From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by sourceware.org (Postfix) with ESMTPS id D9988384B12D for ; Thu, 2 Jun 2022 17:00:34 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org D9988384B12D Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 252ELFlE021898; Thu, 2 Jun 2022 17:00:33 GMT Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3gew9cn1uq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 02 Jun 2022 17:00:33 +0000 Received: from m0098393.ppops.net (m0098393.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 252Gsrn1004026; Thu, 2 Jun 2022 17:00:32 GMT Received: from ppma01dal.us.ibm.com (83.d6.3fa9.ip4.static.sl-reverse.com [169.63.214.131]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3gew9cn1u7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 02 Jun 2022 17:00:32 +0000 Received: from pps.filterd (ppma01dal.us.ibm.com [127.0.0.1]) by ppma01dal.us.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 252Gq7Hr003678; Thu, 2 Jun 2022 17:00:31 GMT Received: from b03cxnp08027.gho.boulder.ibm.com (b03cxnp08027.gho.boulder.ibm.com [9.17.130.19]) by ppma01dal.us.ibm.com with ESMTP id 3gcxt5usn2-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 02 Jun 2022 17:00:31 +0000 Received: from b03ledav001.gho.boulder.ibm.com (b03ledav001.gho.boulder.ibm.com [9.17.130.232]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 252H0UNk9765434 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 2 Jun 2022 17:00:30 GMT Received: from b03ledav001.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 972AF6E064; Thu, 2 Jun 2022 17:00:30 +0000 (GMT) Received: from b03ledav001.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4C09E6E059; Thu, 2 Jun 2022 17:00:30 +0000 (GMT) Received: from li-e362e14c-2378-11b2-a85c-87d605f3c641.ibm.com (unknown [9.211.57.135]) by b03ledav001.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 2 Jun 2022 17:00:30 +0000 (GMT) Message-ID: <8ee42814763cc0e245c93f62c40cdaaad3ac65b2.camel@us.ibm.com> Subject: Re: [PATCH V4] PowerPC: fix for gdb.base/eh_return.exp From: Carl Love To: will schmidt , Pedro Alves , Kevin Buettner , gdb-patches@sourceware.org Date: Thu, 02 Jun 2022 10:00:29 -0700 In-Reply-To: <998d3f4859f16b73afd5103b682246643fef6d42.camel@us.ibm.com> References: <76bea9ad010a71ea5e2c7fd78f818bdb399810a6.camel@us.ibm.com> <20220506110826.5e16c8b6@f35-zws-1> <70a877cc-2f35-3924-6717-9d519c2730c5@palves.net> <099c8f8d8729a0051f83a034d62c18f03c789167.camel@vnet.ibm.com> <37d2a4b6a57b62662f0417f123bda6ba48066554.camel@vnet.ibm.com> <998d3f4859f16b73afd5103b682246643fef6d42.camel@us.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-18.el8) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: wPZxw5sgsAMi-_CyJlcnSdk9Wqw-8szN X-Proofpoint-ORIG-GUID: vSpKPbEu1rhqtfDNktKgXlaeJ-YSvFb2 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.517,FMLib:17.11.64.514 definitions=2022-06-02_04,2022-06-02_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 priorityscore=1501 lowpriorityscore=0 phishscore=0 spamscore=0 impostorscore=0 malwarescore=0 mlxlogscore=999 bulkscore=0 suspectscore=0 mlxscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2204290000 definitions=main-2206020067 X-Spam-Status: No, score=-11.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) 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: Thu, 02 Jun 2022 17:00:36 -0000 Will, Pedro, Kevin, GDB maintainers: Per the comments from Kevin, the patch was updated to check for the gcc and xlc compilers on PowerPC. The patch was also tested and verified on AIX which uses the gcc compiler to build gdb. The attempt to build gdb using the xlc compiler fails due to unrelated compiler errors. The xlc options to disable the Traceback Table was verified but that was it. I have updated the patch per the comments from Will. The new version of the patch uses a PowerPC specific gcc option to suppress the generation of the Traceback Table information. The Traceback information for this function is contained in the .long statements following the last instruction in the function. The Traceback table consists of a series of bit fields. The assembler tries to interpret the Traceback Table as instructions. If the bits in the Traceback Table happen to match a known instruction, the assembler will print a bogus instruction, otherwise the assembler just prints the bits using the .long statement. Unfortunately, the disassembler does not know how to locate the Traceback Table information at the end of a function. With this patch, the existing gdb_test_multiple is able to locate the last instruction in the function correctly. Previously, the break point was set at the last .long statement which gdb will never reach. The test now passes as gdb successfully executes to the identified last instruction. Note, the use of the gcc mtraceback option is not valid on other architectures. I have tested the patch on Linux Power 10 with gcc, AIX with the gcc and Intel with gcc. Please let me know if this patch is acceptable. Thanks for the input and help with the patch. Carl Love ------------------------------------------------------------------ PowerPC: fix for gdb.base/eh_return.exp Disable the Traceback Table generation on PowerPC for this test. The Traceback Table consists of a series of bit fields to indicate things like the Traceback Table version, language, and specific information about the function. The Traceback Table is generated following the end of the code for every function by default. The Traceback Table is defined in the PowerPC ELF ABI and is intended to support debuggers and exception handlers. The Traceback Table is displayed in the disassembly of functions by default and is part of the function length. The table is tyupically interpreted by the disassembler as data represented by .long xxx entries. Generation of the Traceback Table is disabled in this test using the PowerPC specific gcc compiler option -mtraceback=no and the xlc option additional_flags-qtable=none. Disabling the Traceback Table generation in this test results in the gdb_test_multiple statement correctly locating the address of the bclr instruction before the statement "End of assembler dump." in the disassembly output. --- gdb/testsuite/gdb.base/eh_return.exp | 35 +++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-) diff --git a/gdb/testsuite/gdb.base/eh_return.exp b/gdb/testsuite/gdb.base/eh_return.exp index df55dbc72da..41d016486a1 100644 --- a/gdb/testsuite/gdb.base/eh_return.exp +++ b/gdb/testsuite/gdb.base/eh_return.exp @@ -18,8 +18,41 @@ standard_testfile +# Set compiler flags. +if {[istarget "powerpc*"]} then { + # PowerPC generates a Traceback Table, as defined in the PPC64 ABI, + # following each function by default. The Traceback Table information is + # typically interpreted by the disassembler as data represented with + # .long xxxx following the last instruction in the function. For example: + # + # Dump of assembler code for function eh2: + # 0x00000000100009e0 <+0>: lis r2,4098 + # ... + # 0x0000000010000b04 <+292>: add r1,r1,r10 + # 0x0000000010000b08 <+296>: blr + # 0x0000000010000b0c <+300>: .long 0x0 + # 0x0000000010000b10 <+304>: .long 0x1000000 + # 0x0000000010000b14 <+308>: .long 0x1000180 + # End of assembler dump. + # + # Disable the Traceback Table generation, using the PowerPC specific + # compiler option, so the test gdb_test_multiple "disassemble eh2" will + # locate the address of the blr instruction not the last .long statement. + if { [test_compiler_info "gcc-*"] } { + set compile_flags {debug nopie additional_flags=-mtraceback=no} + } elseif { [test_compiler_info "xlc-*"] } { + set compile_flags {debug nopie additional_flags=-qtbtable=none} + } elseif { [test_compiler_info "clang-*"] } { + set compile_flags {debug nopie additional_flags=-mllvm -xcoff-traceback-table=false} + } else { + set compile_flags {debug nopie } + } +} else { + set compile_flags {debug nopie} +} + if {[prepare_for_testing "failed to prepare" $testfile $srcfile \ - {debug nopie}]} { + $compile_flags]} { return -1 } -- 2.31.1