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-rw-r--r--arch/arm64/kernel/ftrace.c27
1 files changed, 14 insertions, 13 deletions
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index c851be795080..ebecf9aa33d1 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -29,12 +29,11 @@ static int ftrace_modify_code(unsigned long pc, u32 old, u32 new,
/*
* Note:
- * Due to modules and __init, code can disappear and change,
- * we need to protect against faulting as well as code changing.
- * We do this by aarch64_insn_*() which use the probe_kernel_*().
- *
- * No lock is held here because all the modifications are run
- * through stop_machine().
+ * We are paranoid about modifying text, as if a bug were to happen, it
+ * could cause us to read or write to someplace that could cause harm.
+ * Carefully read and modify the code with aarch64_insn_*() which uses
+ * probe_kernel_*(), and make sure what we read is what we expected it
+ * to be before modifying it.
*/
if (validate) {
if (aarch64_insn_read((void *)pc, &replaced))
@@ -93,6 +92,11 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
return ftrace_modify_code(pc, old, new, true);
}
+void arch_ftrace_update_code(int command)
+{
+ ftrace_modify_all_code(command);
+}
+
int __init ftrace_dyn_arch_init(void)
{
return 0;
@@ -125,23 +129,20 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
* on other archs. It's unlikely on AArch64.
*/
old = *parent;
- *parent = return_hooker;
trace.func = self_addr;
trace.depth = current->curr_ret_stack + 1;
/* Only trace if the calling function expects to */
- if (!ftrace_graph_entry(&trace)) {
- *parent = old;
+ if (!ftrace_graph_entry(&trace))
return;
- }
err = ftrace_push_return_trace(old, self_addr, &trace.depth,
frame_pointer);
- if (err == -EBUSY) {
- *parent = old;
+ if (err == -EBUSY)
return;
- }
+ else
+ *parent = return_hooker;
}
#ifdef CONFIG_DYNAMIC_FTRACE