From: Josh Kunz via Qemu-devel <qemu-devel@nongnu.org> 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 <j...@google.com> Reviewed-by: Laurent Vivier <laur...@vivier.eu> Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com> Message-Id: <20190816233422.16715-1-...@google.com> [lv: added link to documentation] Signed-off-by: Laurent Vivier <laur...@vivier.eu> --- linux-user/elfload.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 43c16a846d33..f6693e576098 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -2403,6 +2403,8 @@ static void load_elf_image(const char *image_name, int image_fd, } info->load_bias = load_bias; + info->code_offset = load_bias; + info->data_offset = load_bias; info->load_addr = load_addr; info->entry = ehdr->e_entry + load_bias; info->start_code = -1; -- 2.21.0
