2004-06-06 Randolph Chung <tausq@debian.org>

[deliverable/binutils-gdb.git] / gdb / hppa-linux-tdep.c

diff --git a/gdb/hppa-linux-tdep.c b/gdb/hppa-linux-tdep.c
index f1639247bb8d216f77f7b5c45413185b44993239..32c6068dbd9cd5d6737da407871715a83fbf47de 100644 (file)
--- a/gdb/hppa-linux-tdep.c
+++ b/gdb/hppa-linux-tdep.c
@@ -28,8 +28,11 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
 #include "frame-unwind.h"
 #include "trad-frame.h"
 #include "dwarf2-frame.h"
+#include "value.h"
 #include "hppa-tdep.h"
 
+#include "elf/common.h"
+
 #if 0
 /* Convert DWARF register number REG to the appropriate register
    number used by GDB.  */
@@ -466,6 +469,93 @@ hppa_linux_sigtramp_unwind_sniffer (struct frame_info *next_frame)
   return NULL;
 }
 
+/* Attempt to find (and return) the global pointer for the given
+   function.
+
+   This is a rather nasty bit of code searchs for the .dynamic section
+   in the objfile corresponding to the pc of the function we're trying
+   to call.  Once it finds the addresses at which the .dynamic section
+   lives in the child process, it scans the Elf32_Dyn entries for a
+   DT_PLTGOT tag.  If it finds one of these, the corresponding
+   d_un.d_ptr value is the global pointer.  */
+
+static CORE_ADDR
+hppa_linux_find_global_pointer (struct value *function)
+{
+  struct obj_section *faddr_sect;
+  CORE_ADDR faddr;
+  
+  faddr = value_as_address (function);
+
+  /* Is this a plabel? If so, dereference it to get the gp value.  */
+  if (faddr & 2)
+    {
+      int status;
+      char buf[4];
+
+      faddr &= ~3;
+
+      status = target_read_memory (faddr + 4, buf, sizeof (buf));
+      if (status == 0)
+       return extract_unsigned_integer (buf, sizeof (buf));
+    }
+
+  /* If the address is in the plt section, then the real function hasn't 
+     yet been fixed up by the linker so we cannot determine the gp of 
+     that function.  */
+  if (in_plt_section (faddr, NULL))
+    return 0;
+
+  faddr_sect = find_pc_section (faddr);
+  if (faddr_sect != NULL)
+    {
+      struct obj_section *osect;
+
+      ALL_OBJFILE_OSECTIONS (faddr_sect->objfile, osect)
+       {
+         if (strcmp (osect->the_bfd_section->name, ".dynamic") == 0)
+           break;
+       }
+
+      if (osect < faddr_sect->objfile->sections_end)
+       {
+         CORE_ADDR addr;
+
+         addr = osect->addr;
+         while (addr < osect->endaddr)
+           {
+             int status;
+             LONGEST tag;
+             char buf[4];
+
+             status = target_read_memory (addr, buf, sizeof (buf));
+             if (status != 0)
+               break;
+             tag = extract_signed_integer (buf, sizeof (buf));
+
+             if (tag == DT_PLTGOT)
+               {
+                 CORE_ADDR global_pointer;
+
+                 status = target_read_memory (addr + 4, buf, sizeof (buf));
+                 if (status != 0)
+                   break;
+                 global_pointer = extract_unsigned_integer (buf, sizeof (buf));
+
+                 /* The payoff... */
+                 return global_pointer;
+               }
+
+             if (tag == DT_NULL)
+               break;
+
+             addr += 8;
+           }
+       }
+    }
+  return 0;
+}
+
 /* Forward declarations.  */
 extern initialize_file_ftype _initialize_hppa_linux_tdep;
 
@@ -477,6 +567,8 @@ hppa_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   /* Linux is always ELF.  */
   tdep->is_elf = 1;
 
+  tdep->find_global_pointer = hppa_linux_find_global_pointer;
+
   set_gdbarch_write_pc (gdbarch, hppa_linux_target_write_pc);
 
   frame_unwind_append_sniffer (gdbarch, hppa_linux_sigtramp_unwind_sniffer);