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