Function ftrace_modify_call provides a way to replace ftrace_stub
with the ftrace function. This helps the klp_ftrace_handler to be
called via ftrace_ops_no_ops, which in turn will set the pc with
the patched function's starting address. This is used for
livepatching.
Signed-off-by: Abel Vesa <abelv...@linux.com>
---
arch/arm/kernel/ftrace.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index 3f17594..cb4543a 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -139,6 +139,15 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
ret = ftrace_modify_code(pc, 0, new, false);
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+ if (!ret) {
+ pc = (unsigned long)&ftrace_regs_call;
+ new = ftrace_call_replace(pc, (unsigned long)func);
+
+ ret = ftrace_modify_code(pc, 0, new, false);
+ }
+#endif
+
#ifdef CONFIG_OLD_MCOUNT
if (!ret) {
pc = (unsigned long)&ftrace_call_old;
@@ -151,6 +160,18 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
return ret;
}
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+ unsigned long addr)
+{
+ unsigned long pc = rec->ip;
+ u32 old, new;
+
+ old = arm_gen_branch(pc, old_addr);
+ new = arm_gen_branch(pc, addr);
+
+ return ftrace_modify_code(pc, old, new, true);
+}
+
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
unsigned long new, old;
--
2.7.4
