From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by sourceware.org (Postfix) with ESMTPS id 5712F3870845 for ; Thu, 28 May 2020 13:05:09 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 5712F3870845 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=tdevries@suse.de X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id A6E78AB89; Thu, 28 May 2020 13:05:07 +0000 (UTC) Subject: Re: [PATCH v2 28/42] Remove dwarf2_per_cu_data::objfile () To: Simon Marchi , Simon Marchi , gdb-patches@sourceware.org References: <20200512210913.5593-1-simon.marchi@efficios.com> <20200512211250.6230-29-simon.marchi@efficios.com> <04473d43-9719-436b-648a-bdc8e5f55751@suse.de> <354bbf9d-6bca-deaa-c64b-714c8d6b477d@suse.de> From: Tom de Vries Autocrypt: addr=tdevries@suse.de; keydata= xsBNBF0ltCcBCADDhsUnMMdEXiHFfqJdXeRvgqSEUxLCy/pHek88ALuFnPTICTwkf4g7uSR7 HvOFUoUyu8oP5mNb4VZHy3Xy8KRZGaQuaOHNhZAT1xaVo6kxjswUi3vYgGJhFMiLuIHdApoc u5f7UbV+egYVxmkvVLSqsVD4pUgHeSoAcIlm3blZ1sDKviJCwaHxDQkVmSsGXImaAU+ViJ5l CwkvyiiIifWD2SoOuFexZyZ7RUddLosgsO0npVUYbl6dEMq2a5ijGF6/rBs1m3nAoIgpXk6P TCKlSWVW6OCneTaKM5C387972qREtiArTakRQIpvDJuiR2soGfdeJ6igGA1FZjU+IsM5ABEB AAHNH1RvbSBkZSBWcmllcyA8dGRldnJpZXNAc3VzZS5kZT7CwKsEEwEIAD4WIQSsnSe5hKbL MK1mGmjuhV2rbOJEoAUCXSW0JwIbAwUJA8JnAAULCQgHAgYVCgkICwIEFgIDAQIeAQIXgAAh CRDuhV2rbOJEoBYhBKydJ7mEpsswrWYaaO6FXats4kSgc48H/Ra2lq5p3dHsrlQLqM7N68Fo eRDf3PMevXyMlrCYDGLVncQwMw3O/AkousktXKQ42DPJh65zoXB22yUt8m0g12xkLax98KFJ 5NyUloa6HflLl+wQL/uZjIdNUQaHQLw3HKwRMVi4l0/Jh/TygYG1Dtm8I4o708JS4y8GQxoQ UL0z1OM9hyM3gI2WVTTyprsBHy2EjMOu/2Xpod95pF8f90zBLajy6qXEnxlcsqreMaqmkzKn 3KTZpWRxNAS/IH3FbGQ+3RpWkNGSJpwfEMVCeyK5a1n7yt1podd1ajY5mA1jcaUmGppqx827 8TqyteNe1B/pbiUt2L/WhnTgW1NC1QDOwE0EXSW0JwEIAM99H34Bu4MKM7HDJVt864MXbx7B 1M93wVlpJ7Uq+XDFD0A0hIal028j+h6jA6bhzWto4RUfDl/9mn1StngNVFovvwtfzbamp6+W pKHZm9X5YvlIwCx131kTxCNDcF+/adRW4n8CU3pZWYmNVqhMUiPLxElA6QhXTtVBh1RkjCZQ Kmbd1szvcOfaD8s+tJABJzNZsmO2hVuFwkDrRN8Jgrh92a+yHQPd9+RybW2l7sJv26nkUH5Z 5s84P6894ebgimcprJdAkjJTgprl1nhgvptU5M9Uv85Pferoh2groQEAtRPlCGrZ2/2qVNe9 XJfSYbiyedvApWcJs5DOByTaKkcAEQEAAcLAkwQYAQgAJhYhBKydJ7mEpsswrWYaaO6FXats 4kSgBQJdJbQnAhsMBQkDwmcAACEJEO6FXats4kSgFiEErJ0nuYSmyzCtZhpo7oVdq2ziRKD3 twf7BAQBZ8TqR812zKAD7biOnWIJ0McV72PFBxmLIHp24UVe0ZogtYMxSWKLg3csh0yLVwc7 H3vldzJ9AoK3Qxp0Q6K/rDOeUy3HMqewQGcqrsRRh0NXDIQk5CgSrZslPe47qIbe3O7ik/MC q31FNIAQJPmKXX25B115MMzkSKlv4udfx7KdyxHrTSkwWZArLQiEZj5KG4cCKhIoMygPTA3U yGaIvI/BGOtHZ7bEBVUCFDFfOWJ26IOCoPnSVUvKPEOH9dv+sNy7jyBsP5QxeTqwxC/1ZtNS DUCSFQjqA6bEGwM22dP8OUY6SC94x1G81A9/xbtm9LQxKm0EiDH8KBMLfQ== Message-ID: <2cdb90c2-ad74-310d-75db-65a3d694049f@suse.de> Date: Thu, 28 May 2020 15:05:03 +0200 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: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-17.1 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP 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: Thu, 28 May 2020 13:05:11 -0000 On 28-05-2020 04:00, Simon Marchi wrote: > On 2020-05-27 6:16 p.m., Simon Marchi via Gdb-patches wrote: >> Ok, I reproduced it with opensuse/tumbleweed, after installing glibc's debug info. I'll >> look into it. > > Quick update to say that I understand a bit more what happens. It turns out that call sites > can refer indirectly to other objfiles. Here, we deal with an indirect call (through a function > pointer probably). In that case, the call site doesn't know at compile time what it calls. It > provides a DWARF expression to compute the called address. The DIE corresponding to the call site > is: > > 0x0091aa10: DW_TAG_GNU_call_site > DW_AT_low_pc [DW_FORM_addr] (0x00000000001398e0) > DW_AT_GNU_call_site_target [DW_FORM_exprloc] (DW_OP_fbreg -272, DW_OP_deref) > DW_AT_sibling [DW_FORM_ref4] (0x0091aa2b) > > This call site is in the _dl_catch_exception function of libc (which indeed takes a function pointer > as argument). In our case, the function pointer is a function in ld-linux.so. So this is how the > two objfiles can be different. > > For comparison, when the function being called is known at compile time, the call site DIE will refer > directly to the function being called, like in this case: > > 0x0091a9f2: DW_TAG_GNU_call_site > DW_AT_low_pc [DW_FORM_addr] (0x00000000001398cd) > DW_AT_abstract_origin [DW_FORM_ref4] (0x0091ad45 "__GI___sigsetjmp") > DW_AT_sibling [DW_FORM_ref4] (0x0091aa10) > > In that case, I presume that it's not really possible for the caller and calle to be in different > objfiles (this is the scenarion I had in my mind, I didn't know that indirect call sites could be > described as well). > > See the patch below (still missing the commit message). Hi, thanks for looking into this. I tried out the patch, and it fixes all regressions for me. Thanks, - Tom > I think we only need to put and restore the > caller's per_objfile in this->per_objfile. Alternatively, we could maybe just create a new > dwarf_evaluate_loc_desc local object, instead of setting and restoring all the fields. I'll try that > tomorrow. > > Simon > > > From 2381d562b3130b94ad8e266dd034431f80275c8b Mon Sep 17 00:00:00 2001 > From: Simon Marchi > Date: Wed, 27 May 2020 21:54:45 -0400 > Subject: [PATCH] gdb: use caller objfile in > dwarf_evaluate_loc_desc::push_dwarf_reg_entry_value > > Change-Id: Ib227d767ce525c10607ab6621a373aaae982c67a > --- > gdb/dwarf2/loc.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/gdb/dwarf2/loc.c b/gdb/dwarf2/loc.c > index 7953361adeed..1aab1a4f51bc 100644 > --- a/gdb/dwarf2/loc.c > +++ b/gdb/dwarf2/loc.c > @@ -726,8 +726,6 @@ class dwarf_evaluate_loc_desc : public dwarf_expr_context > data_src = deref_size == -1 ? parameter->value : parameter->data_value; > size = deref_size == -1 ? parameter->value_size : parameter->data_value_size; > > - gdb_assert (this->per_objfile == caller_per_objfile); > - > /* DEREF_SIZE size is not verified here. */ > if (data_src == NULL) > throw_error (NO_ENTRY_VALUE_ERROR, > @@ -739,11 +737,13 @@ class dwarf_evaluate_loc_desc : public dwarf_expr_context > caller_per_cu); > scoped_restore save_obj_addr = make_scoped_restore (&this->obj_address, > (CORE_ADDR) 0); > + scoped_restore save_per_objfile = make_scoped_restore (&this->per_objfile, > + caller_per_objfile); > > scoped_restore save_arch = make_scoped_restore (&this->gdbarch); > this->gdbarch = this->per_objfile->objfile->arch (); > scoped_restore save_addr_size = make_scoped_restore (&this->addr_size); > - this->addr_size = per_cu->addr_size (); > + this->addr_size = this->per_cu->addr_size (); > > this->eval (data_src, size); > } >