From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23673 invoked by alias); 29 Jul 2008 00:22:43 -0000 Received: (qmail 23664 invoked by uid 22791); 29 Jul 2008 00:22:42 -0000 X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org (qpsmtpd/0.31) with ESMTP; Tue, 29 Jul 2008 00:22:25 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id m6T0MM39006190 for ; Mon, 28 Jul 2008 20:22:23 -0400 Received: from pobox.corp.redhat.com (pobox.corp.redhat.com [10.11.255.20]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id m6T0MMnu008712 for ; Mon, 28 Jul 2008 20:22:22 -0400 Received: from mesquite.lan (vpn-12-212.rdu.redhat.com [10.11.12.212]) by pobox.corp.redhat.com (8.13.1/8.13.1) with ESMTP id m6T0ML1e026650 for ; Mon, 28 Jul 2008 20:22:22 -0400 Date: Tue, 29 Jul 2008 00:22:00 -0000 From: Kevin Buettner To: gdb-patches@sourceware.org Subject: Re: [RFC] PPC: Skip call to __eabi in main() Message-ID: <20080728172221.3dc3764e@mesquite.lan> In-Reply-To: <20080722181252.03d9ce94@mesquite.lan> References: <20080721155343.404977d3@mesquite.lan> <1216701867.31797.26.camel@localhost.localdomain> <20080722181252.03d9ce94@mesquite.lan> X-Mailer: Claws Mail 3.5.0 (GTK+ 2.12.11; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2008-07/txt/msg00530.txt.bz2 I've done some further testing of my patch and have found that an additional test is needed to accomodate -fleading-underscore. (See the comment in the patch below...) I've also expanded the comment that precedes rs6000_skip_main_prologue(). I'll wait a few more days before committing this change. Kevin * rs6000-tdep.c (BL_MASK, BL_INSTRUCTION, BL_DISPLACEMENT_MASK): New macros. (rs6000_skip_main_prologue): New function. (rs6000_gdb_arch_init): Register rs6000_skip_main_prologue. Index: rs6000-tdep.c =================================================================== RCS file: /cvs/src/src/gdb/rs6000-tdep.c,v retrieving revision 1.318 diff -u -p -r1.318 rs6000-tdep.c --- rs6000-tdep.c 15 Jul 2008 18:32:06 -0000 1.318 +++ rs6000-tdep.c 29 Jul 2008 00:11:52 -0000 @@ -1146,6 +1146,20 @@ bl_to_blrl_insn_p (CORE_ADDR pc, int ins return 0; } +/* Masks for decoding a branch-and-link (bl) instruction. + + BL_MASK and BL_INSTRUCTION are used in combination with each other. + The former is anded with the opcode in question; if the result of + this masking operation is equal to BL_INSTRUCTION, then the opcode in + question is a ``bl'' instruction. + + BL_DISPLACMENT_MASK is anded with the opcode in order to extract + the branch displacement. */ + +#define BL_MASK 0xfc000001 +#define BL_INSTRUCTION 0x48000001 +#define BL_DISPLACEMENT_MASK 0x03fffffc + /* return pc value after skipping a function prologue and also return information about a function frame. @@ -1769,6 +1783,41 @@ rs6000_skip_prologue (struct gdbarch *gd return pc; } +/* When compiling for EABI, some versions of GCC emit a call to __eabi + in the prologue of main(). + + The function below examines the code pointed at by PC and checks to + see if it corresponds to a call to __eabi. If so, it returns the + address of the instruction following that call. Otherwise, it simply + returns PC. */ + +CORE_ADDR +rs6000_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR pc) +{ + gdb_byte buf[4]; + unsigned long op; + + if (target_read_memory (pc, buf, 4)) + return pc; + op = extract_unsigned_integer (buf, 4); + + if ((op & BL_MASK) == BL_INSTRUCTION) + { + CORE_ADDR displ = op & BL_DISPLACEMENT_MASK; + CORE_ADDR call_dest = pc + 4 + displ; + struct minimal_symbol *s = lookup_minimal_symbol_by_pc (call_dest); + + /* We check for ___eabi (three leading underscores) in addition + to __eabi in case the GCC option "-fleading-underscore" was + used to compile the program. */ + if (s != NULL + && SYMBOL_LINKAGE_NAME (s) != NULL + && (strcmp (SYMBOL_LINKAGE_NAME (s), "__eabi") == 0 + || strcmp (SYMBOL_LINKAGE_NAME (s), "___eabi") == 0)) + pc += 4; + } + return pc; +} /* All the ABI's require 16 byte alignment. */ static CORE_ADDR @@ -3238,6 +3287,7 @@ rs6000_gdbarch_init (struct gdbarch_info set_gdbarch_skip_prologue (gdbarch, rs6000_skip_prologue); set_gdbarch_in_function_epilogue_p (gdbarch, rs6000_in_function_epilogue_p); + set_gdbarch_skip_main_prologue (gdbarch, rs6000_skip_main_prologue); set_gdbarch_inner_than (gdbarch, core_addr_lessthan); set_gdbarch_breakpoint_from_pc (gdbarch, rs6000_breakpoint_from_pc);