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author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-11-02 09:17:49 -0500 |
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committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-11-04 09:46:06 -0500 |
commit | 645f224e7ba2f4200bf163153d384ceb0de5462e (patch) | |
tree | 8e4d6abaf425a9cf9b253f0dba60b9ca98102dcb /kernel | |
parent | 561ca66910bf597f170be5a7aa531c4e05f8e9be (diff) | |
download | linux-stable-645f224e7ba2f4200bf163153d384ceb0de5462e.tar.gz linux-stable-645f224e7ba2f4200bf163153d384ceb0de5462e.tar.bz2 linux-stable-645f224e7ba2f4200bf163153d384ceb0de5462e.zip |
kprobes: Tell lockdep about kprobe nesting
Since the kprobe handlers have protection that prohibits other handlers from
executing in other contexts (like if an NMI comes in while processing a
kprobe, and executes the same kprobe, it will get fail with a "busy"
return). Lockdep is unaware of this protection. Use lockdep's nesting api to
differentiate between locks taken in INT3 context and other context to
suppress the false warnings.
Link: https://lore.kernel.org/r/20201102160234.fa0ae70915ad9e2b21c08b85@kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/kprobes.c | 25 |
1 files changed, 21 insertions, 4 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 8a12a25fa40d..41fdbb7953c6 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1249,7 +1249,13 @@ __acquires(hlist_lock) *head = &kretprobe_inst_table[hash]; hlist_lock = kretprobe_table_lock_ptr(hash); - raw_spin_lock_irqsave(hlist_lock, *flags); + /* + * Nested is a workaround that will soon not be needed. + * There's other protections that make sure the same lock + * is not taken on the same CPU that lockdep is unaware of. + * Differentiate when it is taken in NMI context. + */ + raw_spin_lock_irqsave_nested(hlist_lock, *flags, !!in_nmi()); } NOKPROBE_SYMBOL(kretprobe_hash_lock); @@ -1258,7 +1264,13 @@ static void kretprobe_table_lock(unsigned long hash, __acquires(hlist_lock) { raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash); - raw_spin_lock_irqsave(hlist_lock, *flags); + /* + * Nested is a workaround that will soon not be needed. + * There's other protections that make sure the same lock + * is not taken on the same CPU that lockdep is unaware of. + * Differentiate when it is taken in NMI context. + */ + raw_spin_lock_irqsave_nested(hlist_lock, *flags, !!in_nmi()); } NOKPROBE_SYMBOL(kretprobe_table_lock); @@ -2028,7 +2040,12 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) /* TODO: consider to only swap the RA after the last pre_handler fired */ hash = hash_ptr(current, KPROBE_HASH_BITS); - raw_spin_lock_irqsave(&rp->lock, flags); + /* + * Nested is a workaround that will soon not be needed. + * There's other protections that make sure the same lock + * is not taken on the same CPU that lockdep is unaware of. + */ + raw_spin_lock_irqsave_nested(&rp->lock, flags, 1); if (!hlist_empty(&rp->free_instances)) { ri = hlist_entry(rp->free_instances.first, struct kretprobe_instance, hlist); @@ -2039,7 +2056,7 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) ri->task = current; if (rp->entry_handler && rp->entry_handler(ri, regs)) { - raw_spin_lock_irqsave(&rp->lock, flags); + raw_spin_lock_irqsave_nested(&rp->lock, flags, 1); hlist_add_head(&ri->hlist, &rp->free_instances); raw_spin_unlock_irqrestore(&rp->lock, flags); return 0; |