Tux gets for xmass improving the average lookup performance of
kallsyms_lookup_name() by 715x thanks to the work by Zhen Lei, which
upgraded our old implementation from being O(n) to O(log(n)), while also
retaining the old implementation support on /proc/kallsyms. The only
penalty was increasing the memory footprint by 3 * kallsyms_num_syms.
Folks who want to improve this further now also have a dedicated selftest
facility through KALLSYMS_SELFTEST. Since I had to start reviewing other
future kallsyms / modules enhancements by Nick Alcock (his stuff is not
merged, it requires more work) I carefully reviewed and merged Zhen Lei's
kallsyms changes through modules-next tree a bit less than a month ago.
So this has been exposed on linux-next for about a month now with no
reported regressions.
Stephen Boyd added zstd in-kernel decompression support, but the only
users of this would be folks using the load-pin LSM because otherwise
we do module docompression in userspace. This is the newest code and
was merged last week on modules-next.
We spent a lot of time analyzing and coming to grips with a proper
fix to an old modules regression which only recently came to light
(since v5.3-rc1, May 2019) but even though I merged that fix onto
modules-next last week I'm having second thoughts about it now as I was
writing about that fix in this git tag message for you, as I found a few
things we cannot quite justify there yet. So I'm going to push back to the
drawing board again there until all i's are properly dotted. Yes, it's a
regression but the issue has been there for 2 years now and it came up
because of high end CPU count, it can wait a *tiny* bit more for a proper
fix.
The only other thing with mentioning is a minor boot time optimization by
Rasmus Villemoes which deferes param_sysfs_init() to late init. The rest
is cleanups and minor fixes.
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Merge tag 'modules-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux
Pull modules updates from Luis Chamberlain:
"Tux gets for xmas an improvement to the average lookup performance of
kallsyms_lookup_name() by 715x thanks to the work by Zhen Lei, which
upgraded our old implementation from being O(n) to O(log(n)), while
also retaining the old implementation support on /proc/kallsyms.
The only penalty was increasing the memory footprint by 3 *
kallsyms_num_syms. Folks who want to improve this further now also
have a dedicated selftest facility through KALLSYMS_SELFTEST.
Stephen Boyd added zstd in-kernel decompression support, but the only
users of this would be folks using the load-pin LSM because otherwise
we do module decompression in userspace.
The only other thing with mentioning is a minor boot time optimization
by Rasmus Villemoes which deferes param_sysfs_init() to late init. The
rest is cleanups and minor fixes"
* tag 'modules-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
livepatch: Call klp_match_callback() in klp_find_callback() to avoid code duplication
module/decompress: Support zstd in-kernel decompression
kallsyms: Remove unneeded semicolon
kallsyms: Add self-test facility
livepatch: Use kallsyms_on_each_match_symbol() to improve performance
kallsyms: Add helper kallsyms_on_each_match_symbol()
kallsyms: Reduce the memory occupied by kallsyms_seqs_of_names[]
kallsyms: Correctly sequence symbols when CONFIG_LTO_CLANG=y
kallsyms: Improve the performance of kallsyms_lookup_name()
scripts/kallsyms: rename build_initial_tok_table()
module: Fix NULL vs IS_ERR checking for module_get_next_page
kernel/params.c: defer most of param_sysfs_init() to late_initcall time
module: Remove unused macros module_addr_min/max
module: remove redundant module_sysfs_initialized variable
The implementation of function klp_match_callback() is identical to the
partial implementation of function klp_find_callback(). So call function
klp_match_callback() in function klp_find_callback() instead of the
duplicated code.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Acked-by: Song Liu <song@kernel.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
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Merge tag 'livepatching-for-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching
Pull livepatching update from Petr Mladek:
- code cleanup
* tag 'livepatching-for-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching:
livepatch: Move the result-invariant calculation out of the loop
In subsequent patches we'll add a sew of ftrace_regs_{get,set}_*()
helpers. In preparation, this patch renames
ftrace_instruction_pointer_set() to
ftrace_regs_set_instruction_pointer().
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20221103170520.931305-3-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Based on the test results of kallsyms_on_each_match_symbol() and
kallsyms_on_each_symbol(), the average performance can be improved by
more than 1500 times.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
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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Merge tag 'livepatching-for-6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching
Pull livepatching updates from Petr Mladek:
- Fix race between fork and livepatch transition revert
- Add sysfs entry that shows "patched" state for each object (module)
that can be livepatched by the given livepatch
- Some clean up
* tag 'livepatching-for-6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching:
selftests/livepatch: add sysfs test
livepatch: add sysfs entry "patched" for each klp_object
selftests/livepatch: normalize sysctl error message
livepatch: Add a missing newline character in klp_module_coming()
livepatch: fix race between fork and KLP transition
Rust symbols can become quite long due to namespacing introduced
by modules, types, traits, generics, etc. For instance,
the following code:
pub mod my_module {
pub struct MyType;
pub struct MyGenericType<T>(T);
pub trait MyTrait {
fn my_method() -> u32;
}
impl MyTrait for MyGenericType<MyType> {
fn my_method() -> u32 {
42
}
}
}
generates a symbol of length 96 when using the upcoming v0 mangling scheme:
_RNvXNtCshGpAVYOtgW1_7example9my_moduleINtB2_13MyGenericTypeNtB2_6MyTypeENtB2_7MyTrait9my_method
At the moment, Rust symbols may reach up to 300 in length.
Setting 512 as the maximum seems like a reasonable choice to
keep some headroom.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com>
Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com>
Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com>
Co-developed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Gary Guo <gary@garyguo.net>
Co-developed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Add per klp_object sysfs entry "patched". It makes it easier to debug
typos in the module name.
Signed-off-by: Song Liu <song@kernel.org>
Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com>
[pmladek@suse.com: Updated kernel version when the sysfs file will be introduced]
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220902205208.3117798-2-song@kernel.org
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: dcf550e52f ("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
The KLP transition code depends on the TIF_PATCH_PENDING and
the task->patch_state to stay in sync. On a normal (forward)
transition, TIF_PATCH_PENDING will be set on every task in
the system, while on a reverse transition (after a failed
forward one) first TIF_PATCH_PENDING will be cleared from
every task, followed by it being set on tasks that need to
be transitioned back to the original code.
However, the fork code copies over the TIF_PATCH_PENDING flag
from the parent to the child early on, in dup_task_struct and
setup_thread_stack. Much later, klp_copy_process will set
child->patch_state to match that of the parent.
However, the parent's patch_state may have been changed by KLP loading
or unloading since it was initially copied over into the child.
This results in the KLP code occasionally hitting this warning in
klp_complete_transition:
for_each_process_thread(g, task) {
WARN_ON_ONCE(test_tsk_thread_flag(task, TIF_PATCH_PENDING));
task->patch_state = KLP_UNDEFINED;
}
Set, or clear, the TIF_PATCH_PENDING flag in the child task
depending on whether or not it is needed at the time
klp_copy_process is called, at a point in copy_process where the
tasklist_lock is held exclusively, preventing races with the KLP
code.
The KLP code does have a few places where the state is changed
without the tasklist_lock held, but those should not cause
problems because klp_update_patch_state(current) cannot be
called while the current task is in the middle of fork,
klp_check_and_switch_task() which is called under the pi_lock,
which prevents rescheduling, and manipulation of the patch
state of idle tasks, which do not fork.
This should prevent this warning from triggering again in the
future, and close the race for both normal and reverse transitions.
Signed-off-by: Rik van Riel <riel@surriel.com>
Reported-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Fixes: d83a7cb375 ("livepatch: change to a per-task consistency model")
Cc: stable@kernel.org
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220808150019.03d6a67b@imladris.surriel.com
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>
This set of changes removes tracehook.h, moves modification of all of
the ptrace fields inside of siglock to remove races, adds a missing
permission check to ptrace.c
The removal of tracehook.h is quite significant as it has been a major
source of confusion in recent years. Much of that confusion was
around task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled
making the semantics clearer).
For people who don't know tracehook.h is a vestiage of an attempt to
implement uprobes like functionality that was never fully merged, and
was later superseeded by uprobes when uprobes was merged. For many
years now we have been removing what tracehook functionaly a little
bit at a time. To the point where now anything left in tracehook.h is
some weird strange thing that is difficult to understand.
Eric W. Biederman (15):
ptrace: Move ptrace_report_syscall into ptrace.h
ptrace/arm: Rename tracehook_report_syscall report_syscall
ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h
ptrace: Remove arch_syscall_{enter,exit}_tracehook
ptrace: Remove tracehook_signal_handler
task_work: Remove unnecessary include from posix_timers.h
task_work: Introduce task_work_pending
task_work: Call tracehook_notify_signal from get_signal on all architectures
task_work: Decouple TIF_NOTIFY_SIGNAL and task_work
signal: Move set_notify_signal and clear_notify_signal into sched/signal.h
resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume
resume_user_mode: Move to resume_user_mode.h
tracehook: Remove tracehook.h
ptrace: Move setting/clearing ptrace_message into ptrace_stop
ptrace: Return the signal to continue with from ptrace_stop
Jann Horn (1):
ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE
Yang Li (1):
ptrace: Remove duplicated include in ptrace.c
MAINTAINERS | 1 -
arch/Kconfig | 5 +-
arch/alpha/kernel/ptrace.c | 5 +-
arch/alpha/kernel/signal.c | 4 +-
arch/arc/kernel/ptrace.c | 5 +-
arch/arc/kernel/signal.c | 4 +-
arch/arm/kernel/ptrace.c | 12 +-
arch/arm/kernel/signal.c | 4 +-
arch/arm64/kernel/ptrace.c | 14 +--
arch/arm64/kernel/signal.c | 4 +-
arch/csky/kernel/ptrace.c | 5 +-
arch/csky/kernel/signal.c | 4 +-
arch/h8300/kernel/ptrace.c | 5 +-
arch/h8300/kernel/signal.c | 4 +-
arch/hexagon/kernel/process.c | 4 +-
arch/hexagon/kernel/signal.c | 1 -
arch/hexagon/kernel/traps.c | 6 +-
arch/ia64/kernel/process.c | 4 +-
arch/ia64/kernel/ptrace.c | 6 +-
arch/ia64/kernel/signal.c | 1 -
arch/m68k/kernel/ptrace.c | 5 +-
arch/m68k/kernel/signal.c | 4 +-
arch/microblaze/kernel/ptrace.c | 5 +-
arch/microblaze/kernel/signal.c | 4 +-
arch/mips/kernel/ptrace.c | 5 +-
arch/mips/kernel/signal.c | 4 +-
arch/nds32/include/asm/syscall.h | 2 +-
arch/nds32/kernel/ptrace.c | 5 +-
arch/nds32/kernel/signal.c | 4 +-
arch/nios2/kernel/ptrace.c | 5 +-
arch/nios2/kernel/signal.c | 4 +-
arch/openrisc/kernel/ptrace.c | 5 +-
arch/openrisc/kernel/signal.c | 4 +-
arch/parisc/kernel/ptrace.c | 7 +-
arch/parisc/kernel/signal.c | 4 +-
arch/powerpc/kernel/ptrace/ptrace.c | 8 +-
arch/powerpc/kernel/signal.c | 4 +-
arch/riscv/kernel/ptrace.c | 5 +-
arch/riscv/kernel/signal.c | 4 +-
arch/s390/include/asm/entry-common.h | 1 -
arch/s390/kernel/ptrace.c | 1 -
arch/s390/kernel/signal.c | 5 +-
arch/sh/kernel/ptrace_32.c | 5 +-
arch/sh/kernel/signal_32.c | 4 +-
arch/sparc/kernel/ptrace_32.c | 5 +-
arch/sparc/kernel/ptrace_64.c | 5 +-
arch/sparc/kernel/signal32.c | 1 -
arch/sparc/kernel/signal_32.c | 4 +-
arch/sparc/kernel/signal_64.c | 4 +-
arch/um/kernel/process.c | 4 +-
arch/um/kernel/ptrace.c | 5 +-
arch/x86/kernel/ptrace.c | 1 -
arch/x86/kernel/signal.c | 5 +-
arch/x86/mm/tlb.c | 1 +
arch/xtensa/kernel/ptrace.c | 5 +-
arch/xtensa/kernel/signal.c | 4 +-
block/blk-cgroup.c | 2 +-
fs/coredump.c | 1 -
fs/exec.c | 1 -
fs/io-wq.c | 6 +-
fs/io_uring.c | 11 +-
fs/proc/array.c | 1 -
fs/proc/base.c | 1 -
include/asm-generic/syscall.h | 2 +-
include/linux/entry-common.h | 47 +-------
include/linux/entry-kvm.h | 2 +-
include/linux/posix-timers.h | 1 -
include/linux/ptrace.h | 81 ++++++++++++-
include/linux/resume_user_mode.h | 64 ++++++++++
include/linux/sched/signal.h | 17 +++
include/linux/task_work.h | 5 +
include/linux/tracehook.h | 226 -----------------------------------
include/uapi/linux/ptrace.h | 2 +-
kernel/entry/common.c | 19 +--
kernel/entry/kvm.c | 9 +-
kernel/exit.c | 3 +-
kernel/livepatch/transition.c | 1 -
kernel/ptrace.c | 47 +++++---
kernel/seccomp.c | 1 -
kernel/signal.c | 62 +++++-----
kernel/task_work.c | 4 +-
kernel/time/posix-cpu-timers.c | 1 +
mm/memcontrol.c | 2 +-
security/apparmor/domain.c | 1 -
security/selinux/hooks.c | 1 -
85 files changed, 372 insertions(+), 495 deletions(-)
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Merge tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull ptrace cleanups from Eric Biederman:
"This set of changes removes tracehook.h, moves modification of all of
the ptrace fields inside of siglock to remove races, adds a missing
permission check to ptrace.c
The removal of tracehook.h is quite significant as it has been a major
source of confusion in recent years. Much of that confusion was around
task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled making the
semantics clearer).
For people who don't know tracehook.h is a vestiage of an attempt to
implement uprobes like functionality that was never fully merged, and
was later superseeded by uprobes when uprobes was merged. For many
years now we have been removing what tracehook functionaly a little
bit at a time. To the point where anything left in tracehook.h was
some weird strange thing that was difficult to understand"
* tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
ptrace: Remove duplicated include in ptrace.c
ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE
ptrace: Return the signal to continue with from ptrace_stop
ptrace: Move setting/clearing ptrace_message into ptrace_stop
tracehook: Remove tracehook.h
resume_user_mode: Move to resume_user_mode.h
resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume
signal: Move set_notify_signal and clear_notify_signal into sched/signal.h
task_work: Decouple TIF_NOTIFY_SIGNAL and task_work
task_work: Call tracehook_notify_signal from get_signal on all architectures
task_work: Introduce task_work_pending
task_work: Remove unnecessary include from posix_timers.h
ptrace: Remove tracehook_signal_handler
ptrace: Remove arch_syscall_{enter,exit}_tracehook
ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h
ptrace/arm: Rename tracehook_report_syscall report_syscall
ptrace: Move ptrace_report_syscall into ptrace.h
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Merge tag 'livepatching-for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching
Pull livepatching updates from Petr Mladek:
- Forced transitions block only to-be-removed livepatches [Chengming]
- Detect when ftrace handler could not be disabled in self-tests [David]
- Calm down warning from a static analyzer [Tom]
* tag 'livepatching-for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching:
livepatch: Reorder to use before freeing a pointer
livepatch: Don't block removal of patches that are safe to unload
livepatch: Skip livepatch tests if ftrace cannot be configured
coarse grained, hardware based, forward edge Control-Flow-Integrity mechanism
where any indirect CALL/JMP must target an ENDBR instruction or suffer #CP.
Additionally, since Alderlake (12th gen)/Sapphire-Rapids, speculation is
limited to 2 instructions (and typically fewer) on branch targets not starting
with ENDBR. CET-IBT also limits speculation of the next sequential instruction
after the indirect CALL/JMP [1].
CET-IBT is fundamentally incompatible with retpolines, but provides, as
described above, speculation limits itself.
[1] https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/branch-history-injection.html
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Merge tag 'x86_core_for_5.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 CET-IBT (Control-Flow-Integrity) support from Peter Zijlstra:
"Add support for Intel CET-IBT, available since Tigerlake (11th gen),
which is a coarse grained, hardware based, forward edge
Control-Flow-Integrity mechanism where any indirect CALL/JMP must
target an ENDBR instruction or suffer #CP.
Additionally, since Alderlake (12th gen)/Sapphire-Rapids, speculation
is limited to 2 instructions (and typically fewer) on branch targets
not starting with ENDBR. CET-IBT also limits speculation of the next
sequential instruction after the indirect CALL/JMP [1].
CET-IBT is fundamentally incompatible with retpolines, but provides,
as described above, speculation limits itself"
[1] https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/branch-history-injection.html
* tag 'x86_core_for_5.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits)
kvm/emulate: Fix SETcc emulation for ENDBR
x86/Kconfig: Only allow CONFIG_X86_KERNEL_IBT with ld.lld >= 14.0.0
x86/Kconfig: Only enable CONFIG_CC_HAS_IBT for clang >= 14.0.0
kbuild: Fixup the IBT kbuild changes
x86/Kconfig: Do not allow CONFIG_X86_X32_ABI=y with llvm-objcopy
x86: Remove toolchain check for X32 ABI capability
x86/alternative: Use .ibt_endbr_seal to seal indirect calls
objtool: Find unused ENDBR instructions
objtool: Validate IBT assumptions
objtool: Add IBT/ENDBR decoding
objtool: Read the NOENDBR annotation
x86: Annotate idtentry_df()
x86,objtool: Move the ASM_REACHABLE annotation to objtool.h
x86: Annotate call_on_stack()
objtool: Rework ASM_REACHABLE
x86: Mark __invalid_creds() __noreturn
exit: Mark do_group_exit() __noreturn
x86: Mark stop_this_cpu() __noreturn
objtool: Ignore extra-symbol code
objtool: Rename --duplicate to --lto
...
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
Currently livepatch assumes __fentry__ lives at func+0, which is most
likely untrue with IBT on. Instead make it use ftrace_location() by
default which both validates and finds the actual ip if there is any
in the same symbol.
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.285971256@infradead.org
Now that all of the definitions have moved out of tracehook.h into
ptrace.h, sched/signal.h, resume_user_mode.h there is nothing left in
tracehook.h so remove it.
Update the few files that were depending upon tracehook.h to bring in
definitions to use the headers they need directly.
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20220309162454.123006-13-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Merge tag 'livepatching-for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching
Pull livepatching updates from Petr Mladek:
- Correctly handle kobjects when a livepatch init fails
- Avoid CPU hogging when searching for many livepatched symbols
- Add livepatch API page into documentation
* tag 'livepatching-for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching:
livepatch: Avoid CPU hogging with cond_resched
livepatch: Fix missing unlock on error in klp_enable_patch()
livepatch: Fix kobject refcount bug on klp_init_patch_early failure path
Documentation: livepatch: Add livepatch API page
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>
The livepatch subsystem has several exported functions and objects with
kerneldoc comments. Though the livepatch documentation contains handwritten
descriptions of all of these exported functions, they are currently not
pulled into the docs build using the kernel-doc directive.
In order to allow readers of the documentation to see the full kerneldoc
comments in the generated documentation files, this change adds a new
Documentation/livepatch/api.rst page which contains kernel-doc directives
to link the kerneldoc comments directly in the documentation. With this,
all of the hand-written descriptions of the APIs now cross-reference the
kerneldoc comments on the new Livepatching APIs page, and running
./scripts/find-unused-docs.sh on kernel/livepatch no longer shows any files
as missing documentation.
Note that all of the handwritten API descriptions were left alone with the
exception of Documentation/livepatch/system-state.rst, which was updated to
allow the cross-referencing to work correctly. The file now follows the
cross-referencing formatting guidance specified in
Documentation/doc-guide/kernel-doc.rst. Furthermore, some comments around
klp_shadow_free_all() were updated to say <_, id> rather than <*, id> to
match the rest of the file, and to prevent the docs build from emitting an
"Inline emphasis start-string without end string" error.
Signed-off-by: David Vernet <void@manifault.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20211221145743.4098360-1-void@manifault.com
- kprobes: Restructured stack unwinder to show properly on x86 when a stack
dump happens from a kretprobe callback.
- Fix to bootconfig parsing
- Have tracefs allow owner and group permissions by default (only denying
others). There's been pressure to allow non root to tracefs in a
controlled fashion, and using groups is probably the safest.
- Bootconfig memory managament updates.
- Bootconfig clean up to have the tools directory be less dependent on
changes in the kernel tree.
- Allow perf to be traced by function tracer.
- Rewrite of function graph tracer to be a callback from the function tracer
instead of having its own trampoline (this change will happen on an arch
by arch basis, and currently only x86_64 implements it).
- Allow multiple direct trampolines (bpf hooks to functions) be batched
together in one synchronization.
- Allow histogram triggers to add variables that can perform calculations
against the event's fields.
- Use the linker to determine architecture callbacks from the ftrace
trampoline to allow for proper parameter prototypes and prevent warnings
from the compiler.
- Extend histogram triggers to key off of variables.
- Have trace recursion use bit magic to determine preempt context over if
branches.
- Have trace recursion disable preemption as all use cases do anyway.
- Added testing for verification of tracing utilities.
- Various small clean ups and fixes.
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Merge tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
- kprobes: Restructured stack unwinder to show properly on x86 when a
stack dump happens from a kretprobe callback.
- Fix to bootconfig parsing
- Have tracefs allow owner and group permissions by default (only
denying others). There's been pressure to allow non root to tracefs
in a controlled fashion, and using groups is probably the safest.
- Bootconfig memory managament updates.
- Bootconfig clean up to have the tools directory be less dependent on
changes in the kernel tree.
- Allow perf to be traced by function tracer.
- Rewrite of function graph tracer to be a callback from the function
tracer instead of having its own trampoline (this change will happen
on an arch by arch basis, and currently only x86_64 implements it).
- Allow multiple direct trampolines (bpf hooks to functions) be batched
together in one synchronization.
- Allow histogram triggers to add variables that can perform
calculations against the event's fields.
- Use the linker to determine architecture callbacks from the ftrace
trampoline to allow for proper parameter prototypes and prevent
warnings from the compiler.
- Extend histogram triggers to key off of variables.
- Have trace recursion use bit magic to determine preempt context over
if branches.
- Have trace recursion disable preemption as all use cases do anyway.
- Added testing for verification of tracing utilities.
- Various small clean ups and fixes.
* tag 'trace-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (101 commits)
tracing/histogram: Fix semicolon.cocci warnings
tracing/histogram: Fix documentation inline emphasis warning
tracing: Increase PERF_MAX_TRACE_SIZE to handle Sentinel1 and docker together
tracing: Show size of requested perf buffer
bootconfig: Initialize ret in xbc_parse_tree()
ftrace: do CPU checking after preemption disabled
ftrace: disable preemption when recursion locked
tracing/histogram: Document expression arithmetic and constants
tracing/histogram: Optimize division by a power of 2
tracing/histogram: Covert expr to const if both operands are constants
tracing/histogram: Simplify handling of .sym-offset in expressions
tracing: Fix operator precedence for hist triggers expression
tracing: Add division and multiplication support for hist triggers
tracing: Add support for creating hist trigger variables from literal
selftests/ftrace: Stop tracing while reading the trace file by default
MAINTAINERS: Update KPROBES and TRACING entries
test_kprobes: Move it from kernel/ to lib/
docs, kprobes: Remove invalid URL and add new reference
samples/kretprobes: Fix return value if register_kretprobe() failed
lib/bootconfig: Fix the xbc_get_info kerneldoc
...
As the documentation explained, ftrace_test_recursion_trylock()
and ftrace_test_recursion_unlock() were supposed to disable and
enable preemption properly, however currently this work is done
outside of the function, which could be missing by mistake.
And since the internal using of trace_test_and_set_recursion()
and trace_clear_recursion() also require preemption disabled, we
can just merge the logical.
This patch will make sure the preemption has been disabled when
trace_test_and_set_recursion() return bit >= 0, and
trace_clear_recursion() will enable the preemption if previously
enabled.
Link: https://lkml.kernel.org/r/13bde807-779c-aa4c-0672-20515ae365ea@linux.alibaba.com
CC: Petr Mladek <pmladek@suse.com>
Cc: Guo Ren <guoren@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Jisheng Zhang <jszhang@kernel.org>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Miroslav Benes <mbenes@suse.cz>
Reported-by: Abaci <abaci@linux.alibaba.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
[ Removed extra line in comment - SDR ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Make sure to prod idle CPUs so they call klp_update_patch_state().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Tested-by: Vasily Gorbik <gor@linux.ibm.com> # on s390
Link: https://lkml.kernel.org/r/20210929151723.162004989@infradead.org
Instead of frobbing around with scheduler internals, use the shiny new
task_call_func() interface.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Tested-by: Vasily Gorbik <gor@linux.ibm.com> # on s390
Link: https://lkml.kernel.org/r/20210929152428.709906138@infradead.org
The functions get_online_cpus() and put_online_cpus() have been
deprecated during the CPU hotplug rework. They map directly to
cpus_read_lock() and cpus_read_unlock().
Replace deprecated CPU-hotplug functions with the official version.
The behavior remains unchanged.
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: live-patching@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Merge tag 'livepatching-for-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching
Pull livepatching update from Petr Mladek:
- Use TIF_NOTIFY_SIGNAL infrastructure instead of the fake signal
* tag 'livepatching-for-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching:
livepatch: Replace the fake signal sending with TIF_NOTIFY_SIGNAL infrastructure
Livepatch sends a fake signal to all remaining blocking tasks of a
running transition after a set period of time. It uses TIF_SIGPENDING
flag for the purpose. Commit 12db8b6900 ("entry: Add support for
TIF_NOTIFY_SIGNAL") added a generic infrastructure to achieve the same.
Replace our bespoke solution with the generic one.
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Require an explicit call to module_kallsyms_on_each_symbol to look
for symbols in modules instead of the call from kallsyms_on_each_symbol,
and acquire module_mutex inside of module_kallsyms_on_each_symbol instead
of leaving that up to the caller. Note that this slightly changes the
behavior for the livepatch code in that the symbols from vmlinux are not
iterated anymore if objname is set, but that actually is the desired
behavior in this case.
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Allow for a RCU-sched critical section around find_module, following
the lower level find_module_all helper, and switch the two callers
outside of module.c to use such a RCU-sched critical section instead
of module_mutex.
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
When CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS is available, the ftrace call
will be able to set the ip of the calling function. This will improve the
performance of live kernel patching where it does not need all the regs to
be stored just to change the instruction pointer.
If all archs that support live kernel patching also support
HAVE_DYNAMIC_FTRACE_WITH_ARGS, then the architecture specific function
klp_arch_set_pc() could be made generic.
It is possible that an arch can support HAVE_DYNAMIC_FTRACE_WITH_ARGS but
not HAVE_DYNAMIC_FTRACE_WITH_REGS and then have access to live patching.
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: live-patching@vger.kernel.org
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
In preparation to have arguments of a function passed to callbacks attached
to functions as default, change the default callback prototype to receive a
struct ftrace_regs as the forth parameter instead of a pt_regs.
For callbacks that set the FL_SAVE_REGS flag in their ftrace_ops flags, they
will now need to get the pt_regs via a ftrace_get_regs() helper call. If
this is called by a callback that their ftrace_ops did not have a
FL_SAVE_REGS flag set, it that helper function will return NULL.
This will allow the ftrace_regs to hold enough just to get the parameters
and stack pointer, but without the worry that callbacks may have a pt_regs
that is not completely filled.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This adds CONFIG_FTRACE_RECORD_RECURSION that will record to a file
"recursed_functions" all the functions that caused recursion while a
callback to the function tracer was running.
Link: https://lkml.kernel.org/r/20201106023548.102375687@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Guo Ren <guoren@kernel.org>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-csky@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: live-patching@vger.kernel.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
If for some reason a function is called that triggers the recursion
detection of live patching, trigger a warning. By not executing the live
patch code, it is possible that the old unpatched function will be called
placing the system into an unknown state.
Link: https://lore.kernel.org/r/20201029145709.GD16774@alley
Link: https://lkml.kernel.org/r/20201106023547.312639435@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: live-patching@vger.kernel.org
Suggested-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
If a ftrace callback does not supply its own recursion protection and
does not set the RECURSION_SAFE flag in its ftrace_ops, then ftrace will
make a helper trampoline to do so before calling the callback instead of
just calling the callback directly.
The default for ftrace_ops is going to change. It will expect that handlers
provide their own recursion protection, unless its ftrace_ops states
otherwise.
Link: https://lkml.kernel.org/r/20201028115613.291169246@goodmis.org
Link: https://lkml.kernel.org/r/20201106023547.122802424@goodmis.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: live-patching@vger.kernel.org
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Fix multiple occurrences of duplicated words in kernel/.
Fix one typo/spello on the same line as a duplicate word. Change one
instance of "the the" to "that the". Otherwise just drop one of the
repeated words.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/98202fa6-8919-ef63-9efe-c0fad5ca7af1@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix the following sparse warning:
kernel/livepatch/core.c:748:5: warning: symbol 'klp_apply_object_relocs' was
not declared.
The klp_apply_object_relocs() has only one call site within core.c;
it should be static
Fixes: 7c8e2bdd5f ("livepatch: Apply vmlinux-specific KLP relocations early")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Samuel Zou <zou_wei@huawei.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Now that the livepatch code no longer needs the text_mutex for changing
module permissions, move its usage down to apply_relocate_add().
Note the s390 version of apply_relocate_add() doesn't need to use the
text_mutex because it already uses s390_kernel_write_lock, which
accomplishes the same task.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
With arch_klp_init_object_loaded() gone, and apply_relocate_add() now
using text_poke(), livepatch no longer needs to use module_disable_ro().
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Prevent module-specific KLP rela sections from referencing vmlinux
symbols. This helps prevent ordering issues with module special section
initializations. Presumably such symbols are exported and normal relas
can be used instead.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
After the previous patch, vmlinux-specific KLP relocations are now
applied early during KLP module load. This means that .klp.arch
sections are no longer needed for *vmlinux-specific* KLP relocations.
One might think they're still needed for *module-specific* KLP
relocations. If a to-be-patched module is loaded *after* its
corresponding KLP module is loaded, any corresponding KLP relocations
will be delayed until the to-be-patched module is loaded. If any
special sections (.parainstructions, for example) rely on those
relocations, their initializations (apply_paravirt) need to be done
afterwards. Thus the apparent need for arch_klp_init_object_loaded()
and its corresponding .klp.arch sections -- it allows some of the
special section initializations to be done at a later time.
But... if you look closer, that dependency between the special sections
and the module-specific KLP relocations doesn't actually exist in
reality. Looking at the contents of the .altinstructions and
.parainstructions sections, there's not a realistic scenario in which a
KLP module's .altinstructions or .parainstructions section needs to
access a symbol in a to-be-patched module. It might need to access a
local symbol or even a vmlinux symbol; but not another module's symbol.
When a special section needs to reference a local or vmlinux symbol, a
normal rela can be used instead of a KLP rela.
Since the special section initializations don't actually have any real
dependency on module-specific KLP relocations, .klp.arch and
arch_klp_init_object_loaded() no longer have a reason to exist. So
remove them.
As Peter said much more succinctly:
So the reason for .klp.arch was that .klp.rela.* stuff would overwrite
paravirt instructions. If that happens you're doing it wrong. Those
RELAs are core kernel, not module, and thus should've happened in
.rela.* sections at patch-module loading time.
Reverting this removes the two apply_{paravirt,alternatives}() calls
from the late patching path, and means we don't have to worry about
them when removing module_disable_ro().
[ jpoimboe: Rewrote patch description. Tweaked klp_init_object_loaded()
error path. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
KLP relocations are livepatch-specific relocations which are applied to
a KLP module's text or data. They exist for two reasons:
1) Unexported symbols: replacement functions often need to access
unexported symbols (e.g. static functions), which "normal"
relocations don't allow.
2) Late module patching: this is the ability for a KLP module to
bypass normal module dependencies, such that the KLP module can be
loaded *before* a to-be-patched module. This means that
relocations which need to access symbols in the to-be-patched
module might need to be applied to the KLP module well after it has
been loaded.
Non-late-patched KLP relocations are applied from the KLP module's init
function. That usually works fine, unless the patched code wants to use
alternatives, paravirt patching, jump tables, or some other special
section which needs relocations. Then we run into ordering issues and
crashes.
In order for those special sections to work properly, the KLP
relocations should be applied *before* the special section init code
runs, such as apply_paravirt(), apply_alternatives(), or
jump_label_apply_nops().
You might think the obvious solution would be to move the KLP relocation
initialization earlier, but it's not necessarily that simple. The
problem is the above-mentioned late module patching, for which KLP
relocations can get applied well after the KLP module is loaded.
To "fix" this issue in the past, we created .klp.arch sections:
.klp.arch.{module}..altinstructions
.klp.arch.{module}..parainstructions
Those sections allow KLP late module patching code to call
apply_paravirt() and apply_alternatives() after the module-specific KLP
relocations (.klp.rela.{module}.{section}) have been applied.
But that has a lot of drawbacks, including code complexity, the need for
arch-specific code, and the (per-arch) danger that we missed some
special section -- for example the __jump_table section which is used
for jump labels.
It turns out there's a simpler and more functional approach. There are
two kinds of KLP relocation sections:
1) vmlinux-specific KLP relocation sections
.klp.rela.vmlinux.{sec}
These are relocations (applied to the KLP module) which reference
unexported vmlinux symbols.
2) module-specific KLP relocation sections
.klp.rela.{module}.{sec}:
These are relocations (applied to the KLP module) which reference
unexported or exported module symbols.
Up until now, these have been treated the same. However, they're
inherently different.
Because of late module patching, module-specific KLP relocations can be
applied very late, thus they can create the ordering headaches described
above.
But vmlinux-specific KLP relocations don't have that problem. There's
nothing to prevent them from being applied earlier. So apply them at
the same time as normal relocations, when the KLP module is being
loaded.
This means that for vmlinux-specific KLP relocations, we no longer have
any ordering issues. vmlinux-referencing jump labels, alternatives, and
paravirt patching will work automatically, without the need for the
.klp.arch hacks.
All that said, for module-specific KLP relocations, the ordering
problems still exist and we *do* still need .klp.arch. Or do we? Stay
tuned.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This is purely a theoretical issue, but if there were a module named
vmlinux.ko, the livepatch relocation code wouldn't be able to
distinguish between vmlinux-specific and vmlinux.o-specific KLP
relocations.
If CONFIG_LIVEPATCH is enabled, don't allow a module named vmlinux.ko.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
- PERAMAENT flag to ftrace_ops when attaching a callback to a function
As /proc/sys/kernel/ftrace_enabled when set to zero will disable all
attached callbacks in ftrace, this has a detrimental impact on live
kernel tracing, as it disables all that it patched. If a ftrace_ops
is registered to ftrace with the PERMANENT flag set, it will prevent
ftrace_enabled from being disabled, and if ftrace_enabled is already
disabled, it will prevent a ftrace_ops with PREMANENT flag set from
being registered.
- New register_ftrace_direct(). As eBPF would like to register its own
trampolines to be called by the ftrace nop locations directly,
without going through the ftrace trampoline, this function has been
added. This allows for eBPF trampolines to live along side of
ftrace, perf, kprobe and live patching. It also utilizes the ftrace
enabled_functions file that keeps track of functions that have been
modified in the kernel, to allow for security auditing.
- Allow for kernel internal use of ftrace instances. Subsystems in
the kernel can now create and destroy their own tracing instances
which allows them to have their own tracing buffer, and be able
to record events without worrying about other users from writing over
their data.
- New seq_buf_hex_dump() that lets users use the hex_dump() in their
seq_buf usage.
- Notifications now added to tracing_max_latency to allow user space
to know when a new max latency is hit by one of the latency tracers.
- Wider spread use of generic compare operations for use of bsearch and
friends.
- More synthetic event fields may be defined (32 up from 16)
- Use of xarray for architectures with sparse system calls, for the
system call trace events.
This along with small clean ups and fixes.
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Merge tag 'trace-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"New tracing features:
- New PERMANENT flag to ftrace_ops when attaching a callback to a
function.
As /proc/sys/kernel/ftrace_enabled when set to zero will disable
all attached callbacks in ftrace, this has a detrimental impact on
live kernel tracing, as it disables all that it patched. If a
ftrace_ops is registered to ftrace with the PERMANENT flag set, it
will prevent ftrace_enabled from being disabled, and if
ftrace_enabled is already disabled, it will prevent a ftrace_ops
with PREMANENT flag set from being registered.
- New register_ftrace_direct().
As eBPF would like to register its own trampolines to be called by
the ftrace nop locations directly, without going through the ftrace
trampoline, this function has been added. This allows for eBPF
trampolines to live along side of ftrace, perf, kprobe and live
patching. It also utilizes the ftrace enabled_functions file that
keeps track of functions that have been modified in the kernel, to
allow for security auditing.
- Allow for kernel internal use of ftrace instances.
Subsystems in the kernel can now create and destroy their own
tracing instances which allows them to have their own tracing
buffer, and be able to record events without worrying about other
users from writing over their data.
- New seq_buf_hex_dump() that lets users use the hex_dump() in their
seq_buf usage.
- Notifications now added to tracing_max_latency to allow user space
to know when a new max latency is hit by one of the latency
tracers.
- Wider spread use of generic compare operations for use of bsearch
and friends.
- More synthetic event fields may be defined (32 up from 16)
- Use of xarray for architectures with sparse system calls, for the
system call trace events.
This along with small clean ups and fixes"
* tag 'trace-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (51 commits)
tracing: Enable syscall optimization for MIPS
tracing: Use xarray for syscall trace events
tracing: Sample module to demonstrate kernel access to Ftrace instances.
tracing: Adding new functions for kernel access to Ftrace instances
tracing: Fix Kconfig indentation
ring-buffer: Fix typos in function ring_buffer_producer
ftrace: Use BIT() macro
ftrace: Return ENOTSUPP when DYNAMIC_FTRACE_WITH_DIRECT_CALLS is not configured
ftrace: Rename ftrace_graph_stub to ftrace_stub_graph
ftrace: Add a helper function to modify_ftrace_direct() to allow arch optimization
ftrace: Add helper find_direct_entry() to consolidate code
ftrace: Add another check for match in register_ftrace_direct()
ftrace: Fix accounting bug with direct->count in register_ftrace_direct()
ftrace/selftests: Fix spelling mistake "wakeing" -> "waking"
tracing: Increase SYNTH_FIELDS_MAX for synthetic_events
ftrace/samples: Add a sample module that implements modify_ftrace_direct()
ftrace: Add modify_ftrace_direct()
tracing: Add missing "inline" in stub function of latency_fsnotify()
tracing: Remove stray tab in TRACE_EVAL_MAP_FILE's help text
tracing: Use seq_buf_hex_dump() to dump buffers
...
Livepatch uses ftrace for redirection to new patched functions. It means
that if ftrace is disabled, all live patched functions are disabled as
well. Toggling global 'ftrace_enabled' sysctl thus affect it directly.
It is not a problem per se, because only administrator can set sysctl
values, but it still may be surprising.
Introduce PERMANENT ftrace_ops flag to amend this. If the
FTRACE_OPS_FL_PERMANENT is set on any ftrace ops, the tracing cannot be
disabled by disabling ftrace_enabled. Equally, a callback with the flag
set cannot be registered if ftrace_enabled is disabled.
Link: http://lkml.kernel.org/r/20191016113316.13415-2-mbenes@suse.cz
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The atomic replace runs pre/post (un)install callbacks only from the new
livepatch. There are several reasons for this:
+ Simplicity: clear ordering of operations, no interactions between
old and new callbacks.
+ Reliability: only new livepatch knows what changes can already be made
by older livepatches and how to take over the state.
+ Testing: the atomic replace can be properly tested only when a newer
livepatch is available. It might be too late to fix unwanted effect
of callbacks from older livepatches.
It might happen that an older change is not enough and the same system
state has to be modified another way. Different changes need to get
distinguished by a version number added to struct klp_state.
The version can also be used to prevent loading incompatible livepatches.
The check is done when the livepatch is enabled. The rules are:
+ Any completely new system state modification is allowed.
+ System state modifications with the same or higher version are allowed
for already modified system states.
+ Cumulative livepatches must handle all system state modifications from
already installed livepatches.
+ Non-cumulative livepatches are allowed to touch already modified
system states.
Link: http://lkml.kernel.org/r/20191030154313.13263-4-pmladek@suse.com
To: Jiri Kosina <jikos@kernel.org>
Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: live-patching@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Linus Torvalds
Zhen Lei
Mark Rutland
Petr Mladek
Miguel Ojeda
Song Liu
Rik van Riel
Christophe Leroy
Chengming Zhou
Peter Zijlstra
Eric W. Biederman
Yang Yingliang
David Vernet
王贇
Sebastian Andrzej Siewior
Miroslav Benes
Christoph Hellwig
Steven Rostedt (VMware)
Randy Dunlap
Samuel Zou
Josh Poimboeuf