From: Ilias Apalodimas <ilias.apalodimas@linaro.org>
To: linux-arm-kernel@lists.infradead.org
Cc: catalin.marinas@arm.com, labbott@redhat.com,
linux@armlinux.org.uk, mrutland@arm.com,
ard.biesheuvel@linaro.org
Subject: Memory size and section boundary on armv7
Date: Thu, 11 Apr 2019 18:13:20 +0300 [thread overview]
Message-ID: <20190411151320.GA23031@apalos> (raw)
Hello,
While experimenting with u-boot and booting the kernel as an EFI stub i seem to
hit an issue with memory mapping (map_lowmem).
I can only reproduce the crash when using u-boot's dtb (specified in
fdtcontroladdr) and pass that to the kernel, instead of loading an external one
with 'dtb=' on it's command line.
If CONFIG_ARM_LPAE=y, everything works fine. If the latter is not selected
though the kernel seems to crash only if dtb is placed on a section boundary.
The reason is crashes is the BUG_ON() on arm_pte_alloc() triggers.
fdt size is 0xc00 in both scenarios.
So something like this works fine:
In this case ff000 + c000 + f5000 = 200000
[ 0.000000] MAP addr: c7c00000, next c7e00000, phys c7c00000 len 200000
[ 0.000000] INI addr: c7e00000, next c7eff000, len ff000
[ 0.000000] INI addr: c7f0b000, next c8000000, len f5000
[ 0.000000] MAP addr: c8000000, next c8200000, phys c8000000 len 200000
In this working case kernel maps sizes ff000 and f5000 alloc_init_pte() and
skips the 0xc000 of the fdt correctly
The non-working case is:
[ 0.000000] MAP addr: c7e00000, next c7f00000, phys c7e00000 len 100000
[ 0.000000] INI addr: c7f0c000, next c8000000, len f4000
Both entries end up using the same pmd
I am not sure what's the best way to fix that.
Obviously skipping the alloc_init_pte() once this case is detected fixes things,
but is there a better idea?
Thanks
/Ilias
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next reply other threads:[~2019-04-11 15:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-11 15:13 Ilias Apalodimas [this message]
2019-04-11 15:41 ` Memory size and section boundary on armv7 Russell King - ARM Linux admin
2019-04-11 15:50 ` Ilias Apalodimas
2019-04-11 16:22 ` Russell King - ARM Linux admin
2019-04-12 5:23 ` Ilias Apalodimas
2019-04-12 8:40 ` Russell King - ARM Linux admin
2019-04-12 10:10 ` Ilias Apalodimas
2019-04-12 11:16 ` Russell King - ARM Linux admin
2019-04-12 11:26 ` Ilias Apalodimas
2019-04-12 11:43 ` Ilias Apalodimas
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