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ftrace: Setup correct FTRACE_FL_REGS flags for module 

When module loaded and enabled, we will use __ftrace_replace_code
for module if any ftrace_ops referenced it found. But we will get
wrong ftrace_addr for module rec in ftrace_get_addr_new, because
rec->flags has not been setup correctly. It can cause the callback
function of a ftrace_ops has FTRACE_OPS_FL_SAVE_REGS to be called
with pt_regs set to NULL.
So setup correct FTRACE_FL_REGS flags for rec when we call
referenced_filters to find ftrace_ops references it.

Link: https://lkml.kernel.org/r/20200728180554.65203-1-zhouchengming@bytedance.com

Cc: stable@vger.kernel.org
Fixes: 8c4f3c3fa9 ("ftrace: Check module functions being traced on reload")
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Chengming Zhou 2020-07-29 02:05:53 +08:00 committed by Steven Rostedt (VMware)
parent 96b4833b68
commit 8a224ffb3f
1 changed files with 7 additions and 4 deletions
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11
kernel/trace/ftrace.c
View File

@ -6198,8 +6198,11 @@ static int referenced_filters(struct dyn_ftrace *rec)
int cnt = 0;
for (ops = ftrace_ops_list; ops != &ftrace_list_end; ops = ops->next) {
if (ops_references_rec(ops, rec))
cnt++;
if (ops_references_rec(ops, rec)) {
cnt++;
if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
rec->flags |= FTRACE_FL_REGS;
}
}
return cnt;
@ -6378,8 +6381,8 @@ void ftrace_module_enable(struct module *mod)
if (ftrace_start_up)
cnt += referenced_filters(rec);
/* This clears FTRACE_FL_DISABLED */
rec->flags = cnt;
rec->flags &= ~FTRACE_FL_DISABLED;
rec->flags += cnt;
if (ftrace_start_up && cnt) {
int failed = __ftrace_replace_code(rec, 1);