Commit 313151af authored Jan 20, 2020 by Vladimir Murzin Committed by Greg Kroah-Hartman Feb 05, 2020

ARM: 8955/1: virt: Relax arch timer version check during early boot



[ Upstream commit 6849b5eba1965ceb0cad3a75877ef4569dd3638e ]

Updates to the Generic Timer architecture allow ID_PFR1.GenTimer to
have values other than 0 or 1 while still preserving backward
compatibility. At the moment, Linux is quite strict in the way it
handles this field at early boot and will not configure arch timer if
it doesn't find the value 1.

Since here use ubfx for arch timer version extraction (hyb-stub build
with -march=armv7-a, so it is safe)

To help backports (even though the code was correct at the time of writing)

Fixes: 8ec58be9 ("ARM: virt: arch_timers: enable access to physical timers")
Acked-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent edb6590b

arch/arm/kernel/hyp-stub.S

+3 −4

Original line number	Diff line number	Diff line
		@@ -146,10 +146,9 @@ ARM_BE8(orr r7, r7, #(1 << 25)) @ HSCTLR.EE
		#if !defined(ZIMAGE) && defined(CONFIG_ARM_ARCH_TIMER)
		@ make CNTP_* and CNTPCT accessible from PL1
		mrc p15, 0, r7, c0, c1, 1 @ ID_PFR1
		lsr r7, #16
		and r7, #0xf
		cmp r7, #1
		bne 1f
		ubfx r7, r7, #16, #4
		teq r7, #0
		beq 1f
		mrc p15, 4, r7, c14, c1, 0 @ CNTHCTL
		orr r7, r7, #3 @ PL1PCEN \| PL1PCTEN
		mcr p15, 4, r7, c14, c1, 0 @ CNTHCTL