Messages in this thread | | | Subject | Re: [PATCH v2] MIPS: kernel: Reserve exception base early to prevent corruption | From | Florian Fainelli <> | Date | Sat, 6 Mar 2021 20:13:53 -0800 |
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On 3/6/2021 12:29 AM, Thomas Bogendoerfer wrote: > BMIPS is one of the few platforms that do change the exception base. > After commit 2dcb39645441 ("memblock: do not start bottom-up allocations > with kernel_end") we started seeing BMIPS boards fail to boot with the > built-in FDT being corrupted. > > Before the cited commit, early allocations would be in the [kernel_end, > RAM_END] range, but after commit they would be within [RAM_START + > PAGE_SIZE, RAM_END]. > > The custom exception base handler that is installed by > bmips_ebase_setup() done for BMIPS5000 CPUs ends-up trampling on the > memory region allocated by unflatten_and_copy_device_tree() thus > corrupting the FDT used by the kernel. > > To fix this, we need to perform an early reservation of the custom > exception space. So we reserve it already in cpu_probe() for the CPUs > where this is fixed. For CPU with an ebase config register allocation > of exception space will be done in trap_init(). > > Huge thanks to Serget for analysing and proposing a solution to this > issue.
I made a typo on Sergey's name in my original version here.
> > Fixes: 2dcb39645441 ("memblock: do not start bottom-up allocations with kernel_end") > Reported-by: Kamal Dasu <kdasu.kdev@gmail.com> > Debugged-by: Serge Semin <Sergey.Semin@baikalelectronics.ru> > Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Thanks! -- Florian
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