c-pch.c (c_common_no_more_pch): Update for gt_pch_use_address extra arguments.

        * c-pch.c (c_common_no_more_pch): Update for gt_pch_use_address
        extra arguments.
        * config.host (*-*-solaris2*, *-*-linux*): Add out_host_hook_obj
        and host_xmake_file fragments.
        * ggc-common.c (gt_pch_save): Update for gt_pch_get_address change.
        (gt_pch_restore): Similarly for gt_pch_use_address.
        (default_gt_pch_get_address): New.
        (mmap_gt_pch_get_address): Split out of gt_pch_save.
        (default_gt_pch_use_address): Split out of gt_pch_restore.
        (mmap_gt_pch_use_address): Likewise.
        * hooks.c (hook_voidp_size_t_null): Remove.
        (hook_bool_voidp_size_t_false): Remove.
        * hooks.h: Likewise.
        * hosthooks-def.h (HOST_HOOKS_GT_PCH_GET_ADDRESS): Use one of the
        default_ or mmap_ definitions.
        (HOST_HOOKS_GT_PCH_USE_ADDRESS): Likewise.
        * hosthooks.h (struct host_hooks): Update gt_pch_get_address
        and gt_pch_use_address.
        * config/host-linux.c, config/host-solaris.c: New files.
        * config/x-linux, config/x-solaris: New files.
        * config/rs6000/host-darwin.c darwin_rs6000_gt_pch_get_address):
        Update for changed definition.
        (darwin_rs6000_gt_pch_use_address): Likewise.
        * doc/hostconfig.texi: Update docs.

From-SVN: r79295

14 files changed, 400 insertions, 162 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 49ecfe6861f..4dd705f425c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,32 @@
 2004-03-10  Richard Henderson  <rth@redhat.com>
 
+	* c-pch.c (c_common_no_more_pch): Update for gt_pch_use_address
+	extra arguments.
+	* config.host (*-*-solaris2*, *-*-linux*): Add out_host_hook_obj
+	and host_xmake_file fragments.
+	* ggc-common.c (gt_pch_save): Update for gt_pch_get_address change.
+	(gt_pch_restore): Similarly for gt_pch_use_address.
+	(default_gt_pch_get_address): New.
+	(mmap_gt_pch_get_address): Split out of gt_pch_save.
+	(default_gt_pch_use_address): Split out of gt_pch_restore.
+	(mmap_gt_pch_use_address): Likewise.
+	* hooks.c (hook_voidp_size_t_null): Remove.
+	(hook_bool_voidp_size_t_false): Remove.
+	* hooks.h: Likewise.
+	* hosthooks-def.h (HOST_HOOKS_GT_PCH_GET_ADDRESS): Use one of the
+	default_ or mmap_ definitions.
+	(HOST_HOOKS_GT_PCH_USE_ADDRESS): Likewise.
+	* hosthooks.h (struct host_hooks): Update gt_pch_get_address
+	and gt_pch_use_address.
+	* config/host-linux.c, config/host-solaris.c: New files.
+	* config/x-linux, config/x-solaris: New files.
+	* config/rs6000/host-darwin.c darwin_rs6000_gt_pch_get_address): 
+	Update for changed definition.
+	(darwin_rs6000_gt_pch_use_address): Likewise.
+	* doc/hostconfig.texi: Update docs.
+
+2004-03-10  Richard Henderson  <rth@redhat.com>
+
 	PR c/14517
 	* c-decl.c (grokdeclarator): Don't warn for duplicate qualifiers
 	except for pedantic c90 mode.
diff --git a/gcc/c-pch.c b/gcc/c-pch.c
index 157061f9177..cf738759ee4 100644
--- a/gcc/c-pch.c
+++ b/gcc/c-pch.c
@@ -401,6 +401,6 @@ c_common_no_more_pch (void)
   if (cpp_get_callbacks (parse_in)->valid_pch)
     {
       cpp_get_callbacks (parse_in)->valid_pch = NULL;
-      host_hooks.gt_pch_use_address (NULL, 0);
+      host_hooks.gt_pch_use_address (NULL, 0, -1, 0);
     }
 }
diff --git a/gcc/config.host b/gcc/config.host
index fa6bced73db..19566518810 100644
--- a/gcc/config.host
+++ b/gcc/config.host
@@ -113,6 +113,8 @@ case ${host} in
     ;;
   i[34567]86-*-solaris2*)
     host_xm_defines="SMALL_ARG_MAX"
+    out_host_hook_obj=host-solaris.o
+    host_xmake_file=x-solaris
     ;;
   i[34567]86-*-sysv4*) # Intel 80386's running System V Release 4
     host_xm_defines="SMALL_ARG_MAX"
@@ -152,4 +154,12 @@ case ${host} in
     out_host_hook_obj=host-darwin.o
     host_xmake_file=rs6000/x-darwin
     ;;
+  *-*-solaris2*)
+    out_host_hook_obj=host-solaris.o
+    host_xmake_file=x-solaris
+    ;;
+  *-*-linux*)
+    out_host_hook_obj=host-linux.o
+    host_xmake_file=x-linux
+    ;;
 esac
diff --git a/gcc/config/host-linux.c b/gcc/config/host-linux.c
new file mode 100644
index 00000000000..7302d381dbe
--- /dev/null
+++ b/gcc/config/host-linux.c
@@ -0,0 +1,137 @@
+/* Linux host-specific hook definitions.
+   Copyright (C) 2004 Free Software Foundation, Inc.
+
+   This file is part of GCC.
+
+   GCC 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, or (at your
+   option) any later version.
+
+   GCC 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 GCC; see the file COPYING.  If not, write to the
+   Free Software Foundation, 59 Temple Place - Suite 330, Boston,
+   MA 02111-1307, USA.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include <sys/mman.h>
+#include "hosthooks.h"
+#include "hosthooks-def.h"
+
+
+/* Linux has a feature called exec-shield-randomize that perturbs the
+   address of non-fixed mapped segments by a (relatively) small amount.
+   The feature is intended to make it harder to attack the system with
+   buffer overflow attacks, since every invocation of a program will
+   have its libraries and data segments at slightly different addresses.
+
+   This feature causes us problems with PCH because it makes it that
+   much harder to acquire a stable location at which to map our PCH
+   data file.
+
+   [ The feature causes other points of non-determinism within the
+     compiler as well, so we'd *really* like to be able to have the
+     driver disable exec-shield-randomize for the process group, but
+     that isn't possible at present.  ]
+
+   We're going to try several things:
+
+      * Select an architecture specific address as "likely" and see
+	if that's free.  For our 64-bit hosts, we can easily choose
+	an address in Never Never Land.
+
+      * If exec-shield-randomize is disabled, then just use the
+	address chosen by mmap in step one.
+
+      * If exec-shield-randomize is enabled, then temporarily allocate
+	32M of memory as a buffer, then allocate PCH memory, then
+	free the buffer.  The theory here is that the perturbation is
+	no more than 16M, and so by allocating our buffer larger than
+	that we make it considerably more likely that the address will
+	be free when we want to load the data back.
+*/
+
+#undef HOST_HOOKS_GT_PCH_GET_ADDRESS
+#define HOST_HOOKS_GT_PCH_GET_ADDRESS linux_gt_pch_get_address
+
+/* For various ports, try to guess a fixed spot in the vm space
+   that's probably free.  */
+#if defined(__alpha)
+# define TRY_EMPTY_VM_SPACE	0x10000000000
+#elif defined(__ia64)
+# define TRY_EMPTY_VM_SPACE	0x2000000100000000
+#elif defined(__x86_64)
+# define TRY_EMPTY_VM_SPACE	0x1000000000
+#elif defined(__i386)
+# define TRY_EMPTY_VM_SPACE	0x60000000
+#else
+# define TRY_EMPTY_VM_SPACE	0
+#endif
+
+/* Determine a location where we might be able to reliably allocate SIZE
+   bytes.  FD is the PCH file, though we should return with the file 
+   unmapped.  */
+
+static void *
+linux_gt_pch_get_address (size_t size, int fd)
+{
+  size_t buffer_size = 32 * 1024 * 1024;
+  void *addr, *buffer;
+  FILE *f;
+  bool randomize_on;
+
+  addr = mmap ((void *)TRY_EMPTY_VM_SPACE, size, PROT_READ | PROT_WRITE,
+	       MAP_PRIVATE, fd, 0);
+
+  /* If we failed the map, that means there's *no* free space.  */
+  if (addr == (void *) MAP_FAILED)
+    return NULL;
+  /* Unmap the area before returning.  */
+  munmap (addr, size);
+
+  /* If we got the exact area we requested, then that's great.  */
+  if (TRY_EMPTY_VM_SPACE && addr == (void *) TRY_EMPTY_VM_SPACE)
+    return addr;
+
+  /* If we didn't, then we need to look to see if randomization is on.  */
+  f = fopen ("/proc/sys/kernel/exec-shield-randomize", "r");
+  randomize_on = false;
+  if (f != NULL)
+    {
+      char buf[100];
+      size_t c;
+
+      c = fread (buf, 1, sizeof buf - 1, f);
+      if (c > 0)
+	{
+	  buf[c] = '\0';
+	  randomize_on = (atoi (buf) > 0);
+	}
+      fclose (f);
+    }
+
+  /* If it isn't, then accept the address that mmap selected as fine.  */
+  if (!randomize_on)
+    return addr;
+
+  /* Otherwise, we need to try again with buffer space.  */
+  buffer = mmap (0, buffer_size, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
+  addr = mmap (0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+  if (buffer != (void *) MAP_FAILED)
+    munmap (buffer, buffer_size);
+  if (addr == (void *) MAP_FAILED)
+    return NULL;
+  munmap (addr, size);
+
+  return addr;
+}
+
+
+const struct host_hooks host_hooks = HOST_HOOKS_INITIALIZER;
diff --git a/gcc/config/host-solaris.c b/gcc/config/host-solaris.c
new file mode 100644
index 00000000000..43efc5c23e9
--- /dev/null
+++ b/gcc/config/host-solaris.c
@@ -0,0 +1,79 @@
+/* Solaris host-specific hook definitions.
+   Copyright (C) 2004 Free Software Foundation, Inc.
+
+   This file is part of GCC.
+
+   GCC 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, or (at your
+   option) any later version.
+
+   GCC 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 GCC; see the file COPYING.  If not, write to the
+   Free Software Foundation, 59 Temple Place - Suite 330, Boston,
+   MA 02111-1307, USA.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include <sys/mman.h>
+#include "hosthooks.h"
+#include "hosthooks-def.h"
+
+
+#undef HOST_HOOKS_GT_PCH_USE_ADDRESS
+#define HOST_HOOKS_GT_PCH_USE_ADDRESS sol_gt_pch_use_address
+
+/* Map SIZE bytes of FD+OFFSET at BASE.  Return 1 if we succeeded at 
+   mapping the data at BASE, -1 if we couldn't.  */
+
+static int
+sol_gt_pch_use_address (void *base, size_t size, int fd, size_t offset)
+{
+  void *addr;
+
+  /* We're called with size == 0 if we're not planning to load a PCH
+     file at all.  This allows the hook to free any static space that
+     we might have allocated at link time.  */
+  if (size == 0)
+    return -1;
+
+  addr = mmap (base, size, PROT_READ | PROT_WRITE, MAP_PRIVATE,
+	       fd, offset);
+
+  /* Solaris isn't good about honoring the mmap START parameter
+     without MAP_FIXED set.  Before we give up, search the desired
+     address space with mincore to see if the space is really free.
+  if (addr != base)
+    {
+      size_t page_size = getpagesize();
+      char one_byte;
+      size_t i;
+
+      if (addr != (void *) MAP_FAILED)
+	munmap (addr, size);
+
+      errno = 0;
+      for (i = 0; i < size; i += page_size)
+	if (mincore ((char *)base + i, page_size, (void *)&one_byte) == -1
+	    && errno == ENOMEM)
+	  continue; /* The page is not mapped.  */
+	else
+	  break;
+
+      if (i >= size)
+	addr = mmap (base, size, 
+		     PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_FIXED,
+		     fd, offset);
+    }
+
+  return addr == base ? 1 : -1;
+}
+
+
+const struct host_hooks host_hooks = HOST_HOOKS_INITIALIZER;
diff --git a/gcc/config/rs6000/host-darwin.c b/gcc/config/rs6000/host-darwin.c
index 7e8055690e4..1699d488560 100644
--- a/gcc/config/rs6000/host-darwin.c
+++ b/gcc/config/rs6000/host-darwin.c
@@ -137,22 +137,18 @@ darwin_rs6000_extra_signals (void)
     fatal_error ("While setting up signal handler: %m");
 }
 
-static void * darwin_rs6000_gt_pch_get_address (size_t);
-static bool darwin_rs6000_gt_pch_use_address (void *, size_t);
-
 #undef HOST_HOOKS_GT_PCH_GET_ADDRESS
 #define HOST_HOOKS_GT_PCH_GET_ADDRESS darwin_rs6000_gt_pch_get_address
 #undef HOST_HOOKS_GT_PCH_USE_ADDRESS
 #define HOST_HOOKS_GT_PCH_USE_ADDRESS darwin_rs6000_gt_pch_use_address
 
-
 /* Yes, this is really supposed to work.  */
 static char pch_address_space[1024*1024*1024] __attribute__((aligned (4096)));
 
 /* Return the address of the PCH address space, if the PCH will fit in it.  */
 
 static void *
-darwin_rs6000_gt_pch_get_address (size_t sz)
+darwin_rs6000_gt_pch_get_address (size_t sz, int fd ATTRIBUTE_UNUSED)
 {
   if (sz <= sizeof (pch_address_space))
     return pch_address_space;
@@ -163,11 +159,12 @@ darwin_rs6000_gt_pch_get_address (size_t sz)
 /* Check ADDR and SZ for validity, and deallocate (using munmap) that part of
    pch_address_space beyond SZ.  */
 
-static bool
-darwin_rs6000_gt_pch_use_address (void *addr, size_t sz)
+static int
+darwin_rs6000_gt_pch_use_address (void *addr, size_t sz, int fd, size_t off)
 {
   const size_t pagesize = getpagesize();
-  bool result;
+  void *mmap_result;
+  int ret;
 
   if ((size_t)pch_address_space % pagesize != 0
       || sizeof (pch_address_space) % pagesize != 0)
@@ -183,7 +180,19 @@ darwin_rs6000_gt_pch_use_address (void *addr, size_t sz)
   if (munmap (pch_address_space + sz, sizeof (pch_address_space) - sz) != 0)
     fatal_error ("couldn't unmap pch_address_space: %m\n");
 
-  return result;
+  mmap_result = mmap (addr, sz,
+		      PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_FIXED,
+		      fd, off);
+
+  /* The file might not be mmap-able.  */
+  ret = mmap_result == (void *) MAP_FAILED;
+
+  /* Sanity check for broken MAP_FIXED.  */
+  if (ret && mmap_result != base)
+    abort ();
+
+  return ret;
 }
+
 
 const struct host_hooks host_hooks = HOST_HOOKS_INITIALIZER;
diff --git a/gcc/config/x-linux b/gcc/config/x-linux
new file mode 100644
index 00000000000..d14586b0b36
--- /dev/null
+++ b/gcc/config/x-linux
@@ -0,0 +1,4 @@
+host-linux.o : $(srcdir)/config/host-linux.c $(CONFIG_H) $(SYSTEM_H) \
+  coretypes.h hosthooks.h hosthooks-def.h
+	$(CC) -c $(ALL_CFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) \
+		$(srcdir)/config/host-linux.c
diff --git a/gcc/config/x-solaris b/gcc/config/x-solaris
new file mode 100644
index 00000000000..782f4a36802
--- /dev/null
+++ b/gcc/config/x-solaris
@@ -0,0 +1,4 @@
+host-solaris.o : $(srcdir)/config/host-solaris.c $(CONFIG_H) $(SYSTEM_H) \
+  coretypes.h hosthooks.h hosthooks-def.h
+	$(CC) -c $(ALL_CFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) \
+		$(srcdir)/config/host-solaris.c
diff --git a/gcc/doc/hostconfig.texi b/gcc/doc/hostconfig.texi
index 5c38313efd2..8830c6b8ac1 100644
--- a/gcc/doc/hostconfig.texi
+++ b/gcc/doc/hostconfig.texi
@@ -42,35 +42,31 @@ This host hook is used to set up handling for extra signals.  The most
 common thing to do in this hook is to detect stack overflow.
 @end deftypefn
 
-@deftypefn {Host Hook} void * HOST_HOOKS_GT_PCH_GET_ADDRESS (size_t @var{size})
-This host hook returns the address of some space in which a PCH may be
-loaded with @samp{HOST_HOOKS_PCH_LOAD_PCH}.  The space will need to
-have @var{size} bytes.  If insufficient space is available,
-@samp{NULL} may be returned; the PCH machinery will try to find a
-suitable address using a heuristic.
-
-The memory does not have to be available now.  In fact, usually
-@samp{HOST_HOOKS_PCH_LOAD_PCH} will already have been called.  The memory
-need only be available in future invocations of GCC.
+@deftypefn {Host Hook} void * HOST_HOOKS_GT_PCH_GET_ADDRESS (size_t @var{size}, int @var{fd})
+This host hook returns the address of some space that is likely to be
+free in some subsequent invocation of the compiler.  We intend to load
+the PCH data at this address such that the data need not be relocated.
+The area should be able to hold @var{size} bytes.  If the host uses
+@code{mmap}, @var{fd} is an open file descriptor that can be used for
+probing.
 @end deftypefn
 
-@deftypefn {Host Hook} bool HOST_HOOKS_GT_PCH_USE_ADDRESS (size_t @var{size}, void * @var{address})
-This host hook is called when a PCH file is about to be loaded.  If
-@var{address} is the address that would have been returned by
-@samp{HOST_HOOKS_PCH_MEMORY_ADDRESS}, and @var{size} is smaller than
-the maximum than @samp{HOST_HOOKS_PCH_MEMORY_ADDRESS} would have
-accepted, return true, otherwise return false.
+@deftypefn {Host Hook} int HOST_HOOKS_GT_PCH_USE_ADDRESS (void * @var{address}, size_t @var{size}, int @var{fd}, size_t @var{offset})
+This host hook is called when a PCH file is about to be loaded.
+We want to load @var{size} bytes from @var{fd} at @var{offset}
+into memory at @var{address}.  The given address will be the result of
+a previous invocation of @code{HOST_HOOKS_GT_PCH_GET_ADDRESS}.
+Return @minus{}1 if we couldn't allocate @var{size} bytes at @var{address}.
+Return 0 if the memory is allocated but the data is not loaded.  Return 1
+if the hook has performed everything.
 
-In addition, free any address space reserved that isn't needed to hold
-@var{size} bytes (whether or not true is returned).  The PCH machinery will
-use @samp{mmap} with @samp{MAP_FIXED} to load the PCH if @samp{HAVE_MMAP_FILE},
-or will use @samp{fread} otherwise.
-
-If no PCH will be loaded, this hook may be called with @var{size}
-zero, in which case all reserved address space should be freed.
+If the implementation uses reserved address space, free any reserved
+space beyond @var{size}, regardless of the return value.  If no PCH will
+be loaded, this hook may be called with @var{size} zero, in which case
+all reserved address space should be freed.
 
 Do not try to handle values of @var{address} that could not have been
-returned by this executable; just return false.  Such values usually
+returned by this executable; just return @minus{}1.  Such values usually
 indicate an out-of-date PCH file (built by some other GCC executable),
 and such a PCH file won't work.
 @end deftypefn
diff --git a/gcc/ggc-common.c b/gcc/ggc-common.c
index ba951f46ed9..d8a803979c7 100644
--- a/gcc/ggc-common.c
+++ b/gcc/ggc-common.c
@@ -30,6 +30,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #include "toplev.h"
 #include "params.h"
 #include "hosthooks.h"
+#include "hosthooks-def.h"
 
 #ifdef HAVE_SYS_RESOURCE_H
 # include <sys/resource.h>
@@ -459,21 +460,8 @@ gt_pch_save (FILE *f)
      and on the rest it's a lot of work to do better.  
      (The extra work goes in HOST_HOOKS_GT_PCH_GET_ADDRESS and
      HOST_HOOKS_GT_PCH_USE_ADDRESS.)  */
-  mmi.preferred_base = host_hooks.gt_pch_get_address (mmi.size);
+  mmi.preferred_base = host_hooks.gt_pch_get_address (mmi.size, fileno (f));
       
-#if HAVE_MMAP_FILE
-  if (mmi.preferred_base == NULL)
-    {
-      mmi.preferred_base = mmap (NULL, mmi.size,
-				 PROT_READ | PROT_WRITE, MAP_PRIVATE,
-				 fileno (state.f), 0);
-      if (mmi.preferred_base == (void *) MAP_FAILED)
-	mmi.preferred_base = NULL;
-      else
-	munmap (mmi.preferred_base, mmi.size);
-    }
-#endif /* HAVE_MMAP_FILE */
-
   ggc_pch_this_base (state.d, mmi.preferred_base);
 
   state.ptrs = xmalloc (state.count * sizeof (*state.ptrs));
@@ -527,7 +515,8 @@ gt_pch_save (FILE *f)
 				  state.ptrs[i]->note_ptr_cookie,
 				  relocate_ptrs, &state);
       ggc_pch_write_object (state.d, state.f, state.ptrs[i]->obj,
-			    state.ptrs[i]->new_addr, state.ptrs[i]->size, state.ptrs[i]->note_ptr_fn == gt_pch_p_S);
+			    state.ptrs[i]->new_addr, state.ptrs[i]->size,
+			    state.ptrs[i]->note_ptr_fn == gt_pch_p_S);
       if (state.ptrs[i]->note_ptr_fn != gt_pch_p_S)
 	memcpy (state.ptrs[i]->obj, this_object, state.ptrs[i]->size);
     }
@@ -547,8 +536,7 @@ gt_pch_restore (FILE *f)
   const struct ggc_root_tab *rti;
   size_t i;
   struct mmap_info mmi;
-  void *addr;
-  bool needs_read;
+  int result;
 
   /* Delete any deletable objects.  This makes ggc_pch_read much
      faster, as it can be sure that no GCable objects remain other
@@ -581,111 +569,94 @@ gt_pch_restore (FILE *f)
   if (fread (&mmi, sizeof (mmi), 1, f) != 1)
     fatal_error ("can't read PCH file: %m");
 
-  if (host_hooks.gt_pch_use_address (mmi.preferred_base, mmi.size))
+  result = host_hooks.gt_pch_use_address (mmi.preferred_base, mmi.size,
+					  fileno (f), mmi.offset);
+  if (result < 0)
+    fatal_error ("had to relocate PCH");
+  if (result == 0)
     {
-#if HAVE_MMAP_FILE
-      void *mmap_result;
+      if (fseek (f, mmi.offset, SEEK_SET) != 0
+	  || fread (mmi.preferred_base, mmi.size, 1, f) != 1)
+	fatal_error ("can't read PCH file: %m");
+    }
+  else if (fseek (f, mmi.offset + mmi.size, SEEK_SET) != 0)
+    fatal_error ("can't read PCH file: %m");
 
-      mmap_result = mmap (mmi.preferred_base, mmi.size,
-			  PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_FIXED,
-			  fileno (f), mmi.offset);
+  ggc_pch_read (f, mmi.preferred_base);
 
-      /* The file might not be mmap-able.  */
-      needs_read = mmap_result == (void *) MAP_FAILED;
+  gt_pch_restore_stringpool ();
+}
 
-      /* Sanity check for broken MAP_FIXED.  */
-      if (! needs_read && mmap_result != mmi.preferred_base)
-	abort ();
-#else
-      needs_read = true;
-#endif
-      addr = mmi.preferred_base;
-    }
-  else
-    {
-#if HAVE_MMAP_FILE
-      addr = mmap (mmi.preferred_base, mmi.size,
-		   PROT_READ | PROT_WRITE, MAP_PRIVATE,
-		   fileno (f), mmi.offset);
+/* Default version of HOST_HOOKS_GT_PCH_GET_ADDRESS when mmap is not present.
+   Select no address whatsoever, and let gt_pch_save choose what it will with
+   malloc, presumably.  */
 
-#if HAVE_MINCORE
-      if (addr != mmi.preferred_base)
-	{
-	  size_t page_size = getpagesize();
-	  char one_byte;
-
-	  /* We really want to be mapped at mmi.preferred_base
-	     so we're going to resort to MAP_FIXED.  But before,
-	     make sure that we can do so without destroying a
-	     previously mapped area, by looping over all pages
-	     that would be affected by the fixed mapping.  */
-	  errno = 0;
-
-	  for (i = 0; i < mmi.size; i+= page_size)
-	    if (mincore ((char *)mmi.preferred_base + i, page_size, 
-			 (void *)&one_byte) == -1
-		&& errno == ENOMEM)
-	      continue; /* The page is not mapped.  */
-	    else
-	      break;
-
-	  if (i >= mmi.size)
-	    {
-	      if (addr != (void *) MAP_FAILED)
-		munmap (addr, mmi.size);
+void *
+default_gt_pch_get_address (size_t size ATTRIBUTE_UNUSED,
+			    int fd ATTRIBUTE_UNUSED)
+{
+  return NULL;
+}
 
-	      addr = mmap (mmi.preferred_base, mmi.size, 
-			   PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_FIXED,
-			   fileno (f), mmi.offset);
-	    }
-	}
-#endif /* HAVE_MINCORE */
+/* Default version of HOST_HOOKS_GT_PCH_USE_ADDRESS when mmap is not present.
+   Allocate SIZE bytes with malloc.  Return 0 if the address we got is the
+   same as base, indicating that the memory has been allocated but needs to
+   be read in from the file.  Return -1 if the address differs, to relocation
+   of the PCH file would be required.  */
+
+int
+default_gt_pch_use_address (void *base, size_t size, int fd ATTRIBUTE_UNUSED,
+			    size_t offset ATTRIBUTE_UNUSED)
+{
+  void *addr = xmalloc (size);
+  return (addr == base) - 1;
+}
 
-      needs_read = addr == (void *) MAP_FAILED;
+#if HAVE_MMAP_FILE
+/* Default version of HOST_HOOKS_GT_PCH_GET_ADDRESS when mmap is present.
+   We temporarily allocate SIZE bytes, and let the kernel place the data
+   whereever it will.  If it worked, that's our spot, if not we're likely
+   to be in trouble.  */
 
-#else /* HAVE_MMAP_FILE */
-      needs_read = true;
-#endif /* HAVE_MMAP_FILE */
-      if (needs_read)
-	addr = xmalloc (mmi.size);
-    }
+void *
+mmap_gt_pch_get_address (size_t size, int fd)
+{
+  void *ret;
 
-  if (needs_read)
-    {
-      if (fseek (f, mmi.offset, SEEK_SET) != 0
-	  || fread (addr, mmi.size, 1, f) != 1)
-	fatal_error ("can't read PCH file: %m");
-    }
-  else if (fseek (f, mmi.offset + mmi.size, SEEK_SET) != 0)
-    fatal_error ("can't read PCH file: %m");
+  ret = mmap (NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+  if (ret == (void *) MAP_FAILED)
+    ret = NULL;
+  else
+    munmap (ret, size);
 
-  ggc_pch_read (f, addr);
+  return ret;
+}
 
-  if (addr != mmi.preferred_base)
-    {
-      for (rt = gt_ggc_rtab; *rt; rt++)
-	for (rti = *rt; rti->base != NULL; rti++)
-	  for (i = 0; i < rti->nelt; i++)
-	    {
-	      char **ptr = (char **)((char *)rti->base + rti->stride * i);
-	      if (*ptr != NULL)
-		*ptr += (size_t)addr - (size_t)mmi.preferred_base;
-	    }
+/* Default version of HOST_HOOKS_GT_PCH_USE_ADDRESS when mmap is present.
+   Map SIZE bytes of FD+OFFSET at BASE.  Return 1 if we succeeded at 
+   mapping the data at BASE, -1 if we couldn't.
 
-      for (rt = gt_pch_cache_rtab; *rt; rt++)
-	for (rti = *rt; rti->base != NULL; rti++)
-	  for (i = 0; i < rti->nelt; i++)
-	    {
-	      char **ptr = (char **)((char *)rti->base + rti->stride * i);
-	      if (*ptr != NULL)
-		*ptr += (size_t)addr - (size_t)mmi.preferred_base;
-	    }
+   This version assumes that the kernel honors the START operand of mmap
+   even without MAP_FIXED if START through START+SIZE are not currently
+   mapped with something.  */
 
-      fatal_error ("had to relocate PCH");
-    }
+int
+mmap_gt_pch_use_address (void *base, size_t size, int fd, size_t offset)
+{
+  void *addr;
 
-  gt_pch_restore_stringpool ();
+  /* We're called with size == 0 if we're not planning to load a PCH
+     file at all.  This allows the hook to free any static space that
+     we might have allocated at link time.  */
+  if (size == 0)
+    return -1;
+
+  addr = mmap (base, size, PROT_READ | PROT_WRITE, MAP_PRIVATE,
+	       fd, offset);
+
+  return addr == base ? 1 : -1;
 }
+#endif /* HAVE_MMAP_FILE */
 
 /* Modify the bound based on rlimits.  Keep the smallest number found.  */
 static double
diff --git a/gcc/hooks.c b/gcc/hooks.c
index cb6efd4bb6a..5b9bb653996 100644
--- a/gcc/hooks.c
+++ b/gcc/hooks.c
@@ -205,21 +205,6 @@ hook_rtx_tree_int_null (tree a ATTRIBUTE_UNUSED, int b ATTRIBUTE_UNUSED)
   return NULL;
 }
 
-/* Generic hook that takes a size_t and returns NULL.  */
-void *
-hook_voidp_size_t_null (size_t a ATTRIBUTE_UNUSED)
-{
-  return NULL;
-}
-
-/* Generic hook that takes a size_t and a pointer and returns false.  */
-bool
-hook_bool_voidp_size_t_false (void * a ATTRIBUTE_UNUSED,
-			      size_t b ATTRIBUTE_UNUSED)
-{
-  return false;
-}
-
 /* Generic hook that takes a tree and returns it as is.  */
 tree
 hook_tree_tree_identity (tree a)
diff --git a/gcc/hooks.h b/gcc/hooks.h
index a72f6c88013..824683b4cf4 100644
--- a/gcc/hooks.h
+++ b/gcc/hooks.h
@@ -57,8 +57,6 @@ extern bool hook_bool_tree_tree_false (tree, tree);
 extern rtx hook_rtx_rtx_identity (rtx);
 extern rtx hook_rtx_rtx_null (rtx);
 extern rtx hook_rtx_tree_int_null (tree, int);
-extern void * hook_voidp_size_t_null (size_t);
-extern bool hook_bool_voidp_size_t_false (void *, size_t);
 extern tree hook_tree_tree_identity (tree a);
 
 #endif
diff --git a/gcc/hosthooks-def.h b/gcc/hosthooks-def.h
index b1a41e72988..537ac6f2624 100644
--- a/gcc/hosthooks-def.h
+++ b/gcc/hosthooks-def.h
@@ -24,8 +24,18 @@ Boston, MA 02111-1307, USA.  */
 #include "hooks.h"
 
 #define HOST_HOOKS_EXTRA_SIGNALS hook_void_void
-#define HOST_HOOKS_GT_PCH_GET_ADDRESS hook_voidp_size_t_null
-#define HOST_HOOKS_GT_PCH_USE_ADDRESS hook_bool_voidp_size_t_false
+#if HAVE_MMAP_FILE
+#define HOST_HOOKS_GT_PCH_GET_ADDRESS mmap_gt_pch_get_address
+#define HOST_HOOKS_GT_PCH_USE_ADDRESS mmap_gt_pch_use_address
+#else
+#define HOST_HOOKS_GT_PCH_GET_ADDRESS default_gt_pch_get_address
+#define HOST_HOOKS_GT_PCH_USE_ADDRESS default_gt_pch_use_address
+#endif
+
+extern void* default_gt_pch_get_address (size_t, int);
+extern int default_gt_pch_use_address (void *, size_t, int, size_t);
+extern void* mmap_gt_pch_get_address (size_t, int);
+extern int mmap_gt_pch_use_address (void *, size_t, int, size_t);
 
 /* The structure is defined in hosthooks.h.  */
 #define HOST_HOOKS_INITIALIZER {		\
diff --git a/gcc/hosthooks.h b/gcc/hosthooks.h
index bbc28f69d4d..a3fc0c7c430 100644
--- a/gcc/hosthooks.h
+++ b/gcc/hosthooks.h
@@ -25,8 +25,16 @@ struct host_hooks
 {
   void (*extra_signals) (void);
 
-  void * (*gt_pch_get_address) (size_t);
-  bool (*gt_pch_use_address) (void *, size_t);
+  /* Identify an address that's likely to be free in a subsequent invocation
+     of the compiler.  The area should be able to hold SIZE bytes.  FD is an
+     open file descriptor if the host would like to probe with mmap.  */
+  void * (*gt_pch_get_address) (size_t size, int fd);
+
+  /* ADDR is an address returned by gt_pch_get_address.  Attempt to allocate
+     SIZE bytes at the same address and load it with the data from FD at 
+     OFFSET.  Return -1 if we couldn't allocate memory at ADDR, return 0
+     if the memory is allocated but the data not loaded, return 1 if done.  */
+  int (*gt_pch_use_address) (void *addr, size_t size, int fd, size_t offset);
 
   /* Whenever you add entries here, make sure you adjust hosthooks-def.h.  */
 };