From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23214 invoked by alias); 15 Mar 2012 01:04:06 -0000 Received: (qmail 23203 invoked by uid 22791); 15 Mar 2012 01:04:05 -0000 X-SWARE-Spam-Status: No, hits=-2.0 required=5.0 tests=AWL,BAYES_00,TW_CP 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, 15 Mar 2012 01:03:46 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by filtered-rock.gnat.com (Postfix) with ESMTP id 993EF1C61ED; Wed, 14 Mar 2012 21:03:45 -0400 (EDT) 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 m++AJGseZjaG; Wed, 14 Mar 2012 21:03:45 -0400 (EDT) Received: from joel.gnat.com (localhost.localdomain [127.0.0.1]) by rock.gnat.com (Postfix) with ESMTP id 5BF411C6122; Wed, 14 Mar 2012 21:03:45 -0400 (EDT) Received: by joel.gnat.com (Postfix, from userid 1000) id 35EE2145615; Wed, 14 Mar 2012 18:03:36 -0700 (PDT) Date: Thu, 15 Mar 2012 01:04:00 -0000 From: Joel Brobecker To: Pedro Alves Cc: gdb-patches@sourceware.org Subject: Re: [RFA] Problem after hitting breakpoint on Windows (with GDBserver) Message-ID: <20120315010336.GM2853@adacore.com> References: <1331602756-23567-1-git-send-email-brobecker@adacore.com> <1331602756-23567-2-git-send-email-brobecker@adacore.com> <4F5F6187.50209@redhat.com> <20120313215956.GT2853@adacore.com> <4F5FD262.9030708@redhat.com> <20120314215024.GL2853@adacore.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="rMWmSaSbD7nr+du9" Content-Disposition: inline In-Reply-To: <20120314215024.GL2853@adacore.com> User-Agent: Mutt/1.5.20 (2009-06-14) 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: 2012-03/txt/msg00520.txt.bz2 --rMWmSaSbD7nr+du9 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-length: 446 > I think that you also might prefer if I remove all the changes that > document the fact that the read buffer should not be a shadow_contents, > and just document this in one place. I will do that next. I am just > sending this patch now, to have a trace of the patch before I undo > some of my changes. And attached is the simplified version without the extra comments. Tested on x86_64-linux, with and without GDBserver... Thanks, -- Joel --rMWmSaSbD7nr+du9 Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="0001-Problem-after-hitting-breakpoint-on-Windows-with-GDB.patch" Content-length: 5331 >From 8a1c2bb5f60332adcbb00a3d9c20b9e924e3e90b Mon Sep 17 00:00:00 2001 From: Joel Brobecker Date: Mon, 12 Mar 2012 22:44:05 +0100 Subject: [PATCH] Problem after hitting breakpoint on Windows (with GDBserver) gdb/ChangeLog: * breakpoint.c (breakpoint_xfer_memory): Add assertion. Update function description. (insert_bp_location): Do not wipe bl->target_info out. * mem-break.c: #include "gdb_string.h". (default_memory_insert_breakpoint): Do not call target_read_memory with a pointer to the breakpoint's shadow_contents buffer. Use a local buffer instead. * m32r-tdep.c (m32r_memory_insert_breakpoint): Ditto. --- gdb/breakpoint.c | 21 +++++++++++++++++++-- gdb/m32r-tdep.c | 3 ++- gdb/mem-break.c | 17 +++++++++++------ 3 files changed, 32 insertions(+), 9 deletions(-) diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c index d35704d..debf2b2 100644 --- a/gdb/breakpoint.c +++ b/gdb/breakpoint.c @@ -1318,6 +1318,10 @@ bp_location_has_shadow (struct bp_location *bl) /* Update BUF, which is LEN bytes read from the target address MEMADDR, by replacing any memory breakpoints with their shadowed contents. + If READBUF is not NULL, this buffer must not overlap with any of + the breakpoint location's shadow_contents buffers. Otherwise, + a failed assertion internal error will be raised. + The range of shadowed area by each bp_location is: bl->address - bp_location_placed_address_before_address_max up to bl->address + bp_location_shadow_len_after_address_max @@ -1446,6 +1450,12 @@ breakpoint_xfer_memory (gdb_byte *readbuf, gdb_byte *writebuf, if (readbuf != NULL) { + /* Verify that the readbuf buffer does not overlap with + the shadow_contents buffer. */ + gdb_assert (bl->target_info.shadow_contents >= readbuf + len + || readbuf >= (bl->target_info.shadow_contents + + bl->target_info.shadow_len)); + /* Update the read buffer with this inserted breakpoint's shadow. */ memcpy (readbuf + bp_addr - memaddr, @@ -2082,8 +2092,15 @@ insert_bp_location (struct bp_location *bl, if (!should_be_inserted (bl) || (bl->inserted && !bl->needs_update)) return 0; - /* Initialize the target-specific information. */ - memset (&bl->target_info, 0, sizeof (bl->target_info)); + /* Note we don't initialize bl->target_info, as that wipes out + the breakpoint location's shadow_contents if the breakpoint + is still inserted at that location. This in turn breaks + target_read_memory which depends on these buffers when + a memory read is requested at the breakpoint location: + Once the target_info has been wiped, we fail to see that + we have a breakpoint inserted at that address and thus + read the breakpoint instead of returning the data saved in + the breakpoint location's shadow contents. */ bl->target_info.placed_address = bl->address; bl->target_info.placed_address_space = bl->pspace->aspace; bl->target_info.length = bl->length; diff --git a/gdb/m32r-tdep.c b/gdb/m32r-tdep.c index 72872bd..d504eb3 100644 --- a/gdb/m32r-tdep.c +++ b/gdb/m32r-tdep.c @@ -85,7 +85,7 @@ m32r_memory_insert_breakpoint (struct gdbarch *gdbarch, CORE_ADDR addr = bp_tgt->placed_address; int val; gdb_byte buf[4]; - gdb_byte *contents_cache = bp_tgt->shadow_contents; + gdb_byte contents_cache[4]; gdb_byte bp_entry[] = { 0x10, 0xf1 }; /* dpt */ /* Save the memory contents. */ @@ -93,6 +93,7 @@ m32r_memory_insert_breakpoint (struct gdbarch *gdbarch, if (val != 0) return val; /* return error */ + memcpy (bp_tgt->shadow_contents, contents_cache, 4); bp_tgt->placed_size = bp_tgt->shadow_len = 4; /* Determine appropriate breakpoint contents and size for this address. */ diff --git a/gdb/mem-break.c b/gdb/mem-break.c index 7d0e3f1..bd34fb2 100644 --- a/gdb/mem-break.c +++ b/gdb/mem-break.c @@ -29,6 +29,7 @@ #include "breakpoint.h" #include "inferior.h" #include "target.h" +#include "gdb_string.h" /* Insert a breakpoint on targets that don't have any better @@ -46,6 +47,7 @@ default_memory_insert_breakpoint (struct gdbarch *gdbarch, { int val; const unsigned char *bp; + gdb_byte *readbuf; /* Determine appropriate breakpoint contents and size for this address. */ bp = gdbarch_breakpoint_from_pc @@ -53,15 +55,18 @@ default_memory_insert_breakpoint (struct gdbarch *gdbarch, if (bp == NULL) error (_("Software breakpoints not implemented for this target.")); - /* Save the memory contents. */ + /* Save the memory contents in the shadow_contents buffer and then + write the breakpoint instruction. */ bp_tgt->shadow_len = bp_tgt->placed_size; - val = target_read_memory (bp_tgt->placed_address, bp_tgt->shadow_contents, + readbuf = alloca (bp_tgt->placed_size); + val = target_read_memory (bp_tgt->placed_address, readbuf, bp_tgt->placed_size); - - /* Write the breakpoint. */ if (val == 0) - val = target_write_raw_memory (bp_tgt->placed_address, bp, - bp_tgt->placed_size); + { + memcpy (bp_tgt->shadow_contents, readbuf, bp_tgt->placed_size); + val = target_write_raw_memory (bp_tgt->placed_address, bp, + bp_tgt->placed_size); + } return val; } -- 1.7.1 --rMWmSaSbD7nr+du9--