This is a note to let you know that I've just added the patch titled
arm64: entry: Restore tramp_map_kernel ISB
to the 4.9-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:
arm64-entry-restore-tramp_map_kernel-isb.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From james.morse@xxxxxxx Thu Jul 14 20:32:47 2022
From: James Morse <james.morse@xxxxxxx>
Date: Thu, 14 Jul 2022 17:22:25 +0100
Subject: arm64: entry: Restore tramp_map_kernel ISB
To: stable@xxxxxxxxxxxxxxx, linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>, James Morse <james.morse@xxxxxxx>, Sumit Gupta <sumitg@xxxxxxxxxx>
Message-ID: <20220714162225.280073-1-james.morse@xxxxxxx>
From: James Morse <james.morse@xxxxxxx>
Summit reports that the BHB backports for v4.9 prevent vulnerable
platforms from booting when CONFIG_RANDOMIZE_BASE is enabled.
This is because the trampoline code takes a translation fault when
accessing the data page, because the TTBR write hasn't been completed
by an ISB before the access is made.
Upstream has a complex erratum workaround for QCOM_FALKOR_E1003 in
this area, which removes the ISB when the workaround has been applied.
v4.9 lacks this workaround, but should still have the ISB.
Restore the barrier.
Fixes: aee10c2dd013 ("arm64: entry: Add macro for reading symbol addresses from the trampoline")
Reported-by: Sumit Gupta <sumitg@xxxxxxxxxx>
Tested-by: Sumit Gupta <sumitg@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: James Morse <james.morse@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/entry.S | 1 +
1 file changed, 1 insertion(+)
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -964,6 +964,7 @@ __ni_sys_trace:
b .
2:
tramp_map_kernel x30
+ isb
tramp_data_read_var x30, vectors
prfm plil1strm, [x30, #(1b - \vector_start)]
msr vbar_el1, x30
Patches currently in stable-queue which might be from james.morse@xxxxxxx are
queue-4.9/arm64-entry-restore-tramp_map_kernel-isb.patch
