From: Zong Li <zong.li@xxxxxxxxxx>
commit 9d05c18e8d7de566ff68f221fcae65e78708dd1d upstream.
When enabling ftrace graph tracer, it gets the tracing clock in
ftrace_push_return_trace(). Eventually, it invokes riscv_sched_clock()
to get the clock value. If riscv_sched_clock() isn't marked with
'notrace', it will call ftrace_push_return_trace() and cause infinite
loop.
The result of failure as follow:
command: echo function_graph >current_tracer
[ 46.176787] Unable to handle kernel paging request at virtual address ffffffe04fb38c48
[ 46.177309] Oops [#1]
[ 46.177478] Modules linked in:
[ 46.177770] CPU: 0 PID: 256 Comm: $d Not tainted 5.5.0-rc1 #47
[ 46.177981] epc: ffffffe00035e59a ra : ffffffe00035e57e sp : ffffffe03a7569b0
[ 46.178216] gp : ffffffe000d29b90 tp : ffffffe03a756180 t0 : ffffffe03a756968
[ 46.178430] t1 : ffffffe00087f408 t2 : ffffffe03a7569a0 s0 : ffffffe03a7569f0
[ 46.178643] s1 : ffffffe00087f408 a0 : 0000000ac054cda4 a1 : 000000000087f411
[ 46.178856] a2 : 0000000ac054cda4 a3 : 0000000000373ca0 a4 : ffffffe04fb38c48
[ 46.179099] a5 : 00000000153e22a8 a6 : 00000000005522ff a7 : 0000000000000005
[ 46.179338] s2 : ffffffe03a756a90 s3 : ffffffe00032811c s4 : ffffffe03a756a58
[ 46.179570] s5 : ffffffe000d29fe0 s6 : 0000000000000001 s7 : 0000000000000003
[ 46.179809] s8 : 0000000000000003 s9 : 0000000000000002 s10: 0000000000000004
[ 46.180053] s11: 0000000000000000 t3 : 0000003fc815749c t4 : 00000000000efc90
[ 46.180293] t5 : ffffffe000d29658 t6 : 0000000000040000
[ 46.180482] status: 0000000000000100 badaddr: ffffffe04fb38c48 cause: 000000000000000f
Signed-off-by: Zong Li <zong.li@xxxxxxxxxx>
Reviewed-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
[paul.walmsley@xxxxxxxxxx: cleaned up patch description]
Fixes: 92e0d143fdef ("clocksource/drivers/riscv_timer: Provide the sched_clock")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/clocksource/timer-riscv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/clocksource/timer-riscv.c
+++ b/drivers/clocksource/timer-riscv.c
@@ -41,7 +41,7 @@ static unsigned long long riscv_clocksou
return get_cycles64();
}
-static u64 riscv_sched_clock(void)
+static u64 notrace riscv_sched_clock(void)
{
return get_cycles64();
}
