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-rw-r--r--include/linux/ftrace.h18
-rw-r--r--kernel/trace/Kconfig7
-rw-r--r--kernel/trace/ftrace.c109
3 files changed, 125 insertions, 9 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 99f1146614c0..366c730beaa3 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -39,6 +39,7 @@ static inline void ftrace_boot_snapshot(void) { }
struct ftrace_ops;
struct ftrace_regs;
+struct dyn_ftrace;
#ifdef CONFIG_FUNCTION_TRACER
/*
@@ -57,6 +58,9 @@ void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip);
void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs);
#endif
+extern const struct ftrace_ops ftrace_nop_ops;
+extern const struct ftrace_ops ftrace_list_ops;
+struct ftrace_ops *ftrace_find_unique_ops(struct dyn_ftrace *rec);
#endif /* CONFIG_FUNCTION_TRACER */
/* Main tracing buffer and events set up */
@@ -391,8 +395,6 @@ struct ftrace_func_entry {
unsigned long direct; /* for direct lookup only */
};
-struct dyn_ftrace;
-
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
extern int ftrace_direct_func_count;
int register_ftrace_direct(unsigned long ip, unsigned long addr);
@@ -563,6 +565,8 @@ bool is_ftrace_trampoline(unsigned long addr);
* IPMODIFY - the record allows for the IP address to be changed.
* DISABLED - the record is not ready to be touched yet
* DIRECT - there is a direct function to call
+ * CALL_OPS - the record can use callsite-specific ops
+ * CALL_OPS_EN - the function is set up to use callsite-specific ops
*
* When a new ftrace_ops is registered and wants a function to save
* pt_regs, the rec->flags REGS is set. When the function has been
@@ -580,9 +584,11 @@ enum {
FTRACE_FL_DISABLED = (1UL << 25),
FTRACE_FL_DIRECT = (1UL << 24),
FTRACE_FL_DIRECT_EN = (1UL << 23),
+ FTRACE_FL_CALL_OPS = (1UL << 22),
+ FTRACE_FL_CALL_OPS_EN = (1UL << 21),
};
-#define FTRACE_REF_MAX_SHIFT 23
+#define FTRACE_REF_MAX_SHIFT 21
#define FTRACE_REF_MAX ((1UL << FTRACE_REF_MAX_SHIFT) - 1)
#define ftrace_rec_count(rec) ((rec)->flags & FTRACE_REF_MAX)
@@ -820,7 +826,8 @@ static inline int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
*/
extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);
-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+#if defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS) || \
+ defined(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS)
/**
* ftrace_modify_call - convert from one addr to another (no nop)
* @rec: the call site record (e.g. mcount/fentry)
@@ -833,6 +840,9 @@ extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);
* what we expect it to be, and then on success of the compare,
* it should write to the location.
*
+ * When using call ops, this is called when the associated ops change, even
+ * when (addr == old_addr).
+ *
* The code segment at @rec->ip should be a caller to @old_addr
*
* Return must be:
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 197545241ab8..5df427a2321d 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -42,6 +42,9 @@ config HAVE_DYNAMIC_FTRACE_WITH_REGS
config HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
bool
+config HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
+ bool
+
config HAVE_DYNAMIC_FTRACE_WITH_ARGS
bool
help
@@ -257,6 +260,10 @@ config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
depends on DYNAMIC_FTRACE_WITH_REGS
depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
+config DYNAMIC_FTRACE_WITH_CALL_OPS
+ def_bool y
+ depends on HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
+
config DYNAMIC_FTRACE_WITH_ARGS
def_bool y
depends on DYNAMIC_FTRACE
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 442438b93fe9..e634b80f49d1 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -125,6 +125,33 @@ struct ftrace_ops global_ops;
void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs);
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS
+/*
+ * Stub used to invoke the list ops without requiring a separate trampoline.
+ */
+const struct ftrace_ops ftrace_list_ops = {
+ .func = ftrace_ops_list_func,
+ .flags = FTRACE_OPS_FL_STUB,
+};
+
+static void ftrace_ops_nop_func(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op,
+ struct ftrace_regs *fregs)
+{
+ /* do nothing */
+}
+
+/*
+ * Stub used when a call site is disabled. May be called transiently by threads
+ * which have made it into ftrace_caller but haven't yet recovered the ops at
+ * the point the call site is disabled.
+ */
+const struct ftrace_ops ftrace_nop_ops = {
+ .func = ftrace_ops_nop_func,
+ .flags = FTRACE_OPS_FL_STUB,
+};
+#endif
+
static inline void ftrace_ops_init(struct ftrace_ops *ops)
{
#ifdef CONFIG_DYNAMIC_FTRACE
@@ -1814,6 +1841,18 @@ static bool __ftrace_hash_rec_update(struct ftrace_ops *ops,
* if rec count is zero.
*/
}
+
+ /*
+ * If the rec has a single associated ops, and ops->func can be
+ * called directly, allow the call site to call via the ops.
+ */
+ if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS) &&
+ ftrace_rec_count(rec) == 1 &&
+ ftrace_ops_get_func(ops) == ops->func)
+ rec->flags |= FTRACE_FL_CALL_OPS;
+ else
+ rec->flags &= ~FTRACE_FL_CALL_OPS;
+
count++;
/* Must match FTRACE_UPDATE_CALLS in ftrace_modify_all_code() */
@@ -2108,8 +2147,9 @@ void ftrace_bug(int failed, struct dyn_ftrace *rec)
struct ftrace_ops *ops = NULL;
pr_info("ftrace record flags: %lx\n", rec->flags);
- pr_cont(" (%ld)%s", ftrace_rec_count(rec),
- rec->flags & FTRACE_FL_REGS ? " R" : " ");
+ pr_cont(" (%ld)%s%s", ftrace_rec_count(rec),
+ rec->flags & FTRACE_FL_REGS ? " R" : " ",
+ rec->flags & FTRACE_FL_CALL_OPS ? " O" : " ");
if (rec->flags & FTRACE_FL_TRAMP_EN) {
ops = ftrace_find_tramp_ops_any(rec);
if (ops) {
@@ -2177,6 +2217,7 @@ static int ftrace_check_record(struct dyn_ftrace *rec, bool enable, bool update)
* want the direct enabled (it will be done via the
* direct helper). But if DIRECT_EN is set, and
* the count is not one, we need to clear it.
+ *
*/
if (ftrace_rec_count(rec) == 1) {
if (!(rec->flags & FTRACE_FL_DIRECT) !=
@@ -2185,6 +2226,19 @@ static int ftrace_check_record(struct dyn_ftrace *rec, bool enable, bool update)
} else if (rec->flags & FTRACE_FL_DIRECT_EN) {
flag |= FTRACE_FL_DIRECT;
}
+
+ /*
+ * Ops calls are special, as count matters.
+ * As with direct calls, they must only be enabled when count
+ * is one, otherwise they'll be handled via the list ops.
+ */
+ if (ftrace_rec_count(rec) == 1) {
+ if (!(rec->flags & FTRACE_FL_CALL_OPS) !=
+ !(rec->flags & FTRACE_FL_CALL_OPS_EN))
+ flag |= FTRACE_FL_CALL_OPS;
+ } else if (rec->flags & FTRACE_FL_CALL_OPS_EN) {
+ flag |= FTRACE_FL_CALL_OPS;
+ }
}
/* If the state of this record hasn't changed, then do nothing */
@@ -2229,6 +2283,21 @@ static int ftrace_check_record(struct dyn_ftrace *rec, bool enable, bool update)
rec->flags &= ~FTRACE_FL_DIRECT_EN;
}
}
+
+ if (flag & FTRACE_FL_CALL_OPS) {
+ if (ftrace_rec_count(rec) == 1) {
+ if (rec->flags & FTRACE_FL_CALL_OPS)
+ rec->flags |= FTRACE_FL_CALL_OPS_EN;
+ else
+ rec->flags &= ~FTRACE_FL_CALL_OPS_EN;
+ } else {
+ /*
+ * Can only call directly if there's
+ * only one set of associated ops.
+ */
+ rec->flags &= ~FTRACE_FL_CALL_OPS_EN;
+ }
+ }
}
/*
@@ -2258,7 +2327,8 @@ static int ftrace_check_record(struct dyn_ftrace *rec, bool enable, bool update)
* and REGS states. The _EN flags must be disabled though.
*/
rec->flags &= ~(FTRACE_FL_ENABLED | FTRACE_FL_TRAMP_EN |
- FTRACE_FL_REGS_EN | FTRACE_FL_DIRECT_EN);
+ FTRACE_FL_REGS_EN | FTRACE_FL_DIRECT_EN |
+ FTRACE_FL_CALL_OPS_EN);
}
ftrace_bug_type = FTRACE_BUG_NOP;
@@ -2431,6 +2501,25 @@ ftrace_find_tramp_ops_new(struct dyn_ftrace *rec)
return NULL;
}
+struct ftrace_ops *
+ftrace_find_unique_ops(struct dyn_ftrace *rec)
+{
+ struct ftrace_ops *op, *found = NULL;
+ unsigned long ip = rec->ip;
+
+ do_for_each_ftrace_op(op, ftrace_ops_list) {
+
+ if (hash_contains_ip(ip, op->func_hash)) {
+ if (found)
+ return NULL;
+ found = op;
+ }
+
+ } while_for_each_ftrace_op(op);
+
+ return found;
+}
+
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
/* Protected by rcu_tasks for reading, and direct_mutex for writing */
static struct ftrace_hash *direct_functions = EMPTY_HASH;
@@ -3780,11 +3869,12 @@ static int t_show(struct seq_file *m, void *v)
if (iter->flags & FTRACE_ITER_ENABLED) {
struct ftrace_ops *ops;
- seq_printf(m, " (%ld)%s%s%s",
+ seq_printf(m, " (%ld)%s%s%s%s",
ftrace_rec_count(rec),
rec->flags & FTRACE_FL_REGS ? " R" : " ",
rec->flags & FTRACE_FL_IPMODIFY ? " I" : " ",
- rec->flags & FTRACE_FL_DIRECT ? " D" : " ");
+ rec->flags & FTRACE_FL_DIRECT ? " D" : " ",
+ rec->flags & FTRACE_FL_CALL_OPS ? " O" : " ");
if (rec->flags & FTRACE_FL_TRAMP_EN) {
ops = ftrace_find_tramp_ops_any(rec);
if (ops) {
@@ -3800,6 +3890,15 @@ static int t_show(struct seq_file *m, void *v)
} else {
add_trampoline_func(m, NULL, rec);
}
+ if (rec->flags & FTRACE_FL_CALL_OPS_EN) {
+ ops = ftrace_find_unique_ops(rec);
+ if (ops) {
+ seq_printf(m, "\tops: %pS (%pS)",
+ ops, ops->func);
+ } else {
+ seq_puts(m, "\tops: ERROR!");
+ }
+ }
if (rec->flags & FTRACE_FL_DIRECT) {
unsigned long direct;
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-02 08:33:20 +0000