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ftrace: avoid modifying kprobe'd records
Avoid modifying the mcount call-site if there is a kprobe installed on it. These records are not marked as failed however. This allowed the filter rules on them to remain up-to-date. Whenever the kprobe on the corresponding record is removed, the record gets updated as normal. Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -21,6 +21,7 @@
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#include <linux/hardirq.h>
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#include <linux/kthread.h>
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#include <linux/uaccess.h>
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#include <linux/kprobes.h>
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#include <linux/ftrace.h>
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#include <linux/sysctl.h>
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#include <linux/ctype.h>
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@ -500,6 +501,10 @@ static void ftrace_replace_code(int enable)
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if (rec->flags & FTRACE_FL_FAILED)
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continue;
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/* ignore updates to this record's mcount site */
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if (get_kprobe((void *)rec->ip))
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continue;
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failed = __ftrace_replace_code(rec, old, new, enable);
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if (failed && (rec->flags & FTRACE_FL_CONVERTED)) {
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rec->flags |= FTRACE_FL_FAILED;
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@ -692,11 +697,11 @@ unsigned long ftrace_update_tot_cnt;
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static int __ftrace_update_code(void *ignore)
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{
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int i, save_ftrace_enabled;
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cycle_t start, stop;
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struct dyn_ftrace *p;
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struct hlist_node *t, *n;
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int save_ftrace_enabled;
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cycle_t start, stop;
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int i;
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struct hlist_head *head, temp_list;
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/* Don't be recording funcs now */
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ftrace_record_suspend++;
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@ -708,8 +713,11 @@ static int __ftrace_update_code(void *ignore)
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/* No locks needed, the machine is stopped! */
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for (i = 0; i < FTRACE_HASHSIZE; i++) {
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INIT_HLIST_HEAD(&temp_list);
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head = &ftrace_hash[i];
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/* all CPUS are stopped, we are safe to modify code */
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hlist_for_each_entry_safe(p, t, n, &ftrace_hash[i], node) {
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hlist_for_each_entry_safe(p, t, n, head, node) {
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/* Skip over failed records which have not been
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* freed. */
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if (p->flags & FTRACE_FL_FAILED)
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@ -723,6 +731,19 @@ static int __ftrace_update_code(void *ignore)
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if (p->flags & (FTRACE_FL_CONVERTED))
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break;
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/* Ignore updates to this record's mcount site.
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* Reintroduce this record at the head of this
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* bucket to attempt to "convert" it again if
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* the kprobe on it is unregistered before the
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* next run. */
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if (get_kprobe((void *)p->ip)) {
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ftrace_del_hash(p);
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INIT_HLIST_NODE(&p->node);
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hlist_add_head(&p->node, &temp_list);
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continue;
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}
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/* convert record (i.e, patch mcount-call with NOP) */
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if (ftrace_code_disable(p)) {
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p->flags |= FTRACE_FL_CONVERTED;
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ftrace_update_cnt++;
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@ -734,6 +755,12 @@ static int __ftrace_update_code(void *ignore)
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}
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}
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}
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hlist_for_each_entry_safe(p, t, n, &temp_list, node) {
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hlist_del(&p->node);
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INIT_HLIST_NODE(&p->node);
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hlist_add_head(&p->node, head);
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}
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}
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stop = ftrace_now(raw_smp_processor_id());
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