* 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.

1 files changed, 40 insertions, 0 deletions

diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c
index 5b82a91..269e16d 100644
--- a/gdb/ppc-linux-tdep.c
+++ b/gdb/ppc-linux-tdep.c
@@ -894,6 +894,41 @@ ppc64_skip_trampoline_code (CORE_ADDR pc)
 }
 
 
+/* Support for CONVERT_FROM_FUNC_PTR_ADDR(ADDR) on PPC64 Linux.
+
+   Usually a function pointer's representation is simply the address
+   of the function. On Linux on the 64-bit PowerPC 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 pointer to a descriptor, not
+     the entry point.  */
+  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
@@ -1027,6 +1062,11 @@ ppc_linux_init_abi (struct gdbarch_info info,
   
   if (tdep->wordsize == 8)
     {
+      /* 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