| e3ff7c60 | 24-Feb-2023 |
Josh Poimboeuf <jpoimboe@kernel.org> |
livepatch,sched: Add livepatch task switching to cond_resched()
There have been reports [1][2] of live patches failing to complete
within a reasonable amount of time due to CPU-bound kthreads.
Fix
livepatch,sched: Add livepatch task switching to cond_resched()
There have been reports [1][2] of live patches failing to complete
within a reasonable amount of time due to CPU-bound kthreads.
Fix it by patching tasks in cond_resched().
There are four different flavors of cond_resched(), depending on the
kernel configuration. Hook into all of them.
A more elegant solution might be to use a preempt notifier. However,
non-ORC unwinders can't unwind a preempted task reliably.
[1] https://lore.kernel.org/lkml/20220507174628.2086373-1-song@kernel.org/
[2] https://lkml.kernel.org/lkml/20230120-vhost-klp-switching-v1-0-7c2b65519c43@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
Link: https://lore.kernel.org/r/4ae981466b7814ec221014fc2554b2f86f3fb70b.1677257135.git.jpoimboe@kernel.org
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| 383439d3 | 24-Feb-2023 |
Josh Poimboeuf <jpoimboe@kernel.org> |
livepatch: Skip task_call_func() for current task
The current task doesn't need the scheduler's protection to unwind its
own stack.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by
livepatch: Skip task_call_func() for current task
The current task doesn't need the scheduler's protection to unwind its
own stack.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
Link: https://lore.kernel.org/r/4b92e793462d532a05f03767151fa29db3e68e13.1677257135.git.jpoimboe@kernel.org
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| 1b47b80e | 16-Feb-2023 |
Thomas Weißschuh <linux@weissschuh.net> |
livepatch: Make kobj_type structures constant
Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.")
the driver core allows the usage of const struct kobj_type.
Take advantage of this
livepatch: Make kobj_type structures constant
Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.")
the driver core allows the usage of const struct kobj_type.
Take advantage of this to constify the structure definitions to prevent
modification at runtime.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20230217-kobj_type-livepatch-v1-1-06ded292e897@weissschuh.net
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| 0c05e7bd | 25-Jan-2023 |
Song Liu <song@kernel.org> |
livepatch,x86: Clear relocation targets on a module removal
Josh reported a bug:
When the object to be patched is a module, and that module is
rmmod'ed and reloaded, it fails to load with:
m
livepatch,x86: Clear relocation targets on a module removal
Josh reported a bug:
When the object to be patched is a module, and that module is
rmmod'ed and reloaded, it fails to load with:
module: x86/modules: Skipping invalid relocation target, existing value is nonzero for type 2, loc 00000000ba0302e9, val ffffffffa03e293c
livepatch: failed to initialize patch 'livepatch_nfsd' for module 'nfsd' (-8)
livepatch: patch 'livepatch_nfsd' failed for module 'nfsd', refusing to load module 'nfsd'
The livepatch module has a relocation which references a symbol
in the _previous_ loading of nfsd. When apply_relocate_add()
tries to replace the old relocation with a new one, it sees that
the previous one is nonzero and it errors out.
He also proposed three different solutions. We could remove the error
check in apply_relocate_add() introduced by commit eda9cec4c9a1
("x86/module: Detect and skip invalid relocations"). However the check
is useful for detecting corrupted modules.
We could also deny the patched modules to be removed. If it proved to be
a major drawback for users, we could still implement a different
approach. The solution would also complicate the existing code a lot.
We thus decided to reverse the relocation patching (clear all relocation
targets on x86_64). The solution is not
universal and is too much arch-specific, but it may prove to be simpler
in the end.
Reported-by: Josh Poimboeuf <jpoimboe@redhat.com>
Originally-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Song Liu <song@kernel.org>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20230125185401.279042-2-song@kernel.org
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| 53910ef7 | 29-Sep-2022 |
Zhen Lei <thunder.leizhen@huawei.com> |
livepatch: Move the result-invariant calculation out of the loop
The calculation results of the variables 'func_addr' and 'func_size' are
not affected by the for loop and do not change due to the ch
livepatch: Move the result-invariant calculation out of the loop
The calculation results of the variables 'func_addr' and 'func_size' are
not affected by the for loop and do not change due to the changes of
entries[i]. The performance can be improved by moving it outside the loop.
No functional change.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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| 66d8529d | 30-Aug-2022 |
Zhen Lei <thunder.leizhen@huawei.com> |
livepatch: Add a missing newline character in klp_module_coming()
The error message is not printed immediately because it does not end with
a newline character.
Before:
root@localhost:~# insmod vml
livepatch: Add a missing newline character in klp_module_coming()
The error message is not printed immediately because it does not end with
a newline character.
Before:
root@localhost:~# insmod vmlinux.ko
insmod: ERROR: could not insert module vmlinux.ko: Invalid parameters
After:
root@localhost:~# insmod vmlinux.ko
[ 43.982558] livepatch: vmlinux.ko: invalid module name
insmod: ERROR: could not insert module vmlinux.ko: Invalid parameters
Fixes: dcf550e52f56 ("livepatch: Disallow vmlinux.ko")
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220830112855.749-1-thunder.leizhen@huawei.com
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| 5d7c8545 | 28-Mar-2022 |
Christophe Leroy <christophe.leroy@csgroup.eu> |
livepatch: Remove klp_arch_set_pc() and asm/livepatch.h
All three versions of klp_arch_set_pc() do exactly the same: they
call ftrace_instruction_pointer_set().
Call ftrace_instruction_pointer_set(
livepatch: Remove klp_arch_set_pc() and asm/livepatch.h
All three versions of klp_arch_set_pc() do exactly the same: they
call ftrace_instruction_pointer_set().
Call ftrace_instruction_pointer_set() directly and remove
klp_arch_set_pc().
As klp_arch_set_pc() was the only thing remaining in asm/livepatch.h
on x86 and s390, remove asm/livepatch.h
livepatch.h remains on powerpc but its content is exclusively used
by powerpc specific code.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Petr Mladek <pmladek@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Petr Mladek <pmladek@suse.com>
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| 29573083 | 12-Mar-2022 |
Chengming Zhou <zhouchengming@bytedance.com> |
livepatch: Don't block removal of patches that are safe to unload
module_put() is not called for a patch with "forced" flag. It should
block the removal of the livepatch module when the code might s
livepatch: Don't block removal of patches that are safe to unload
module_put() is not called for a patch with "forced" flag. It should
block the removal of the livepatch module when the code might still
be in use after forced transition.
klp_force_transition() currently sets "forced" flag for all patches on
the list.
In fact, any patch can be safely unloaded when it passed through
the consistency model in KLP_UNPATCHED transition.
In other words, the "forced" flag must be set only for livepatches
that are being removed. In particular, set the "forced" flag:
+ only for klp_transition_patch when the transition to KLP_UNPATCHED
state was forced.
+ all replaced patches when the transition to KLP_PATCHED state was
forced and the patch was replacing the existing patches.
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
[mbenes@suse.cz: wording improvements]
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220312152220.88127-1-zhouchengming@bytedance.com
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| 50a0f3f5 | 24-Dec-2021 |
Yang Yingliang <yangyingliang@huawei.com> |
livepatch: Fix missing unlock on error in klp_enable_patch()
Add missing unlock when try_module_get() fails in klp_enable_patch().
Fixes: 5ef3dd20555e8e8 ("livepatch: Fix kobject refcount bug on kl
livepatch: Fix missing unlock on error in klp_enable_patch()
Add missing unlock when try_module_get() fails in klp_enable_patch().
Fixes: 5ef3dd20555e8e8 ("livepatch: Fix kobject refcount bug on klp_init_patch_early failure path")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Acked-by: David Vernet <void@manifault.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20211225025115.475348-1-yangyingliang@huawei.com
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| 5ef3dd20 | 21-Dec-2021 |
David Vernet <void@manifault.com> |
livepatch: Fix kobject refcount bug on klp_init_patch_early failure path
When enabling a klp patch with klp_enable_patch(), klp_init_patch_early()
is invoked to initialize the kobjects for the patch
livepatch: Fix kobject refcount bug on klp_init_patch_early failure path
When enabling a klp patch with klp_enable_patch(), klp_init_patch_early()
is invoked to initialize the kobjects for the patch itself, as well as the
'struct klp_object' and 'struct klp_func' objects that comprise it.
However, there are some error paths in klp_enable_patch() where some
kobjects may have been initialized with kobject_init(), but an error code
is still returned due to e.g. a 'struct klp_object' having a NULL funcs
pointer.
In these paths, the initial reference of the kobject of the 'struct
klp_patch' may never be released, along with one or more of its objects and
their functions, as kobject_put() is not invoked on the cleanup path if
klp_init_patch_early() returns an error code.
For example, if an object entry such as the following were added to the
sample livepatch module's klp patch, it would cause the vmlinux klp_object,
and its klp_func which updates 'cmdline_proc_show', to never be released:
static struct klp_object objs[] = {
{
/* name being NULL means vmlinux */
.funcs = funcs,
},
{
/* NULL funcs -- would cause reference leak */
.name = "kvm",
}, { }
};
Without this change, if CONFIG_DEBUG_KOBJECT is enabled, and the sample klp
patch is loaded, the kobjects (the patch, the vmlinux 'struct klp_object',
and its func) are observed as initialized, but never released, in the dmesg
log output. With the change, these kobject references no longer fail to be
released as the error case is properly handled before they are initialized.
Signed-off-by: David Vernet <void@manifault.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
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