Team, 2000-2012
4 5 6 7 8
 *
 * RTS Object Linker
 *
 * ---------------------------------------------------------------------------*/

sof's avatar
sof committed
9
#if 0
10
#include "PosixSource.h"
sof's avatar
sof committed
11
#endif
12

13
/* Linux needs _GNU_SOURCE to get RTLD_DEFAULT from <dlfcn.h> and
14 15
   MREMAP_MAYMOVE from <sys/mman.h>.
 */
16 17
#if defined(__linux__)  || defined(__GLIBC__)
#define _GNU_SOURCE 1
18 19
#endif

20 21
#include "Rts.h"
#include "HsFFI.h"
Simon Marlow's avatar
Simon Marlow committed
22 23

#include "sm/Storage.h"
Simon Marlow's avatar
Simon Marlow committed
24
#include "Stats.h"
25
#include "Hash.h"
26
#include "LinkerInternals.h"
27
#include "RtsUtils.h"
28
#include "Trace.h"
Simon Marlow's avatar
Simon Marlow committed
29
#include "StgPrimFloat.h" // for __int_encodeFloat etc.
30
#include "Proftimer.h"
31
#include "GetEnv.h"
32
#include "Stable.h"
33
#include "RtsSymbols.h"
34
#include "Profiling.h"
Simon Marlow's avatar
Simon Marlow committed
35 36 37 38

#if !defined(mingw32_HOST_OS)
#include "posix/Signals.h"
#endif
39

Simon Marlow's avatar
Simon Marlow committed
40 41 42
// get protos for is*()
#include <ctype.h>

43
#ifdef HAVE_SYS_TYPES_H
44
#include <sys/types.h>
45 46
#endif

Ian Lynagh's avatar
Ian Lynagh committed
47
#include <inttypes.h>
48 49
#include <stdlib.h>
#include <string.h>
50 51
#include <stdio.h>
#include <assert.h>
Simon Marlow's avatar
Simon Marlow committed
52
#include <libgen.h>
53

54
#ifdef HAVE_SYS_STAT_H
55
#include <sys/stat.h>
56
#endif
57

58
#if defined(HAVE_DLFCN_H)
59
#include <dlfcn.h>
60
#endif
61

62 63 64
#if (defined(powerpc_HOST_ARCH) && defined(linux_HOST_OS)) \
 || (!defined(powerpc_HOST_ARCH) && \
    (   defined(linux_HOST_OS)     || defined(freebsd_HOST_OS) || \
65 66
        defined(dragonfly_HOST_OS) || defined(netbsd_HOST_OS ) || \
        defined(openbsd_HOST_OS  ) || defined(darwin_HOST_OS ) || \
67 68
        defined(kfreebsdgnu_HOST_OS) || defined(gnu_HOST_OS  ) || \
        defined(solaris2_HOST_OS)))
69
/* Don't use mmap on powerpc/darwin as the mmap there doesn't support
70 71 72 73
 * reallocating but we need to allocate jump islands just after each
 * object images. Otherwise relative branches to jump islands can fail
 * due to 24-bits displacement overflow.
 */
74
#define USE_MMAP 1
75 76
#include <fcntl.h>
#include <sys/mman.h>
dons's avatar
dons committed
77 78 79 80 81

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

82 83 84 85
#else

#define USE_MMAP 0

86 87
#endif

88 89 90 91

/* PowerPC has relative branch instructions with only 24 bit displacements
 * and therefore needs jump islands contiguous with each object code module.
 */
92
#if (USE_MMAP && defined(powerpc_HOST_ARCH) && defined(linux_HOST_OS))
93 94 95 96 97
#define USE_CONTIGUOUS_MMAP 1
#else
#define USE_CONTIGUOUS_MMAP 0
#endif

pcapriotti's avatar
pcapriotti committed
98
#if defined(linux_HOST_OS) || defined(solaris2_HOST_OS) || defined(freebsd_HOST_OS) || defined(kfreebsdgnu_HOST_OS) || defined(dragonfly_HOST_OS) || defined(netbsd_HOST_OS) || defined(openbsd_HOST_OS) || defined(gnu_HOST_OS)
99
#  define OBJFORMAT_ELF
Ian Lynagh's avatar
Ian Lynagh committed
100 101
#  include <regex.h>    // regex is already used by dlopen() so this is OK
                        // to use here without requiring an additional lib
102
#elif defined (mingw32_HOST_OS)
103
#  define OBJFORMAT_PEi386
104
#  include <windows.h>
105
#  include <shfolder.h> /* SHGetFolderPathW */
sof's avatar
sof committed
106
#  include <math.h>
107
#elif defined(darwin_HOST_OS)
108
#  define OBJFORMAT_MACHO
109
#  include <regex.h>
Ian Lynagh's avatar
Ian Lynagh committed
110 111
#  include <mach/machine.h>
#  include <mach-o/fat.h>
112 113 114
#  include <mach-o/loader.h>
#  include <mach-o/nlist.h>
#  include <mach-o/reloc.h>
115 116 117
#if defined(powerpc_HOST_ARCH)
#  include <mach-o/ppc/reloc.h>
#endif
118 119 120
#if defined(x86_64_HOST_ARCH)
#  include <mach-o/x86_64/reloc.h>
#endif
121 122
#endif

123 124 125 126
#if defined(x86_64_HOST_ARCH) && defined(darwin_HOST_OS)
#define ALWAYS_PIC
#endif

127 128 129 130
#if defined(dragonfly_HOST_OS)
#include <sys/tls.h>
#endif

131 132 133 134 135 136 137
typedef struct _RtsSymbolInfo {
    void *value;
    const ObjectCode *owner;
    HsBool weak;
} RtsSymbolInfo;

/* Hash table mapping symbol names to RtsSymbolInfo */
138
static /*Str*/HashTable *symhash;
139

140
/* List of currently loaded objects */
Ian Lynagh's avatar
Ian Lynagh committed
141
ObjectCode *objects = NULL;     /* initially empty */
142

143 144 145 146
/* List of objects that have been unloaded via unloadObj(), but are waiting
   to be actually freed via checkUnload() */
ObjectCode *unloaded_objects = NULL; /* initially empty */

147
#ifdef THREADED_RTS
148
/* This protects all the Linker's global state except unloaded_objects */
149
Mutex linker_mutex;
150 151 152 153
/*
 * This protects unloaded_objects.  We have a separate mutex for this, because
 * the GC needs to access unloaded_objects in checkUnload, while the linker only
 * needs to access unloaded_objects in unloadObj(), so this allows most linker
154
 * operations proceed concurrently with the GC.
155 156
 */
Mutex linker_unloaded_mutex;
157 158
#endif

159 160 161
/* Type of the initializer */
typedef void (*init_t) (int argc, char **argv, char **env);

162
static HsInt isAlreadyLoaded( pathchar *path );
163
static HsInt loadOc( ObjectCode* oc );
164
static ObjectCode* mkOc( pathchar *path, char *image, int imageSize,
Erik de Castro Lopo's avatar
Erik de Castro Lopo committed
165 166
                         rtsBool mapped, char *archiveMemberName,
                         int misalignment
167 168
                       );

169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200
// Use wchar_t for pathnames on Windows (#5697)
#if defined(mingw32_HOST_OS)
#define pathcmp wcscmp
#define pathlen wcslen
#define pathopen _wfopen
#define pathstat _wstat
#define struct_stat struct _stat
#define open wopen
#define WSTR(s) L##s
#else
#define pathcmp strcmp
#define pathlen strlen
#define pathopen fopen
#define pathstat stat
#define struct_stat struct stat
#define WSTR(s) s
#endif

static pathchar* pathdup(pathchar *path)
{
    pathchar *ret;
#if defined(mingw32_HOST_OS)
    ret = wcsdup(path);
#else
    /* sigh, strdup() isn't a POSIX function, so do it the long way */
    ret = stgMallocBytes( strlen(path)+1, "loadObj" );
    strcpy(ret, path);
#endif
    return ret;
}


201
#if defined(OBJFORMAT_ELF)
202 203 204
static int ocVerifyImage_ELF    ( ObjectCode* oc );
static int ocGetNames_ELF       ( ObjectCode* oc );
static int ocResolve_ELF        ( ObjectCode* oc );
205
static int ocRunInit_ELF        ( ObjectCode* oc );
206
#if NEED_SYMBOL_EXTRAS
207
static int ocAllocateSymbolExtras_ELF ( ObjectCode* oc );
208
#endif
209
#elif defined(OBJFORMAT_PEi386)
210 211 212
static int ocVerifyImage_PEi386 ( ObjectCode* oc );
static int ocGetNames_PEi386    ( ObjectCode* oc );
static int ocResolve_PEi386     ( ObjectCode* oc );
213
static int ocRunInit_PEi386     ( ObjectCode* oc );
214
static void *lookupSymbolInDLLs ( unsigned char *lbl );
215 216 217 218
/* See Note [mingw-w64 name decoration scheme] */
#ifndef x86_64_HOST_ARCH
 static void zapTrailingAtSign   ( unsigned char *sym );
#endif
219
static char *allocateImageAndTrampolines (
Austin Seipp's avatar
Austin Seipp committed
220
   pathchar* arch_name, char* member_name,
221
#if defined(x86_64_HOST_ARCH)
Austin Seipp's avatar
Austin Seipp committed
222
   FILE* f,
223 224 225 226 227 228 229 230 231
#endif
   int size );
#if defined(x86_64_HOST_ARCH)
static int ocAllocateSymbolExtras_PEi386 ( ObjectCode* oc );
static size_t makeSymbolExtra_PEi386( ObjectCode* oc, size_t, char* symbol );
#define PEi386_IMAGE_OFFSET 4
#else
#define PEi386_IMAGE_OFFSET 0
#endif
232 233 234 235
#elif defined(OBJFORMAT_MACHO)
static int ocVerifyImage_MachO    ( ObjectCode* oc );
static int ocGetNames_MachO       ( ObjectCode* oc );
static int ocResolve_MachO        ( ObjectCode* oc );
236
static int ocRunInit_MachO        ( ObjectCode* oc );
237

238
#if (USE_MMAP == 0)
239
static int machoGetMisalignment( FILE * );
Ian Lynagh's avatar
Ian Lynagh committed
240
#endif
241
#if NEED_SYMBOL_EXTRAS
242 243
static int ocAllocateSymbolExtras_MachO ( ObjectCode* oc );
#endif
244
#ifdef powerpc_HOST_ARCH
245
static void machoInitSymbolsWithoutUnderscore( void );
246
#endif
247
#endif
248

249 250
static void freeProddableBlocks (ObjectCode *oc);

251
#if USE_MMAP
252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278
/**
 * An allocated page being filled by the allocator
 */
struct m32_alloc_t {
   void * base_addr;             // Page address
   unsigned int current_size;    // Number of bytes already reserved
};

#define M32_MAX_PAGES 32

/**
 * Allocator
 *
 * Currently an allocator is just a set of pages being filled. The maximum
 * number of pages can be configured with M32_MAX_PAGES.
 */
typedef struct m32_allocator_t {
   struct m32_alloc_t pages[M32_MAX_PAGES];
} * m32_allocator;

// We use a global memory allocator
static struct m32_allocator_t allocator;

struct m32_allocator_t;
static void m32_allocator_init(struct m32_allocator_t *m32);
#endif

279 280 281 282 283 284 285 286 287 288 289 290 291
/* on x86_64 we have a problem with relocating symbol references in
 * code that was compiled without -fPIC.  By default, the small memory
 * model is used, which assumes that symbol references can fit in a
 * 32-bit slot.  The system dynamic linker makes this work for
 * references to shared libraries by either (a) allocating a jump
 * table slot for code references, or (b) moving the symbol at load
 * time (and copying its contents, if necessary) for data references.
 *
 * We unfortunately can't tell whether symbol references are to code
 * or data.  So for now we assume they are code (the vast majority
 * are), and allocate jump-table slots.  Unfortunately this will
 * SILENTLY generate crashing code for data references.  This hack is
 * enabled by X86_64_ELF_NONPIC_HACK.
Ian Lynagh's avatar
Ian Lynagh committed
292
 *
293 294 295 296 297 298 299 300
 * One workaround is to use shared Haskell libraries.  This is
 * coming.  Another workaround is to keep the static libraries but
 * compile them with -fPIC, because that will generate PIC references
 * to data which can be relocated.  The PIC code is still too green to
 * do this systematically, though.
 *
 * See bug #781
 * See thread http://www.haskell.org/pipermail/cvs-ghc/2007-September/038458.html
301 302 303 304 305 306 307 308 309 310 311 312
 *
 * Naming Scheme for Symbol Macros
 *
 * SymI_*: symbol is internal to the RTS. It resides in an object
 *         file/library that is statically.
 * SymE_*: symbol is external to the RTS library. It might be linked
 *         dynamically.
 *
 * Sym*_HasProto  : the symbol prototype is imported in an include file
 *                  or defined explicitly
 * Sym*_NeedsProto: the symbol is undefined and we add a dummy
 *                  default proto extern void sym(void);
313 314
 */
#define X86_64_ELF_NONPIC_HACK 1
315

316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341
/* Link objects into the lower 2Gb on x86_64.  GHC assumes the
 * small memory model on this architecture (see gcc docs,
 * -mcmodel=small).
 *
 * MAP_32BIT not available on OpenBSD/amd64
 */
#if defined(x86_64_HOST_ARCH) && defined(MAP_32BIT)
#define TRY_MAP_32BIT MAP_32BIT
#else
#define TRY_MAP_32BIT 0
#endif

/*
 * Due to the small memory model (see above), on x86_64 we have to map
 * all our non-PIC object files into the low 2Gb of the address space
 * (why 2Gb and not 4Gb?  Because all addresses must be reachable
 * using a 32-bit signed PC-relative offset). On Linux we can do this
 * using the MAP_32BIT flag to mmap(), however on other OSs
 * (e.g. *BSD, see #2063, and also on Linux inside Xen, see #2512), we
 * can't do this.  So on these systems, we have to pick a base address
 * in the low 2Gb of the address space and try to allocate memory from
 * there.
 *
 * We pick a default address based on the OS, but also make this
 * configurable via an RTS flag (+RTS -xm)
 */
342
#if !defined(ALWAYS_PIC) && defined(x86_64_HOST_ARCH)
343 344 345 346 347 348 349 350 351

#if defined(MAP_32BIT)
// Try to use MAP_32BIT
#define MMAP_32BIT_BASE_DEFAULT 0
#else
// A guess: 1Gb.
#define MMAP_32BIT_BASE_DEFAULT 0x40000000
#endif

Ian Lynagh's avatar
Ian Lynagh committed
352
static void *mmap_32bit_base = (void *)MMAP_32BIT_BASE_DEFAULT;
353 354 355 356 357 358 359
#endif

/* MAP_ANONYMOUS is MAP_ANON on some systems, e.g. OpenBSD */
#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
#define MAP_ANONYMOUS MAP_ANON
#endif

360 361
/* -----------------------------------------------------------------------------
 * Insert symbols into hash tables, checking for duplicates.
362 363
 *
 * Returns: 0 on failure, nonzero on success
364
 */
365

366
static int ghciInsertSymbolTable(
367 368
   pathchar* obj_name,
   HashTable *table,
369
   const char* key,
370 371 372
   void *data,
   HsBool weak,
   ObjectCode *owner)
373
{
374 375 376 377 378 379 380 381
   RtsSymbolInfo *pinfo = lookupStrHashTable(table, key);
   if (!pinfo) /* new entry */
   {
      pinfo = stgMallocBytes(sizeof (*pinfo), "ghciInsertToSymbolTable");
      pinfo->value = data;
      pinfo->owner = owner;
      pinfo->weak = weak;
      insertStrHashTable(table, key, pinfo);
382 383 384 385 386 387 388
      return 1;
   }
   else if ((!pinfo->weak || pinfo->value) && weak)
   {
     return 1; /* duplicate weak symbol, throw it away */
   }
   else if (pinfo->weak) /* weak symbol is in the table */
Simon Marlow's avatar
Simon Marlow committed
389
   {
390 391 392 393
      /* override the weak definition with the non-weak one */
      pinfo->value = data;
      pinfo->owner = owner;
      pinfo->weak = HS_BOOL_FALSE;
394
      return 1;
Simon Marlow's avatar
Simon Marlow committed
395 396
   }
   debugBelch(
397
      "GHC runtime linker: fatal error: I found a duplicate definition for symbol\n"
398 399
      "   %s\n"
      "whilst processing object file\n"
400
      "   %" PATH_FMT "\n"
401 402 403 404
      "This could be caused by:\n"
      "   * Loading two different object files which export the same symbol\n"
      "   * Specifying the same object file twice on the GHCi command line\n"
      "   * An incorrect `package.conf' entry, causing some object to be\n"
405
      "     loaded twice.\n",
406 407
      (char*)key,
      obj_name
Simon Marlow's avatar
Simon Marlow committed
408
   );
409
   return 0;
410
}
411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436

static HsBool ghciLookupSymbolTable(HashTable *table,
    const char *key, void **result)
{
    RtsSymbolInfo *pinfo = lookupStrHashTable(table, key);
    if (!pinfo) {
        *result = NULL;
        return HS_BOOL_FALSE;
    }
    if (pinfo->weak)
        IF_DEBUG(linker, debugBelch("lookup: promoting %s\n", key));
    /* Once it's looked up, it can no longer be overridden */
    pinfo->weak = HS_BOOL_FALSE;

    *result = pinfo->value;
    return HS_BOOL_TRUE;
}

static void ghciRemoveSymbolTable(HashTable *table, const char *key,
    ObjectCode *owner)
{
    RtsSymbolInfo *pinfo = lookupStrHashTable(table, key);
    if (!pinfo || owner != pinfo->owner) return;
    removeStrHashTable(table, key, NULL);
    stgFree(pinfo);
}
437 438 439
/* -----------------------------------------------------------------------------
 * initialize the object linker
 */
440 441 442 443


static int linker_init_done = 0 ;

444
#if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
445
static void *dl_prog_handle;
446 447 448 449 450
static regex_t re_invalid;
static regex_t re_realso;
#ifdef THREADED_RTS
static Mutex dl_mutex; // mutex to protect dlopen/dlerror critical section
#endif
451 452
#elif defined(OBJFORMAT_PEi386)
void addDLLHandle(pathchar* dll_name, HINSTANCE instance);
453
#endif
454

455 456 457 458
void initLinker (void)
{
    // default to retaining CAFs for backwards compatibility.  Most
    // users will want initLinker_(0): otherwise unloadObj() will not
Gabor Greif's avatar
Gabor Greif committed
459
    // be able to unload object files when they contain CAFs.
460 461 462
    initLinker_(1);
}

463
void
464
initLinker_ (int retain_cafs)
465
{
466
    RtsSymbolVal *sym;
Simon Marlow's avatar
Simon Marlow committed
467
#if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
468
    int compileResult;
Simon Marlow's avatar
Simon Marlow committed
469
#endif
470

471 472
    IF_DEBUG(linker, debugBelch("initLinker: start\n"));

473
    /* Make initLinker idempotent, so we can call it
Gabor Greif's avatar
typo  
Gabor Greif committed
474
       before every relevant operation; that means we
475
       don't need to initialise the linker separately */
Ian Lynagh's avatar
Ian Lynagh committed
476 477 478
    if (linker_init_done == 1) {
        IF_DEBUG(linker, debugBelch("initLinker: idempotent return\n"));
        return;
479 480
    } else {
        linker_init_done = 1;
481 482
    }

483 484 485
    objects = NULL;
    unloaded_objects = NULL;

486 487
#if defined(THREADED_RTS)
    initMutex(&linker_mutex);
488
    initMutex(&linker_unloaded_mutex);
489
#if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
490
    initMutex(&dl_mutex);
491
#endif
492
#endif
493 494 495 496
    symhash = allocStrHashTable();

    /* populate the symbol table with stuff from the RTS */
    for (sym = rtsSyms; sym->lbl != NULL; sym++) {
497 498 499 500
        if (! ghciInsertSymbolTable(WSTR("(GHCi built-in symbols)"),
                                    symhash, sym->lbl, sym->addr, HS_BOOL_FALSE, NULL)) {
            barf("ghciInsertSymbolTable failed");
        }
Ian Lynagh's avatar
Ian Lynagh committed
501
        IF_DEBUG(linker, debugBelch("initLinker: inserting rts symbol %s, %p\n", sym->lbl, sym->addr));
502
    }
503
#   if defined(OBJFORMAT_MACHO) && defined(powerpc_HOST_ARCH)
504 505
    machoInitSymbolsWithoutUnderscore();
#   endif
506 507 508 509 510
    /* GCC defines a special symbol __dso_handle which is resolved to NULL if
       referenced from a statically linked module. We need to mimic this, but
       we cannot use NULL because we use it to mean nonexistent symbols. So we
       use an arbitrary (hopefully unique) address here.
    */
511 512 513 514
    if (! ghciInsertSymbolTable(WSTR("(GHCi special symbols)"),
                                symhash, "__dso_handle", (void *)0x12345687, HS_BOOL_FALSE, NULL)) {
        barf("ghciInsertSymbolTable failed");
    }
515

Gabor Greif's avatar
Gabor Greif committed
516
    // Redirect newCAF to newRetainedCAF if retain_cafs is true.
517 518
    if (! ghciInsertSymbolTable(WSTR("(GHCi built-in symbols)"), symhash,
                                MAYBE_LEADING_UNDERSCORE_STR("newCAF"),
519
                                retain_cafs ? newRetainedCAF : newGCdCAF,
520 521 522
                                HS_BOOL_FALSE, NULL)) {
        barf("ghciInsertSymbolTable failed");
    }
523

524
#   if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
525
#   if defined(RTLD_DEFAULT)
526 527
    dl_prog_handle = RTLD_DEFAULT;
#   else
528
    dl_prog_handle = dlopen(NULL, RTLD_LAZY);
529
#   endif /* RTLD_DEFAULT */
530 531

    compileResult = regcomp(&re_invalid,
532
           "(([^ \t()])+\\.so([^ \t:()])*):([ \t])*(invalid ELF header|file too short)",
533
           REG_EXTENDED);
Ian Lynagh's avatar
Ian Lynagh committed
534 535 536
    if (compileResult != 0) {
        barf("Compiling re_invalid failed");
    }
537
    compileResult = regcomp(&re_realso,
538
           "(GROUP|INPUT) *\\( *([^ )]+)",
539
           REG_EXTENDED);
Ian Lynagh's avatar
Ian Lynagh committed
540 541 542
    if (compileResult != 0) {
        barf("Compiling re_realso failed");
    }
543
#   endif
544

545
#if !defined(ALWAYS_PIC) && defined(x86_64_HOST_ARCH)
546 547 548 549 550
    if (RtsFlags.MiscFlags.linkerMemBase != 0) {
        // User-override for mmap_32bit_base
        mmap_32bit_base = (void*)RtsFlags.MiscFlags.linkerMemBase;
    }
#endif
551 552 553 554 555 556 557

#if defined(mingw32_HOST_OS)
    /*
     * These two libraries cause problems when added to the static link,
     * but are necessary for resolving symbols in GHCi, hence we load
     * them manually here.
     */
558 559
    addDLL(WSTR("msvcrt"));
    addDLL(WSTR("kernel32"));
560
    addDLLHandle(WSTR("*.exe"), GetModuleHandle(NULL));
561
#endif
562

563
#if USE_MMAP
564
    m32_allocator_init(&allocator);
Tamar Christina's avatar
Tamar Christina committed
565
#endif
566

567 568
    IF_DEBUG(linker, debugBelch("initLinker: done\n"));
    return;
569 570
}

571 572 573 574 575 576 577 578 579 580 581
void
exitLinker( void ) {
#if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
   if (linker_init_done == 1) {
      regfree(&re_invalid);
      regfree(&re_realso);
#ifdef THREADED_RTS
      closeMutex(&dl_mutex);
#endif
   }
#endif
582 583 584
   if (linker_init_done == 1) {
       freeHashTable(symhash, free);
   }
585 586 587
#ifdef THREADED_RTS
   closeMutex(&linker_mutex);
#endif
588 589
}

590
/* -----------------------------------------------------------------------------
591 592 593
 *                  Loading DLL or .so dynamic libraries
 * -----------------------------------------------------------------------------
 *
594 595 596 597
 * Add a DLL from which symbols may be found.  In the ELF case, just
 * do RTLD_GLOBAL-style add, so no further messing around needs to
 * happen in order that symbols in the loaded .so are findable --
 * lookupSymbol() will subsequently see them by dlsym on the program's
598 599
 * dl-handle.  Returns NULL if success, otherwise ptr to an err msg.
 *
600
 * In the PEi386 case, open the DLLs and put handles to them in a
601
 * linked list.  When looking for a symbol, try all handles in the
602 603 604 605 606
 * list.  This means that we need to load even DLLs that are guaranteed
 * to be in the ghc.exe image already, just so we can get a handle
 * to give to loadSymbol, so that we can find the symbols.  For such
 * libraries, the LoadLibrary call should be a no-op except for returning
 * the handle.
607
 *
608
 */
609 610 611 612 613 614

#if defined(OBJFORMAT_PEi386)
/* A record for storing handles into DLLs. */

typedef
   struct _OpenedDLL {
615
      pathchar*          name;
616 617
      struct _OpenedDLL* next;
      HINSTANCE instance;
618
   }
619 620 621 622
   OpenedDLL;

/* A list thereof. */
static OpenedDLL* opened_dlls = NULL;
623 624 625 626 627 628 629 630 631 632 633 634

/* A record for storing indirectly linked functions from DLLs. */
typedef
   struct _IndirectAddr {
      void*                 addr;
      struct _IndirectAddr* next;
   }
   IndirectAddr;

/* A list thereof. */
static IndirectAddr* indirects = NULL;

635 636 637 638 639 640 641 642 643 644
/* Adds a DLL instance to the list of DLLs in which to search for symbols. */
void addDLLHandle(pathchar* dll_name, HINSTANCE instance) {
   OpenedDLL* o_dll;
   o_dll = stgMallocBytes( sizeof(OpenedDLL), "addDLLHandle" );
   o_dll->name     = dll_name ? pathdup(dll_name) : NULL;
   o_dll->instance = instance;
   o_dll->next     = opened_dlls;
   opened_dlls     = o_dll;
}

645 646
#endif

647
#  if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
648

649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670
/* Suppose in ghci we load a temporary SO for a module containing
       f = 1
   and then modify the module, recompile, and load another temporary
   SO with
       f = 2
   Then as we don't unload the first SO, dlsym will find the
       f = 1
   symbol whereas we want the
       f = 2
   symbol. We therefore need to keep our own SO handle list, and
   try SOs in the right order. */

typedef
   struct _OpenedSO {
      struct _OpenedSO* next;
      void *handle;
   }
   OpenedSO;

/* A list thereof. */
static OpenedSO* openedSOs = NULL;

671
static const char *
672 673
internal_dlopen(const char *dll_name)
{
674
   OpenedSO* o_so;
675
   void *hdl;
676 677
   const char *errmsg;
   char *errmsg_copy;
678

679 680
   // omitted: RTLD_NOW
   // see http://www.haskell.org/pipermail/cvs-ghc/2007-September/038570.html
681 682 683 684 685 686 687 688 689 690
   IF_DEBUG(linker,
      debugBelch("internal_dlopen: dll_name = '%s'\n", dll_name));

   //-------------- Begin critical section ------------------
   // This critical section is necessary because dlerror() is not
   // required to be reentrant (see POSIX -- IEEE Std 1003.1-2008)
   // Also, the error message returned must be copied to preserve it
   // (see POSIX also)

   ACQUIRE_LOCK(&dl_mutex);
691
   hdl = dlopen(dll_name, RTLD_LAZY|RTLD_LOCAL); /* see Note [RTLD_LOCAL] */
dons's avatar
dons committed
692

693
   errmsg = NULL;
694 695 696 697
   if (hdl == NULL) {
      /* dlopen failed; return a ptr to the error msg. */
      errmsg = dlerror();
      if (errmsg == NULL) errmsg = "addDLL: unknown error";
698 699 700
      errmsg_copy = stgMallocBytes(strlen(errmsg)+1, "addDLL");
      strcpy(errmsg_copy, errmsg);
      errmsg = errmsg_copy;
701 702 703 704 705
   } else {
      o_so = stgMallocBytes(sizeof(OpenedSO), "addDLL");
      o_so->handle = hdl;
      o_so->next   = openedSOs;
      openedSOs    = o_so;
706
   }
707

708 709 710 711 712
   RELEASE_LOCK(&dl_mutex);
   //--------------- End critical section -------------------

   return errmsg;
}
713

714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731
/*
  Note [RTLD_LOCAL]

  In GHCi we want to be able to override previous .so's with newly
  loaded .so's when we recompile something.  This further implies that
  when we look up a symbol in internal_dlsym() we have to iterate
  through the loaded libraries (in order from most recently loaded to
  oldest) looking up the symbol in each one until we find it.

  However, this can cause problems for some symbols that are copied
  by the linker into the executable image at runtime - see #8935 for a
  lengthy discussion.  To solve that problem we need to look up
  symbols in the main executable *first*, before attempting to look
  them up in the loaded .so's.  But in order to make that work, we
  have to always call dlopen with RTLD_LOCAL, so that the loaded
  libraries don't populate the global symbol table.
*/

732
static void *
733
internal_dlsym(const char *symbol) {
734 735 736 737 738 739
    OpenedSO* o_so;
    void *v;

    // We acquire dl_mutex as concurrent dl* calls may alter dlerror
    ACQUIRE_LOCK(&dl_mutex);
    dlerror();
740 741 742 743 744 745 746
    // look in program first
    v = dlsym(dl_prog_handle, symbol);
    if (dlerror() == NULL) {
        RELEASE_LOCK(&dl_mutex);
        return v;
    }

747 748 749 750 751 752 753 754 755 756
    for (o_so = openedSOs; o_so != NULL; o_so = o_so->next) {
        v = dlsym(o_so->handle, symbol);
        if (dlerror() == NULL) {
            RELEASE_LOCK(&dl_mutex);
            return v;
        }
    }
    RELEASE_LOCK(&dl_mutex);
    return v;
}
757 758 759
#  endif

const char *
760
addDLL( pathchar *dll_name )
761 762 763 764 765 766
{
#  if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
   /* ------------------- ELF DLL loader ------------------- */

#define NMATCH 5
   regmatch_t match[NMATCH];
767
   const char *errmsg;
768 769 770 771 772 773 774 775 776 777
   FILE* fp;
   size_t match_length;
#define MAXLINE 1000
   char line[MAXLINE];
   int result;

   IF_DEBUG(linker, debugBelch("addDLL: dll_name = '%s'\n", dll_name));
   errmsg = internal_dlopen(dll_name);

   if (errmsg == NULL) {
778 779
      return NULL;
   }
780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801

   // GHC Trac ticket #2615
   // On some systems (e.g., Gentoo Linux) dynamic files (e.g. libc.so)
   // contain linker scripts rather than ELF-format object code. This
   // code handles the situation by recognizing the real object code
   // file name given in the linker script.
   //
   // If an "invalid ELF header" error occurs, it is assumed that the
   // .so file contains a linker script instead of ELF object code.
   // In this case, the code looks for the GROUP ( ... ) linker
   // directive. If one is found, the first file name inside the
   // parentheses is treated as the name of a dynamic library and the
   // code attempts to dlopen that file. If this is also unsuccessful,
   // an error message is returned.

   // see if the error message is due to an invalid ELF header
   IF_DEBUG(linker, debugBelch("errmsg = '%s'\n", errmsg));
   result = regexec(&re_invalid, errmsg, (size_t) NMATCH, match, 0);
   IF_DEBUG(linker, debugBelch("result = %i\n", result));
   if (result == 0) {
      // success -- try to read the named file as a linker script
      match_length = (size_t) stg_min((match[1].rm_eo - match[1].rm_so),
Ian Lynagh's avatar
Ian Lynagh committed
802
                                 MAXLINE-1);
803 804 805 806
      strncpy(line, (errmsg+(match[1].rm_so)),match_length);
      line[match_length] = '\0'; // make sure string is null-terminated
      IF_DEBUG(linker, debugBelch ("file name = '%s'\n", line));
      if ((fp = fopen(line, "r")) == NULL) {
Ian Lynagh's avatar
Ian Lynagh committed
807
         return errmsg; // return original error if open fails
808
      }
809
      // try to find a GROUP or INPUT ( ... ) command
810
      while (fgets(line, MAXLINE, fp) != NULL) {
Ian Lynagh's avatar
Ian Lynagh committed
811 812
         IF_DEBUG(linker, debugBelch("input line = %s", line));
         if (regexec(&re_realso, line, (size_t) NMATCH, match, 0) == 0) {
813 814
            // success -- try to dlopen the first named file
            IF_DEBUG(linker, debugBelch("match%s\n",""));
815
            line[match[2].rm_eo] = '\0';
816
            stgFree((void*)errmsg); // Free old message before creating new one
817
            errmsg = internal_dlopen(line+match[2].rm_so);
Ian Lynagh's avatar
Ian Lynagh committed
818 819
            break;
         }
820 821 822
         // if control reaches here, no GROUP or INPUT ( ... ) directive
         // was found and the original error message is returned to the
         // caller
823 824 825 826
      }
      fclose(fp);
   }
   return errmsg;
827

828
#  elif defined(OBJFORMAT_PEi386)
829
   /* ------------------- Win32 DLL loader ------------------- */
830

831
   pathchar*      buf;
832
   OpenedDLL* o_dll;
833
   HINSTANCE  instance;
834

835
   /* debugBelch("\naddDLL; dll_name = `%s'\n", dll_name); */
836 837 838

   /* See if we've already got it, and ignore if so. */
   for (o_dll = opened_dlls; o_dll != NULL; o_dll = o_dll->next) {
839
      if (0 == pathcmp(o_dll->name, dll_name))
840
         return NULL;
841 842
   }

843 844 845 846
   /* The file name has no suffix (yet) so that we can try
      both foo.dll and foo.drv

      The documentation for LoadLibrary says:
Ian Lynagh's avatar
Ian Lynagh committed
847 848 849 850 851
        If no file name extension is specified in the lpFileName
        parameter, the default library extension .dll is
        appended. However, the file name string can include a trailing
        point character (.) to indicate that the module name has no
        extension. */
852

853 854 855
   size_t bufsize = pathlen(dll_name) + 10;
   buf = stgMallocBytes(bufsize * sizeof(wchar_t), "addDLL");
   snwprintf(buf, bufsize, L"%s.DLL", dll_name);
856
   instance = LoadLibraryW(buf);
857
   if (instance == NULL) {
858 859
       if (GetLastError() != ERROR_MOD_NOT_FOUND) goto error;
       // KAA: allow loading of drivers (like winspool.drv)
860
       snwprintf(buf, bufsize, L"%s.DRV", dll_name);
861
       instance = LoadLibraryW(buf);
862 863 864
       if (instance == NULL) {
           if (GetLastError() != ERROR_MOD_NOT_FOUND) goto error;
           // #1883: allow loading of unix-style libfoo.dll DLLs
865
           snwprintf(buf, bufsize, L"lib%s.DLL", dll_name);
866
           instance = LoadLibraryW(buf);
867 868 869 870
           if (instance == NULL) {
               goto error;
           }
       }
871
   }
sof's avatar
sof committed
872
   stgFree(buf);
873

874
   addDLLHandle(dll_name, instance);
875 876

   return NULL;
877 878 879

error:
   stgFree(buf);
880
   sysErrorBelch("%" PATH_FMT, dll_name);
Simon Marlow's avatar
Simon Marlow committed
881

882 883
   /* LoadLibrary failed; return a ptr to the error msg. */
   return "addDLL: could not load DLL";
Simon Marlow's avatar
Simon Marlow committed
884 885 886 887

#  else
   barf("addDLL: not implemented on this platform");
#  endif
888 889
}

890 891
/* -----------------------------------------------------------------------------
 * insert a symbol in the hash table
892 893
 *
 * Returns: 0 on failure, nozero on success
894
 */
895
HsInt insertSymbol(pathchar* obj_name, char* key, void* data)
896
{
897
    return ghciInsertSymbolTable(obj_name, symhash, key, data, HS_BOOL_FALSE, NULL);
898 899
}

900 901
/* -----------------------------------------------------------------------------
 * lookup a symbol in the hash table
902
 */
903
static void* lookupSymbol_ (char *lbl)
904
{
905
    void *val;
906
    IF_DEBUG(linker, debugBelch("lookupSymbol: looking up %s\n", lbl));
907

908
    ASSERT(symhash != NULL);
909

910
    if (!ghciLookupSymbolTable(symhash, lbl, &val)) {
Ian Lynagh's avatar
Ian Lynagh committed
911
        IF_DEBUG(linker, debugBelch("lookupSymbol: symbol not found\n"));
912
#       if defined(OBJFORMAT_ELF)
913
        return internal_dlsym(lbl);
914
#       elif defined(OBJFORMAT_MACHO)
915

916
        /* HACK: On OS X, all symbols are prefixed with an underscore.
917
                 However, dlsym wants us to omit the leading underscore from the
918
                 symbol name -- the dlsym routine puts it back on before searching
Austin Seipp's avatar
Austin Seipp committed
919
                 for the symbol. For now, we simply strip it off here (and ONLY
920 921
                 here).
        */
922
        IF_DEBUG(linker, debugBelch("lookupSymbol: looking up %s with dlsym\n", lbl));
Austin Seipp's avatar
Austin Seipp committed
923
        ASSERT(lbl[0] == '_');
924
        return internal_dlsym(lbl + 1);
925
#       elif defined(OBJFORMAT_PEi386)
926
        void* sym;
927

928 929 930 931
/* See Note [mingw-w64 name decoration scheme] */
#ifndef x86_64_HOST_ARCH
         zapTrailingAtSign ( (unsigned char*)lbl );
#endif
Simon Marlow's avatar
Simon Marlow committed
932
        sym = lookupSymbolInDLLs((unsigned char*)lbl);
933
        return sym; // might be NULL if not found
934

ken's avatar
ken committed
935 936 937
#       else
        ASSERT(2+2 == 5);
        return NULL;
938
#       endif
939
    } else {
Ian Lynagh's avatar
Ian Lynagh committed
940 941
        IF_DEBUG(linker, debugBelch("lookupSymbol: value of %s is %p\n", lbl, val));
        return val;
942 943 944
    }
}

945 946 947 948 949 950 951 952
void* lookupSymbol( char *lbl )
{
    ACQUIRE_LOCK(&linker_mutex);
    char *r = lookupSymbol_(lbl);
    RELEASE_LOCK(&linker_mutex);
    return r;
}

953
/* -----------------------------------------------------------------------------
Gabor Greif's avatar
Gabor Greif committed
954
   Create a StablePtr for a foreign export.  This is normally called by
955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983
   a C function with __attribute__((constructor)), which is generated
   by GHC and linked into the module.

   If the object code is being loaded dynamically, then we remember
   which StablePtrs were allocated by the constructors and free them
   again in unloadObj().
   -------------------------------------------------------------------------- */

static ObjectCode *loading_obj = NULL;

StgStablePtr foreignExportStablePtr (StgPtr p)
{
    ForeignExportStablePtr *fe_sptr;
    StgStablePtr *sptr;

    sptr = getStablePtr(p);

    if (loading_obj != NULL) {
        fe_sptr = stgMallocBytes(sizeof(ForeignExportStablePtr),
                                 "foreignExportStablePtr");
        fe_sptr->stable_ptr = sptr;
        fe_sptr->next = loading_obj->stable_ptrs;
        loading_obj->stable_ptrs = fe_sptr;
    }

    return sptr;
}


984 985 986 987 988 989 990 991 992 993 994 995 996 997
/* -----------------------------------------------------------------------------
 * Debugging aid: look in GHCi's object symbol tables for symbols
 * within DELTA bytes of the specified address, and show their names.
 */
#ifdef DEBUG
void ghci_enquire ( char* addr );

void ghci_enquire ( char* addr )
{
   int   i;
   char* sym;
   char* a;
   const int DELTA = 64;
   ObjectCode* oc;
998

999 1000 1001 1002 1003
   for (oc = objects; oc; oc = oc->next) {
      for (i = 0; i < oc->n_symbols; i++) {
         sym = oc->symbols[i];
         if (sym == NULL) continue;
         a = NULL;
1004
         if (a == NULL) {
1005
            ghciLookupSymbolTable(symhash, sym, (void **)&a);
Ian Lynagh's avatar
Ian Lynagh committed
1006
         }
1007
         if (a == NULL) {
Ian Lynagh's avatar
Ian Lynagh committed
1008
             // debugBelch("ghci_enquire: can't find %s\n", sym);
1009
         }
1010
         else if (addr-DELTA <= a && a <= addr+DELTA) {
1011
            debugBelch("%p + %3d  ==  `%s'\n", addr, (int)(a - addr), sym);
1012 1013 1014 1015 1016 1017
         }
      }
   }
}
#endif

1018
#if USE_MMAP
1019
#define ROUND_UP(x,size) ((x + size - 1) & ~(size - 1))
1020 1021 1022 1023 1024 1025
#define ROUND_DOWN(x,size) (x & ~(size - 1))

static StgWord getPageSize(void)
{
    static StgWord pagesize = 0;
    if (pagesize == 0) {
Simon Marlow's avatar
Simon Marlow committed
1026
        pagesize = sysconf(_SC_PAGESIZE);
1027
    }
Simon Marlow's avatar
Simon Marlow committed
1028
    return pagesize;
1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041
}

static StgWord roundUpToPage (StgWord size)
{
    return ROUND_UP(size, getPageSize());
}

#ifdef OBJFORMAT_ELF
static StgWord roundDownToPage (StgWord size)
{
    return ROUND_DOWN(size, getPageSize());
}
#endif
1042

1043 1044 1045
//
// Returns NULL on failure.
//
1046
static void * mmapForLinker (size_t bytes, nat flags, int fd, int offset)