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clocksource: riscv: add notrace to riscv_sched_clock
commit 9d05c18 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 [hardkernel#1] [ 46.177478] Modules linked in: [ 46.177770] CPU: 0 PID: 256 Comm: $d Not tainted 5.5.0-rc1 hardkernel#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 <[email protected]> Reviewed-by: Steven Rostedt (VMware) <[email protected]> [[email protected]: cleaned up patch description] Fixes: 92e0d14 ("clocksource/drivers/riscv_timer: Provide the sched_clock") Cc: [email protected] Signed-off-by: Paul Walmsley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
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