Bug 1497800

Summary:	something broken in ppc64 backtracing
Product:	DevTools	Reporter:	Martin Cermak <mcermak>
Component:	rust	Assignee:	Josh Stone <jistone>
Status:	CLOSED ERRATA	QA Contact:	Martin Cermak <mcermak>
Severity:	unspecified	Docs Contact:	Vladimír Slávik <vslavik>
Priority:	unspecified
Version:	rust-toolset-7	CC:	emachado, jcajka, jistone, kanderso, law, sbharadw, tstellar, vslavik
Target Milestone:	rc
Target Release:	2018.4
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:	Cause: Rust's backtrace library didn't support ppc64 ELFv1. Consequence: Backtraces printed during Rust panics with RUST_BACKTRACE=1 showed "<unknown>" symbol information. Fix: Rust's backtrace library has been updated in Rust 1.28 to include support for ppc64 ELFv1. Result: RUST_BACKTRACE=1 shows appropriate symbols.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-11-13 15:24:31 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:

Description Martin Cermak 2017-10-02 17:22:20 UTC

Description of problem:
  The run-pass/backtrace.rs fails on ppc64

Version-Release number of selected component (if applicable):
  rust-toolset-7-rust-1.20.0-2.el7

How reproducible:
  100% on ppc64

Steps to Reproduce:
1. scl enable rust-toolset-7 llvm-toolset-7 bash
2. rpmbuild -bp rust.spec
3. go to src/test/run-pass
4. env RUSTC_BOOTSTRAP=1 rustc -O backtrace.rs
5. ./backtrace

Actual results:
 7.4 Server ppc64 # ./backtrace
thread 'main' panicked at 'bad output: thread 'main' panicked at 'explicit panic', backtrace.rs:24:8
stack backtrace:
   0: <unknown>
   1: <unknown>
   2: <unknown>
   3: <unknown>
   4: <unknown>
   5: <unknown>
   6: <unknown>
   7: <unknown>
   8: <unknown>
   9: <unknown>
  10: <unknown>
  11: <unknown>
  12: <unknown>
  13: <unknown>
', backtrace.rs:59:4
note: Run with `RUST_BACKTRACE=1` for a backtrace.
 7.4 Server ppc64 #

Expected results:
No output.

Comment 2 Josh Stone 2018-02-28 18:39:16 UTC

Deferring to a future release, but we'll keep the bug open for tracking.

Comment 11 Josh Stone 2018-07-31 22:32:49 UTC

Rust uses a fork of https://github.com/ianlancetaylor/libbacktrace, which is based on GCC's libbacktrace.  It appears that code just didn't handle .opd at all, which you need for PPC64 ELFv1 (big-endian).  This was reported in GCC 82368, fixed by Jakub in r257685, and will reach Rust in 1.28.

Comment 12 Josh Stone 2018-07-31 22:45:12 UTC

Rather, GCC r257658 was the actual fix; r257685 was a followup tweak.

Comment 21 errata-xmlrpc 2018-11-13 15:24:31 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, 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/RHEA-2018:3584