linux.git/kernel/livepatch, branch v6.18.21

livepatch: Match old_sympos 0 and 1 in klp_find_func()

2026-01-02T11:56:39+00:00

[ Upstream commit 139560e8b973402140cafeb68c656c1374bd4c20 ]

When there is only one function of the same name, old_sympos of 0 and 1
are logically identical. Match them in klp_find_func().

This is to avoid a corner case with different toolchain behavior.

In this specific issue, two versions of kpatch-build were used to
build livepatch for the same kernel. One assigns old_sympos == 0 for
unique local functions, the other assigns old_sympos == 1 for unique
local functions. Both versions work fine by themselves. (PS: This
behavior change was introduced in a downstream version of kpatch-build.
This change does not exist in upstream kpatch-build.)

However, during livepatch upgrade (with the replace flag set) from a
patch built with one version of kpatch-build to the same fix built with
the other version of kpatch-build, livepatching fails with errors like:

[   14.218706] sysfs: cannot create duplicate filename 'xxx/somefunc,1'
...
[   14.219466] Call Trace:
[   14.219468]  
[   14.219469]  dump_stack_lvl+0x47/0x60
[   14.219474]  sysfs_warn_dup.cold+0x17/0x27
[   14.219476]  sysfs_create_dir_ns+0x95/0xb0
[   14.219479]  kobject_add_internal+0x9e/0x260
[   14.219483]  kobject_add+0x68/0x80
[   14.219485]  ? kstrdup+0x3c/0xa0
[   14.219486]  klp_enable_patch+0x320/0x830
[   14.219488]  patch_init+0x443/0x1000 [ccc_0_6]
[   14.219491]  ? 0xffffffffa05eb000
[   14.219492]  do_one_initcall+0x2e/0x190
[   14.219494]  do_init_module+0x67/0x270
[   14.219496]  init_module_from_file+0x75/0xa0
[   14.219499]  idempotent_init_module+0x15a/0x240
[   14.219501]  __x64_sys_finit_module+0x61/0xc0
[   14.219503]  do_syscall_64+0x5b/0x160
[   14.219505]  entry_SYSCALL_64_after_hwframe+0x4b/0x53
[   14.219507] RIP: 0033:0x7f545a4bd96d
...
[   14.219516] kobject: kobject_add_internal failed for somefunc,1 with
    -EEXIST, don't try to register things with the same name ...

This happens because klp_find_func() thinks somefunc with old_sympos==0
is not the same as somefunc with old_sympos==1, and klp_add_object_nops
adds another xxx/func,1 to the list of functions to patch.

Signed-off-by: Song Liu 
Acked-by: Josh Poimboeuf 
[pmladek@suse.com: Fixed some typos.]
Reviewed-by: Petr Mladek 
Tested-by: Petr Mladek 
Signed-off-by: Petr Mladek 
Signed-off-by: Sasha Levin

sched,livepatch: Untangle cond_resched() and live-patching

2025-05-14T11:16:24+00:00

With the goal of deprecating / removing VOLUNTARY preempt, live-patch
needs to stop relying on cond_resched() to make forward progress.

Instead, rely on schedule() with TASK_FREEZABLE set. Just like
live-patching, the freezer needs to be able to stop tasks in a safe /
known state.

[bigeasy: use likely() in __klp_sched_try_switch() and update comments]

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Thomas Gleixner 
Reviewed-by: Petr Mladek 
Tested-by: Petr Mladek 
Tested-by: Miroslav Benes 
Acked-by: Miroslav Benes 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/20250509113659.wkP_HJ5z@linutronix.de

Merge tag 'modules-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux

2025-03-30T22:44:36+00:00

Pull modules updates from Petr Pavlu:

 - Use RCU instead of RCU-sched

   The mix of rcu_read_lock(), rcu_read_lock_sched() and
   preempt_disable() in the module code and its users has
   been replaced with just rcu_read_lock()

 - The rest of changes are smaller fixes and updates

* tag 'modules-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux: (32 commits)
  MAINTAINERS: Update the MODULE SUPPORT section
  module: Remove unnecessary size argument when calling strscpy()
  module: Replace deprecated strncpy() with strscpy()
  params: Annotate struct module_param_attrs with __counted_by()
  bug: Use RCU instead RCU-sched to protect module_bug_list.
  static_call: Use RCU in all users of __module_text_address().
  kprobes: Use RCU in all users of __module_text_address().
  bpf: Use RCU in all users of __module_text_address().
  jump_label: Use RCU in all users of __module_text_address().
  jump_label: Use RCU in all users of __module_address().
  x86: Use RCU in all users of __module_address().
  cfi: Use RCU while invoking __module_address().
  powerpc/ftrace: Use RCU in all users of __module_text_address().
  LoongArch: ftrace: Use RCU in all users of __module_text_address().
  LoongArch/orc: Use RCU in all users of __module_address().
  arm64: module: Use RCU in all users of __module_text_address().
  ARM: module: Use RCU in all users of __module_text_address().
  module: Use RCU in all users of __module_text_address().
  module: Use RCU in all users of __module_address().
  module: Use RCU in search_module_extables().
  ...

module: Use RCU in find_module_all().

2025-03-10T10:54:44+00:00

The modules list and module::kallsyms can be accessed under RCU
assumption.

Remove module_assert_mutex_or_preempt() from find_module_all() so it can
be used under RCU protection without warnings. Update its callers to use
RCU protection instead of preempt_disable().

Cc: Jiri Kosina 
Cc: Joe Lawrence 
Cc: Josh Poimboeuf 
Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Cc: Miroslav Benes 
Cc: Petr Mladek 
Cc: Steven Rostedt 
Cc: linux-trace-kernel@vger.kernel.org
Cc: live-patching@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior 
Acked-by: Peter Zijlstra (Intel) 
Reviewed-by: Petr Mladek 
Link: https://lore.kernel.org/r/20250108090457.512198-7-bigeasy@linutronix.de
Signed-off-by: Petr Pavlu

livepatch: Add comment to clarify klp_add_nops()

2025-03-04T14:59:07+00:00

Add detailed comments to clarify the purpose of klp_add_nops() function.
These comments are based on Petr's explanation[0].

Link: https://lore.kernel.org/all/Z6XUA7D0eU_YDMVp@pathway.suse.cz/ [0]
Suggested-by: Petr Mladek 
Suggested-by: Josh Poimboeuf 
Signed-off-by: Yafang Shao 
Reviewed-by: Petr Mladek 
Link: https://lore.kernel.org/r/20250227024733.16989-2-laoar.shao@gmail.com
Signed-off-by: Petr Mladek

livepatch: Add stack_order sysfs attribute

2024-12-09T10:44:03+00:00

Add "stack_order" sysfs attribute which holds the order in which a live
patch module was loaded into the system. A user can then determine an
active live patched version of a function.

cat /sys/kernel/livepatch/livepatch_1/stack_order -> 1

means that livepatch_1 is the first live patch applied

cat /sys/kernel/livepatch/livepatch_module/stack_order -> N

means that livepatch_module is the Nth live patch applied

Suggested-by: Petr Mladek 
Suggested-by: Miroslav Benes 
Suggested-by: Josh Poimboeuf 
Signed-off-by: Wardenjohn 
Acked-by: Josh Poimboeuf 
Reviewed-by: Petr Mladek 
Tested-by: Petr Mladek 
Reviewed-by: Miroslav Benes 
Link: https://lore.kernel.org/r/20241008014856.3729-2-zhangwarden@gmail.com
[pmladek@suse.com: Updated kernel version and date in the ABI documentation.]
Signed-off-by: Petr Mladek

livepatch: Replace snprintf() with sysfs_emit()

2024-07-02T14:56:18+00:00

Let's use sysfs_emit() instead of snprintf().

Suggested-by: Miroslav Benes 
Signed-off-by: Yafang Shao 
Reviewed-by: Petr Mladek 
Acked-by: Miroslav Benes 
Link: https://lore.kernel.org/r/20240625151123.2750-4-laoar.shao@gmail.com
Signed-off-by: Petr Mladek

livepatch: Add "replace" sysfs attribute

2024-07-02T14:56:18+00:00

There are situations when it might make sense to combine livepatches
with and without the atomic replace on the same system. For example,
the livepatch without the atomic replace might provide a hotfix
or extra tuning.

Managing livepatches on such systems might be challenging. And the
information which of the installed livepatches do not use the atomic
replace would be useful.

Add new sysfs interface 'replace'. It works as follows:

   $ cat /sys/kernel/livepatch/livepatch-non_replace/replace
   0

   $ cat /sys/kernel/livepatch/livepatch-replace/replace
   1

[ commit log improved by Petr ]

Signed-off-by: Yafang Shao 
Reviewed-by: Petr Mladek 
Acked-by: Miroslav Benes 
Link: https://lore.kernel.org/r/20240625151123.2750-2-laoar.shao@gmail.com
Signed-off-by: Petr Mladek

livepatch: Rename KLP_* to KLP_TRANSITION_*

2024-05-09T13:48:01+00:00

The original macros of KLP_* is about the state of the transition.
Rename macros of KLP_* to KLP_TRANSITION_* to fix the confusing
description of klp transition state.

Signed-off-by: Wardenjohn 
Reviewed-by: Petr Mladek 
Tested-by: Petr Mladek 
Acked-by: Josh Poimboeuf 
Acked-by: Miroslav Benes 
Link: https://lore.kernel.org/r/20240507050111.38195-2-zhangwarden@gmail.com
Signed-off-by: Petr Mladek

livepatch: Fix missing newline character in klp_resolve_symbols()

2023-09-20T09:24:18+00:00

Without the newline character, the log may not be printed immediately
after the error occurs.

Fixes: ca376a937486 ("livepatch: Prevent module-specific KLP rela sections from referencing vmlinux symbols")
Signed-off-by: Zheng Yejian 
Reviewed-by: Petr Mladek 
Signed-off-by: Petr Mladek 
Link: https://lore.kernel.org/r/20230914072644.4098857-1-zhengyejian1@huawei.com