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![Jianlin Lv](/assets/img/avatar_default.png)
In the case of keeping the system running, the preferred method for tracing the kernel is dynamic tracing (kprobe), but the drawback of this method is that events are lost, especially when tracing packages in the network stack. Livepatching provides a potential solution, which is to reimplement the function you want to replace and insert a static tracepoint. In such a way, custom stable static tracepoints can be expanded without rebooting the system. Link: https://lkml.kernel.org/r/20221102160236.11696-1-iecedge@gmail.com Signed-off-by: Jianlin Lv <iecedge@gmail.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
787 lines
20 KiB
C
787 lines
20 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2008-2014 Mathieu Desnoyers
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*/
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/types.h>
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#include <linux/jhash.h>
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#include <linux/list.h>
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#include <linux/rcupdate.h>
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#include <linux/tracepoint.h>
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#include <linux/err.h>
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#include <linux/slab.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/task.h>
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#include <linux/static_key.h>
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enum tp_func_state {
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TP_FUNC_0,
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TP_FUNC_1,
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TP_FUNC_2,
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TP_FUNC_N,
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};
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extern tracepoint_ptr_t __start___tracepoints_ptrs[];
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extern tracepoint_ptr_t __stop___tracepoints_ptrs[];
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DEFINE_SRCU(tracepoint_srcu);
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EXPORT_SYMBOL_GPL(tracepoint_srcu);
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enum tp_transition_sync {
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TP_TRANSITION_SYNC_1_0_1,
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TP_TRANSITION_SYNC_N_2_1,
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_NR_TP_TRANSITION_SYNC,
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};
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struct tp_transition_snapshot {
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unsigned long rcu;
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unsigned long srcu;
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bool ongoing;
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};
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/* Protected by tracepoints_mutex */
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static struct tp_transition_snapshot tp_transition_snapshot[_NR_TP_TRANSITION_SYNC];
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static void tp_rcu_get_state(enum tp_transition_sync sync)
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{
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struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync];
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/* Keep the latest get_state snapshot. */
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snapshot->rcu = get_state_synchronize_rcu();
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snapshot->srcu = start_poll_synchronize_srcu(&tracepoint_srcu);
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snapshot->ongoing = true;
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}
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static void tp_rcu_cond_sync(enum tp_transition_sync sync)
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{
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struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync];
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if (!snapshot->ongoing)
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return;
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cond_synchronize_rcu(snapshot->rcu);
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if (!poll_state_synchronize_srcu(&tracepoint_srcu, snapshot->srcu))
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synchronize_srcu(&tracepoint_srcu);
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snapshot->ongoing = false;
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}
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/* Set to 1 to enable tracepoint debug output */
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static const int tracepoint_debug;
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#ifdef CONFIG_MODULES
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/*
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* Tracepoint module list mutex protects the local module list.
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*/
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static DEFINE_MUTEX(tracepoint_module_list_mutex);
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/* Local list of struct tp_module */
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static LIST_HEAD(tracepoint_module_list);
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#endif /* CONFIG_MODULES */
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/*
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* tracepoints_mutex protects the builtin and module tracepoints.
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* tracepoints_mutex nests inside tracepoint_module_list_mutex.
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*/
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static DEFINE_MUTEX(tracepoints_mutex);
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static struct rcu_head *early_probes;
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static bool ok_to_free_tracepoints;
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/*
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* Note about RCU :
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* It is used to delay the free of multiple probes array until a quiescent
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* state is reached.
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*/
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struct tp_probes {
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struct rcu_head rcu;
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struct tracepoint_func probes[];
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};
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/* Called in removal of a func but failed to allocate a new tp_funcs */
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static void tp_stub_func(void)
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{
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return;
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}
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static inline void *allocate_probes(int count)
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{
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struct tp_probes *p = kmalloc(struct_size(p, probes, count),
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GFP_KERNEL);
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return p == NULL ? NULL : p->probes;
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}
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static void srcu_free_old_probes(struct rcu_head *head)
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{
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kfree(container_of(head, struct tp_probes, rcu));
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}
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static void rcu_free_old_probes(struct rcu_head *head)
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{
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call_srcu(&tracepoint_srcu, head, srcu_free_old_probes);
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}
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static __init int release_early_probes(void)
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{
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struct rcu_head *tmp;
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ok_to_free_tracepoints = true;
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while (early_probes) {
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tmp = early_probes;
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early_probes = tmp->next;
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call_rcu(tmp, rcu_free_old_probes);
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}
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return 0;
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}
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/* SRCU is initialized at core_initcall */
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postcore_initcall(release_early_probes);
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static inline void release_probes(struct tracepoint_func *old)
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{
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if (old) {
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struct tp_probes *tp_probes = container_of(old,
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struct tp_probes, probes[0]);
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/*
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* We can't free probes if SRCU is not initialized yet.
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* Postpone the freeing till after SRCU is initialized.
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*/
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if (unlikely(!ok_to_free_tracepoints)) {
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tp_probes->rcu.next = early_probes;
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early_probes = &tp_probes->rcu;
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return;
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}
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/*
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* Tracepoint probes are protected by both sched RCU and SRCU,
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* by calling the SRCU callback in the sched RCU callback we
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* cover both cases. So let us chain the SRCU and sched RCU
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* callbacks to wait for both grace periods.
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*/
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call_rcu(&tp_probes->rcu, rcu_free_old_probes);
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}
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}
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static void debug_print_probes(struct tracepoint_func *funcs)
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{
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int i;
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if (!tracepoint_debug || !funcs)
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return;
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for (i = 0; funcs[i].func; i++)
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printk(KERN_DEBUG "Probe %d : %p\n", i, funcs[i].func);
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}
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static struct tracepoint_func *
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func_add(struct tracepoint_func **funcs, struct tracepoint_func *tp_func,
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int prio)
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{
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struct tracepoint_func *old, *new;
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int iter_probes; /* Iterate over old probe array. */
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int nr_probes = 0; /* Counter for probes */
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int pos = -1; /* Insertion position into new array */
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if (WARN_ON(!tp_func->func))
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return ERR_PTR(-EINVAL);
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debug_print_probes(*funcs);
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old = *funcs;
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if (old) {
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/* (N -> N+1), (N != 0, 1) probes */
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for (iter_probes = 0; old[iter_probes].func; iter_probes++) {
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if (old[iter_probes].func == tp_stub_func)
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continue; /* Skip stub functions. */
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if (old[iter_probes].func == tp_func->func &&
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old[iter_probes].data == tp_func->data)
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return ERR_PTR(-EEXIST);
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nr_probes++;
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}
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}
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/* + 2 : one for new probe, one for NULL func */
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new = allocate_probes(nr_probes + 2);
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if (new == NULL)
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return ERR_PTR(-ENOMEM);
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if (old) {
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nr_probes = 0;
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for (iter_probes = 0; old[iter_probes].func; iter_probes++) {
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if (old[iter_probes].func == tp_stub_func)
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continue;
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/* Insert before probes of lower priority */
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if (pos < 0 && old[iter_probes].prio < prio)
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pos = nr_probes++;
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new[nr_probes++] = old[iter_probes];
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}
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if (pos < 0)
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pos = nr_probes++;
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/* nr_probes now points to the end of the new array */
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} else {
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pos = 0;
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nr_probes = 1; /* must point at end of array */
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}
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new[pos] = *tp_func;
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new[nr_probes].func = NULL;
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*funcs = new;
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debug_print_probes(*funcs);
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return old;
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}
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static void *func_remove(struct tracepoint_func **funcs,
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struct tracepoint_func *tp_func)
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{
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int nr_probes = 0, nr_del = 0, i;
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struct tracepoint_func *old, *new;
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old = *funcs;
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if (!old)
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return ERR_PTR(-ENOENT);
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debug_print_probes(*funcs);
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/* (N -> M), (N > 1, M >= 0) probes */
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if (tp_func->func) {
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for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
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if ((old[nr_probes].func == tp_func->func &&
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old[nr_probes].data == tp_func->data) ||
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old[nr_probes].func == tp_stub_func)
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nr_del++;
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}
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}
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/*
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* If probe is NULL, then nr_probes = nr_del = 0, and then the
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* entire entry will be removed.
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*/
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if (nr_probes - nr_del == 0) {
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/* N -> 0, (N > 1) */
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*funcs = NULL;
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debug_print_probes(*funcs);
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return old;
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} else {
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int j = 0;
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/* N -> M, (N > 1, M > 0) */
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/* + 1 for NULL */
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new = allocate_probes(nr_probes - nr_del + 1);
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if (new) {
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for (i = 0; old[i].func; i++) {
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if ((old[i].func != tp_func->func ||
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old[i].data != tp_func->data) &&
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old[i].func != tp_stub_func)
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new[j++] = old[i];
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}
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new[nr_probes - nr_del].func = NULL;
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*funcs = new;
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} else {
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/*
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* Failed to allocate, replace the old function
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* with calls to tp_stub_func.
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*/
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for (i = 0; old[i].func; i++) {
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if (old[i].func == tp_func->func &&
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old[i].data == tp_func->data)
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WRITE_ONCE(old[i].func, tp_stub_func);
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}
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*funcs = old;
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}
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}
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debug_print_probes(*funcs);
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return old;
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}
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/*
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* Count the number of functions (enum tp_func_state) in a tp_funcs array.
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*/
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static enum tp_func_state nr_func_state(const struct tracepoint_func *tp_funcs)
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{
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if (!tp_funcs)
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return TP_FUNC_0;
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if (!tp_funcs[1].func)
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return TP_FUNC_1;
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if (!tp_funcs[2].func)
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return TP_FUNC_2;
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return TP_FUNC_N; /* 3 or more */
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}
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static void tracepoint_update_call(struct tracepoint *tp, struct tracepoint_func *tp_funcs)
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{
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void *func = tp->iterator;
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/* Synthetic events do not have static call sites */
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if (!tp->static_call_key)
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return;
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if (nr_func_state(tp_funcs) == TP_FUNC_1)
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func = tp_funcs[0].func;
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__static_call_update(tp->static_call_key, tp->static_call_tramp, func);
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}
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/*
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* Add the probe function to a tracepoint.
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*/
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static int tracepoint_add_func(struct tracepoint *tp,
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struct tracepoint_func *func, int prio,
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bool warn)
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{
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struct tracepoint_func *old, *tp_funcs;
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int ret;
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if (tp->regfunc && !static_key_enabled(&tp->key)) {
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ret = tp->regfunc();
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if (ret < 0)
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return ret;
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}
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tp_funcs = rcu_dereference_protected(tp->funcs,
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lockdep_is_held(&tracepoints_mutex));
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old = func_add(&tp_funcs, func, prio);
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if (IS_ERR(old)) {
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WARN_ON_ONCE(warn && PTR_ERR(old) != -ENOMEM);
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return PTR_ERR(old);
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}
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/*
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* rcu_assign_pointer has as smp_store_release() which makes sure
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* that the new probe callbacks array is consistent before setting
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* a pointer to it. This array is referenced by __DO_TRACE from
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* include/linux/tracepoint.h using rcu_dereference_sched().
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*/
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switch (nr_func_state(tp_funcs)) {
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case TP_FUNC_1: /* 0->1 */
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/*
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* Make sure new static func never uses old data after a
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* 1->0->1 transition sequence.
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*/
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tp_rcu_cond_sync(TP_TRANSITION_SYNC_1_0_1);
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/* Set static call to first function */
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tracepoint_update_call(tp, tp_funcs);
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/* Both iterator and static call handle NULL tp->funcs */
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rcu_assign_pointer(tp->funcs, tp_funcs);
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static_key_enable(&tp->key);
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break;
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case TP_FUNC_2: /* 1->2 */
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/* Set iterator static call */
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tracepoint_update_call(tp, tp_funcs);
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/*
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* Iterator callback installed before updating tp->funcs.
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* Requires ordering between RCU assign/dereference and
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* static call update/call.
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*/
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fallthrough;
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case TP_FUNC_N: /* N->N+1 (N>1) */
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rcu_assign_pointer(tp->funcs, tp_funcs);
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/*
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* Make sure static func never uses incorrect data after a
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* N->...->2->1 (N>1) transition sequence.
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*/
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if (tp_funcs[0].data != old[0].data)
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tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
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break;
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default:
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WARN_ON_ONCE(1);
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break;
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}
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release_probes(old);
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return 0;
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}
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/*
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* Remove a probe function from a tracepoint.
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* Note: only waiting an RCU period after setting elem->call to the empty
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* function insures that the original callback is not used anymore. This insured
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* by preempt_disable around the call site.
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*/
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static int tracepoint_remove_func(struct tracepoint *tp,
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struct tracepoint_func *func)
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{
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struct tracepoint_func *old, *tp_funcs;
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tp_funcs = rcu_dereference_protected(tp->funcs,
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lockdep_is_held(&tracepoints_mutex));
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old = func_remove(&tp_funcs, func);
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if (WARN_ON_ONCE(IS_ERR(old)))
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return PTR_ERR(old);
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if (tp_funcs == old)
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/* Failed allocating new tp_funcs, replaced func with stub */
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return 0;
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switch (nr_func_state(tp_funcs)) {
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case TP_FUNC_0: /* 1->0 */
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/* Removed last function */
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if (tp->unregfunc && static_key_enabled(&tp->key))
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tp->unregfunc();
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static_key_disable(&tp->key);
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/* Set iterator static call */
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tracepoint_update_call(tp, tp_funcs);
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/* Both iterator and static call handle NULL tp->funcs */
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rcu_assign_pointer(tp->funcs, NULL);
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/*
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* Make sure new static func never uses old data after a
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* 1->0->1 transition sequence.
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*/
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tp_rcu_get_state(TP_TRANSITION_SYNC_1_0_1);
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break;
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case TP_FUNC_1: /* 2->1 */
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rcu_assign_pointer(tp->funcs, tp_funcs);
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/*
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* Make sure static func never uses incorrect data after a
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* N->...->2->1 (N>2) transition sequence. If the first
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* element's data has changed, then force the synchronization
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* to prevent current readers that have loaded the old data
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* from calling the new function.
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*/
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if (tp_funcs[0].data != old[0].data)
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tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
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tp_rcu_cond_sync(TP_TRANSITION_SYNC_N_2_1);
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/* Set static call to first function */
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tracepoint_update_call(tp, tp_funcs);
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break;
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case TP_FUNC_2: /* N->N-1 (N>2) */
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fallthrough;
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case TP_FUNC_N:
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rcu_assign_pointer(tp->funcs, tp_funcs);
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/*
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* Make sure static func never uses incorrect data after a
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* N->...->2->1 (N>2) transition sequence.
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*/
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if (tp_funcs[0].data != old[0].data)
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tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
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break;
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default:
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WARN_ON_ONCE(1);
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break;
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}
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release_probes(old);
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return 0;
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}
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/**
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* tracepoint_probe_register_prio_may_exist - Connect a probe to a tracepoint with priority
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* @tp: tracepoint
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* @probe: probe handler
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* @data: tracepoint data
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* @prio: priority of this function over other registered functions
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*
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* Same as tracepoint_probe_register_prio() except that it will not warn
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* if the tracepoint is already registered.
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*/
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int tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe,
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void *data, int prio)
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{
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struct tracepoint_func tp_func;
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int ret;
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mutex_lock(&tracepoints_mutex);
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tp_func.func = probe;
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tp_func.data = data;
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tp_func.prio = prio;
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ret = tracepoint_add_func(tp, &tp_func, prio, false);
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mutex_unlock(&tracepoints_mutex);
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return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio_may_exist);
|
|
|
|
/**
|
|
* tracepoint_probe_register_prio - Connect a probe to a tracepoint with priority
|
|
* @tp: tracepoint
|
|
* @probe: probe handler
|
|
* @data: tracepoint data
|
|
* @prio: priority of this function over other registered functions
|
|
*
|
|
* Returns 0 if ok, error value on error.
|
|
* Note: if @tp is within a module, the caller is responsible for
|
|
* unregistering the probe before the module is gone. This can be
|
|
* performed either with a tracepoint module going notifier, or from
|
|
* within module exit functions.
|
|
*/
|
|
int tracepoint_probe_register_prio(struct tracepoint *tp, void *probe,
|
|
void *data, int prio)
|
|
{
|
|
struct tracepoint_func tp_func;
|
|
int ret;
|
|
|
|
mutex_lock(&tracepoints_mutex);
|
|
tp_func.func = probe;
|
|
tp_func.data = data;
|
|
tp_func.prio = prio;
|
|
ret = tracepoint_add_func(tp, &tp_func, prio, true);
|
|
mutex_unlock(&tracepoints_mutex);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio);
|
|
|
|
/**
|
|
* tracepoint_probe_register - Connect a probe to a tracepoint
|
|
* @tp: tracepoint
|
|
* @probe: probe handler
|
|
* @data: tracepoint data
|
|
*
|
|
* Returns 0 if ok, error value on error.
|
|
* Note: if @tp is within a module, the caller is responsible for
|
|
* unregistering the probe before the module is gone. This can be
|
|
* performed either with a tracepoint module going notifier, or from
|
|
* within module exit functions.
|
|
*/
|
|
int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data)
|
|
{
|
|
return tracepoint_probe_register_prio(tp, probe, data, TRACEPOINT_DEFAULT_PRIO);
|
|
}
|
|
EXPORT_SYMBOL_GPL(tracepoint_probe_register);
|
|
|
|
/**
|
|
* tracepoint_probe_unregister - Disconnect a probe from a tracepoint
|
|
* @tp: tracepoint
|
|
* @probe: probe function pointer
|
|
* @data: tracepoint data
|
|
*
|
|
* Returns 0 if ok, error value on error.
|
|
*/
|
|
int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data)
|
|
{
|
|
struct tracepoint_func tp_func;
|
|
int ret;
|
|
|
|
mutex_lock(&tracepoints_mutex);
|
|
tp_func.func = probe;
|
|
tp_func.data = data;
|
|
ret = tracepoint_remove_func(tp, &tp_func);
|
|
mutex_unlock(&tracepoints_mutex);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
|
|
|
|
static void for_each_tracepoint_range(
|
|
tracepoint_ptr_t *begin, tracepoint_ptr_t *end,
|
|
void (*fct)(struct tracepoint *tp, void *priv),
|
|
void *priv)
|
|
{
|
|
tracepoint_ptr_t *iter;
|
|
|
|
if (!begin)
|
|
return;
|
|
for (iter = begin; iter < end; iter++)
|
|
fct(tracepoint_ptr_deref(iter), priv);
|
|
}
|
|
|
|
#ifdef CONFIG_MODULES
|
|
bool trace_module_has_bad_taint(struct module *mod)
|
|
{
|
|
return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP) |
|
|
(1 << TAINT_UNSIGNED_MODULE) | (1 << TAINT_TEST) |
|
|
(1 << TAINT_LIVEPATCH));
|
|
}
|
|
|
|
static BLOCKING_NOTIFIER_HEAD(tracepoint_notify_list);
|
|
|
|
/**
|
|
* register_tracepoint_module_notifier - register tracepoint coming/going notifier
|
|
* @nb: notifier block
|
|
*
|
|
* Notifiers registered with this function are called on module
|
|
* coming/going with the tracepoint_module_list_mutex held.
|
|
* The notifier block callback should expect a "struct tp_module" data
|
|
* pointer.
|
|
*/
|
|
int register_tracepoint_module_notifier(struct notifier_block *nb)
|
|
{
|
|
struct tp_module *tp_mod;
|
|
int ret;
|
|
|
|
mutex_lock(&tracepoint_module_list_mutex);
|
|
ret = blocking_notifier_chain_register(&tracepoint_notify_list, nb);
|
|
if (ret)
|
|
goto end;
|
|
list_for_each_entry(tp_mod, &tracepoint_module_list, list)
|
|
(void) nb->notifier_call(nb, MODULE_STATE_COMING, tp_mod);
|
|
end:
|
|
mutex_unlock(&tracepoint_module_list_mutex);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(register_tracepoint_module_notifier);
|
|
|
|
/**
|
|
* unregister_tracepoint_module_notifier - unregister tracepoint coming/going notifier
|
|
* @nb: notifier block
|
|
*
|
|
* The notifier block callback should expect a "struct tp_module" data
|
|
* pointer.
|
|
*/
|
|
int unregister_tracepoint_module_notifier(struct notifier_block *nb)
|
|
{
|
|
struct tp_module *tp_mod;
|
|
int ret;
|
|
|
|
mutex_lock(&tracepoint_module_list_mutex);
|
|
ret = blocking_notifier_chain_unregister(&tracepoint_notify_list, nb);
|
|
if (ret)
|
|
goto end;
|
|
list_for_each_entry(tp_mod, &tracepoint_module_list, list)
|
|
(void) nb->notifier_call(nb, MODULE_STATE_GOING, tp_mod);
|
|
end:
|
|
mutex_unlock(&tracepoint_module_list_mutex);
|
|
return ret;
|
|
|
|
}
|
|
EXPORT_SYMBOL_GPL(unregister_tracepoint_module_notifier);
|
|
|
|
/*
|
|
* Ensure the tracer unregistered the module's probes before the module
|
|
* teardown is performed. Prevents leaks of probe and data pointers.
|
|
*/
|
|
static void tp_module_going_check_quiescent(struct tracepoint *tp, void *priv)
|
|
{
|
|
WARN_ON_ONCE(tp->funcs);
|
|
}
|
|
|
|
static int tracepoint_module_coming(struct module *mod)
|
|
{
|
|
struct tp_module *tp_mod;
|
|
|
|
if (!mod->num_tracepoints)
|
|
return 0;
|
|
|
|
/*
|
|
* We skip modules that taint the kernel, especially those with different
|
|
* module headers (for forced load), to make sure we don't cause a crash.
|
|
* Staging, out-of-tree, unsigned GPL, and test modules are fine.
|
|
*/
|
|
if (trace_module_has_bad_taint(mod))
|
|
return 0;
|
|
|
|
tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL);
|
|
if (!tp_mod)
|
|
return -ENOMEM;
|
|
tp_mod->mod = mod;
|
|
|
|
mutex_lock(&tracepoint_module_list_mutex);
|
|
list_add_tail(&tp_mod->list, &tracepoint_module_list);
|
|
blocking_notifier_call_chain(&tracepoint_notify_list,
|
|
MODULE_STATE_COMING, tp_mod);
|
|
mutex_unlock(&tracepoint_module_list_mutex);
|
|
return 0;
|
|
}
|
|
|
|
static void tracepoint_module_going(struct module *mod)
|
|
{
|
|
struct tp_module *tp_mod;
|
|
|
|
if (!mod->num_tracepoints)
|
|
return;
|
|
|
|
mutex_lock(&tracepoint_module_list_mutex);
|
|
list_for_each_entry(tp_mod, &tracepoint_module_list, list) {
|
|
if (tp_mod->mod == mod) {
|
|
blocking_notifier_call_chain(&tracepoint_notify_list,
|
|
MODULE_STATE_GOING, tp_mod);
|
|
list_del(&tp_mod->list);
|
|
kfree(tp_mod);
|
|
/*
|
|
* Called the going notifier before checking for
|
|
* quiescence.
|
|
*/
|
|
for_each_tracepoint_range(mod->tracepoints_ptrs,
|
|
mod->tracepoints_ptrs + mod->num_tracepoints,
|
|
tp_module_going_check_quiescent, NULL);
|
|
break;
|
|
}
|
|
}
|
|
/*
|
|
* In the case of modules that were tainted at "coming", we'll simply
|
|
* walk through the list without finding it. We cannot use the "tainted"
|
|
* flag on "going", in case a module taints the kernel only after being
|
|
* loaded.
|
|
*/
|
|
mutex_unlock(&tracepoint_module_list_mutex);
|
|
}
|
|
|
|
static int tracepoint_module_notify(struct notifier_block *self,
|
|
unsigned long val, void *data)
|
|
{
|
|
struct module *mod = data;
|
|
int ret = 0;
|
|
|
|
switch (val) {
|
|
case MODULE_STATE_COMING:
|
|
ret = tracepoint_module_coming(mod);
|
|
break;
|
|
case MODULE_STATE_LIVE:
|
|
break;
|
|
case MODULE_STATE_GOING:
|
|
tracepoint_module_going(mod);
|
|
break;
|
|
case MODULE_STATE_UNFORMED:
|
|
break;
|
|
}
|
|
return notifier_from_errno(ret);
|
|
}
|
|
|
|
static struct notifier_block tracepoint_module_nb = {
|
|
.notifier_call = tracepoint_module_notify,
|
|
.priority = 0,
|
|
};
|
|
|
|
static __init int init_tracepoints(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = register_module_notifier(&tracepoint_module_nb);
|
|
if (ret)
|
|
pr_warn("Failed to register tracepoint module enter notifier\n");
|
|
|
|
return ret;
|
|
}
|
|
__initcall(init_tracepoints);
|
|
#endif /* CONFIG_MODULES */
|
|
|
|
/**
|
|
* for_each_kernel_tracepoint - iteration on all kernel tracepoints
|
|
* @fct: callback
|
|
* @priv: private data
|
|
*/
|
|
void for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
|
|
void *priv)
|
|
{
|
|
for_each_tracepoint_range(__start___tracepoints_ptrs,
|
|
__stop___tracepoints_ptrs, fct, priv);
|
|
}
|
|
EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint);
|
|
|
|
#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
|
|
|
|
/* NB: reg/unreg are called while guarded with the tracepoints_mutex */
|
|
static int sys_tracepoint_refcount;
|
|
|
|
int syscall_regfunc(void)
|
|
{
|
|
struct task_struct *p, *t;
|
|
|
|
if (!sys_tracepoint_refcount) {
|
|
read_lock(&tasklist_lock);
|
|
for_each_process_thread(p, t) {
|
|
set_task_syscall_work(t, SYSCALL_TRACEPOINT);
|
|
}
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
sys_tracepoint_refcount++;
|
|
|
|
return 0;
|
|
}
|
|
|
|
void syscall_unregfunc(void)
|
|
{
|
|
struct task_struct *p, *t;
|
|
|
|
sys_tracepoint_refcount--;
|
|
if (!sys_tracepoint_refcount) {
|
|
read_lock(&tasklist_lock);
|
|
for_each_process_thread(p, t) {
|
|
clear_task_syscall_work(t, SYSCALL_TRACEPOINT);
|
|
}
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
}
|
|
#endif
|