* [PATCH] coresight: trbe: Defer the probe on offline CPUs
@ 2021-10-13 16:33 Suzuki K Poulose
2021-10-14 3:28 ` Anshuman Khandual
0 siblings, 1 reply; 3+ messages in thread
From: Suzuki K Poulose @ 2021-10-13 16:33 UTC (permalink / raw)
To: mathieu.poirier
Cc: linux-arm-kernel, linux-kernel, coresight, Suzuki K Poulose,
Bransilav Rankov, Anshuman Khandual, Mike Leach, Leo Yan
If a CPU is offline during the driver init, we could end up causing
a kernel crash trying to register the coresight device for the TRBE
instance.
e.g:
[ 0.149999] coresight ete0: CPU0: ete v1.1 initialized
[ 0.149999] coresight-etm4x ete_1: ETM arch init failed
[ 0.149999] coresight-etm4x: probe of ete_1 failed with error -22
[ 0.150085] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000050
[ 0.150085] Mem abort info:
[ 0.150085] ESR = 0x96000005
[ 0.150085] EC = 0x25: DABT (current EL), IL = 32 bits
[ 0.150085] SET = 0, FnV = 0
[ 0.150085] EA = 0, S1PTW = 0
[ 0.150085] Data abort info:
[ 0.150085] ISV = 0, ISS = 0x00000005
[ 0.150085] CM = 0, WnR = 0
[ 0.150085] [0000000000000050] user address but active_mm is swapper
[ 0.150085] Internal error: Oops: 96000005 [#1] PREEMPT SMP
[ 0.150085] Modules linked in:
[ 0.150085] Hardware name: FVP Base RevC (DT)
[ 0.150085] pstate: 00800009 (nzcv daif -PAN +UAO -TCO BTYPE=--)
[ 0.150155] pc : arm_trbe_register_coresight_cpu+0x74/0x144
[ 0.150155] lr : arm_trbe_register_coresight_cpu+0x48/0x144
...
[ 0.150237] Call trace:
[ 0.150237] arm_trbe_register_coresight_cpu+0x74/0x144
[ 0.150237] arm_trbe_device_probe+0x1c0/0x2d8
[ 0.150259] platform_drv_probe+0x94/0xbc
[ 0.150259] really_probe+0x1bc/0x4a8
[ 0.150266] driver_probe_device+0x7c/0xb8
[ 0.150266] device_driver_attach+0x6c/0xac
[ 0.150266] __driver_attach+0xc4/0x148
[ 0.150266] bus_for_each_dev+0x7c/0xc8
[ 0.150266] driver_attach+0x24/0x30
[ 0.150266] bus_add_driver+0x100/0x1e0
[ 0.150266] driver_register+0x78/0x110
[ 0.150266] __platform_driver_register+0x44/0x50
[ 0.150266] arm_trbe_init+0x28/0x84
[ 0.150266] do_one_initcall+0x94/0x2bc
[ 0.150266] do_initcall_level+0xa4/0x158
[ 0.150266] do_initcalls+0x54/0x94
[ 0.150319] do_basic_setup+0x24/0x30
[ 0.150319] kernel_init_freeable+0xe8/0x14c
[ 0.150319] kernel_init+0x14/0x18c
[ 0.150319] ret_from_fork+0x10/0x30
[ 0.150319] Code: f94012c8 b0004ce2 9134a442 52819801 (f9402917)
[ 0.150319] ---[ end trace d23e0cfe5098535e ]---
[ 0.150346] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
Fix this by skipping the step, if we are unable to probe the CPU.
Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")
Reported-by: Bransilav Rankov <branislav.rankov@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Tested-by: Branislav Rankov <branislav.rankov@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
drivers/hwtracing/coresight/coresight-trbe.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 5d350acef798..85ceda68af82 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -1286,7 +1286,9 @@ static int arm_trbe_probe_coresight(struct trbe_drvdata *drvdata)
return -ENOMEM;
for_each_cpu(cpu, &drvdata->supported_cpus) {
- smp_call_function_single(cpu, arm_trbe_probe_cpu, drvdata, 1);
+ /* If we fail to probe the CPU, let us defer it to hotplug callbacks */
+ if (smp_call_function_single(cpu, arm_trbe_probe_cpu, drvdata, 1))
+ continue;
if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
arm_trbe_register_coresight_cpu(drvdata, cpu);
if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
--
2.25.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] coresight: trbe: Defer the probe on offline CPUs
2021-10-13 16:33 [PATCH] coresight: trbe: Defer the probe on offline CPUs Suzuki K Poulose
@ 2021-10-14 3:28 ` Anshuman Khandual
2021-10-14 12:39 ` Suzuki K Poulose
0 siblings, 1 reply; 3+ messages in thread
From: Anshuman Khandual @ 2021-10-14 3:28 UTC (permalink / raw)
To: Suzuki K Poulose, mathieu.poirier
Cc: linux-arm-kernel, linux-kernel, coresight, Bransilav Rankov,
Mike Leach, Leo Yan
Hi Suzuki,
On 10/13/21 10:03 PM, Suzuki K Poulose wrote:
> If a CPU is offline during the driver init, we could end up causing
> a kernel crash trying to register the coresight device for the TRBE
> instance.
Which pointer deference fails here exactly ?
static void arm_trbe_register_coresight_cpu(struct trbe_drvdata *drvdata, int cpu)
{
struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
struct coresight_device *trbe_csdev = coresight_get_percpu_sink(cpu);
struct coresight_desc desc = { 0 };
struct device *dev;
if (WARN_ON(trbe_csdev))
return;
dev = &cpudata->drvdata->pdev->dev; <---- Fails here
cpudata->drvdata link gets established in arm_trbe_probe_cpu() which
would not have run on an offline cpu.
>
> e.g:
Should probably also mention the exact point of dereference failure
before this error message here.
>
> [ 0.149999] coresight ete0: CPU0: ete v1.1 initialized
> [ 0.149999] coresight-etm4x ete_1: ETM arch init failed
> [ 0.149999] coresight-etm4x: probe of ete_1 failed with error -22
> [ 0.150085] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000050
> [ 0.150085] Mem abort info:
> [ 0.150085] ESR = 0x96000005
> [ 0.150085] EC = 0x25: DABT (current EL), IL = 32 bits
> [ 0.150085] SET = 0, FnV = 0
> [ 0.150085] EA = 0, S1PTW = 0
> [ 0.150085] Data abort info:
> [ 0.150085] ISV = 0, ISS = 0x00000005
> [ 0.150085] CM = 0, WnR = 0
> [ 0.150085] [0000000000000050] user address but active_mm is swapper
> [ 0.150085] Internal error: Oops: 96000005 [#1] PREEMPT SMP
> [ 0.150085] Modules linked in:
> [ 0.150085] Hardware name: FVP Base RevC (DT)
> [ 0.150085] pstate: 00800009 (nzcv daif -PAN +UAO -TCO BTYPE=--)
> [ 0.150155] pc : arm_trbe_register_coresight_cpu+0x74/0x144
> [ 0.150155] lr : arm_trbe_register_coresight_cpu+0x48/0x144
> ...
>
> [ 0.150237] Call trace:
> [ 0.150237] arm_trbe_register_coresight_cpu+0x74/0x144
> [ 0.150237] arm_trbe_device_probe+0x1c0/0x2d8
> [ 0.150259] platform_drv_probe+0x94/0xbc
> [ 0.150259] really_probe+0x1bc/0x4a8
> [ 0.150266] driver_probe_device+0x7c/0xb8
> [ 0.150266] device_driver_attach+0x6c/0xac
> [ 0.150266] __driver_attach+0xc4/0x148
> [ 0.150266] bus_for_each_dev+0x7c/0xc8
> [ 0.150266] driver_attach+0x24/0x30
> [ 0.150266] bus_add_driver+0x100/0x1e0
> [ 0.150266] driver_register+0x78/0x110
> [ 0.150266] __platform_driver_register+0x44/0x50
> [ 0.150266] arm_trbe_init+0x28/0x84
> [ 0.150266] do_one_initcall+0x94/0x2bc
> [ 0.150266] do_initcall_level+0xa4/0x158
> [ 0.150266] do_initcalls+0x54/0x94
> [ 0.150319] do_basic_setup+0x24/0x30
> [ 0.150319] kernel_init_freeable+0xe8/0x14c
> [ 0.150319] kernel_init+0x14/0x18c
> [ 0.150319] ret_from_fork+0x10/0x30
> [ 0.150319] Code: f94012c8 b0004ce2 9134a442 52819801 (f9402917)
> [ 0.150319] ---[ end trace d23e0cfe5098535e ]---
> [ 0.150346] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
>
> Fix this by skipping the step, if we are unable to probe the CPU.
>
> Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")
> Reported-by: Bransilav Rankov <branislav.rankov@arm.com>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: Mike Leach <mike.leach@linaro.org>
> Cc: Leo Yan <leo.yan@linaro.org>
> Tested-by: Branislav Rankov <branislav.rankov@arm.com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
> drivers/hwtracing/coresight/coresight-trbe.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
> index 5d350acef798..85ceda68af82 100644
> --- a/drivers/hwtracing/coresight/coresight-trbe.c
> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
> @@ -1286,7 +1286,9 @@ static int arm_trbe_probe_coresight(struct trbe_drvdata *drvdata)
> return -ENOMEM;
>
> for_each_cpu(cpu, &drvdata->supported_cpus) {
> - smp_call_function_single(cpu, arm_trbe_probe_cpu, drvdata, 1);
> + /* If we fail to probe the CPU, let us defer it to hotplug callbacks */
> + if (smp_call_function_single(cpu, arm_trbe_probe_cpu, drvdata, 1))
> + continue;
> if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
> arm_trbe_register_coresight_cpu(drvdata, cpu);
> if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>
Right, LGTM. Although I guess the following addition might be worthwhile
just to highlight the fact that cpudata->drvdata is not valid unless the
cpu has gone through arm_trbe_probe_cpu() first.
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -869,6 +869,7 @@ static void arm_trbe_register_coresight_cpu(struct trbe_drvdata *drvdata, int cp
if (WARN_ON(trbe_csdev))
return;
+ WARN_ON(!cpudata->drvdata);
dev = &cpudata->drvdata->pdev->dev;
desc.name = devm_kasprintf(dev, GFP_KERNEL, "trbe%d", cpu);
if (!desc.name)
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] coresight: trbe: Defer the probe on offline CPUs
2021-10-14 3:28 ` Anshuman Khandual
@ 2021-10-14 12:39 ` Suzuki K Poulose
0 siblings, 0 replies; 3+ messages in thread
From: Suzuki K Poulose @ 2021-10-14 12:39 UTC (permalink / raw)
To: Anshuman Khandual, mathieu.poirier
Cc: linux-arm-kernel, linux-kernel, coresight, Bransilav Rankov,
Mike Leach, Leo Yan
On 14/10/2021 04:28, Anshuman Khandual wrote:
> Hi Suzuki,
>
> On 10/13/21 10:03 PM, Suzuki K Poulose wrote:
>> If a CPU is offline during the driver init, we could end up causing
>> a kernel crash trying to register the coresight device for the TRBE
>> instance.
>
> Which pointer deference fails here exactly ?
>
> static void arm_trbe_register_coresight_cpu(struct trbe_drvdata *drvdata, int cpu)
> {
> struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
> struct coresight_device *trbe_csdev = coresight_get_percpu_sink(cpu);
> struct coresight_desc desc = { 0 };
> struct device *dev;
>
> if (WARN_ON(trbe_csdev))
> return;
>
> dev = &cpudata->drvdata->pdev->dev; <---- Fails here
>
> cpudata->drvdata link gets established in arm_trbe_probe_cpu() which
> would not have run on an offline cpu.
Yes, that is correct.
>
>>
>> e.g:
>
> Should probably also mention the exact point of dereference failure
> before this error message here.
>
>>
>> [ 0.149999] coresight ete0: CPU0: ete v1.1 initialized
>> [ 0.149999] coresight-etm4x ete_1: ETM arch init failed
>> [ 0.149999] coresight-etm4x: probe of ete_1 failed with error -22
>> [ 0.150085] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000050
>> [ 0.150085] Mem abort info:
>> [ 0.150085] ESR = 0x96000005
>> [ 0.150085] EC = 0x25: DABT (current EL), IL = 32 bits
>> [ 0.150085] SET = 0, FnV = 0
>> [ 0.150085] EA = 0, S1PTW = 0
>> [ 0.150085] Data abort info:
>> [ 0.150085] ISV = 0, ISS = 0x00000005
>> [ 0.150085] CM = 0, WnR = 0
>> [ 0.150085] [0000000000000050] user address but active_mm is swapper
>> [ 0.150085] Internal error: Oops: 96000005 [#1] PREEMPT SMP
>> [ 0.150085] Modules linked in:
>> [ 0.150085] Hardware name: FVP Base RevC (DT)
>> [ 0.150085] pstate: 00800009 (nzcv daif -PAN +UAO -TCO BTYPE=--)
>> [ 0.150155] pc : arm_trbe_register_coresight_cpu+0x74/0x144
>> [ 0.150155] lr : arm_trbe_register_coresight_cpu+0x48/0x144
>> ...
>>
>> [ 0.150237] Call trace:
>> [ 0.150237] arm_trbe_register_coresight_cpu+0x74/0x144
>> [ 0.150237] arm_trbe_device_probe+0x1c0/0x2d8
>> [ 0.150259] platform_drv_probe+0x94/0xbc
>> [ 0.150259] really_probe+0x1bc/0x4a8
>> [ 0.150266] driver_probe_device+0x7c/0xb8
>> [ 0.150266] device_driver_attach+0x6c/0xac
>> [ 0.150266] __driver_attach+0xc4/0x148
>> [ 0.150266] bus_for_each_dev+0x7c/0xc8
>> [ 0.150266] driver_attach+0x24/0x30
>> [ 0.150266] bus_add_driver+0x100/0x1e0
>> [ 0.150266] driver_register+0x78/0x110
>> [ 0.150266] __platform_driver_register+0x44/0x50
>> [ 0.150266] arm_trbe_init+0x28/0x84
>> [ 0.150266] do_one_initcall+0x94/0x2bc
>> [ 0.150266] do_initcall_level+0xa4/0x158
>> [ 0.150266] do_initcalls+0x54/0x94
>> [ 0.150319] do_basic_setup+0x24/0x30
>> [ 0.150319] kernel_init_freeable+0xe8/0x14c
>> [ 0.150319] kernel_init+0x14/0x18c
>> [ 0.150319] ret_from_fork+0x10/0x30
>> [ 0.150319] Code: f94012c8 b0004ce2 9134a442 52819801 (f9402917)
>> [ 0.150319] ---[ end trace d23e0cfe5098535e ]---
>> [ 0.150346] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
>>
>> Fix this by skipping the step, if we are unable to probe the CPU.
>>
>> Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")
>> Reported-by: Bransilav Rankov <branislav.rankov@arm.com>
>> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
>> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
>> Cc: Mike Leach <mike.leach@linaro.org>
>> Cc: Leo Yan <leo.yan@linaro.org>
>> Tested-by: Branislav Rankov <branislav.rankov@arm.com>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>> ---
>> drivers/hwtracing/coresight/coresight-trbe.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
>> index 5d350acef798..85ceda68af82 100644
>> --- a/drivers/hwtracing/coresight/coresight-trbe.c
>> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
>> @@ -1286,7 +1286,9 @@ static int arm_trbe_probe_coresight(struct trbe_drvdata *drvdata)
>> return -ENOMEM;
>>
>> for_each_cpu(cpu, &drvdata->supported_cpus) {
>> - smp_call_function_single(cpu, arm_trbe_probe_cpu, drvdata, 1);
>> + /* If we fail to probe the CPU, let us defer it to hotplug callbacks */
>> + if (smp_call_function_single(cpu, arm_trbe_probe_cpu, drvdata, 1))
>> + continue;
>> if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>> arm_trbe_register_coresight_cpu(drvdata, cpu);
>> if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>>
>
> Right, LGTM. Although I guess the following addition might be worthwhile
> just to highlight the fact that cpudata->drvdata is not valid unless the
> cpu has gone through arm_trbe_probe_cpu() first.
>
> --- a/drivers/hwtracing/coresight/coresight-trbe.c
> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
> @@ -869,6 +869,7 @@ static void arm_trbe_register_coresight_cpu(struct trbe_drvdata *drvdata, int cp
> if (WARN_ON(trbe_csdev))
> return;
>
> + WARN_ON(!cpudata->drvdata);
Ok, I would rather return here with the warning. I will send
a revision.
Thanks !
Suzuki
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-10-14 12:39 UTC | newest]
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2021-10-13 16:33 [PATCH] coresight: trbe: Defer the probe on offline CPUs Suzuki K Poulose
2021-10-14 3:28 ` Anshuman Khandual
2021-10-14 12:39 ` Suzuki K Poulose
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