arm64: stacktrace: fix the usage of ftrace_graph_ret_addr()

ftrace_graph_ret_addr() takes an 'idx' integer pointer that is used to
optimize the stack unwinding process. arm64 currently passes `NULL` for
this parameter which stops it from utilizing these optimizations.

Further, the current code for ftrace_graph_ret_addr() will just return
the passed in return address if it is NULL which will break this usage.

Pass a valid integer pointer to ftrace_graph_ret_addr() similar to
x86_64's stack unwinder.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Fixes: 29c1c24a2707 ("function_graph: Fix up ftrace_graph_ret_addr()")
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20240618162342.28275-1-puranjay@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 6b32588603778da3662a99f5d71b934ab44278b4..2729faaee4b4c20884f5f54289e1f5afa871c2c9 100644 (file)
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -25,6 +25,7 @@
  *
  * @common:      Common unwind state.
  * @task:        The task being unwound.
+ * @graph_idx:   Used by ftrace_graph_ret_addr() for optimized stack unwinding.
  * @kr_cur:      When KRETPROBES is selected, holds the kretprobe instance
  *               associated with the most recently encountered replacement lr
  *               value.
@@ -32,6 +33,7 @@
 struct kunwind_state {
        struct unwind_state common;
        struct task_struct *task;
+       int graph_idx;
 #ifdef CONFIG_KRETPROBES
        struct llist_node *kr_cur;
 #endif
@@ -106,7 +108,7 @@ kunwind_recover_return_address(struct kunwind_state *state)
        if (state->task->ret_stack &&
            (state->common.pc == (unsigned long)return_to_handler)) {
                unsigned long orig_pc;
-               orig_pc = ftrace_graph_ret_addr(state->task, NULL,
+               orig_pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
                                                state->common.pc,
                                                (void *)state->common.fp);
                if (WARN_ON_ONCE(state->common.pc == orig_pc))