Replace SKIP_SOLIB_RESOLVER stub with something that works.

2000-05-25  Scott Bambrough <scottb@netwinder.org>

	* arm-linux-tdep.c (find_minsym_and_objfile): New.
	(skip_hurd_resolver): New.
	(arm_linux_skip_solib_resolver): New.
	(arm_skip_solib_resolver): Removed.

	* config/arm/tm-linux.h (SKIP_SOLIB_RESOLVER): Changed to use
	arm_linux_skip_solib_resolver.

1 files changed, 88 insertions, 2 deletions

diff --git a/gdb/arm-linux-tdep.c b/gdb/arm-linux-tdep.c
index 667fd0bd18c..cbe8c182def 100644
--- a/gdb/arm-linux-tdep.c
+++ b/gdb/arm-linux-tdep.c
@@ -24,6 +24,11 @@
 #include "gdbtypes.h"
 #include "floatformat.h"
 
+/* For arm_linux_skip_solib_resolver.  */
+#include "symtab.h"
+#include "symfile.h"
+#include "objfiles.h"
+
 #ifdef GET_LONGJMP_TARGET
 
 /* Figure out where the longjmp will land.  We expect that we have
@@ -340,10 +345,91 @@ arm_linux_push_arguments (int nargs, value_ptr * args, CORE_ADDR sp,
    with.  Before the fixup/resolver code returns, it actually calls
    the requested function and repairs &GOT[n+3].  */
 
+/* Find the minimal symbol named NAME, and return both the minsym
+   struct and its objfile.  This probably ought to be in minsym.c, but
+   everything there is trying to deal with things like C++ and
+   SOFUN_ADDRESS_MAYBE_TURQUOISE, ...  Since this is so simple, it may
+   be considered too special-purpose for general consumption.  */
+
+static struct minimal_symbol *
+find_minsym_and_objfile (char *name, struct objfile **objfile_p)
+{
+  struct objfile *objfile;
+
+  ALL_OBJFILES (objfile)
+    {
+      struct minimal_symbol *msym;
+
+      ALL_OBJFILE_MSYMBOLS (objfile, msym)
+	{
+	  if (SYMBOL_NAME (msym)
+	      && STREQ (SYMBOL_NAME (msym), name))
+	    {
+	      *objfile_p = objfile;
+	      return msym;
+	    }
+	}
+    }
+
+  return 0;
+}
+
+
+static CORE_ADDR
+skip_hurd_resolver (CORE_ADDR pc)
+{
+  /* The HURD dynamic linker is part of the GNU C library, so many
+     GNU/Linux distributions use it.  (All ELF versions, as far as I
+     know.)  An unresolved PLT entry points to "_dl_runtime_resolve",
+     which calls "fixup" to patch the PLT, and then passes control to
+     the function.
+
+     We look for the symbol `_dl_runtime_resolve', and find `fixup' in
+     the same objfile.  If we are at the entry point of `fixup', then
+     we set a breakpoint at the return address (at the top of the
+     stack), and continue.
+  
+     It's kind of gross to do all these checks every time we're
+     called, since they don't change once the executable has gotten
+     started.  But this is only a temporary hack --- upcoming versions
+     of Linux will provide a portable, efficient interface for
+     debugging programs that use shared libraries.  */
+
+  struct objfile *objfile;
+  struct minimal_symbol *resolver 
+    = find_minsym_and_objfile ("_dl_runtime_resolve", &objfile);
+
+  if (resolver)
+    {
+      struct minimal_symbol *fixup
+	= lookup_minimal_symbol ("fixup", 0, objfile);
+
+      if (fixup && SYMBOL_VALUE_ADDRESS (fixup) == pc)
+	return (SAVED_PC_AFTER_CALL (get_current_frame ()));
+    }
+
+  return 0;
+}      
+
+/* See the comments for SKIP_SOLIB_RESOLVER at the top of infrun.c.
+   This function:
+   1) decides whether a PLT has sent us into the linker to resolve
+      a function reference, and 
+   2) if so, tells us where to set a temporary breakpoint that will
+      trigger when the dynamic linker is done.  */
+
 CORE_ADDR
-arm_skip_solib_resolver (CORE_ADDR pc)
+arm_linux_skip_solib_resolver (CORE_ADDR pc)
 {
-  /* FIXME */
+  CORE_ADDR result;
+
+  /* Plug in functions for other kinds of resolvers here.  */
+  result = skip_hurd_resolver (pc);
+  printf ("Result = 0x%08x\n");
+  if (result)
+    return result;
+
+  
   return 0;
 }