* ppc-linux-tdep.c (ppc64_linux_convert_from_func_ptr_addr): New

function.
(ppc_linux_init_abi): Register it as the
CONVERT_FROM_FUNC_PTR_ADDR method under the PPC64 Linux ABI.

2 files changed, 43 insertions, 0 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 474b51ad3d7..13c8430bef0 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
 2003-06-11  Jim Blandy  <jimb@redhat.com>
 
+	* ppc-linux-tdep.c (ppc64_linux_convert_from_func_ptr_addr): New
+	function.
+	(ppc_linux_init_abi): Register it as the
+	CONVERT_FROM_FUNC_PTR_ADDR method under the PPC64 Linux ABI.
+
 	* ppc-linux-tdep.c (ppc_linux_init_abi): long doubles are 16 bytes
 	long.
 
diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c
index d9ce27fe9bc..532b338d0de 100644
--- a/gdb/ppc-linux-tdep.c
+++ b/gdb/ppc-linux-tdep.c
@@ -894,6 +894,39 @@ ppc64_skip_trampoline_code (CORE_ADDR pc)
 }
 
 
+/* Support for CONVERT_FROM_FUNC_PTR_ADDR(ADDR).
+
+   Usually a function pointer's representation is simply the address
+   of the function. On the RS/6000 however, a function pointer is
+   represented by a pointer to a TOC entry. This TOC entry contains
+   three words, the first word is the address of the function, the
+   second word is the TOC pointer (r2), and the third word is the
+   static chain value.  Throughout GDB it is currently assumed that a
+   function pointer contains the address of the function, which is not
+   easy to fix.  In addition, the conversion of a function address to
+   a function pointer would require allocation of a TOC entry in the
+   inferior's memory space, with all its drawbacks.  To be able to
+   call C++ virtual methods in the inferior (which are called via
+   function pointers), find_function_addr uses this function to get the
+   function address from a function pointer.  */
+
+/* Return real function address if ADDR (a function pointer) is in the data
+   space and is therefore a special function pointer.  */
+
+static CORE_ADDR
+ppc64_linux_convert_from_func_ptr_addr (CORE_ADDR addr)
+{
+  struct obj_section *s;
+
+  s = find_pc_section (addr);
+  if (s && s->the_bfd_section->flags & SEC_CODE)
+    return addr;
+
+  /* ADDR is in the data space, so it's a special function pointer. */
+  return ppc64_desc_entry_point (addr);
+}
+
+
 /* On 64-bit PowerPC Linux, the ELF header's e_entry field is the
    address of a function descriptor for the entry point function, not
    the actual entry point itself.  So to find the actual address at
@@ -1029,6 +1062,11 @@ ppc_linux_init_abi (struct gdbarch_info info,
     {
       set_gdbarch_long_double_bit (gdbarch, 16 * TARGET_CHAR_BIT);
 
+      /* Handle PPC64 Linux function pointers (which are really
+         function descriptors).  */
+      set_gdbarch_convert_from_func_ptr_addr
+        (gdbarch, ppc64_linux_convert_from_func_ptr_addr);
+
       set_gdbarch_call_dummy_address (gdbarch, ppc64_call_dummy_address);
 
       set_gdbarch_in_solib_call_trampoline