_coresight_build_path assumes that all the connections of a csdev
has the child_dev initialised. This may not be true if the particular
component is not supported by the kernel config(e.g TPIU) but is
present in the DT. In which case, building a path can cause a crash like this :
Unable to handle kernel NULL pointer dereference at virtual address 00000010
pgd = ffffffc9750dd000
[00000010] *pgd=00000009f5e90003, *pud=00000009f5e90003, *pmd=0000000000000000
Internal error: Oops: 96000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 4 PID: 1348 Comm: bash Not tainted 4.6.0-next-20160517 #1646
Hardware name: ARM Juno development board (r0) (DT)
task: ffffffc97517a280 ti: ffffffc9762c4000 task.ti: ffffffc9762c4000
PC is at _coresight_build_path+0x18/0xe4
LR is at _coresight_build_path+0xc0/0xe4
pc : [<ffffff80083d5130>] lr : [<ffffff80083d51d8>] pstate: 20000145
sp : ffffffc9762c7ba0
[<ffffff80083d5130>] _coresight_build_path+0x18/0xe4
[<ffffff80083d51d8>] _coresight_build_path+0xc0/0xe4
[<ffffff80083d51d8>] _coresight_build_path+0xc0/0xe4
[<ffffff80083d51d8>] _coresight_build_path+0xc0/0xe4
[<ffffff80083d51d8>] _coresight_build_path+0xc0/0xe4
[<ffffff80083d51d8>] _coresight_build_path+0xc0/0xe4
[<ffffff80083d5cdc>] coresight_build_path+0x40/0x68
[<ffffff80083d5e14>] coresight_enable+0x74/0x1bc
[<ffffff80083d60a0>] enable_source_store+0x3c/0x6c
[<ffffff800830b17c>] dev_attr_store+0x18/0x28
[<ffffff80081ca9c4>] sysfs_kf_write+0x40/0x50
[<ffffff80081c9e38>] kernfs_fop_write+0x140/0x1cc
[<ffffff8008163ec8>] __vfs_write+0x28/0x110
[<ffffff8008164bf0>] vfs_write+0xa0/0x174
[<ffffff8008165d18>] SyS_write+0x44/0xa0
[<ffffff8008084e70>] el0_svc_naked+0x24/0x28
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ec48a1d981