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Bug 1905701

Summary: Backport "Fortran dynamic type related fixes"
Product: Red Hat Enterprise Linux 8 Reporter: Keith Seitz <keiths>
Component: gdbAssignee: Keith Seitz <keiths>
gdb sub component: system-version QA Contact: Michal Kolar <mkolar>
Status: CLOSED ERRATA Docs Contact:
Severity: medium    
Priority: unspecified CC: extras-qa, gdb-bugs, jan.kratochvil, keiths, kevinb, mcermak, ohudlick, sergiodj
Version: 8.4Keywords: Triaged
Target Milestone: rc   
Target Release: 8.0   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: gdb-8.2-15.el8 Doc Type: No Doc Update
Doc Text:
Story Points: ---
Clone Of: 1905687 Environment:
Last Closed: 2021-05-18 15:46:02 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1905687    
Bug Blocks:    

Description Keith Seitz 2020-12-08 21:17:03 UTC
+++ This bug was initially created as a clone of Bug #1905687 +++

Originally reported/triaged by Andrew Dinn:

I have run up against a problem with the versions of gdb that are out in the field that relates to the use of data_location properties on DWARF class/struct info records. I need to use this DWARF feature in order to fully implement Java debuginfo for GraalVM native Java apps. The data_location attribute is needed to ensure that Java oops (typed as DWARF pointer types which reference the underlying class/struct data) are adjusted from a Java-specific encoding of the address to a direct memory pointer before gdb dereferences the oop to locate the underlying data.

 - In one mode of image generation oops are addresses modulo extra tag info in the bottom 3 bits so a locexpr describes how to mask off the relevant bits.

 - In another mode of image generation oops are offsets from a heap base held in a register so a locexpr describes how to fetch the relevant register value and add it to the oop (offset).

The data_location attribute on the target object provides the necessary locexpr.

My problem is not to do with the conversion itself. That all works fine. It goes wrong when I ask gdb to print the relevant object data (see example after sig). The value that gets inserted into the history has an unresolved dynamic type and this trips an assert .

This problem should be caught and dealt with before the value is passed to the print code and indeed it has been fixed in gdb 10.1. The patch is detailed in the asssociated ChangeLog as follows:

2020-07-25  Andrew Burgess  <andrew.burgess>

    PR fortran/23051
    PR fortran/26139
    * valops.c (value_ind): Pass address to
    readjust_indirect_value_type.
    * value.c (readjust_indirect_value_type): Make parameter
    non-const, and add extra address parameter.  Resolve original type
    before using it.
    * value.h (readjust_indirect_value_type): Update function
    signature and comment.

--- Additional comment from Keith Seitz on 2020-12-08 20:30:10 UTC ---



--- Additional comment from Keith Seitz on 2020-12-08 20:31:00 UTC ---

Testing patch.

Comment 3 Michal Kolar 2021-01-05 08:13:13 UTC
Tested against gdb-8.2-15.el8.

Comment 6 Michal Kolar 2021-01-05 12:26:44 UTC
Reproduced against gdb-8.2-12.el8 and verified against gdb-8.2-15.el8

Comment 9 errata-xmlrpc 2021-05-18 15:46:02 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (gdb bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2021:1836