commit dc12567a53c88d7a91b9d71db3775782c7f35c84
author Josh Kunz <jkz@google.com> Fri Aug 16 16:34:22 2019 -0700
committer Laurent Vivier <laurent@vivier.eu> Wed Sep 11 08:46:52 2019 +0200
tree 67a0c2b6e805448a0c6aaa16e9c8bf8bd775f636
parent 0b689da375a689efe04ad8381f607d1292471d96

linux-user: Support gdb 'qOffsets' query for ELF

This is needed to support debugging PIE ELF binaries running under QEMU
user mode. Currently, `code_offset` and `data_offset` remain unset for
all ELF binaries, so GDB is unable to correctly locate the position of
the binary's text and data.

The fields `code_offset`, and `data_offset` were originally added way
back in 2006 to support debugging of bFMT executables (978efd6aac6),
and support was just never added for ELF. Since non-PIE binaries are
loaded at exactly the address specified in the binary, GDB does not need
to relocate any symbols, so the buggy behavior is not normally observed.

http://sourceware.org/gdb/onlinedocs/gdb/General-Query-Packets.html#index-qOffsets-packet

Buglink: https://bugs.launchpad.net/qemu/+bug/1528239
Signed-off-by: Josh Kunz <jkz@google.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190816233422.16715-1-jkz@google.com>
[lv: added link to documentation]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>