The quilt patch titled
Subject: scripts/gdb/symbols: determine KASLR offset on s390
has been removed from the -mm tree. Its filename was
scripts-gdb-symbols-determine-kaslr-offset-on-s390.patch
This patch was dropped because it was merged into the mm-nonmm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Subject: scripts/gdb/symbols: determine KASLR offset on s390
Date: Mon, 3 Mar 2025 12:03:58 +0100
Use QEMU's qemu.PhyMemMode [1] functionality to read vmcore from the
physical memory the same way the existing dump tooling does this.
Gracefully handle non-QEMU targets, early boot, and memory corruptions;
print a warning if such situation is detected.
[1] https://qemu-project.gitlab.io/qemu/system/gdb.html#examining-physical-memory
Link: https://lkml.kernel.org/r/20250303110437.79070-1-iii@xxxxxxxxxxxxx
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Acked-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Andrew Donnellan <ajd@xxxxxxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Kieran Bingham <kbingham@xxxxxxxxxx>
Cc: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
scripts/gdb/linux/symbols.py | 31 ++++++++++++++++++++++++++++-
scripts/gdb/linux/utils.py | 35 +++++++++++++++++++++++++++++++++
2 files changed, 65 insertions(+), 1 deletion(-)
--- a/scripts/gdb/linux/symbols.py~scripts-gdb-symbols-determine-kaslr-offset-on-s390
+++ a/scripts/gdb/linux/symbols.py
@@ -14,6 +14,7 @@
import gdb
import os
import re
+import struct
from itertools import count
from linux import modules, utils, constants
@@ -54,6 +55,29 @@ if hasattr(gdb, 'Breakpoint'):
return False
+def get_vmcore_s390():
+ with utils.qemu_phy_mem_mode():
+ vmcore_info = 0x0e0c
+ paddr_vmcoreinfo_note = gdb.parse_and_eval("*(unsigned long long *)" +
+ hex(vmcore_info))
+ inferior = gdb.selected_inferior()
+ elf_note = inferior.read_memory(paddr_vmcoreinfo_note, 12)
+ n_namesz, n_descsz, n_type = struct.unpack(">III", elf_note)
+ desc_paddr = paddr_vmcoreinfo_note + len(elf_note) + n_namesz + 1
+ return gdb.parse_and_eval("(char *)" + hex(desc_paddr)).string()
+
+
+def get_kerneloffset():
+ if utils.is_target_arch('s390'):
+ try:
+ vmcore_str = get_vmcore_s390()
+ except gdb.error as e:
+ gdb.write("{}\n".format(e))
+ return None
+ return utils.parse_vmcore(vmcore_str).kerneloffset
+ return None
+
+
class LxSymbols(gdb.Command):
"""(Re-)load symbols of Linux kernel and currently loaded modules.
@@ -160,7 +184,12 @@ lx-symbols command."""
obj.filename.endswith('vmlinux.debug')):
orig_vmlinux = obj.filename
gdb.execute("symbol-file", to_string=True)
- gdb.execute("symbol-file {0}".format(orig_vmlinux))
+ kerneloffset = get_kerneloffset()
+ if kerneloffset is None:
+ offset_arg = ""
+ else:
+ offset_arg = " -o " + hex(kerneloffset)
+ gdb.execute("symbol-file {0}{1}".format(orig_vmlinux, offset_arg))
self.loaded_modules = []
module_list = modules.module_list()
--- a/scripts/gdb/linux/utils.py~scripts-gdb-symbols-determine-kaslr-offset-on-s390
+++ a/scripts/gdb/linux/utils.py
@@ -11,6 +11,11 @@
# This work is licensed under the terms of the GNU GPL version 2.
#
+import contextlib
+import dataclasses
+import re
+import typing
+
import gdb
@@ -216,3 +221,33 @@ def gdb_eval_or_none(expresssion):
return gdb.parse_and_eval(expresssion)
except gdb.error:
return None
+
+
+@contextlib.contextmanager
+def qemu_phy_mem_mode():
+ connection = gdb.selected_inferior().connection
+ orig = connection.send_packet("qqemu.PhyMemMode")
+ if orig not in b"01":
+ raise gdb.error("Unexpected qemu.PhyMemMode")
+ orig = orig.decode()
+ if connection.send_packet("Qqemu.PhyMemMode:1") != b"OK":
+ raise gdb.error("Failed to set qemu.PhyMemMode")
+ try:
+ yield
+ finally:
+ if connection.send_packet("Qqemu.PhyMemMode:" + orig) != b"OK":
+ raise gdb.error("Failed to restore qemu.PhyMemMode")
+
+
+@dataclasses.dataclass
+class VmCore:
+ kerneloffset: typing.Optional[int]
+
+
+def parse_vmcore(s):
+ match = re.search(r"KERNELOFFSET=([0-9a-f]+)", s)
+ if match is None:
+ kerneloffset = None
+ else:
+ kerneloffset = int(match.group(1), 16)
+ return VmCore(kerneloffset=kerneloffset)
_
Patches currently in -mm which might be from iii@xxxxxxxxxxxxx are
