From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 30428 invoked by alias); 3 Mar 2020 05:46:23 -0000 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 Received: (qmail 30150 invoked by uid 89); 3 Mar 2020 05:45:52 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-17.7 required=5.0 tests=AWL,BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.1 spammy=Environment X-HELO: simark.ca Received: from simark.ca (HELO simark.ca) (158.69.221.121) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 03 Mar 2020 05:45:50 +0000 Received: from [10.0.0.11] (unknown [192.222.164.54]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by simark.ca (Postfix) with ESMTPSA id BEE581E4B2; Tue, 3 Mar 2020 00:45:42 -0500 (EST) Subject: Re: [PATCH v2] Rebase executable to match relocated base address To: Hannes Domani , gdb-patches@sourceware.org References: <20200213181430.11259-1-ssbssa.ref@yahoo.de> <20200213181430.11259-1-ssbssa@yahoo.de> From: Simon Marchi Message-ID: Date: Tue, 03 Mar 2020 05:46:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200213181430.11259-1-ssbssa@yahoo.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2020-03/txt/msg00048.txt On 2020-02-13 1:14 p.m., Hannes Domani via gdb-patches wrote: > Windows executables linked with -dynamicbase get a new base address > when loaded, which makes debugging impossible if the executable isn't > also rebased in gdb. > > The new base address is read from the Process Environment Block. > --- > v2: > This version now no longer needs the fake auxv entry. Thanks, hopefully that way of finding the base address is sufficient for what you need. I like it, it's much more self-contained. > --- > gdb/windows-tdep.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 49 insertions(+) > > diff --git a/gdb/windows-tdep.c b/gdb/windows-tdep.c > index 6eef3fbd96..29c0a828a7 100644 > --- a/gdb/windows-tdep.c > +++ b/gdb/windows-tdep.c > @@ -34,6 +34,9 @@ > #include "solib.h" > #include "solib-target.h" > #include "gdbcore.h" > +#include "coff/internal.h" > +#include "libcoff.h" > +#include "solist.h" > > /* Windows signal numbers differ between MinGW flavors and between > those and Cygwin. The below enumeration was gleaned from the > @@ -812,6 +815,50 @@ windows_get_siginfo_type (struct gdbarch *gdbarch) > return siginfo_type; > } > > +/* Implement the "solib_create_inferior_hook" target_so_ops method. */ > + > +static void > +windows_solib_create_inferior_hook (int from_tty) > +{ > + CORE_ADDR exec_base = 0; > + > + /* Find base address of main executable in > + TIB->process_environment_block->image_base_address. */ > + struct gdbarch *gdbarch = target_gdbarch (); > + enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); > + int ptr_bytes; > + int peb_offset; /* Offset of process_environment_block in TIB. */ > + int base_offset; /* Offset of image_base_address in PEB. */ > + if (gdbarch_ptr_bit (gdbarch) == 32) > + { > + ptr_bytes = 4; > + peb_offset = 48; > + base_offset = 8; > + } > + else > + { > + ptr_bytes = 8; > + peb_offset = 96; > + base_offset = 16; > + } > + CORE_ADDR tlb; > + gdb_byte buf[8]; > + if (target_get_tib_address (inferior_ptid, &tlb) > + && !target_read_memory (tlb + peb_offset, buf, ptr_bytes)) > + { > + CORE_ADDR peb = extract_unsigned_integer (buf, ptr_bytes, byte_order); > + if (!target_read_memory (peb + base_offset, buf, ptr_bytes)) > + exec_base = extract_unsigned_integer (buf, ptr_bytes, byte_order); > + } > + > + if (symfile_objfile && exec_base) Use explicit comparison operators when comparing pointers and integers (except those that are really meant to represent boolean values and haven't been converted to `bool` yet). So, if (symfile_objfile != nullptr && exec_base != 0) > + { > + CORE_ADDR vmaddr = pe_data (exec_bfd)->pe_opthdr.ImageBase; > + if (vmaddr != exec_base) > + objfile_rebase (symfile_objfile, exec_base - vmaddr); > + } > +} > + > /* To be called from the various GDB_OSABI_CYGWIN handlers for the > various Windows architectures and machine types. */ > > @@ -830,6 +877,8 @@ windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) > > set_gdbarch_gdb_signal_to_target (gdbarch, windows_gdb_signal_to_target); > > + solib_target_so_ops.solib_create_inferior_hook > + = windows_solib_create_inferior_hook; I don't think this bit is right. Some other architecture/target could be using solib_target_so_ops, and you force that solib_create_inferior_hook value for them too. I mean, it won't matter for you in practice when debugging a single process on Windows, but still let's do it right. Ideally, all this would be a C++ class hierarchy and you would extend the solib_target_so_ops class to implement the solib_create_inferior_hook method. But here, we have a structure with function pointers, so you need to copy solib_target_so_ops into a windows-specific version, and assign the solib_create_inferior_hook pointer in that one. Check how mips_linux_init_abi does it, it's not very complicated. Simon