Re: [PATCH] arm64: dts: qcom: qcs615: fix a crash issue caused by infinite loop for Coresight

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 5/22/25 2:50 AM, Jie Gan wrote:
> An infinite loop has been created by the Coresight devices. When only a
> source device is enabled, the coresight_find_activated_sysfs_sink function
> is recursively invoked in an attempt to locate an active sink device,
> ultimately leading to a stack overflow and system crash. Therefore, disable
> the replicator1 to break the infinite loop and prevent a potential stack
> overflow.

Is it something we can fix the driver not to do instead?

Konrad

> 
> replicator1_out   ->   funnel_swao_in6   ->   tmc_etf_swao_in   ->  tmc_etf_swao_out
>      |                                                                     |
> replicator1_in                                                     replicator_swao_in
>      |                                                                     |
> replicator0_out1                                                   replicator_swao_out0
>      |                                                                     |
> replicator0_in                                                     funnel_in1_in3
>      |                                                                     |
> tmc_etf_out <- tmc_etf_in <- funnel_merg_out <- funnel_merg_in1 <- funnel_in1_out
> 
> [call trace]
>    dump_backtrace+0x9c/0x128
>    show_stack+0x20/0x38
>    dump_stack_lvl+0x48/0x60
>    dump_stack+0x18/0x28
>    panic+0x340/0x3b0
>    nmi_panic+0x94/0xa0
>    panic_bad_stack+0x114/0x138
>    handle_bad_stack+0x34/0xb8
>    __bad_stack+0x78/0x80
>    coresight_find_activated_sysfs_sink+0x28/0xa0 [coresight]
>    coresight_find_activated_sysfs_sink+0x5c/0xa0 [coresight]
>    coresight_find_activated_sysfs_sink+0x5c/0xa0 [coresight]
>    coresight_find_activated_sysfs_sink+0x5c/0xa0 [coresight]
>    coresight_find_activated_sysfs_sink+0x5c/0xa0 [coresight]
>    ...
>    coresight_find_activated_sysfs_sink+0x5c/0xa0 [coresight]
>    coresight_enable_sysfs+0x80/0x2a0 [coresight]
> 
> side effect after the change:
> Only trace data originating from AOSS can reach the ETF_SWAO and EUD sinks.
> 
> Fixes: bf469630552a ("arm64: dts: qcom: qcs615: Add coresight nodes")
> Signed-off-by: Jie Gan <jie.gan@oss.qualcomm.com>
> ---
>  arch/arm64/boot/dts/qcom/qcs615.dtsi | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/qcs615.dtsi b/arch/arm64/boot/dts/qcom/qcs615.dtsi
> index f08ba09772f3..b67c1f8a1118 100644
> --- a/arch/arm64/boot/dts/qcom/qcs615.dtsi
> +++ b/arch/arm64/boot/dts/qcom/qcs615.dtsi
> @@ -1902,6 +1902,7 @@ replicator@604a000 {
>  
>  			clocks = <&aoss_qmp>;
>  			clock-names = "apb_pclk";
> +			status = "disabled";
>  
>  			in-ports {
>  				port {