dyn_load.c

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    if (!did_something) {
	/* dl_iterate_phdr may forget the static data segment in	*/
	/* statically linked executables.				*/
	GC_add_roots_inner(DATASTART, (char *)(DATAEND), TRUE);
#       if defined(DATASTART2)
          GC_add_roots_inner(DATASTART2, (char *)(DATAEND2), TRUE);
#       endif
    }

    return TRUE;
  } else {
    return FALSE;
  }
}

/* Do we need to separately register the main static data segment? */
GC_bool GC_register_main_static_data()
{
  return (dl_iterate_phdr == 0);
}

#define HAVE_REGISTER_MAIN_STATIC_DATA

# else /* !LINUX || version(glibc) < 2.2.4 */

/* Dynamic loading code for Linux running ELF. Somewhat tested on
 * Linux/x86, untested but hopefully should work on Linux/Alpha. 
 * This code was derived from the Solaris/ELF support. Thanks to
 * whatever kind soul wrote that.  - Patrick Bridges */

/* This doesn't necessarily work in all cases, e.g. with preloaded
 * dynamic libraries.						*/

#if defined(NETBSD)
#  include <sys/exec_elf.h>
/* for compatibility with 1.4.x */
#  ifndef DT_DEBUG
#  define DT_DEBUG     21
#  endif
#  ifndef PT_LOAD
#  define PT_LOAD      1
#  endif
#  ifndef PF_W
#  define PF_W         2
#  endif
#else
#  include <elf.h>
#endif
#include <link.h>

# endif

#ifdef __GNUC__
# pragma weak _DYNAMIC
#endif
extern ElfW(Dyn) _DYNAMIC[];

static struct link_map *
GC_FirstDLOpenedLinkMap()
{
    ElfW(Dyn) *dp;
    static struct link_map *cachedResult = 0;

    if( _DYNAMIC == 0) {
        return(0);
    }
    if( cachedResult == 0 ) {
        int tag;
        for( dp = _DYNAMIC; (tag = dp->d_tag) != 0; dp++ ) {
	    /* FIXME: The DT_DEBUG header is not mandated by the	*/
	    /* ELF spec.  This code appears to be dependent on		*/
	    /* idiosynchracies of older GNU tool chains.  If this code	*/
	    /* fails for you, the real problem is probably that it is	*/
	    /* being used at all.  You should be getting the 		*/
	    /* dl_iterate_phdr version.					*/
            if( tag == DT_DEBUG ) {
                struct link_map *lm
                        = ((struct r_debug *)(dp->d_un.d_ptr))->r_map;
                if( lm != 0 ) cachedResult = lm->l_next; /* might be NIL */
                break;
            }
        }
    }
    return cachedResult;
}


void GC_register_dynamic_libraries()
{
  struct link_map *lm;
  

# ifdef HAVE_DL_ITERATE_PHDR
    if (GC_register_dynamic_libraries_dl_iterate_phdr()) {
	return;
    }
# endif
  lm = GC_FirstDLOpenedLinkMap();
  for (lm = GC_FirstDLOpenedLinkMap();
       lm != (struct link_map *) 0;  lm = lm->l_next)
    {
	ElfW(Ehdr) * e;
        ElfW(Phdr) * p;
        unsigned long offset;
        char * start;
        register int i;
        
	e = (ElfW(Ehdr) *) lm->l_addr;
        p = ((ElfW(Phdr) *)(((char *)(e)) + e->e_phoff));
        offset = ((unsigned long)(lm->l_addr));
        for( i = 0; i < (int)(e->e_phnum); ((i++),(p++)) ) {
          switch( p->p_type ) {
            case PT_LOAD:
              {
                if( !(p->p_flags & PF_W) ) break;
                start = ((char *)(p->p_vaddr)) + offset;
                GC_add_roots_inner(start, start + p->p_memsz, TRUE);
              }
              break;
            default:
              break;
          }
	}
    }
}

#endif /* !USE_PROC_FOR_LIBRARIES */

#endif /* LINUX */

#if defined(IRIX5) || (defined(USE_PROC_FOR_LIBRARIES) && !defined(LINUX))

#include <sys/procfs.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <elf.h>
#include <errno.h>
#include <signal.h>  /* Only for the following test. */
#ifndef _sigargs
# define IRIX6
#endif

extern void * GC_roots_present();
	/* The type is a lie, since the real type doesn't make sense here, */
	/* and we only test for NULL.					   */


/* We use /proc to track down all parts of the address space that are	*/
/* mapped by the process, and throw out regions we know we shouldn't	*/
/* worry about.  This may also work under other SVR4 variants.		*/
void GC_register_dynamic_libraries()
{
    static int fd = -1;
    char buf[30];
    static prmap_t * addr_map = 0;
    static int current_sz = 0;	/* Number of records currently in addr_map */
    static int needed_sz;	/* Required size of addr_map		*/
    register int i;
    register long flags;
    register ptr_t start;
    register ptr_t limit;
    ptr_t heap_start = (ptr_t)HEAP_START;
    ptr_t heap_end = heap_start;

#   ifdef SUNOS5DL
#     define MA_PHYS 0
#   endif /* SUNOS5DL */

    if (fd < 0) {
      sprintf(buf, "/proc/%d", getpid());
	/* The above generates a lint complaint, since pid_t varies.	*/
	/* It's unclear how to improve this.				*/
      fd = open(buf, O_RDONLY);
      if (fd < 0) {
    	ABORT("/proc open failed");
      }
    }
    if (ioctl(fd, PIOCNMAP, &needed_sz) < 0) {
	GC_err_printf2("fd = %d, errno = %d\n", fd, errno);
    	ABORT("/proc PIOCNMAP ioctl failed");
    }
    if (needed_sz >= current_sz) {
        current_sz = needed_sz * 2 + 1;
        		/* Expansion, plus room for 0 record */
        addr_map = (prmap_t *)GC_scratch_alloc((word)
						(current_sz * sizeof(prmap_t)));
    }
    if (ioctl(fd, PIOCMAP, addr_map) < 0) {
        GC_err_printf4("fd = %d, errno = %d, needed_sz = %d, addr_map = 0x%X\n",
                        fd, errno, needed_sz, addr_map);
    	ABORT("/proc PIOCMAP ioctl failed");
    };
    if (GC_n_heap_sects > 0) {
    	heap_end = GC_heap_sects[GC_n_heap_sects-1].hs_start
    			+ GC_heap_sects[GC_n_heap_sects-1].hs_bytes;
    	if (heap_end < GC_scratch_last_end_ptr) heap_end = GC_scratch_last_end_ptr; 
    }
    for (i = 0; i < needed_sz; i++) {
        flags = addr_map[i].pr_mflags;
        if ((flags & (MA_BREAK | MA_STACK | MA_PHYS
		      | MA_FETCHOP | MA_NOTCACHED)) != 0) goto irrelevant;
        if ((flags & (MA_READ | MA_WRITE)) != (MA_READ | MA_WRITE))
            goto irrelevant;
          /* The latter test is empirically useless in very old Irix	*/
	  /* versions.  Other than the					*/
          /* main data and stack segments, everything appears to be	*/
          /* mapped readable, writable, executable, and shared(!!).	*/
          /* This makes no sense to me.	- HB				*/
        start = (ptr_t)(addr_map[i].pr_vaddr);
        if (GC_roots_present(start)) goto irrelevant;
        if (start < heap_end && start >= heap_start)
        	goto irrelevant;
#	ifdef MMAP_STACKS
	  if (GC_is_thread_stack(start)) goto irrelevant;
#	endif /* MMAP_STACKS */

        limit = start + addr_map[i].pr_size;
	/* The following seemed to be necessary for very old versions 	*/
	/* of Irix, but it has been reported to discard relevant	*/
	/* segments under Irix 6.5.  					*/
#	ifndef IRIX6
	  if (addr_map[i].pr_off == 0 && strncmp(start, ELFMAG, 4) == 0) {
	    /* Discard text segments, i.e. 0-offset mappings against	*/
	    /* executable files which appear to have ELF headers.	*/
	    caddr_t arg;
	    int obj;
#	    define MAP_IRR_SZ 10
	    static ptr_t map_irr[MAP_IRR_SZ];
	    				/* Known irrelevant map entries	*/
	    static int n_irr = 0;
	    struct stat buf;
	    register int i;
	    
	    for (i = 0; i < n_irr; i++) {
	        if (map_irr[i] == start) goto irrelevant;
	    }
	    arg = (caddr_t)start;
	    obj = ioctl(fd, PIOCOPENM, &arg);
	    if (obj >= 0) {
	        fstat(obj, &buf);
	        close(obj);
	        if ((buf.st_mode & 0111) != 0) {
	            if (n_irr < MAP_IRR_SZ) {
	                map_irr[n_irr++] = start;
	            }
	            goto irrelevant;
	        }
	    }
	  }
#	endif /* !IRIX6 */
        GC_add_roots_inner(start, limit, TRUE);
      irrelevant: ;
    }
    /* Dont keep cached descriptor, for now.  Some kernels don't like us */
    /* to keep a /proc file descriptor around during kill -9.		 */
    	if (close(fd) < 0) ABORT("Couldnt close /proc file");
	fd = -1;
}

# endif /* USE_PROC || IRIX5 */

# if defined(MSWIN32) || defined(MSWINCE)

# define WIN32_LEAN_AND_MEAN
# define NOSERVICE
# include <windows.h>
# include <stdlib.h>

  /* We traverse the entire address space and register all segments 	*/
  /* that could possibly have been written to.				*/
  
  extern GC_bool GC_is_heap_base (ptr_t p);

# ifdef GC_WIN32_THREADS
    extern void GC_get_next_stack(char *start, char **lo, char **hi);
    void GC_cond_add_roots(char *base, char * limit)
    {
      char * curr_base = base;
      char * next_stack_lo;
      char * next_stack_hi;
   
      if (base == limit) return;
      for(;;) {
	  GC_get_next_stack(curr_base, &next_stack_lo, &next_stack_hi);
	  if (next_stack_lo >= limit) break;
	  GC_add_roots_inner(curr_base, next_stack_lo, TRUE);
	  curr_base = next_stack_hi;
      }
      if (curr_base < limit) GC_add_roots_inner(curr_base, limit, TRUE);
    }
# else
    void GC_cond_add_roots(char *base, char * limit)
    {
      char dummy;
      char * stack_top
	 = (char *) ((word)(&dummy) & ~(GC_sysinfo.dwAllocationGranularity-1));
      if (base == limit) return;
      if (limit > stack_top && base < GC_stackbottom) {
    	  /* Part of the stack; ignore it. */
    	  return;
      }
      GC_add_roots_inner(base, limit, TRUE);
    }
# endif

# ifdef MSWINCE
  /* Do we need to separately register the main static data segment? */
  GC_bool GC_register_main_static_data()
  {
    return FALSE;
  }
# else /* win32 */
  extern GC_bool GC_no_win32_dlls;

  GC_bool GC_register_main_static_data()
  {
    return GC_no_win32_dlls;
  }
# endif /* win32 */
  
# define HAVE_REGISTER_MAIN_STATIC_DATA

  /* The frame buffer testing code is dead in this version.	*/
  /* We leave it here temporarily in case the switch to just 	*/
  /* testing for MEM_IMAGE sections causes un expected 		*/
  /* problems.							*/
  GC_bool GC_warn_fb = TRUE;	/* Warn about traced likely 	*/
  				/* graphics memory.		*/
  GC_bool GC_disallow_ignore_fb = FALSE;
  int GC_ignore_fb_mb;	/* Ignore mappings bigger than the 	*/
  			/* specified number of MB.		*/
  GC_bool GC_ignore_fb = FALSE; /* Enable frame buffer 	*/
  				/* checking.		*/
  
  /* Issue warning if tracing apparent framebuffer. 		*/
  /* This limits us to one warning, and it's a back door to	*/
  /* disable that.						*/
 
  /* Should [start, start+len) be treated as a frame buffer	*/
  /* and ignored?						*/
  /* Unfortunately, we currently are not quite sure how to tell	*/
  /* this automatically, and rely largely on user input.	*/
  /* We expect that any mapping with type MEM_MAPPED (which 	*/
  /* apparently excludes library data sections) can be safely	*/
  /* ignored.  But we're too chicken to do that in this 	*/
  /* version.							*/
  /* Based on a very limited sample, it appears that:		*/
  /* 	- Frame buffer mappings appear as mappings of large	*/
  /*	  length, usually a bit less than a power of two.	*/
  /*	- The definition of "a bit less" in the above cannot	*/
  /*	  be made more precise.					*/
  /*	- Have a starting address at best 64K aligned.		*/
  /*	- Have type == MEM_MAPPED.				*/
  static GC_bool is_frame_buffer(ptr_t start, size_t len, DWORD tp)
  {
    static GC_bool initialized = FALSE;
#   define MB (1024*1024)
#   define DEFAULT_FB_MB 15
#   define MIN_FB_MB 3

    if (GC_disallow_ignore_fb || tp != MEM_MAPPED) return FALSE;
    if (!initialized) {
      char * ignore_fb_string =  GETENV("GC_IGNORE_FB");

      if (0 != ignore_fb_string) {
	while (*ignore_fb_string == ' ' || *ignore_fb_string == '\t')
	  ++ignore_fb_string;
	if (*ignore_fb_string == '\0') {
	  GC_ignore_fb_mb = DEFAULT_FB_MB;
	} else {
	  GC_ignore_fb_mb = atoi(ignore_fb_string);
	  if (GC_ignore_fb_mb < MIN_FB_MB) {
	    WARN("Bad GC_IGNORE_FB value.  Using %ld\n", DEFAULT_FB_MB);
	    GC_ignore_fb_mb = DEFAULT_FB_MB;
	  }
	}
	GC_ignore_fb = TRUE;
      } else {
	GC_ignore_fb_mb = DEFAULT_FB_MB;  /* For warning */
      }
      initialized = TRUE;
    }
    if (len >= ((size_t)GC_ignore_fb_mb << 20)) {
      if (GC_ignore_fb) {
	return TRUE;
      } else {
	if (GC_warn_fb) {
	  WARN("Possible frame buffer mapping at 0x%lx: \n"
	       "\tConsider setting GC_IGNORE_FB to improve performance.\n",
	       start);
	  GC_warn_fb = FALSE;
	}
	return FALSE;
      }
    } else {
      return FALSE;
    }
  }

# ifdef DEBUG_VIRTUALQUERY
  void GC_dump_meminfo(MEMORY_BASIC_INFORMATION *buf)
  {
    GC_printf4("BaseAddress = %lx, AllocationBase = %lx, RegionSize = %lx(%lu)\n",
	       buf -> BaseAddress, buf -> AllocationBase, buf -> RegionSize,
	       buf -> RegionSize);
    GC_printf4("\tAllocationProtect = %lx, State = %lx, Protect = %lx, "
	       "Type = %lx\n",
	       buf -> AllocationProtect, buf -> State, buf -> Protect,
	       buf -> Type);
  }
# endif /* DEBUG_VIRTUALQUERY */

  void GC_register_dynamic_libraries()
  {
    MEMORY_BASIC_INFORMATION buf;
    DWORD result;
    DWORD protect;
    LPVOID p;
    char * base;
    char * limit, * new_limit;

#   ifdef MSWIN32
      if (GC_no_win32_dlls) return;
#   endif
    base = limit = p = GC_sysinfo.lpMinimumApplicationAddress;
#   if defined(MSWINCE) && !defined(_WIN32_WCE_EMULATION)
    /* Only the first 32 MB of address space belongs to the current process */
    while (p < (LPVOID)0x02000000) {
        result = VirtualQuery(p, &buf, sizeof(buf));
	if (result == 0) {
	    /* Page is free; advance to the next possible allocation base */
	    new_limit = (char *)
		(((DWORD) p + GC_sysinfo.dwAllocationGranularity)
		 & ~(GC_sysinfo.dwAllocationGranularity-1));