From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 24203 invoked by alias); 12 Jun 2003 21:11:23 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 24168 invoked from network); 12 Jun 2003 21:11:22 -0000 Received: from unknown (HELO zenia.home) (12.223.225.216) by sources.redhat.com with SMTP; 12 Jun 2003 21:11:22 -0000 Received: by zenia.home (Postfix, from userid 5433) id 466EF20D85; Thu, 12 Jun 2003 16:11:32 -0500 (EST) To: Kevin Buettner Cc: gdb-patches@sources.redhat.com Subject: Re: [ppc64-linux]: register CONVERT_FROM_FUNC_PTR_ADDR method References: <1030611224249.ZM27163@localhost.localdomain> From: Jim Blandy Date: Thu, 12 Jun 2003 21:11:00 -0000 In-Reply-To: <1030611224249.ZM27163@localhost.localdomain> Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-SW-Source: 2003-06/txt/msg00429.txt.bz2 Kevin Buettner writes: > On Jun 11, 3:53am, Jim Blandy wrote: > > > 2003-06-11 Jim Blandy > > > > * 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. > > Okay, but could you revise the comment to not mention RS/6000 and > to make it clear that the representation in question only pertains > to the 64-bit ABI? How's this? 2003-06-11 Jim Blandy * 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. Index: gdb/ppc-linux-tdep.c =================================================================== RCS file: /cvs/src/src/gdb/ppc-linux-tdep.c,v retrieving revision 1.28.8.17 diff -c -r1.28.8.17 ppc-linux-tdep.c *** gdb/ppc-linux-tdep.c 12 Jun 2003 21:09:22 -0000 1.28.8.17 --- gdb/ppc-linux-tdep.c 12 Jun 2003 21:09:42 -0000 *************** *** 894,899 **** --- 894,934 ---- } + /* 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 *************** *** 1027,1032 **** --- 1062,1072 ---- 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