@@ -100,6 +100,28 @@ static void notrace arm64_stack_index(struct stackframe *frame,
/* should not go beyond this frame */
if (trace->index[x] == THREAD_SIZE)
trace->index[x] = 0;
+
+ if (trace->entries[x] ==
+ ((unsigned long)return_to_handler + 0x8)) {
+ /*
+ * This is a case where return_to_handler() is calling
+ * ftrace_return_to_handler(). As we are already on
+ * an original function's stack, we have no way to fetch
+ * a correct pc value, just skip it.
+ */
+ trace->entries[x] = 0x0;
+ } else if (trace->entries[x] ==
+ (unsigned long)return_to_handler - AARCH64_INSN_SIZE) {
+ /*
+ * This is a case where function graph tracer has
+ * modified lr register on a stack to hook a function
+ * return.
+ * So replace it to original value.
+ */
+ trace->entries[x] =
+ current->ret_stack[data->ret_stack_index--].ret
+ - AARCH64_INSN_SIZE;
+ }
}
#endif /* CONFIG_STACK_TRACER */
Function graph tracer modifies a saved lr register on stack in order to hook a function return. This results in finding many bogus entries in a stack trace list. This patch replaces such entries with originals values stored in current->ret_stack[]. Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> --- arch/arm64/kernel/stacktrace.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)