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Subject[PATCH 1/3] ftrace: introdue ftrace_call_init
Date
On some arch, the FTRACE_WITH_REGS is implemented with gcc's
-fpatchable-function-entry (=2), gcc adds 2 NOPs at the beginning
of each function, so this makes the MCOUNT_ADDR useless. In ftrace
common framework, MCOUNT_ADDR is mostly used to "init" the nop, so
let's introcude ftrace_call_init().

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
---
include/linux/ftrace.h | 1 +
kernel/trace/ftrace.c | 4 ++++
2 files changed, 5 insertions(+)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 8a8cb3c401b2..8175ffb671f0 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -458,6 +458,7 @@ extern void ftrace_regs_caller(void);
extern void ftrace_call(void);
extern void ftrace_regs_call(void);
extern void mcount_call(void);
+extern int ftrace_call_init(struct module *mod, struct dyn_ftrace *rec);

void ftrace_modify_all_code(int command);

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index eca34503f178..9df5a66a6811 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2500,7 +2500,11 @@ ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec)
if (unlikely(ftrace_disabled))
return 0;

+#ifdef MCOUNT_ADDR
ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
+#else
+ ret = ftrace_call_init(mod, rec);
+#endif
if (ret) {
ftrace_bug_type = FTRACE_BUG_INIT;
ftrace_bug(ret, rec);
--
2.23.0.rc1
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