From: "Steven Rostedt (Google)" <[email protected]> [ Upstream commit 712292308af2265cd9b126aedfa987f10f452a33 ]
As the ring buffer recording requires cmpxchg() to work, if the architecture does not support cmpxchg in NMI, then do not do any recording within an NMI. Link: https://lore.kernel.org/linux-trace-kernel/[email protected] Cc: Masami Hiramatsu <[email protected]> Cc: Mark Rutland <[email protected]> Cc: Mathieu Desnoyers <[email protected]> Signed-off-by: Steven Rostedt (Google) <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- kernel/trace/ring_buffer.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index c02a4cb879913..c821b618a622f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -3711,6 +3711,12 @@ rb_reserve_next_event(struct trace_buffer *buffer, int nr_loops = 0; int add_ts_default; + /* ring buffer does cmpxchg, make sure it is safe in NMI context */ + if (!IS_ENABLED(CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG) && + (unlikely(in_nmi()))) { + return NULL; + } + rb_start_commit(cpu_buffer); /* The commit page can not change after this */ -- 2.43.0
