diff options
| -rw-r--r-- | arch/arm/kernel/ftrace.c | 17 |
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(¤t->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, |