[PATCH AUTOSEL 4.4 17/17] scripts/gdb: fix debugging modules on s390

Sasha Levin
2019-10-26T13:23:45Z

From: Ilya Leoshkevich <iii@linux.ibm.com>

[ Upstream commit 585d730d41120926e3f79a601edad3930fa28366 ]

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().

Link: http://lkml.kernel.org/r/20191017085917.81791-1-iii@linux.ibm.com
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Kieran Bingham <kbingham@kernel.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 627750cb420d0..54deae59869b5 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'):
@@ -116,6 +116,12 @@ 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(
--
2.20.1