Re: [PATCH v2] scripts/gdb: fix debugging modules on s390

Jan Kiszka
2019-10-17T14:11:42Z

On 17.10.19 10:59, Ilya Leoshkevich wrote:
> Currently lx-symbols assumes that module text is always located at
> module->core_layout->base, but s390 uses the following layout:
>
> +------+ <- module->core_layout->base
> | GOT |
> +------+ <- module->core_layout->base + module->arch->plt_offset
> | PLT |
> +------+ <- module->core_layout->base + module->arch->plt_offset +
> | TEXT | module->arch->plt_size
> +------+
>
> Therefore, when trying to debug modules on s390, all the symbol
> addresses are skewed by plt_offset + plt_size.
>
> Fix by adding plt_offset + plt_size to module_addr in
> load_module_symbols().
>
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
>
> v1 -> v2: print the adjusted address.
>
> scripts/gdb/linux/symbols.py | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/gdb/linux/symbols.py b/scripts/gdb/linux/symbols.py
> index f0d8f2ecfde7..df4c810de663 100644
> --- a/scripts/gdb/linux/symbols.py
> +++ b/scripts/gdb/linux/symbols.py
> @@ -15,7 +15,7 @@ import gdb
> import os
> import re
>
> -from linux import modules
> +from linux import modules, utils
>
>
> if hasattr(gdb, 'Breakpoint'):
> @@ -111,6 +111,12 @@ lx-symbols command."""
> module_file = self._get_module_file(module_name)
>
> if module_file:
> + if utils.is_target_arch('s390'):
> + # Module text is preceded by PLT stubs on s390.
> + module_arch = module['arch']
> + plt_offset = int(module_arch['plt_offset'])
> + plt_size = int(module_arch['plt_size'])
> + module_addr = hex(int(module_addr, 0) + plt_offset + plt_size)
> gdb.write("loading @{addr}: {filename}\n".format(
> addr=module_addr, filename=module_file))
> cmdline = "add-symbol-file {filename} {addr}{sections}".format(
>

Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>

Thanks,
Jan

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