This is a note to let you know that I've just added the patch titled
ARM: 9046/1: decompressor: Do not clear SCTLR.nTLSMD for ARMv7+ cores
to the 5.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm-9046-1-decompressor-do-not-clear-sctlr.ntlsmd-fo.patch
and it can be found in the queue-5.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit fc9b24eaaa85fab4b7718ac6a1e7795c2b2306fa
Author: Vladimir Murzin <vladimir.murzin@xxxxxxx>
Date: Thu Jan 7 10:47:24 2021 +0100
ARM: 9046/1: decompressor: Do not clear SCTLR.nTLSMD for ARMv7+ cores
[ Upstream commit 2acb909750431030b65a0a2a17fd8afcbd813a84 ]
It was observed that decompressor running on hardware implementing ARM v8.2
Load/Store Multiple Atomicity and Ordering Control (LSMAOC), say, as guest,
would stuck just after:
Uncompressing Linux... done, booting the kernel.
The reason is that it clears nTLSMD bit when disabling caches:
nTLSMD, bit [3]
When ARMv8.2-LSMAOC is implemented:
No Trap Load Multiple and Store Multiple to
Device-nGRE/Device-nGnRE/Device-nGnRnE memory.
0b0 All memory accesses by A32 and T32 Load Multiple and Store
Multiple at EL1 or EL0 that are marked at stage 1 as
Device-nGRE/Device-nGnRE/Device-nGnRnE memory are trapped and
generate a stage 1 Alignment fault.
0b1 All memory accesses by A32 and T32 Load Multiple and Store
Multiple at EL1 or EL0 that are marked at stage 1 as
Device-nGRE/Device-nGnRE/Device-nGnRnE memory are not trapped.
This bit is permitted to be cached in a TLB.
This field resets to 1.
Otherwise:
Reserved, RES1
So as effect we start getting traps we are not quite ready for.
Looking into history it seems that mask used for SCTLR clear came from
the similar code for ARMv4, where bit[3] is the enable/disable bit for
the write buffer. That not applicable to ARMv7 and onwards, so retire
that bit from the masks.
Fixes: 7d09e85448dfa78e3e58186c934449aaf6d49b50 ("[ARM] 4393/2: ARMv7: Add uncompressing code for the new CPU Id format")
Signed-off-by: Vladimir Murzin <vladimir.murzin@xxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index d9cce7238a365..73eee41826e2d 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -1164,9 +1164,9 @@ __armv4_mmu_cache_off:
__armv7_mmu_cache_off:
mrc p15, 0, r0, c1, c0
#ifdef CONFIG_MMU
- bic r0, r0, #0x000d
+ bic r0, r0, #0x0005
#else
- bic r0, r0, #0x000c
+ bic r0, r0, #0x0004
#endif
mcr p15, 0, r0, c1, c0 @ turn MMU and cache off
mov r0, #0
