linux-toradex.git/kernel/kprobes.c, branch v6.19-rc2

kprobes: Add missing kerneldoc for __get_insn_slot

2025-07-15T09:45:34+00:00

Add kerneldoc for '__get_insn_slot' function to fix W=1 warnings:

  kernel/kprobes.c:141 function parameter 'c' not described in '__get_insn_slot'

Link: https://lore.kernel.org/all/20250704143817707TOCcfTRWsO5OAbQ2eYoU9@zte.com.cn/

Signed-off-by: Peng Jiang 
Signed-off-by: Masami Hiramatsu (Google)

kprobes: Use RCU in all users of __module_text_address().

2025-03-10T10:54:46+00:00

__module_text_address() can be invoked within a RCU section, there is no
requirement to have preemption disabled.

Replace the preempt_disable() section around __module_text_address()
with RCU.

Cc: David S. Miller 
Cc: Anil S Keshavamurthy 
Cc: Masami Hiramatsu 
Cc: Naveen N Rao 
Cc: linux-trace-kernel@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior 
Acked-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/r/20250129084925.9ppBjGLC@linutronix.de
Signed-off-by: Petr Pavlu

treewide: const qualify ctl_tables where applicable

2025-01-28T12:48:37+00:00

Add the const qualifier to all the ctl_tables in the tree except for
watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
loadpin_sysctl_table and the ones calling register_net_sysctl (./net,
drivers/inifiniband dirs). These are special cases as they use a
registration function with a non-const qualified ctl_table argument or
modify the arrays before passing them on to the registration function.

Constifying ctl_table structs will prevent the modification of
proc_handler function pointers as the arrays would reside in .rodata.
This is made possible after commit 78eb4ea25cd5 ("sysctl: treewide:
constify the ctl_table argument of proc_handlers") constified all the
proc_handlers.

Created this by running an spatch followed by a sed command:
Spatch:
    virtual patch

    @
    depends on !(file in "net")
    disable optional_qualifier
    @

    identifier table_name != {
      watchdog_hardlockup_sysctl,
      iwcm_ctl_table,
      ucma_ctl_table,
      memory_allocation_profiling_sysctls,
      loadpin_sysctl_table
    };
    @@

    + const
    struct ctl_table table_name [] = { ... };

sed:
    sed --in-place \
      -e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \
      kernel/utsname_sysctl.c

Reviewed-by: Song Liu 
Acked-by: Steven Rostedt (Google)  # for kernel/trace/
Reviewed-by: Martin K. Petersen  # SCSI
Reviewed-by: Darrick J. Wong  # xfs
Acked-by: Jani Nikula 
Acked-by: Corey Minyard 
Acked-by: Wei Liu 
Acked-by: Thomas Gleixner 
Reviewed-by: Bill O'Donnell 
Acked-by: Baoquan He 
Acked-by: Ashutosh Dixit 
Acked-by: Anna Schumaker 
Signed-off-by: Joel Granados

kprobes: Remove remaining gotos

2025-01-10T00:00:13+00:00

Remove remaining gotos from kprobes.c to clean up the code.
This does not use cleanup macros, but changes code flow for avoiding
gotos.

Link: https://lore.kernel.org/all/173371212474.480397.5684523564137819115.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google)

kprobes: Remove unneeded goto

2025-01-10T00:00:13+00:00

Remove unneeded gotos. Since the labels referred by these gotos have
only one reference for each, we can replace those gotos with the
referred code.

Link: https://lore.kernel.org/all/173371211203.480397.13988907319659165160.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google)

kprobes: Use guard for rcu_read_lock

2025-01-10T00:00:13+00:00

Use guard(rcu) for rcu_read_lock so that it can remove unneeded
gotos and make it more structured.

Link: https://lore.kernel.org/all/173371209846.480397.3852648910271029695.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google)

kprobes: Use guard() for external locks

2025-01-10T00:00:13+00:00

Use guard() for text_mutex, cpu_read_lock, and jump_label_lock in
the kprobes.

Link: https://lore.kernel.org/all/173371208663.480397.7535769878667655223.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google)

kprobes: Adopt guard() and scoped_guard()

2025-01-10T00:00:12+00:00

Use guard() or scoped_guard() for critical sections rather than
discrete lock/unlock pairs.

Link: https://lore.kernel.org/all/173289887835.73724.608223217359025939.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google)

kprobes: Reduce preempt disable scope in check_kprobe_access_safe()

2025-01-10T00:00:12+00:00

Commit a189d0350f387 ("kprobes: disable preempt for module_text_address() and kernel_text_address()")
introduced a preempt_disable() region to protect against concurrent
module unloading. However this region also includes the call to
jump_label_text_reserved() which takes a long time;
up to 400us, iterating over approx 6000 jump tables.

The scope protected by preempt_disable() is largen than necessary.
core_kernel_text() does not need to be protected as it does not interact
with module code at all.
Only the scope from __module_text_address() to try_module_get() needs to
be protected.
By limiting the critical section to __module_text_address() and
try_module_get() the function responsible for the latency spike remains
preemptible.

This works fine even when !CONFIG_MODULES as in that case
try_module_get() will always return true and that block can be optimized
away.

Limit the critical section to __module_text_address() and
try_module_get(). Use guard(preempt)() for easier error handling.

While at it also remove a spurious *probed_mod = NULL in an error
path. On errors the output parameter is never inspected by the caller.
Some error paths were clearing the parameters, some didn't.
Align them for clarity.

Link: https://lore.kernel.org/all/20241121-kprobes-preempt-v1-1-fd581ee7fcbb@linutronix.de/

Signed-off-by: Thomas Weißschuh 
Reviewed-by: Sebastian Andrzej Siewior 
Signed-off-by: Masami Hiramatsu (Google)

kprobes: Use struct_size() in __get_insn_slot()

2024-10-31T02:00:58+00:00

__get_insn_slot() allocates 'struct kprobe_insn_page' using a custom
structure size calculation macro, KPROBE_INSN_PAGE_SIZE. Replace
KPROBE_INSN_PAGE_SIZE with the struct_size() macro, which is the
preferred way to calculate the size of flexible structures in the kernel
because it handles overflow and makes it easier to change and audit how
flexible structures are allocated across the entire tree.

Link: https://lore.kernel.org/all/20241030-kprobes-fix-counted-by-annotation-v1-2-8f266001fad0@kernel.org/
(Masami modofied this to be applicable without the 1st patch in the series.)

Signed-off-by: Nathan Chancellor 
Signed-off-by: Masami Hiramatsu (Google)