* doc/extend.texi (MIPS DSP Built-in Functions): Document the DSP

[pf3gnuchains/gcc-fork.git] / gcc / config / host-linux.c

diff --git a/gcc/config/host-linux.c b/gcc/config/host-linux.c
index 717f96c..795bb55 100644 (file)
--- a/gcc/config/host-linux.c
+++ b/gcc/config/host-linux.c
@@ -1,5 +1,5 @@
 /* Linux host-specific hook definitions.
-   Copyright (C) 2004 Free Software Foundation, Inc.
+   Copyright (C) 2004, 2005 Free Software Foundation, Inc.
 
    This file is part of GCC.
 
@@ -15,13 +15,14 @@
 
    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.  */
+   Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
+   MA 02110-1301, USA.  */
 
 #include "config.h"
 #include "system.h"
 #include "coretypes.h"
 #include <sys/mman.h>
+#include <limits.h>
 #include "hosthooks.h"
 #include "hosthooks-def.h"
 
@@ -61,6 +62,9 @@
 #undef HOST_HOOKS_GT_PCH_GET_ADDRESS
 #define HOST_HOOKS_GT_PCH_GET_ADDRESS linux_gt_pch_get_address
 
+#undef HOST_HOOKS_GT_PCH_USE_ADDRESS
+#define HOST_HOOKS_GT_PCH_USE_ADDRESS linux_gt_pch_use_address
+
 /* For various ports, try to guess a fixed spot in the vm space
    that's probably free.  */
 #if defined(__alpha)
@@ -110,8 +114,13 @@ linux_gt_pch_get_address (size_t size, int fd)
   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");
+  /* If we didn't, then we need to look to see if virtual address
+     randomization is on.  That is recorded in
+     kernel.randomize_va_space.  An older implementation used
+     kernel.exec-shield-randomize.  */
+  f = fopen ("/proc/sys/kernel/randomize_va_space", "r");
+  if (f == NULL)
+    f = fopen ("/proc/sys/kernel/exec-shield-randomize", "r");
   randomize_on = false;
   if (f != NULL)
     {
@@ -143,5 +152,68 @@ linux_gt_pch_get_address (size_t size, int fd)
   return addr;
 }
 
+/* Map SIZE bytes of FD+OFFSET at BASE.  Return 1 if we succeeded at
+   mapping the data at BASE, -1 if we couldn't.
+
+   It's not possibly to reliably mmap a file using MAP_PRIVATE to
+   a specific START address on either hpux or linux.  First we see
+   if mmap with MAP_PRIVATE works.  If it does, we are off to the
+   races.  If it doesn't, we try an anonymous private mmap since the
+   kernel is more likely to honor the BASE address in anonymous maps.
+   We then copy the data to the anonymous private map.  This assumes
+   of course that we don't need to change the data in the PCH file
+   after it is created.
+
+   This approach obviously causes a performance penalty but there is
+   little else we can do given the current PCH implementation.  */
+
+static int
+linux_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;
+
+  /* Try to map the file with MAP_PRIVATE.  */
+  addr = mmap (base, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, offset);
+
+  if (addr == base)
+    return 1;
+
+  if (addr != (void *) MAP_FAILED)
+    munmap (addr, size);
+
+  /* Try to make an anonymous private mmap at the desired location.  */
+  addr = mmap (base, size, PROT_READ | PROT_WRITE,
+              MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+  if (addr != base)
+    {
+      if (addr != (void *) MAP_FAILED)
+        munmap (addr, size);
+      return -1;
+    }
+
+  if (lseek (fd, offset, SEEK_SET) == (off_t)-1)
+    return -1;
+
+  while (size)
+    {
+      ssize_t nbytes;
+
+      nbytes = read (fd, base, MIN (size, SSIZE_MAX));
+      if (nbytes <= 0)
+        return -1;
+      base = (char *) base + nbytes;
+      size -= nbytes;
+    }
+
+  return 1;
+}
+
 \f
 const struct host_hooks host_hooks = HOST_HOOKS_INITIALIZER;