[PATCH 4.19 095/168] coresight: tmc: Fix TMC mode read in tmc_read_unprepare_etb()

Greg Kroah-Hartman
2020-08-17T17:44:46Z

From: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>

[ Upstream commit d021f5c5ff679432c5e9faee0fd7350db2efb97c ]

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>
Tested-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200716175746.3338735-14-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.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 e90af39283b19..29dc2eac5b065 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -583,15 +583,14 @@ 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
--
2.25.1