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kprobes: Fix optimize_kprobe()/unoptimize_kprobe() cancellation logic
optimize_kprobe() and unoptimize_kprobe() cancels if a given kprobe is on the optimizing_list or unoptimizing_list already. However, since the following commit:f66c0447cc
("kprobes: Set unoptimized flag after unoptimizing code") modified the update timing of the KPROBE_FLAG_OPTIMIZED, it doesn't work as expected anymore. The optimized_kprobe could be in the following states: - [optimizing]: Before inserting jump instruction op.kp->flags has KPROBE_FLAG_OPTIMIZED and op->list is not empty. - [optimized]: jump inserted op.kp->flags has KPROBE_FLAG_OPTIMIZED and op->list is empty. - [unoptimizing]: Before removing jump instruction (including unused optprobe) op.kp->flags has KPROBE_FLAG_OPTIMIZED and op->list is not empty. - [unoptimized]: jump removed op.kp->flags doesn't have KPROBE_FLAG_OPTIMIZED and op->list is empty. Current code mis-expects [unoptimizing] state doesn't have KPROBE_FLAG_OPTIMIZED, and that can cause incorrect results. To fix this, introduce optprobe_queued_unopt() to distinguish [optimizing] and [unoptimizing] states and fixes the logic in optimize_kprobe() and unoptimize_kprobe(). [ mingo: Cleaned up the changelog and the code a bit. ] Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: bristot@redhat.com Fixes:f66c0447cc
("kprobes: Set unoptimized flag after unoptimizing code") Link: https://lkml.kernel.org/r/157840814418.7181.13478003006386303481.stgit@devnote2 Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
parent
2040cf9f59
commit
e4add24778
@ -612,6 +612,18 @@ void wait_for_kprobe_optimizer(void)
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mutex_unlock(&kprobe_mutex);
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}
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static bool optprobe_queued_unopt(struct optimized_kprobe *op)
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{
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struct optimized_kprobe *_op;
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list_for_each_entry(_op, &unoptimizing_list, list) {
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if (op == _op)
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return true;
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}
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return false;
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}
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/* Optimize kprobe if p is ready to be optimized */
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static void optimize_kprobe(struct kprobe *p)
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{
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@ -633,17 +645,21 @@ static void optimize_kprobe(struct kprobe *p)
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return;
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/* Check if it is already optimized. */
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if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
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return;
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op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
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if (!list_empty(&op->list))
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if (op->kp.flags & KPROBE_FLAG_OPTIMIZED) {
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if (optprobe_queued_unopt(op)) {
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/* This is under unoptimizing. Just dequeue the probe */
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list_del_init(&op->list);
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else {
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}
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return;
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}
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op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
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/* On unoptimizing/optimizing_list, op must have OPTIMIZED flag */
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if (WARN_ON_ONCE(!list_empty(&op->list)))
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return;
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list_add(&op->list, &optimizing_list);
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kick_kprobe_optimizer();
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}
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}
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/* Short cut to direct unoptimizing */
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@ -665,30 +681,33 @@ static void unoptimize_kprobe(struct kprobe *p, bool force)
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return; /* This is not an optprobe nor optimized */
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op = container_of(p, struct optimized_kprobe, kp);
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if (!kprobe_optimized(p)) {
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/* Unoptimized or unoptimizing case */
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if (force && !list_empty(&op->list)) {
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if (!kprobe_optimized(p))
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return;
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if (!list_empty(&op->list)) {
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if (optprobe_queued_unopt(op)) {
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/* Queued in unoptimizing queue */
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if (force) {
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/*
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* Only if this is unoptimizing kprobe and forced,
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* forcibly unoptimize it. (No need to unoptimize
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* unoptimized kprobe again :)
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* Forcibly unoptimize the kprobe here, and queue it
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* in the freeing list for release afterwards.
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*/
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list_del_init(&op->list);
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force_unoptimize_kprobe(op);
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list_move(&op->list, &freeing_list);
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}
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} else {
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/* Dequeue from the optimizing queue */
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list_del_init(&op->list);
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op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
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}
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return;
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}
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if (!list_empty(&op->list)) {
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/* Dequeue from the optimization queue */
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list_del_init(&op->list);
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return;
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}
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/* Optimized kprobe case */
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if (force)
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if (force) {
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/* Forcibly update the code: this is a special case */
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force_unoptimize_kprobe(op);
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else {
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} else {
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list_add(&op->list, &unoptimizing_list);
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kick_kprobe_optimizer();
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}
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