https://sourceware.org/bugzilla/show_bug.cgi?id=21894
Bug ID: 21894
Summary: gdb-index fails to parse debug_ranges base address
specifiers in 32 bit address files
Product: binutils
Version: unspecified
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: gold
Assignee: ccoutant at gmail dot com
Reporter: dblaikie at gmail dot com
CC: ian at airs dot com
Target Milestone: ---
LLVM recently gained support for using DWARF debug_range base address
specifiers to reduce relocations.
This broke Chromium builds using gold's gdb-index in a 32 bit build.
https://bugs.llvm.org/show_bug.cgi?id=34007
Looks like this is a bug in gold's parsing of debug_range. From the last
comment in the above bug:
"Yep, gold bug in parsing 32 bit range lists. The value in the table is read as
32 bit unsigned, widened to long, then compared to -1."
"Here's a dodgy change but at least demonstrates that gold seems to work fine
with this issue addressed:
---
../.citc/baseline/google3/third_party/binutils/binutils/gold/dwarf_reader.cc
2017-06-22 19:38:27.000000000 -0700
+++ third_party/binutils/binutils/gold/dwarf_reader.cc 2017-07-31
16:48:58.000000000 -0700
@@ -442,12 +442,12 @@
break;
// A "base address selection entry" is identified by
// 0xffffffff for the first value of the pair. The second
// value is used as a base for subsequent range list entries.
- if (shndx1 == 0 && start == -1)
- base = end;
+ if (shndx1 == 0 && start == (addr_size == 4 ? 4294967295 : -1))
+ base = end;
else if (shndx1 == shndx2)
{
if (shndx1 == 0 || object->is_section_included(shndx1))
ranges->add(shndx1, base + start, base + end);
}
A little above in the code the 'start' value is read as an unsigned 4 byte int,
widened into an signed 8 byte int, which doesn't sign extend (since it wasn't
signed)."
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