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-rw-r--r--arch/arm/kernel/ftrace.c17
1 files changed, 15 insertions, 2 deletions
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index a0b6d1e3812f..e61591f33a6c 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -232,11 +232,24 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
unsigned long old;
if (unlikely(atomic_read(&current->tracing_graph_pause)))
+err_out:
return;
if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER)) {
- /* FP points one word below parent's top of stack */
- frame_pointer += 4;
+ /*
+ * Usually, the stack frames are contiguous in memory but cases
+ * have been observed where the next stack frame does not live
+ * at 'frame_pointer + 4' as this code used to assume.
+ *
+ * Instead, dereference the field in the stack frame that
+ * stores the SP of the calling frame: to avoid unbounded
+ * recursion, this cannot involve any ftrace instrumented
+ * functions, so use the __get_kernel_nofault() primitive
+ * directly.
+ */
+ __get_kernel_nofault(&frame_pointer,
+ (unsigned long *)(frame_pointer - 8),
+ unsigned long, err_out);
} else {
struct stackframe frame = {
.fp = frame_pointer,