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 5.4-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-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 88fa3140217d96d88474241f8e6c84211a277896 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 93dffed0ac6e0..cbe126297f549 100644 --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -1142,9 +1142,9 @@ __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 r12, lr