From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from barracuda.ebox.ca (barracuda.ebox.ca [96.127.255.19]) by sourceware.org (Postfix) with ESMTPS id 1DE9F394D892 for ; Mon, 16 Mar 2020 17:08:54 +0000 (GMT) X-ASG-Debug-ID: 1584378531-0c856e18f3b31cc0001-fS2M51 Received: from smtp.ebox.ca (smtp.ebox.ca [96.127.255.82]) by barracuda.ebox.ca with ESMTP id pDQANa63RZBNKjkP (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 16 Mar 2020 13:08:51 -0400 (EDT) X-Barracuda-Envelope-From: simon.marchi@polymtl.ca X-Barracuda-RBL-Trusted-Forwarder: 96.127.255.82 Received: from simark.lan (unknown [192.222.164.54]) by smtp.ebox.ca (Postfix) with ESMTP id A7351441B21; Mon, 16 Mar 2020 13:08:51 -0400 (EDT) From: Simon Marchi X-Barracuda-Effective-Source-IP: 192-222-164-54.qc.cable.ebox.net[192.222.164.54] X-Barracuda-Apparent-Source-IP: 192.222.164.54 X-Barracuda-RBL-IP: 192.222.164.54 To: gdb-patches@sourceware.org Cc: Eli Zaretskii , Jon Turney , Simon Marchi Subject: [PATCH 6/7] gdb: select "Cygwin" OS ABI for Cygwin binaries Date: Mon, 16 Mar 2020 13:08:44 -0400 X-ASG-Orig-Subj: [PATCH 6/7] gdb: select "Cygwin" OS ABI for Cygwin binaries Message-Id: <20200316170845.184386-7-simon.marchi@polymtl.ca> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200316170845.184386-1-simon.marchi@polymtl.ca> References: <20200316170845.184386-1-simon.marchi@polymtl.ca> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Barracuda-Connect: smtp.ebox.ca[96.127.255.82] X-Barracuda-Start-Time: 1584378531 X-Barracuda-Encrypted: DHE-RSA-AES256-SHA X-Barracuda-URL: https://96.127.255.19:443/cgi-mod/mark.cgi X-Barracuda-Scan-Msg-Size: 8055 X-Barracuda-BRTS-Status: 1 X-Virus-Scanned: by bsmtpd at ebox.ca X-Barracuda-Spam-Score: 0.50 X-Barracuda-Spam-Status: No, SCORE=0.50 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=8.0 tests=BSF_RULE_7582B, INFO_TLD X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.3.80637 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- 0.00 INFO_TLD URI: Contains an URL in the INFO top-level domain 0.50 BSF_RULE_7582B Custom Rule 7582B X-Spam-Status: No, score=-23.5 required=5.0 tests=GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_DMARC_QUARANTINE, KAM_DMARC_STATUS, RCVD_IN_DNSWL_LOW, SPF_HELO_NONE, SPF_SOFTFAIL autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 16 Mar 2020 17:08:55 -0000 From: Simon Marchi Before this patch, the "Windows" OS ABI is selected for all Windows executables, including Cygwin ones. This patch makes GDB differentiate Cygwin binaries from non-Cygwin ones, and selects the "Cygwin" OS ABI for the Cygwin ones. To check whether a Windows PE executable is a Cygwin one, we check the library list in the .idata section, see if it contains "cygwin1.dll". I had to add code to parse the .idata section, because BFD doesn't seem to expose this information. BFD does parse this information, but only to print it in textual form (function pe_print_idata): https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=bfd/peXXigen.c;h=e42d646552a0ca1e856e082256cd3d943b54ddf0;hb=HEAD#l1261 Here's the relevant portion of the PE format documentation: https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#the-idata-section This page was also useful: https://blog.kowalczyk.info/articles/pefileformat.html#9ccef823-67e7-4372-9172-045d7b1fb006 With this patch applied, this is what I get: (gdb) file some_mingw_x86_64_binary.exe Reading symbols from some_mingw_x86_64_binary.exe... (gdb) show osabi The current OS ABI is "auto" (currently "Windows"). The default OS ABI is "GNU/Linux". (gdb) file some_mingw_i386_binary.exe Reading symbols from some_mingw_i386_binary.exe... (gdb) show osabi The current OS ABI is "auto" (currently "Windows"). The default OS ABI is "GNU/Linux". (gdb) file some_cygwin_x86_64_binary.exe Reading symbols from some_cygwin_x86_64_binary.exe... (gdb) show osabi The current OS ABI is "auto" (currently "Cygwin"). The default OS ABI is "GNU/Linux". gdb/ChangeLog: * windows-tdep.h (is_linked_with_cygwin_dll): New declaration. * windows-tdep.c (CYGWIN_DLL_NAME): New. (pe_import_directory_entry): New struct type. (is_linked_with_cygwin_dll): New function. * amd64-windows-tdep.c (amd64_windows_osabi_sniffer): Select GDB_OSABI_CYGWIN if the BFD is linked with the Cygwin DLL. * i386-windows-tdep.c (i386_windows_osabi_sniffer): Likewise. --- gdb/amd64-windows-tdep.c | 9 ++-- gdb/i386-windows-tdep.c | 9 ++-- gdb/windows-tdep.c | 101 +++++++++++++++++++++++++++++++++++++++ gdb/windows-tdep.h | 6 +++ 4 files changed, 119 insertions(+), 6 deletions(-) diff --git a/gdb/amd64-windows-tdep.c b/gdb/amd64-windows-tdep.c index 88ff794abcb6..e0346f8628fe 100644 --- a/gdb/amd64-windows-tdep.c +++ b/gdb/amd64-windows-tdep.c @@ -1249,10 +1249,13 @@ amd64_windows_osabi_sniffer (bfd *abfd) { const char *target_name = bfd_get_target (abfd); - if (strcmp (target_name, "pei-x86-64") == 0) - return GDB_OSABI_WINDOWS; + if (!streq (target_name, "pei-x86-64")) + return GDB_OSABI_UNKNOWN; - return GDB_OSABI_UNKNOWN; + if (is_linked_with_cygwin_dll (abfd)) + return GDB_OSABI_CYGWIN; + + return GDB_OSABI_WINDOWS; } void _initialize_amd64_windows_tdep (); diff --git a/gdb/i386-windows-tdep.c b/gdb/i386-windows-tdep.c index a71ceda781f8..bd6107b02f1f 100644 --- a/gdb/i386-windows-tdep.c +++ b/gdb/i386-windows-tdep.c @@ -232,10 +232,13 @@ i386_windows_osabi_sniffer (bfd *abfd) { const char *target_name = bfd_get_target (abfd); - if (strcmp (target_name, "pei-i386") == 0) - return GDB_OSABI_WINDOWS; + if (!streq (target_name, "pei-i386")) + return GDB_OSABI_UNKNOWN; - return GDB_OSABI_UNKNOWN; + if (is_linked_with_cygwin_dll (abfd)) + return GDB_OSABI_CYGWIN; + + return GDB_OSABI_WINDOWS; } static enum gdb_osabi diff --git a/gdb/windows-tdep.c b/gdb/windows-tdep.c index e02b1ceed387..32e551bcb175 100644 --- a/gdb/windows-tdep.c +++ b/gdb/windows-tdep.c @@ -38,6 +38,8 @@ #include "libcoff.h" #include "solist.h" +#define CYGWIN_DLL_NAME "cygwin1.dll" + /* Windows signal numbers differ between MinGW flavors and between those and Cygwin. The below enumeration was gleaned from the respective headers; the ones marked with MinGW64/Cygwin are defined @@ -898,6 +900,105 @@ static const struct internalvar_funcs tlb_funcs = NULL }; +/* Layout of an element of a PE's Import Directory Table. Based on: + + https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-directory-table + */ + +struct pe_import_directory_entry +{ + uint32_t import_lookup_table_rva; + uint32_t timestamp; + uint32_t forwarder_chain; + uint32_t name_rva; + uint32_t import_address_table_rva; +}; + +gdb_static_assert (sizeof (pe_import_directory_entry) == 20); + +/* Return true if the Portable Executable behind ABFD uses the Cygwin dll + (cygwin1.dll). */ +/* See windows-tdep.h. */ + +bool +is_linked_with_cygwin_dll (bfd *abfd) +{ + /* The list of DLLs a PE is linked to is in the .idata section. See: + + https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#the-idata-section + */ + asection *idata_section = bfd_get_section_by_name (abfd, ".idata"); + if (idata_section == nullptr) + return false; + + /* Find the virtual address of the .idata section. We must subtract this + from the RVAs (relative virtual addresses) to obtain an offset in the + section. */ + bfd_vma idata_addr = + pe_data (abfd)->pe_opthdr.DataDirectory[PE_IMPORT_TABLE].VirtualAddress; + + /* Map the section's data. */ + bfd_size_type idata_size; + const gdb_byte *const idata_contents + = gdb_bfd_map_section (idata_section, &idata_size); + if (idata_contents == nullptr) + { + warning (_("Failed to get content of .idata section.")); + return false; + } + + const gdb_byte *iter = idata_contents; + const gdb_byte *end = idata_contents + idata_size; + const pe_import_directory_entry null_dir_entry = { 0 }; + + /* Iterate through all directory entries. */ + while (true) + { + /* Is there enough space left in the section for another entry? */ + if (iter + sizeof (pe_import_directory_entry) > end) + { + warning (_("Failed to parse .idata section: unexpected end of " + ".idata section.")); + break; + } + + pe_import_directory_entry *dir_entry = (pe_import_directory_entry *) iter; + + /* Is it the end of list marker? */ + if (memcmp (dir_entry, &null_dir_entry, + sizeof (pe_import_directory_entry)) == 0) + break; + + bfd_vma name_addr = dir_entry->name_rva; + + /* If the name's virtual address is smaller than the section's virtual + address, there's a problem. */ + if (name_addr < idata_addr + || name_addr >= (idata_addr + idata_size)) + { + warning (_("\ +Failed to parse .idata section: name's virtual address (0x%" BFD_VMA_FMT "x) \ +is outside .idata section's range [0x%" BFD_VMA_FMT "x, 0x%" BFD_VMA_FMT "x[."), + name_addr, idata_addr, idata_addr + idata_size); + break; + } + + const gdb_byte *name = &idata_contents[name_addr - idata_addr]; + + /* Make sure we don't overshoot the end of the section with the streq. */ + if (name + sizeof(CYGWIN_DLL_NAME) > end) + continue; + + /* Finally, check if this is the dll name we are looking for. */ + if (streq ((const char *) name, CYGWIN_DLL_NAME)) + return true; + + iter += sizeof(pe_import_directory_entry); + } + + return false; +} + void _initialize_windows_tdep (); void _initialize_windows_tdep () diff --git a/gdb/windows-tdep.h b/gdb/windows-tdep.h index 34474f259c2a..f2dc4260469d 100644 --- a/gdb/windows-tdep.h +++ b/gdb/windows-tdep.h @@ -33,4 +33,10 @@ extern void windows_xfer_shared_library (const char* so_name, extern void windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch); + +/* Return true if the Portable Executable behind ABFD uses the Cygwin dll + (cygwin1.dll). */ + +extern bool is_linked_with_cygwin_dll (bfd *abfd); + #endif -- 2.25.1