Re: [PATCH v2 12/12] powerpc/64s: system reset do not trace
From: Naveen N. Rao <hidden>
Date: 2020-03-26 17:26:14
Nicholas Piggin wrote:
Similarly to the previous patch, do not trace system reset. This code is used when there is a crash or hang, and tracing disturbs the system more and has been known to crash in the crash handling path. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/kernel/traps.c | 5 +++++ 1 file changed, 5 insertions(+)
For the ftrace bits: Acked-by: Naveen N. Rao <redacted>
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index 1845fd7e161a..ed7b7a6e2dc0 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c@@ -443,6 +443,9 @@ void system_reset_exception(struct pt_regs *regs) unsigned long hsrr0, hsrr1; bool nested = in_nmi(); bool saved_hsrrs = false; + u8 ftrace_enabled = local_paca->ftrace_enabled; + + local_paca->ftrace_enabled = 0; /* * Avoid crashes in case of nested NMI exceptions. Recoverability@@ -524,6 +527,8 @@ void system_reset_exception(struct pt_regs *regs) if (!nested) nmi_exit(); + local_paca->ftrace_enabled = ftrace_enabled; +
I suppose we could add helpers to save/restore the state. But, since we only have these two users as of now, we can revisit that if the need arises. - Naveen