On Tue, 16 Jun 2020 at 05:55, Sai Prakash Ranjan saiprakash.ranjan@codeaurora.org wrote:

Reading TMC mode register without proper coresight power management can lead to exceptions like the one in the call trace below in tmc_read_unprepare_etb() when the trace data is read after the sink is disabled. So fix this by having a check for coresight sysfs mode before reading TMC mode management register in tmc_read_unprepare_etb() similar to tmc_read_prepare_etb().

SError Interrupt on CPU6, code 0xbe000411 -- SError pstate: 80400089 (Nzcv daIf +PAN -UAO) pc : tmc_read_unprepare_etb+0x74/0x108 lr : tmc_read_unprepare_etb+0x54/0x108 sp : ffffff80d9507c30 x29: ffffff80d9507c30 x28: ffffff80b3569a0c x27: 0000000000000000 x26: 00000000000a0001 x25: ffffff80cbae9550 x24: 0000000000000010 x23: ffffffd07296b0f0 x22: ffffffd0109ee028 x21: 0000000000000000 x20: ffffff80d19e70e0 x19: ffffff80d19e7080 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: dfffffd000000001 x9 : 0000000000000000 x8 : 0000000000000002 x7 : ffffffd071d0fe78 x6 : 0000000000000000 x5 : 0000000000000080 x4 : 0000000000000001 x3 : ffffffd071d0fe98 x2 : 0000000000000000 x1 : 0000000000000004 x0 : 0000000000000001 Kernel panic - not syncing: Asynchronous SError Interrupt

Fixes: 4525412a5046 ("coresight: tmc: making prepare/unprepare functions generic") Reported-by: Mike Leach mike.leach@linaro.org Signed-off-by: Sai Prakash Ranjan saiprakash.ranjan@codeaurora.org

---

drivers/hwtracing/coresight/coresight-tmc-etf.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c index 36cce2bfb744..6375504ba8b0 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c @@ -639,15 +639,14 @@ int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata)

    spin_lock_irqsave(&drvdata->spinlock, flags);

•   /* There is no point in reading a TMC in HW FIFO mode */
  

•   mode = readl_relaxed(drvdata->base + TMC_MODE);
  

•   if (mode != TMC_MODE_CIRCULAR_BUFFER) {
  

•           spin_unlock_irqrestore(&drvdata->spinlock, flags);
  

•           return -EINVAL;
  

•   }
  

•   /* Re-enable the TMC if need be */
    if (drvdata->mode == CS_MODE_SYSFS) {
  

•           /* There is no point in reading a TMC in HW FIFO mode */
  

•           mode = readl_relaxed(drvdata->base + TMC_MODE);
  

•           if (mode != TMC_MODE_CIRCULAR_BUFFER) {
  

•                   spin_unlock_irqrestore(&drvdata->spinlock, flags);
  

•                   return -EINVAL;
  

•           }
            /*
             * The trace run will continue with the same allocated trace
             * buffer. As such zero-out the buffer so that we don't end
  
  

base-commit: 3d439a6c349778f129de19595db564a8366c3634

QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

Tested OK on my DB410c / Linux 5.8-rc1

Tested-by: Mike Leach mike.leach@linaro.org