| Message ID | 20191223084614.67126-3-zong.li@sifive.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | RISC-V: fixes issues of ftrace graph tracer | expand |
On Mon, 23 Dec 2019, Zong Li wrote: > When enabling ftrace graph tracer, it gets the tracing clock in > ftrace_push_return_trace. Eventually, it invokes the riscv_sched_clock to > get the clock. If add mcount instrument in riscv_sched_clock, 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@sifive.com> Thanks; below is what's been queued for v5.5-rc. - Paul From: Zong Li <zong.li@sifive.com> Date: Mon, 23 Dec 2019 16:46:14 +0800 Subject: [PATCH 1/2] clocksource/drivers/riscv: add notrace to riscv_sched_clock 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@sifive.com> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> [paul.walmsley@sifive.com: cleaned up patch description] Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com> --- drivers/clocksource/timer-riscv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c index 4e54856ce2a5..c4f15c4068c0 100644 --- a/drivers/clocksource/timer-riscv.c +++ b/drivers/clocksource/timer-riscv.c @@ -56,7 +56,7 @@ static unsigned long long riscv_clocksource_rdtime(struct clocksource *cs) return get_cycles64(); } -static u64 riscv_sched_clock(void) +static u64 notrace riscv_sched_clock(void) { return get_cycles64(); }
diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c index 4e54856ce2a5..c4f15c4068c0 100644 --- a/drivers/clocksource/timer-riscv.c +++ b/drivers/clocksource/timer-riscv.c @@ -56,7 +56,7 @@ static unsigned long long riscv_clocksource_rdtime(struct clocksource *cs) return get_cycles64(); } -static u64 riscv_sched_clock(void) +static u64 notrace riscv_sched_clock(void) { return get_cycles64(); }
When enabling ftrace graph tracer, it gets the tracing clock in ftrace_push_return_trace. Eventually, it invokes the riscv_sched_clock to get the clock. If add mcount instrument in riscv_sched_clock, 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@sifive.com> --- drivers/clocksource/timer-riscv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)