2 fixes for rt.backtrace.dwarf #2151

kinke · 2018-03-25T15:44:46Z

No description provided.

kinke · 2018-03-25T15:47:11Z

src/rt/backtrace/dwarf.d

+        {
+            buffer[0 .. 5] = "??:? ";
+            bufferLength = 5;
+        }


Fix 1:

addressBuffer[] = "??:? \0";

=> object.Error@(0): Array lengths don't match for copy https://run.dlang.io/is/4RQZWh

Any chance we can add a test for this to prevent future regressions?

It's pretty bad with -release, causing a segfault as long as the destination buffer is sufficiently large: https://run.dlang.io/is/NEqZOB. Without -release an exception is thrown during stacktrace generation, which is also pretty bad.

The latter is how I stumbled on this. LLVM 6.0 led to DWARF v4 debuginfos, rt.backtrace.dwarf doesn't support that version, so no file/line infos => "??:? \0" + exception (debug druntime only; release druntime compiled with -release happily reads beyond the string constant, causing no segfault on x86 apparently). The exception with debug-druntime is swallowed in my test case, it only manifests itself in an incomplete stack trace (single entry).

@wilzbach: There's no debug druntime (i.e., compiled with enabled bounds checks) available for CI, right? Then it's untestable.

kinke · 2018-03-25T15:48:22Z

src/rt/backtrace/dwarf.d

+        static if (size_t.sizeof == 8)
+            appendToBuffer("[0x%llx]", callstack[i]);
+        else
+            appendToBuffer("[0x%x]", callstack[i]);


Fix 2: don't restrict to lower 32 bits of address on 64-bit platforms, e.g., now ??:? __libc_start_main [0x7f7bb141182f].

JinShil · 2018-03-25T15:53:30Z

Does this fix https://issues.dlang.org/show_bug.cgi?id=18068?

kinke · 2018-03-25T15:59:04Z

Nope, but I discovered bug no. 1 because of missing file/line infos too, or rather because the code here doesn't handle Dwarf v4+ debuginfos.

dlang-bot · 2018-03-25T17:49:13Z

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kinke · 2018-05-01T15:13:30Z

I extended the previous trivial fix by a revised version of rt.backtrace.dwarf, tackling:

Support for DWARF v4.
Support for 64-bit DWARF.
Alignment issues on non-x86 architectures (DWARF data is packed).
Issue #18068; DSO-relative DWARF addresses vs. absolute addresses returned by backtrace().

Tests are missing, I'm unsure how to tackle that in a robust fashion (for DMD, I'd know how for LDC ;)).

Basically applying dlang#2151.

wilzbach · 2018-06-28T08:24:30Z

With #2230 merged at least the getMemoryRegion part should become obsolete.

kinke · 2018-06-28T21:48:51Z

Rebased and obsolete 18068 fix removed. FWIW, the first commit is part of LDC 1.9, the second in 1.10.

Fix 1: mismatching array lengths for a copy (the `??:? \0` piece). Luckily, these bounds checks are disabled in non-debug druntime, so that people haven't seen this bug (in backtrace-printing code!) that often. Fix 2: print the full 64-bit address on 64-bit systems, not just the 32 lower bits. That's one part of Issue 19653.

kinke · 2019-04-14T23:30:43Z

I restricted this to the first trivial fixes again and moved the 2nd commit to #2559. @thewilsonator: Please push.

kinke requested review from andralex and wilzbach as code owners March 25, 2018 15:44

kinke commented Mar 25, 2018

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kinke mentioned this pull request Mar 25, 2018

Add support for LLD 6.0.0 & switch CI to LDC-LLVM 6.0.0 ldc-developers/ldc#2608

Merged

kinke force-pushed the bt_dwarf branch from e84da34 to d6a3418 Compare March 25, 2018 17:49

kinke mentioned this pull request Mar 25, 2018

Fix rt.backtrace.dwarf ldc-developers/druntime#124

Merged

kinke closed this in ldc-developers/druntime#124 Apr 29, 2018

kinke reopened this May 1, 2018

dlang-bot added the Bug Fix Include reference to corresponding bugzilla issue label May 1, 2018

kinke changed the title ~~Fix rt.backtrace.dwarf~~ Revise & fix rt.backtrace.dwarf (DWARF v4, 64-bit DWARF, DSO-relative addresses) May 1, 2018

kinke mentioned this pull request May 1, 2018

druntime: Fix rt.backtrace.dwarf ldc-developers/ldc#2677

Merged

kinke force-pushed the bt_dwarf branch from 14ba7e8 to d109d53 Compare May 3, 2018 18:32

kinke mentioned this pull request May 3, 2018

Fix Issue 18068 - No file names and line numbers in stack trace #2172

Closed

kinke force-pushed the bt_dwarf branch from d109d53 to 0a7955b Compare May 14, 2018 22:22

ibuclaw mentioned this pull request May 19, 2018

change size_t to uint for OSX 64 bit dlang/dmd#8249

Merged

kinke added a commit to ldc-developers/druntime that referenced this pull request Jun 18, 2018

Fix rt.backtrace merge regressions

c74faa4

Basically applying dlang#2151.

kinke added a commit to ldc-developers/druntime that referenced this pull request Jun 18, 2018

Fix rt.backtrace merge regressions

a382ade

Basically applying dlang#2151.

kinke force-pushed the bt_dwarf branch from 0a7955b to 002c3c0 Compare June 28, 2018 21:46

kinke changed the title ~~Revise & fix rt.backtrace.dwarf (DWARF v4, 64-bit DWARF, DSO-relative addresses)~~ Revise & fix rt.backtrace.dwarf (DWARF v4, 64-bit DWARF) Jul 11, 2018

kinke force-pushed the bt_dwarf branch from 002c3c0 to 7565530 Compare April 14, 2019 23:27

kinke changed the title ~~Revise & fix rt.backtrace.dwarf (DWARF v4, 64-bit DWARF)~~ 2 fixes for rt.backtrace.dwarf Apr 14, 2019

kinke mentioned this pull request Apr 14, 2019

rt.backtrace.dwarf: Add support for DWARF v4 & 64-bit DWARF and fix non-x86 alignment issues #2559

Merged

thewilsonator approved these changes Apr 15, 2019

View reviewed changes

thewilsonator merged commit 50d8d09 into dlang:master Apr 15, 2019

kinke deleted the bt_dwarf branch April 15, 2019 21:23

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2 fixes for rt.backtrace.dwarf #2151

2 fixes for rt.backtrace.dwarf #2151

kinke commented Mar 25, 2018

kinke Mar 25, 2018

wilzbach Mar 25, 2018

kinke Mar 25, 2018

kinke Apr 3, 2018

kinke Mar 25, 2018 •

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JinShil commented Mar 25, 2018

kinke commented Mar 25, 2018 •

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dlang-bot commented Mar 25, 2018 •

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kinke commented May 1, 2018

wilzbach commented Jun 28, 2018 •

edited

kinke commented Jun 28, 2018

kinke commented Apr 14, 2019

2 fixes for rt.backtrace.dwarf #2151

2 fixes for rt.backtrace.dwarf #2151

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Bugzilla references

Testing this PR locally

kinke commented May 1, 2018

wilzbach commented Jun 28, 2018 • edited

kinke commented Jun 28, 2018

kinke commented Apr 14, 2019

kinke Mar 25, 2018 •

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kinke commented Mar 25, 2018 •

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dlang-bot commented Mar 25, 2018 •

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wilzbach commented Jun 28, 2018 •

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