Messages in this thread | | | Date | Mon, 8 Mar 2021 20:00:57 +0100 | From | Thomas Bogendoerfer <> | Subject | Re: [PATCH v3] MIPS: kernel: Reserve exception base early to prevent corruption |
| |
On Mon, Mar 08, 2021 at 10:21:10AM -0800, Florian Fainelli wrote: > On 3/8/21 1:24 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. Additional we reserve the first 4k (1k for R3k) for > > either normal exception vector space (legacy CPUs) or special vectors > > like cache exceptions. > > > > Huge thanks to Serge for analysing and proposing a solution to this > > issue. > > > > 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> > > --- > > Changes in v3: > > - always reserve the first 4k for all CPUs (1k for R3k) > > > > Changes in v2: > > - do only memblock reservation in reserve_exception_space() > > - reserve 0..0x400 for all CPUs without ebase register and > > to addtional reserve_exception_space for BMIPS CPUs > > Thomas, do you mind CC'ing me for subsequent versions so you can get a > chance to have a Tested-by tag? Thank you!
sure, I hope it's the last version ;-)
> Tested-by: Florian Fainelli <f.fainelli@gmail.com>
thank you.
Thomas.
-- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]
| |