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Vous pouvez aussi obtenir de l’aide en visitant le portail de WSP au help.wsp.com Merci ----- Original Message ----- From: dwarf-discuss-requ...@lists.dwarfstd.org To: dwarf-discuss@lists.dwarfstd.org Sent: Saturday, September 28, 2019 1:37:16 PM GMT-07:00 Subject: Dwarf-Discuss Digest, Vol 119, Issue 6 >Send Dwarf-Discuss mailing list submissions to > dwarf-discuss@lists.dwarfstd.org > >To subscribe or unsubscribe via the World Wide Web, visit > http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org >or, via email, send a message with subject or body 'help' to > dwarf-discuss-requ...@lists.dwarfstd.org > >You can reach the person managing the list at > dwarf-discuss-ow...@lists.dwarfstd.org > >When replying, please edit your Subject line so it is more specific >than "Re: Contents of Dwarf-Discuss digest..." > > >Today's Topics: > > 1. Notification (serviced...@help.wsp.com) > > >---------------------------------------------------------------------- > >Message: 1 >Date: Sat, 28 Sep 2019 22:37:13 +0200 >From: <serviced...@help.wsp.com> >To: <dwarf-discuss@lists.dwarfstd.org> >Subject: [Dwarf-Discuss] Notification >Message-ID: <000m0aer1r6cr...@atos-services.net> >Content-Type: text/plain; charset="utf-8" > > >Your email to the Global IT Service Desk has been received - if this is an >issue requiring URGENT assistance, please CALL us using your in-country phone >number. We will respond to your e-mail during our regular hours of operation >between 7:00 AM to 6:00 PM local time. We provide limited support outside of >the local business hours. > >You can also obtain support through our Service Desk Portal on the web at >help.wsp.com > >Thank you > >-- > >Votre courriel achemin? au Centre d?assistance TI global a bien ?t? re?u- si >ce probl?me requiert une assistance IMM?DIATE SVP nous contacter par t?l?phone >en utilisant votre num?ro local. Nous r?pondrons ? votre courriel durant les >heures ouvrables soit entre 7 heures et 18 heures (heure locale). Le soutien >technique en dehors des heures ouvrables est limit?. > >Vous pouvez aussi obtenir de l?aide en visitant le portail de WSP au >help.wsp.com > >Merci > >----- Original Message ----- >From: dwarf-discuss-requ...@lists.dwarfstd.org >To: dwarf-discuss@lists.dwarfstd.org >Sent: Saturday, September 28, 2019 1:35:22 PM GMT-07:00 >Subject: Dwarf-Discuss Digest, Vol 119, Issue 5 > >>Send Dwarf-Discuss mailing list submissions to >> dwarf-discuss@lists.dwarfstd.org >> >>To subscribe or unsubscribe via the World Wide Web, visit >> http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org >>or, via email, send a message with subject or body 'help' to >> dwarf-discuss-requ...@lists.dwarfstd.org >> >>You can reach the person managing the list at >> dwarf-discuss-ow...@lists.dwarfstd.org >> >>When replying, please edit your Subject line so it is more specific >>than "Re: Contents of Dwarf-Discuss digest..." >> >> >>Today's Topics: >> >> 1. Notification (serviced...@help.wsp.com) >> >> >>---------------------------------------------------------------------- >> >>Message: 1 >>Date: Sat, 28 Sep 2019 00:07:01 +0200 >>From: <serviced...@help.wsp.com> >>To: <dwarf-discuss@lists.dwarfstd.org> >>Subject: [Dwarf-Discuss] Notification >>Message-ID: <000m0aer1r6cq...@atos-services.net> >>Content-Type: text/plain; charset="utf-8" >> >> >>Your email to the Global IT Service Desk has been received - if this is an >>issue requiring URGENT assistance, please CALL us using your in-country phone >>number. We will respond to your e-mail during our regular hours of operation >>between 7:00 AM to 6:00 PM local time. We provide limited support outside of >>the local business hours. >> >>You can also obtain support through our Service Desk Portal on the web at >>help.wsp.com >> >>Thank you >> >>-- >> >>Votre courriel achemin? au Centre d?assistance TI global a bien ?t? re?u- si >>ce probl?me requiert une assistance IMM?DIATE SVP nous contacter par >>t?l?phone en utilisant votre num?ro local. Nous r?pondrons ? votre courriel >>durant les heures ouvrables soit entre 7 heures et 18 heures (heure locale). >>Le soutien technique en dehors des heures ouvrables est limit?. >> >>Vous pouvez aussi obtenir de l?aide en visitant le portail de WSP au >>help.wsp.com >> >>Merci >> >>----- Original Message ----- >>From: dwarf-discuss-requ...@lists.dwarfstd.org >>To: dwarf-discuss@lists.dwarfstd.org >>Sent: Friday, September 27, 2019 3:04:29 PM GMT-07:00 >>Subject: Dwarf-Discuss Digest, Vol 119, Issue 4 >> >>>Send Dwarf-Discuss mailing list submissions to >>> dwarf-discuss@lists.dwarfstd.org >>> >>>To subscribe or unsubscribe via the World Wide Web, visit >>> http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org >>>or, via email, send a message with subject or body 'help' to >>> dwarf-discuss-requ...@lists.dwarfstd.org >>> >>>You can reach the person managing the list at >>> dwarf-discuss-ow...@lists.dwarfstd.org >>> >>>When replying, please edit your Subject line so it is more specific >>>than "Re: Contents of Dwarf-Discuss digest..." >>> >>> >>>Today's Topics: >>> >>> 1. Notification (serviced...@help.wsp.com) >>> 2. Re: DW_AT_segment and relocation (Ron Brender) >>> 3. Re: DW_AT_segment and relocation (Michael Eager) >>> >>> >>>---------------------------------------------------------------------- >>> >>>Message: 1 >>>Date: Fri, 27 Sep 2019 22:40:57 +0200 >>>From: <serviced...@help.wsp.com> >>>To: <dwarf-discuss@lists.dwarfstd.org> >>>Subject: [Dwarf-Discuss] Notification >>>Message-ID: <000m0aer1r6cq...@atos-services.net> >>>Content-Type: text/plain; charset="utf-8" >>> >>> >>>Your email to the Global IT Service Desk has been received - if this is an >>>issue requiring URGENT assistance, please CALL us using your in-country >>>phone number. We will respond to your e-mail during our regular hours of >>>operation between 7:00 AM to 6:00 PM local time. We provide limited support >>>outside of the local business hours. >>> >>>You can also obtain support through our Service Desk Portal on the web at >>>help.wsp.com >>> >>>Thank you >>> >>>-- >>> >>>Votre courriel achemin? au Centre d?assistance TI global a bien ?t? re?u- si >>>ce probl?me requiert une assistance IMM?DIATE SVP nous contacter par >>>t?l?phone en utilisant votre num?ro local. Nous r?pondrons ? votre courriel >>>durant les heures ouvrables soit entre 7 heures et 18 heures (heure locale). >>>Le soutien technique en dehors des heures ouvrables est limit?. >>> >>>Vous pouvez aussi obtenir de l?aide en visitant le portail de WSP au >>>help.wsp.com >>> >>>Merci >>> >>>----- Original Message ----- >>>From: dwarf-discuss-requ...@lists.dwarfstd.org >>>To: dwarf-discuss@lists.dwarfstd.org >>>Sent: Friday, September 27, 2019 1:40:13 PM GMT-07:00 >>>Subject: Dwarf-Discuss Digest, Vol 119, Issue 3 >>> >>>>Send Dwarf-Discuss mailing list submissions to >>>> dwarf-discuss@lists.dwarfstd.org >>>> >>>>To subscribe or unsubscribe via the World Wide Web, visit >>>> http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org >>>>or, via email, send a message with subject or body 'help' to >>>> dwarf-discuss-requ...@lists.dwarfstd.org >>>> >>>>You can reach the person managing the list at >>>> dwarf-discuss-ow...@lists.dwarfstd.org >>>> >>>>When replying, please edit your Subject line so it is more specific >>>>than "Re: Contents of Dwarf-Discuss digest..." >>>> >>>> >>>>Today's Topics: >>>> >>>> 1. Notification (serviced...@help.wsp.com) >>>> >>>> >>>>---------------------------------------------------------------------- >>>> >>>>Message: 1 >>>>Date: Fri, 27 Sep 2019 22:33:57 +0200 >>>>From: <serviced...@help.wsp.com> >>>>To: <dwarf-discuss@lists.dwarfstd.org> >>>>Subject: [Dwarf-Discuss] Notification >>>>Message-ID: <000m0aer1r6cq...@atos-services.net> >>>>Content-Type: text/plain; charset="utf-8" >>>> >>>> >>>>Your email to the Global IT Service Desk has been received - if this is an >>>>issue requiring URGENT assistance, please CALL us using your in-country >>>>phone number. We will respond to your e-mail during our regular hours of >>>>operation between 7:00 AM to 6:00 PM local time. We provide limited support >>>>outside of the local business hours. >>>> >>>>You can also obtain support through our Service Desk Portal on the web at >>>>help.wsp.com >>>> >>>>Thank you >>>> >>>>-- >>>> >>>>Votre courriel achemin? au Centre d?assistance TI global a bien ?t? re?u- >>>>si ce probl?me requiert une assistance IMM?DIATE SVP nous contacter par >>>>t?l?phone en utilisant votre num?ro local. Nous r?pondrons ? votre courriel >>>>durant les heures ouvrables soit entre 7 heures et 18 heures (heure >>>>locale). Le soutien technique en dehors des heures ouvrables est limit?. >>>> >>>>Vous pouvez aussi obtenir de l?aide en visitant le portail de WSP au >>>>help.wsp.com >>>> >>>>Merci >>>> >>>>----- Original Message ----- >>>>From: dwarf-discuss-requ...@lists.dwarfstd.org >>>>To: dwarf-discuss@lists.dwarfstd.org >>>>Sent: Friday, September 27, 2019 1:32:55 PM GMT-07:00 >>>>Subject: Dwarf-Discuss Digest, Vol 119, Issue 2 >>>> >>>>>Send Dwarf-Discuss mailing list submissions to >>>>> dwarf-discuss@lists.dwarfstd.org >>>>> >>>>>To subscribe or unsubscribe via the World Wide Web, visit >>>>> http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org >>>>>or, via email, send a message with subject or body 'help' to >>>>> dwarf-discuss-requ...@lists.dwarfstd.org >>>>> >>>>>You can reach the person managing the list at >>>>> dwarf-discuss-ow...@lists.dwarfstd.org >>>>> >>>>>When replying, please edit your Subject line so it is more specific >>>>>than "Re: Contents of Dwarf-Discuss digest..." >>>>> >>>>> >>>>>Today's Topics: >>>>> >>>>> 1. Re: DW_AT_segment and relocation (Michael Eager) >>>>> 2. Re: DW_AT_segment and relocation (Jayvee Neumann) >>>>> >>>>> >>>>>---------------------------------------------------------------------- >>>>> >>>>>Message: 1 >>>>>Date: Thu, 26 Sep 2019 14:11:52 -0700 >>>>>From: Michael Eager <ea...@eagerm.com> >>>>>To: Jayvee Neumann <jayvee.neum...@gmail.com>, >>>>> dwarf-discuss@lists.dwarfstd.org >>>>>Subject: Re: [Dwarf-Discuss] DW_AT_segment and relocation >>>>>Message-ID: <0d19af28-3aa4-f199-3487-6578e3396...@eagerm.com> >>>>>Content-Type: text/plain; charset=utf-8; format=flowed >>>>> >>>>>On 9/26/19 3:33 AM, Jayvee Neumann via Dwarf-Discuss wrote: >>>>>> Dear DWARF experts, >>>>>> >>>>>> I have a question regarding the attribute DW_AT_segment. I do not quite >>>>>> understand how to handle it, yet. >>>>>> It can appear in a DIE (or its parent) whenever DW_AT_low_pc, >>>>>> DW_AT_high_pc, DW_AT_ranges, DW_AT_entry_pc, or a location description >>>>>> that evaluates to an Address are used. >>>>>> It can contain a location expression itself. So it can depend not only >>>>>> on compile-time information but also on run-time information. >>>>>> >>>>>> Assume, I have an attribute DW_AT_low_pc. If there is no DW_AT_segment, >>>>>> this attribute is simply the low_pc as it was determined during >>>>>> compile-time. While debugging, this value has to be relocated if the >>>>>> image had been relocated. If there is a DW_AT_segment expression is >>>>>> relocation still necessary? Evaluating the expression could also >>>>>> incorporate the usage of run-time information and relocated addresses >>>>>> (i.e. the DS/CS/SS registers). >>>>>> >>>>>> I hope I was able to articulate my question well, English is not my >>>>>> native language. >>>>>> >>>>>> Kind Regards >>>>>> Jayvee >>>>> >>>>>Your question is quite clear, but we don't know the context. What >>>>>architecture are you working with and what ar you trying to do? >>>>> >>>>>As Ron mentioned, AT_segment is intended to support architectures like >>>>>the X86 where an address is composed of a [segment,offset] pair. Most >>>>>architectures do not use segments. >>>>> >>>>>-- >>>>>Michael Eager ea...@eagerm.com >>>>>1960 Park Blvd., Palo Alto, CA 94306 >>>>> >>>>> >>>>>------------------------------ >>>>> >>>>>Message: 2 >>>>>Date: Fri, 27 Sep 2019 10:29:03 +0200 >>>>>From: Jayvee Neumann <jayvee.neum...@gmail.com> >>>>>To: Michael Eager <ea...@eagerm.com>, dwarf-discuss@lists.dwarfstd.org >>>>>Subject: Re: [Dwarf-Discuss] DW_AT_segment and relocation >>>>>Message-ID: >>>>> >>>>> <CALak_8ZmkjiEzA7X4+PK_Pzf+dSor5dgnnV7mG23Wk=32um...@mail.gmail.com> >>>>>Content-Type: text/plain; charset="utf-8" >>>>> >>>>>Thank you Michael and Ron, >>>>> >>>>>what I am trying to do is write a consumer that is able to handle images >>>>>from several targets: i386, AMD64, and also ARM. The target images will be >>>>>loaded and running (and debugged during run-time). >>>>>I want to find a way to handle addresses in a simple way, abstracting from >>>>>the underlying architecture. So my first Idea was giving each address a >>>>>segment that can either be zero or an expression. >>>>> >>>>>That lead to the problem I mentioned in the first email. I think this is >>>>>best explained with an example. If the image (e.g. a DLL or a shared >>>>>library) has a preferred loading address of 0x1000, this address is used in >>>>>DWARF. But the image could be loaded at e.g. 0x2000 (or any other address). >>>>>The consumer has to adjust all the pc values in DWARF in that case. A >>>>>function whose DWARF information say is loaded from e.g. 0x10E8 to 0x1120 >>>>>is actually loaded from 0x20E8 to 0x2120. An attribute DW_AT_low_pc with >>>>>the value 0x1500 would represent the address 0x2500 when the image is >>>>>actually loaded. But an address like Segment:Offset (e.g. CS:0x0123) would >>>>>be valid during run-time without any adjustment, since the segment is >>>>>computed from registers during run-time and thus necessarily adjusted to >>>>>the load-time addresses and not build-time addresses. So the rule of thumb >>>>>would be: Do not adjust segmented addresses in the consumer. Or have I >>>>>misunderstood something about this matter? >>>>> >>>>>What is kind of counter intuitive is the fact that the DWARF5 standard >>>>>says: if DW_AT_segment is specified at any parent DIE it is valid at its >>>>>subsequent child DIEs. Consumer libraries like libdwarf have no function >>>>>that allows for determining the parent DIE if only the child DIE is known. >>>>>It would be necessary to go through all DIEs and check which one is an >>>>>ancestor of the DIE in question. So this little sentence implies a lot of >>>>>difficulties for a consumer. >>>>> >>>>>Kind regards, >>>>>Jayvee >>>>> >>>>>Am Do., 26. Sept. 2019 um 23:12 Uhr schrieb Michael Eager <ea...@eagerm.com >>>>>>: >>>>> >>>>>> On 9/26/19 3:33 AM, Jayvee Neumann via Dwarf-Discuss wrote: >>>>>> > Dear DWARF experts, >>>>>> > >>>>>> > I have a question regarding the attribute DW_AT_segment. I do not quite >>>>>> > understand how to handle it, yet. >>>>>> > It can appear in a DIE (or its parent) whenever DW_AT_low_pc, >>>>>> > DW_AT_high_pc, DW_AT_ranges, DW_AT_entry_pc, or a location description >>>>>> > that evaluates to an Address are used. >>>>>> > It can contain a location expression itself. So it can depend not only >>>>>> > on compile-time information but also on run-time information. >>>>>> > >>>>>> > Assume, I have an attribute DW_AT_low_pc. If there is no DW_AT_segment, >>>>>> > this attribute is simply the low_pc as it was determined during >>>>>> > compile-time. While debugging, this value has to be relocated if the >>>>>> > image had been relocated. If there is a DW_AT_segment expression is >>>>>> > relocation still necessary? Evaluating the expression could also >>>>>> > incorporate the usage of run-time information and relocated addresses >>>>>> > (i.e. the DS/CS/SS registers). >>>>>> > >>>>>> > I hope I was able to articulate my question well, English is not my >>>>>> > native language. >>>>>> > >>>>>> > Kind Regards >>>>>> > Jayvee >>>>>> >>>>>> Your question is quite clear, but we don't know the context. What >>>>>> architecture are you working with and what ar you trying to do? >>>>>> >>>>>> As Ron mentioned, AT_segment is intended to support architectures like >>>>>> the X86 where an address is composed of a [segment,offset] pair. Most >>>>>> architectures do not use segments. >>>>>> >>>>>> -- >>>>>> Michael Eager ea...@eagerm.com >>>>>> 1960 Park Blvd., Palo Alto, CA 94306 >>>>>> >>>>>-------------- next part -------------- >>>>>An HTML attachment was scrubbed... >>>>>URL: >>>>><http://lists.dwarfstd.org/pipermail/dwarf-discuss-dwarfstd.org/attachments/20190927/9c050397/attachment-0001.html> >>>>> >>>>>------------------------------ >>>>> >>>>>Subject: Digest Footer >>>>> >>>>>_______________________________________________ >>>>>Dwarf-Discuss mailing list >>>>>Dwarf-Discuss@lists.dwarfstd.org >>>>>http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org >>>>> >>>>> >>>>>------------------------------ >>>>> >>>>>End of Dwarf-Discuss Digest, Vol 119, Issue 2 >>>>>********************************************* >>>>> >>>>>________________________________ >>>>> >>>>> >>>>>NOTICE: This communication and any attachments ("this message") may >>>>>contain information which is privileged, confidential, proprietary or >>>>>otherwise subject to restricted disclosure under applicable law. This >>>>>message is for the sole use of the intended recipient(s). Any unauthorized >>>>>use, disclosure, viewing, copying, alteration, dissemination or >>>>>distribution of, or reliance on, this message is strictly prohibited. If >>>>>you have received this message in error, or you are not an authorized or >>>>>intended recipient, please notify the sender immediately by replying to >>>>>this message, delete this message and all copies from your e-mail system >>>>>and destroy any printed copies. >>>>> >>>>> >>>>> >>>>>-LAEmHhHzdJzBlTWfa4Hgs7pbKl >>>> >>>> >>>> >>>>------------------------------ >>>> >>>>Subject: Digest Footer >>>> >>>>_______________________________________________ >>>>Dwarf-Discuss mailing list >>>>Dwarf-Discuss@lists.dwarfstd.org >>>>http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org >>>> >>>> >>>>------------------------------ >>>> >>>>End of Dwarf-Discuss Digest, Vol 119, Issue 3 >>>>********************************************* >>> >>> >>> >>>------------------------------ >>> >>>Message: 2 >>>Date: Fri, 27 Sep 2019 17:12:19 -0400 >>>From: Ron Brender <ron.bren...@gmail.com> >>>To: Jayvee Neumann <jayvee.neum...@gmail.com> >>>Cc: Michael Eager <ea...@eagerm.com>, DWARF-Discuss >>> <dwarf-discuss@lists.dwarfstd.org> >>>Subject: Re: [Dwarf-Discuss] DW_AT_segment and relocation >>>Message-ID: >>> <CANSbVTiGt-Gc6Wty2cuKAn1utTh2pHDc_txACf1KPzQac0=z=w...@mail.gmail.com> >>>Content-Type: text/plain; charset="utf-8" >>> >>>Jayvee, >>> >>>If you are dealing with a linear 32- or 64-bit address space then there are >>>no segments to worry about, so the question is moot. If you are dealing >>>with a segmented address space, then the problems you describe are exactly >>>those that debuggers on segmented machine dealt with all the time. Guess >>>why linear address space "won" as the most common, preferred addressing >>>method! >>> >>>As for the scoping problem, you are quite right. My impression is most >>>DWARF debuggers (the most common kind of consumer) do some kind of simple >>>initial pass over the DWARF info during startup to build some kind of >>>auxiliary data structure of its own to help speed dealing with such issues. >>> >>>Ron >>> >>> >>> >>>On Fri, Sep 27, 2019 at 4:29 AM Jayvee Neumann via Dwarf-Discuss < >>>dwarf-discuss@lists.dwarfstd.org> wrote: >>> >>>> Thank you Michael and Ron, >>>> >>>> what I am trying to do is write a consumer that is able to handle images >>>> from several targets: i386, AMD64, and also ARM. The target images will be >>>> loaded and running (and debugged during run-time). >>>> I want to find a way to handle addresses in a simple way, abstracting from >>>> the underlying architecture. So my first Idea was giving each address a >>>> segment that can either be zero or an expression. >>>> >>>> That lead to the problem I mentioned in the first email. I think this is >>>> best explained with an example. If the image (e.g. a DLL or a shared >>>> library) has a preferred loading address of 0x1000, this address is used in >>>> DWARF. But the image could be loaded at e.g. 0x2000 (or any other address). >>>> The consumer has to adjust all the pc values in DWARF in that case. A >>>> function whose DWARF information say is loaded from e.g. 0x10E8 to 0x1120 >>>> is actually loaded from 0x20E8 to 0x2120. An attribute DW_AT_low_pc with >>>> the value 0x1500 would represent the address 0x2500 when the image is >>>> actually loaded. But an address like Segment:Offset (e.g. CS:0x0123) would >>>> be valid during run-time without any adjustment, since the segment is >>>> computed from registers during run-time and thus necessarily adjusted to >>>> the load-time addresses and not build-time addresses. So the rule of thumb >>>> would be: Do not adjust segmented addresses in the consumer. Or have I >>>> misunderstood something about this matter? >>>> >>>> What is kind of counter intuitive is the fact that the DWARF5 standard >>>> says: if DW_AT_segment is specified at any parent DIE it is valid at its >>>> subsequent child DIEs. Consumer libraries like libdwarf have no function >>>> that allows for determining the parent DIE if only the child DIE is known. >>>> It would be necessary to go through all DIEs and check which one is an >>>> ancestor of the DIE in question. So this little sentence implies a lot of >>>> difficulties for a consumer. >>>> >>>> Kind regards, >>>> Jayvee >>>> >>>> Am Do., 26. Sept. 2019 um 23:12 Uhr schrieb Michael Eager < >>>> ea...@eagerm.com>: >>>> >>>>> On 9/26/19 3:33 AM, Jayvee Neumann via Dwarf-Discuss wrote: >>>>> > Dear DWARF experts, >>>>> > >>>>> > I have a question regarding the attribute DW_AT_segment. I do not quite >>>>> > understand how to handle it, yet. >>>>> > It can appear in a DIE (or its parent) whenever DW_AT_low_pc, >>>>> > DW_AT_high_pc, DW_AT_ranges, DW_AT_entry_pc, or a location description >>>>> > that evaluates to an Address are used. >>>>> > It can contain a location expression itself. So it can depend not only >>>>> > on compile-time information but also on run-time information. >>>>> > >>>>> > Assume, I have an attribute DW_AT_low_pc. If there is no DW_AT_segment, >>>>> > this attribute is simply the low_pc as it was determined during >>>>> > compile-time. While debugging, this value has to be relocated if the >>>>> > image had been relocated. If there is a DW_AT_segment expression is >>>>> > relocation still necessary? Evaluating the expression could also >>>>> > incorporate the usage of run-time information and relocated addresses >>>>> > (i.e. the DS/CS/SS registers). >>>>> > >>>>> > I hope I was able to articulate my question well, English is not my >>>>> > native language. >>>>> > >>>>> > Kind Regards >>>>> > Jayvee >>>>> >>>>> Your question is quite clear, but we don't know the context. What >>>>> architecture are you working with and what ar you trying to do? >>>>> >>>>> As Ron mentioned, AT_segment is intended to support architectures like >>>>> the X86 where an address is composed of a [segment,offset] pair. Most >>>>> architectures do not use segments. >>>>> >>>>> -- >>>>> Michael Eager ea...@eagerm.com >>>>> 1960 Park Blvd., Palo Alto, CA 94306 >>>>> >>>> _______________________________________________ >>>> Dwarf-Discuss mailing list >>>> Dwarf-Discuss@lists.dwarfstd.org >>>> http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org >>>> >>>-------------- next part -------------- >>>An HTML attachment was scrubbed... >>>URL: >>><http://lists.dwarfstd.org/pipermail/dwarf-discuss-dwarfstd.org/attachments/20190927/3645523b/attachment-0001.html> >>> >>>------------------------------ >>> >>>Message: 3 >>>Date: Fri, 27 Sep 2019 15:04:19 -0700 >>>From: Michael Eager <ea...@eagerm.com> >>>To: Jayvee Neumann <jayvee.neum...@gmail.com>, >>> dwarf-discuss@lists.dwarfstd.org >>>Subject: Re: [Dwarf-Discuss] DW_AT_segment and relocation >>>Message-ID: <7db5bc15-53e1-1fcb-7eb1-018c488a3...@eagerm.com> >>>Content-Type: text/plain; charset=utf-8; format=flowed >>> >>>On 9/27/19 1:29 AM, Jayvee Neumann wrote: >>>> Thank you Michael and Ron, >>>> >>>> what I am trying to do is write a consumer that is able to handle images >>>> from several targets: i386, AMD64, and also ARM. The target images will >>>> be loaded and running (and debugged during run-time). >>>> I want to find a way to handle addresses in a simple way, abstracting >>>> from the underlying architecture. So my first Idea was giving each >>>> address a segment that can either be zero or an expression. >>>> >>>> That lead to the problem I mentioned in the first email. I think this is >>>> best explained with an example. If the image (e.g. a DLL or a shared >>>> library) has a preferred loading address of 0x1000, this address is used >>>> in DWARF. But the image could be loaded at e.g. 0x2000 (or any other >>>> address). The consumer has to adjust all the pc values in DWARF in that >>>> case. A function whose DWARF information say is loaded from e.g. 0x10E8 >>>> to 0x1120 is actually loaded from 0x20E8 to 0x2120. An attribute >>>> DW_AT_low_pc with the value 0x1500 would represent the address 0x2500 >>>> when the image is actually loaded. But an address like Segment:Offset >>>> (e.g. CS:0x0123) would be valid during run-time without any adjustment, >>>> since the segment is computed from registers during run-time and thus >>>> necessarily adjusted to the load-time addresses and not build-time >>>> addresses. So the rule of thumb would be: Do not adjust segmented >>>> addresses in the consumer. Or have I misunderstood something about this >>>> matter? >>> >>>When it reads the debug info, a debugger has to go through the same >>>relocation process as happens when the executable or library is loaded. >>>Every relocatable reference needs to be adjusted to account for the >>>situation you describe, where the code is loaded at a different offset. >>> >>>DW_AT_segment really cannot be used to do this. There is (in general) >>>no register or other expression which will perform this relocation for >>>you, since the computation depends on information (e. g., the load >>>addresses for each piece of the executable) which may not be accessible >>>to the program. >>> >>>Unless you are planning to support 286 or 386 in 16-bit mode in one of >>>the segmented memory schemes used on these processors, you do not need >>>support for DW_AT_segment. >>> >>>> What is kind of counter intuitive is the fact that the DWARF5 standard >>>> says: if DW_AT_segment is specified at any parent DIE it is valid at its >>>> subsequent child DIEs. Consumer libraries like libdwarf have no function >>>> that allows for determining the parent DIE if only the child DIE is >>>> known. It would be necessary to go through all DIEs and check which one >>>> is an ancestor of the DIE in question. So this little sentence implies a >>>> lot of difficulties for a consumer. >>> >>>I haven't looked at how debuggers like GDB handle segments in a very >>>long time. I believe that when the DWARF info is read and used to >>>create an internal representation, a current segment value is maintained >>>as the debug info is parsed recursively. This is set as you descend the >>>parse tree, pushing previous values, and popped when ascend the tree. >>> >>>Almost all architectures, and specifically the ARM and AMD64 >>>architectures you mention, use linear, not segmented, address spaces. >>> >>>> >>>> Kind regards, >>>> Jayvee >>>> >>>> Am Do., 26. Sept. 2019 um 23:12?Uhr schrieb Michael Eager >>>> <ea...@eagerm.com <mailto:ea...@eagerm.com>>: >>>> >>>> On 9/26/19 3:33 AM, Jayvee Neumann via Dwarf-Discuss wrote: >>>> > Dear DWARF experts, >>>> > >>>> > I have a question regarding the attribute DW_AT_segment. I do not >>>> quite >>>> > understand how to handle it, yet. >>>> > It can appear in a DIE (or its parent) whenever DW_AT_low_pc, >>>> > DW_AT_high_pc, DW_AT_ranges, DW_AT_entry_pc, or a location >>>> description >>>> > that evaluates to an Address are used. >>>> > It can contain a location expression itself. So it can depend not >>>> only >>>> > on compile-time information but also on run-time information. >>>> > >>>> > Assume, I have an attribute DW_AT_low_pc. If there is no >>>> DW_AT_segment, >>>> > this attribute is simply the low_pc as it was determined during >>>> > compile-time. While debugging, this value has to be relocated if the >>>> > image had been relocated. If there is a DW_AT_segment expression is >>>> > relocation still necessary? Evaluating the expression could also >>>> > incorporate the usage of run-time information and relocated >>>> addresses >>>> > (i.e. the DS/CS/SS registers). >>>> > >>>> > I hope I was able to articulate my question well, English is not my >>>> > native language. >>>> > >>>> > Kind Regards >>>> > Jayvee >>>> >>>> Your question is quite clear, but we don't know the context.? What >>>> architecture are you working with and what ar you trying to do? >>>> >>>> As Ron mentioned, AT_segment is intended to support architectures like >>>> the X86 where an address is composed of a [segment,offset] pair.? Most >>>> architectures do not use segments. >>>> >>>> -- >>>> Michael Eager ea...@eagerm.com <mailto:ea...@eagerm.com> >>>> 1960 Park Blvd., Palo Alto, CA 94306 >>>> >>> >>>-- >>>Michael Eager ea...@eagerm.com >>>1960 Park Blvd., Palo Alto, CA 94306 >>> >>> >>>------------------------------ >>> >>>Subject: Digest Footer >>> >>>_______________________________________________ >>>Dwarf-Discuss mailing list >>>Dwarf-Discuss@lists.dwarfstd.org >>>http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org >>> >>> >>>------------------------------ >>> >>>End of Dwarf-Discuss Digest, Vol 119, Issue 4 >>>********************************************* >> >> >> >>------------------------------ >> >>Subject: Digest Footer >> >>_______________________________________________ >>Dwarf-Discuss mailing list >>Dwarf-Discuss@lists.dwarfstd.org >>http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org >> >> >>------------------------------ >> >>End of Dwarf-Discuss Digest, Vol 119, Issue 5 >>********************************************* > > > >------------------------------ > >Subject: Digest Footer > >_______________________________________________ >Dwarf-Discuss mailing list >Dwarf-Discuss@lists.dwarfstd.org >http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org > > >------------------------------ > >End of Dwarf-Discuss Digest, Vol 119, Issue 6 >********************************************* _______________________________________________ Dwarf-Discuss mailing list Dwarf-Discuss@lists.dwarfstd.org http://lists.dwarfstd.org/listinfo.cgi/dwarf-discuss-dwarfstd.org
