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linux-sg2042/arch/arc
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Vineet Gupta 3b57533b46 ARC: [plat-hsdk] Remap CCMs super early in asm boot trampoline 
ARC HSDK platform stopped booting on released v5.10-rc1, getting stuck
in startup of non master SMP cores.

This was bisected to upstream commit 7fef431be9
"(mm/page_alloc: place pages to tail in __free_pages_core())"
That commit itself is harmless, it just exposed a subtle assumption in
our platform code (hence CC'ing linux-mm just as FYI in case some other
arches / platforms trip on it).

The upstream commit is semantically disruptive as it reverses the order
of page allocations (actually it can be good test for hardware
verification to exercise different memory patterns altogether).
For ARC HSDK platform that meant a remapped memory region (pertaining to
unused Closely Coupled Memory) started getting used early for dynamice
allocations, while not effectively remapped on all the cores, triggering
memory error exception on those cores.

The fix is to move the CCM remapping from early platform code to to early core
boot code. And while it is undesirable to riddle common boot code with
platform quirks, there is no other way to do this since the faltering code
involves setting up stack itself so even function calls are not allowed at
that point.

If anyone is interested, all the gory details can be found at Link below.

Link: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/32
Cc: David Hildenbrand <david@redhat.com>
Cc: linux-mm@kvack.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
 		2020-11-02 11:45:09 -08:00
..
boot ARC: [dts] fix the errors detected by dtbs_check 2020-10-05 21:02:29 -07:00
configs ARC: [plat-eznps]: Drop support for EZChip NPS platform 2020-10-05 21:02:29 -07:00
include treewide: Convert macro and uses of __section(foo) to __section("foo") 2020-10-25 14:51:49 -07:00
kernel ARC: [plat-hsdk] Remap CCMs super early in asm boot trampoline 2020-11-02 11:45:09 -08:00
lib treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
mm ARC changes for 5.10 2020-10-20 09:09:44 -07:00
oprofile treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
plat-axs10x treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
plat-hsdk ARC: [plat-hsdk] Remap CCMs super early in asm boot trampoline 2020-11-02 11:45:09 -08:00
plat-sim ARC: merge HAPS-HS with nSIM-HS configs 2019-10-28 12:12:31 -07:00
plat-tb10x treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333 2019-06-05 17:37:06 +02:00
Kbuild treewide: Add SPDX license identifier - Kbuild 2019-05-30 11:32:33 -07:00
Kconfig Merge branch 'work.set_fs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-22 09:59:21 -07:00
Kconfig.debug Kconfig: consolidate the "Kernel hacking" menu 2018-08-02 08:06:48 +09:00
Makefile ARC: [plat-eznps]: Drop support for EZChip NPS platform 2020-10-05 21:02:29 -07:00