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-rw-r--r--include/linux/ftrace.h8
-rw-r--r--kernel/trace/ftrace.c158
2 files changed, 148 insertions, 18 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 6658a51390fe..ab1c46e70bb6 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -37,6 +37,7 @@ struct ftrace_ops {
#ifdef CONFIG_DYNAMIC_FTRACE
struct ftrace_hash *notrace_hash;
struct ftrace_hash *filter_hash;
+ unsigned long flags;
#endif
};
@@ -152,10 +153,13 @@ extern void unregister_ftrace_function_probe_all(char *glob);
extern int ftrace_text_reserved(void *start, void *end);
enum {
- FTRACE_FL_FREE = (1 << 0),
- FTRACE_FL_ENABLED = (1 << 1),
+ FTRACE_FL_ENABLED = (1 << 30),
+ FTRACE_FL_FREE = (1 << 31),
};
+#define FTRACE_FL_MASK (0x3UL << 30)
+#define FTRACE_REF_MAX ((1 << 30) - 1)
+
struct dyn_ftrace {
union {
unsigned long ip; /* address of mcount call-site */
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 46f08264980b..5dd332cc5aa8 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -890,6 +890,10 @@ static const struct ftrace_hash empty_hash = {
};
#define EMPTY_HASH ((struct ftrace_hash *)&empty_hash)
+enum {
+ FTRACE_OPS_FL_ENABLED = 1,
+};
+
struct ftrace_ops global_ops = {
.func = ftrace_stub,
.notrace_hash = EMPTY_HASH,
@@ -1161,6 +1165,105 @@ ftrace_hash_move(struct ftrace_hash **dst, struct ftrace_hash *src)
} \
}
+static void __ftrace_hash_rec_update(struct ftrace_ops *ops,
+ int filter_hash,
+ bool inc)
+{
+ struct ftrace_hash *hash;
+ struct ftrace_hash *other_hash;
+ struct ftrace_page *pg;
+ struct dyn_ftrace *rec;
+ int count = 0;
+ int all = 0;
+
+ /* Only update if the ops has been registered */
+ if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
+ return;
+
+ /*
+ * In the filter_hash case:
+ * If the count is zero, we update all records.
+ * Otherwise we just update the items in the hash.
+ *
+ * In the notrace_hash case:
+ * We enable the update in the hash.
+ * As disabling notrace means enabling the tracing,
+ * and enabling notrace means disabling, the inc variable
+ * gets inversed.
+ */
+ if (filter_hash) {
+ hash = ops->filter_hash;
+ other_hash = ops->notrace_hash;
+ if (!hash->count)
+ all = 1;
+ } else {
+ inc = !inc;
+ hash = ops->notrace_hash;
+ other_hash = ops->filter_hash;
+ /*
+ * If the notrace hash has no items,
+ * then there's nothing to do.
+ */
+ if (!hash->count)
+ return;
+ }
+
+ do_for_each_ftrace_rec(pg, rec) {
+ int in_other_hash = 0;
+ int in_hash = 0;
+ int match = 0;
+
+ if (all) {
+ /*
+ * Only the filter_hash affects all records.
+ * Update if the record is not in the notrace hash.
+ */
+ if (!ftrace_lookup_ip(other_hash, rec->ip))
+ match = 1;
+ } else {
+ in_hash = !!ftrace_lookup_ip(hash, rec->ip);
+ in_other_hash = !!ftrace_lookup_ip(other_hash, rec->ip);
+
+ /*
+ *
+ */
+ if (filter_hash && in_hash && !in_other_hash)
+ match = 1;
+ else if (!filter_hash && in_hash &&
+ (in_other_hash || !other_hash->count))
+ match = 1;
+ }
+ if (!match)
+ continue;
+
+ if (inc) {
+ rec->flags++;
+ if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == FTRACE_REF_MAX))
+ return;
+ } else {
+ if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == 0))
+ return;
+ rec->flags--;
+ }
+ count++;
+ /* Shortcut, if we handled all records, we are done. */
+ if (!all && count == hash->count)
+ return;
+ } while_for_each_ftrace_rec();
+}
+
+static void ftrace_hash_rec_disable(struct ftrace_ops *ops,
+ int filter_hash)
+{
+ __ftrace_hash_rec_update(ops, filter_hash, 0);
+}
+
+static void ftrace_hash_rec_enable(struct ftrace_ops *ops,
+ int filter_hash)
+{
+ __ftrace_hash_rec_update(ops, filter_hash, 1);
+}
+
static void ftrace_free_rec(struct dyn_ftrace *rec)
{
rec->freelist = ftrace_free_records;
@@ -1276,26 +1379,24 @@ int ftrace_text_reserved(void *start, void *end)
static int
__ftrace_replace_code(struct dyn_ftrace *rec, int enable)
{
- struct ftrace_ops *ops = &global_ops;
unsigned long ftrace_addr;
unsigned long flag = 0UL;
ftrace_addr = (unsigned long)FTRACE_ADDR;
/*
- * If this record is not to be traced or we want to disable it,
- * then disable it.
+ * If we are enabling tracing:
*
- * If we want to enable it and filtering is off, then enable it.
+ * If the record has a ref count, then we need to enable it
+ * because someone is using it.
*
- * If we want to enable it and filtering is on, enable it only if
- * it's filtered
+ * Otherwise we make sure its disabled.
+ *
+ * If we are disabling tracing, then disable all records that
+ * are enabled.
*/
- if (enable && !ftrace_lookup_ip(ops->notrace_hash, rec->ip)) {
- if (!ops->filter_hash->count ||
- ftrace_lookup_ip(ops->filter_hash, rec->ip))
- flag = FTRACE_FL_ENABLED;
- }
+ if (enable && (rec->flags & ~FTRACE_FL_MASK))
+ flag = FTRACE_FL_ENABLED;
/* If the state of this record hasn't changed, then do nothing */
if ((rec->flags & FTRACE_FL_ENABLED) == flag)
@@ -1423,17 +1524,25 @@ static void ftrace_startup_enable(int command)
static void ftrace_startup(int command)
{
+ struct ftrace_ops *ops = &global_ops;
+
if (unlikely(ftrace_disabled))
return;
ftrace_start_up++;
command |= FTRACE_ENABLE_CALLS;
+ ops->flags |= FTRACE_OPS_FL_ENABLED;
+ if (ftrace_start_up == 1)
+ ftrace_hash_rec_enable(ops, 1);
+
ftrace_startup_enable(command);
}
static void ftrace_shutdown(int command)
{
+ struct ftrace_ops *ops = &global_ops;
+
if (unlikely(ftrace_disabled))
return;
@@ -1446,7 +1555,12 @@ static void ftrace_shutdown(int command)
WARN_ON_ONCE(ftrace_start_up < 0);
if (!ftrace_start_up)
+ ftrace_hash_rec_disable(ops, 1);
+
+ if (!ftrace_start_up) {
command |= FTRACE_DISABLE_CALLS;
+ ops->flags &= ~FTRACE_OPS_FL_ENABLED;
+ }
if (saved_ftrace_func != ftrace_trace_function) {
saved_ftrace_func = ftrace_trace_function;
@@ -2668,6 +2782,7 @@ ftrace_regex_release(struct inode *inode, struct file *file)
struct ftrace_iterator *iter;
struct ftrace_hash **orig_hash;
struct trace_parser *parser;
+ int filter_hash;
int ret;
mutex_lock(&ftrace_regex_lock);
@@ -2687,15 +2802,26 @@ ftrace_regex_release(struct inode *inode, struct file *file)
trace_parser_put(parser);
if (file->f_mode & FMODE_WRITE) {
- if (iter->flags & FTRACE_ITER_NOTRACE)
- orig_hash = &iter->ops->notrace_hash;
- else
+ filter_hash = !!(iter->flags & FTRACE_ITER_FILTER);
+
+ if (filter_hash)
orig_hash = &iter->ops->filter_hash;
+ else
+ orig_hash = &iter->ops->notrace_hash;
mutex_lock(&ftrace_lock);
+ /*
+ * Remove the current set, update the hash and add
+ * them back.
+ */
+ ftrace_hash_rec_disable(iter->ops, filter_hash);
ret = ftrace_hash_move(orig_hash, iter->hash);
- if (!ret && ftrace_start_up && ftrace_enabled)
- ftrace_run_update_code(FTRACE_ENABLE_CALLS);
+ if (!ret) {
+ ftrace_hash_rec_enable(iter->ops, filter_hash);
+ if (iter->ops->flags & FTRACE_OPS_FL_ENABLED
+ && ftrace_enabled)
+ ftrace_run_update_code(FTRACE_ENABLE_CALLS);
+ }
mutex_unlock(&ftrace_lock);
}
free_ftrace_hash(iter->hash);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.