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| author | Abhishek Sagar <sagar.abhishek@gmail.com> | 2008-06-21 23:50:29 +0530 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-06-23 22:10:59 +0200 |
| commit | f22f9a89ce6857d377bf22dba4c1a8cd256c5136 (patch) | |
| tree | 34899ea2a9dc603014052742f774e8aeb51d9591 | |
| parent | ecea656d1d5e912d2f3d332657ea4a6d8380f891 (diff) | |
| download | linux-f22f9a89ce6857d377bf22dba4c1a8cd256c5136.tar.bz2 | |
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>
| -rw-r--r-- | kernel/trace/ftrace.c | 35 |
1 files changed, 31 insertions, 4 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index d1238163155f..85e841335417 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -21,6 +21,7 @@ #include <linux/hardirq.h> #include <linux/kthread.h> #include <linux/uaccess.h> +#include <linux/kprobes.h> #include <linux/ftrace.h> #include <linux/sysctl.h> #include <linux/ctype.h> @@ -500,6 +501,10 @@ static void ftrace_replace_code(int enable) if (rec->flags & FTRACE_FL_FAILED) continue; + /* ignore updates to this record's mcount site */ + if (get_kprobe((void *)rec->ip)) + continue; + failed = __ftrace_replace_code(rec, old, new, enable); if (failed && (rec->flags & FTRACE_FL_CONVERTED)) { rec->flags |= FTRACE_FL_FAILED; @@ -692,11 +697,11 @@ unsigned long ftrace_update_tot_cnt; static int __ftrace_update_code(void *ignore) { + int i, save_ftrace_enabled; + cycle_t start, stop; struct dyn_ftrace *p; struct hlist_node *t, *n; - int save_ftrace_enabled; - cycle_t start, stop; - int i; + struct hlist_head *head, temp_list; /* Don't be recording funcs now */ ftrace_record_suspend++; @@ -708,8 +713,11 @@ static int __ftrace_update_code(void *ignore) /* No locks needed, the machine is stopped! */ for (i = 0; i < FTRACE_HASHSIZE; i++) { + INIT_HLIST_HEAD(&temp_list); + head = &ftrace_hash[i]; + /* all CPUS are stopped, we are safe to modify code */ - hlist_for_each_entry_safe(p, t, n, &ftrace_hash[i], node) { + hlist_for_each_entry_safe(p, t, n, head, node) { /* Skip over failed records which have not been * freed. */ if (p->flags & FTRACE_FL_FAILED) @@ -723,6 +731,19 @@ static int __ftrace_update_code(void *ignore) if (p->flags & (FTRACE_FL_CONVERTED)) break; + /* Ignore updates to this record's mcount site. + * Reintroduce this record at the head of this + * bucket to attempt to "convert" it again if + * the kprobe on it is unregistered before the + * next run. */ + if (get_kprobe((void *)p->ip)) { + ftrace_del_hash(p); + INIT_HLIST_NODE(&p->node); + hlist_add_head(&p->node, &temp_list); + continue; + } + + /* convert record (i.e, patch mcount-call with NOP) */ if (ftrace_code_disable(p)) { p->flags |= FTRACE_FL_CONVERTED; ftrace_update_cnt++; @@ -734,6 +755,12 @@ static int __ftrace_update_code(void *ignore) } } } + + hlist_for_each_entry_safe(p, t, n, &temp_list, node) { + hlist_del(&p->node); + INIT_HLIST_NODE(&p->node); + hlist_add_head(&p->node, head); + } } stop = ftrace_now(raw_smp_processor_id()); |