On some QCOM platforms like SC7180, SDM845 and SM8150,
reading TMC mode register without proper coresight power
management can lead to async exceptions like the one in
the call trace below in tmc_read_prepare_etb(). This can
happen if the user tries to read the TMC etf data via
device node without setting up source and the sink first.
Fix this by having a check for coresight sysfs mode
before reading TMC mode management register.
Kernel panic - not syncing: Asynchronous SError Interrupt
CPU: 7 PID: 2605 Comm: hexdump Tainted: G S 5.4.30 #122
Call trace:
dump_backtrace+0x0/0x188
show_stack+0x20/0x2c
dump_stack+0xdc/0x144
panic+0x168/0x36c
panic+0x0/0x36c
arm64_serror_panic+0x78/0x84
do_serror+0x130/0x138
el1_error+0x84/0xf8
tmc_read_prepare_etb+0x88/0xb8
tmc_open+0x40/0xd8
misc_open+0x120/0x158
chrdev_open+0xb8/0x1a4
do_dentry_open+0x268/0x3a0
vfs_open+0x34/0x40
path_openat+0x39c/0xdf4
do_filp_open+0x90/0x10c
do_sys_open+0x150/0x3e8
__arm64_compat_sys_openat+0x28/0x34
el0_svc_common+0xa8/0x160
el0_svc_compat_handler+0x2c/0x38
el0_svc_compat+0x8/0x10
Fixes: 4525412a5046 ("coresight: tmc: making prepare/unprepare functions generic")
Reported-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Suggested-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
---
v2:
* Move the TMC mode read under CS_MODE_SYSFS as per Mathieu
---
drivers/hwtracing/coresight/coresight-tmc-etf.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index d0cc3985b72a..36cce2bfb744 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -596,13 +596,6 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)
goto out;
}
- /* 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) {
- ret = -EINVAL;
- goto out;
- }
-
/* Don't interfere if operated from Perf */
if (drvdata->mode == CS_MODE_PERF) {
ret = -EINVAL;
@@ -616,8 +609,15 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)
}
/* Disable the TMC if need be */
- if (drvdata->mode == CS_MODE_SYSFS)
+ 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) {
+ ret = -EINVAL;
+ goto out;
+ }
__tmc_etb_disable_hw(drvdata);
+ }
drvdata->reading = true;
out:
--
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