From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 2178 invoked by alias); 13 Jan 2011 23:04:42 -0000 Received: (qmail 2169 invoked by uid 22791); 13 Jan 2011 23:04:41 -0000 X-SWARE-Spam-Status: No, hits=-2.0 required=5.0 tests=AWL,BAYES_00,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from rock.gnat.com (HELO rock.gnat.com) (205.232.38.15) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 13 Jan 2011 23:04:34 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by filtered-rock.gnat.com (Postfix) with ESMTP id 2608C2BAC46; Thu, 13 Jan 2011 18:04:33 -0500 (EST) Received: from rock.gnat.com ([127.0.0.1]) by localhost (rock.gnat.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id G4aSDNkJtoM9; Thu, 13 Jan 2011 18:04:33 -0500 (EST) Received: from joel.gnat.com (localhost.localdomain [127.0.0.1]) by rock.gnat.com (Postfix) with ESMTP id 144DB2BAC43; Thu, 13 Jan 2011 18:04:33 -0500 (EST) Received: by joel.gnat.com (Postfix, from userid 1000) id 38F3B1459AD; Thu, 13 Jan 2011 18:04:32 -0500 (EST) From: Joel Brobecker To: gdb-patches@sourceware.org Cc: Joel Brobecker Subject: [RFA/commit/powerpc] breakpoint inserted past function end Date: Thu, 13 Jan 2011 23:05:00 -0000 Message-Id: <1294959871-12637-1-git-send-email-brobecker@adacore.com> 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: 2011-01/txt/msg00310.txt.bz2 On powerpc, the prologue scanner reads instruction after instruction, and just skips instructions that do not affect a frame. This means that it does not stop if if finds and unexpected instruction (which could possibly happen with optimization, I presume). To avoid scanning too many instructions, it tries to establish an upper limit. The upper limit is first computed using the debugging (line) info, but if that fails, it falls back on an arbitrary 100 bytes (or 25 instructions). The problem is that, if the function is shorter than those 25 instructions, we run the risk of skipping the entire function and returning a PC that's outside our function. In the event where we can find a symbol for a given PC (and therefore can determine function start and end addresses), but cannot find an upper limit using skip_prologue_using_sal, then we can at least limit make sure that the 25 instructions do not put us beyour our function. If it does, then further reduce the upper-limit to the end of the function. gdb/ChangeLog: * rs6000-tdep.c (rs6000_skip_prologue): Make sure that the prologue upper limit address is not greater than the function end address when the upper limit could not be computed using the debugging info. This seems fairly straightforward, but I couldn't run the testsuite (only the AdaCore testsuite) because I don't have access to a powerpc machine running an OS that we can run the testsuite on (I ran the AdaCore testsuite on VxWorks). I'll commit in a few days, pending comments. --- gdb/rs6000-tdep.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/gdb/rs6000-tdep.c b/gdb/rs6000-tdep.c index c16e933..9832b5b 100644 --- a/gdb/rs6000-tdep.c +++ b/gdb/rs6000-tdep.c @@ -2090,12 +2090,12 @@ static CORE_ADDR rs6000_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc) { struct rs6000_framedata frame; - CORE_ADDR limit_pc, func_addr; + CORE_ADDR limit_pc, func_addr, func_end_addr = 0; /* See if we can determine the end of the prologue via the symbol table. If so, then return either PC, or the PC after the prologue, whichever is greater. */ - if (find_pc_partial_function (pc, NULL, &func_addr, NULL)) + if (find_pc_partial_function (pc, NULL, &func_addr, &func_end_addr)) { CORE_ADDR post_prologue_pc = skip_prologue_using_sal (gdbarch, func_addr); @@ -2113,6 +2113,11 @@ rs6000_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc) if (limit_pc == 0) limit_pc = pc + 100; /* Magic. */ + /* Do not allow limit_pc to be past the function end, if we know + where that end is... */ + if (func_end_addr && limit_pc > func_end_addr) + limit_pc = func_end_addr; + pc = skip_prologue (gdbarch, pc, limit_pc, &frame); return pc; } -- 1.7.1