On Mon, Mar 22, 2021 at 07:44:05PM +0530, Naresh Kamboju wrote:

On Mon, 22 Mar 2021 at 18:14, Greg Kroah-Hartman
[off-list ref] wrote:

quoted

From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

[ Upstream commit bd67b711bfaa02cf19e88aa2d9edae5c1c1d2739 ]

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 <redacted>
Debugged-by: Serge Semin [off-list ref]
Acked-by: Mike Rapoport <redacted>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Serge Semin <redacted>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/mips/include/asm/traps.h    |  3 +++
 arch/mips/kernel/cpu-probe.c     |  6 ++++++
 arch/mips/kernel/cpu-r3k-probe.c |  3 +++
 arch/mips/kernel/traps.c         | 10 +++++-----

mipc tinyconfig and allnoconfig builds failed on stable-rc 5.10 branch

make --silent --keep-going --jobs=8
O=/home/tuxbuild/.cache/tuxmake/builds/1/tmp ARCH=mips
CROSS_COMPILE=mips-linux-gnu- 'CC=sccache mips-linux-gnu-gcc'
'HOSTCC=sccache gcc'
WARNING: modpost: vmlinux.o(.text+0x6a88): Section mismatch in
reference from the function reserve_exception_space() to the function
.meminit.text:memblock_reserve()
The function reserve_exception_space() references
the function __meminit memblock_reserve().
This is often because reserve_exception_space lacks a __meminit
annotation or the annotation of memblock_reserve is wrong.

FATAL: modpost: Section mismatches detected.
Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them.
make[2]: *** [/builds/linux/scripts/Makefile.modpost:59:
vmlinux.symvers] Error 1

Here is the list of build failed,
 - gcc-8-allnoconfig
 - gcc-8-tinyconfig
 - gcc-9-allnoconfig
 - gcc-9-tinyconfig
 - gcc-10-allnoconfig
 - gcc-10-tinyconfig
 - clang-10-tinyconfig
 - clang-10-allnoconfig
 - clang-11-allnoconfig
 - clang-11-tinyconfig
 - clang-12-tinyconfig
 - clang-12-allnoconfig

Reported-by: Naresh Kamboju <redacted>

link:
https://gitlab.com/Linaro/lkft/mirrors/stable/linux-stable-rc/-/jobs/1117167411#L142

steps to reproduce:
---------------------------
# TuxMake is a command line tool and Python library that provides
# portable and repeatable Linux kernel builds across a variety of
# architectures, toolchains, kernel configurations, and make targets.
#
# TuxMake supports the concept of runtimes.
# See https://docs.tuxmake.org/runtimes/, for that to work it requires
# that you install podman or docker on your system.
#
# To install tuxmake on your system globally:
# sudo pip3 install -U tuxmake
#
# See https://docs.tuxmake.org/ for complete documentation.


tuxmake --runtime podman --target-arch mips --toolchain gcc-10
--kconfig tinyconfig

Thanks for letting me know, I'll go drop this and push out a new -rc...

greg k-h