a08025b3fe
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. The trbe_cpudata for the TRBE instance is initialized only when it is probed. Otherwise, we could end up dereferencing a NULL cpudata->drvdata. 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> Cc: stable <stable@vger.kernel.org> Tested-by: Branislav Rankov <branislav.rankov@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Link: https://lore.kernel.org/r/20211014142238.2221248-1-suzuki.poulose@arm.com Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.