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ring-buffer: Do not record in NMI if the arch does not support cmpxchg in NMI 

[ Upstream commit 712292308a ]

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/20231213175403.6fc18540@gandalf.local.home

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
pull/1175/head
Steven Rostedt (Google) 2023-12-13 17:54:03 -05:00 committed by Greg Kroah-Hartman
parent 07787918c6
commit b0407f68d9
1 changed files with 6 additions and 0 deletions
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6
kernel/trace/ring_buffer.c
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@ -3644,6 +3644,12 @@ 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 */