Commit 64fd44dc authored by Marc Zyngier's avatar Marc Zyngier Committed by Albert ARIBAUD

ARM: non-sec: reset CNTVOFF to zero

Before switching to non-secure, make sure that CNTVOFF is set
to zero on all CPUs. Otherwise, kernel running in non-secure
without HYP enabled (hence using virtual timers) may observe
timers that are not synchronized, effectively seeing time
going backward...
Signed-off-by: default avatarMarc Zyngier <>
Acked-by: default avatarIan Campbell <>
parent 800c8352
......@@ -38,10 +38,10 @@ _secure_monitor:
bic r1, r1, #0x4e @ clear IRQ, FIQ, EA, nET bits
orr r1, r1, #0x31 @ enable NS, AW, FW bits
mrc p15, 0, r0, c0, c1, 1 @ read ID_PFR1
and r0, r0, #CPUID_ARM_VIRT_MASK @ mask virtualization bits
cmp r0, #(1 << CPUID_ARM_VIRT_SHIFT)
orreq r1, r1, #0x100 @ allow HVC instruction
......@@ -52,7 +52,14 @@ _secure_monitor:
mrceq p15, 0, r0, c12, c0, 1 @ get MVBAR value
mcreq p15, 4, r0, c12, c0, 0 @ write HVBAR
bne 1f
@ Reset CNTVOFF to 0 before leaving monitor mode
mrc p15, 0, r0, c0, c1, 1 @ read ID_PFR1
ands r0, r0, #CPUID_ARM_GENTIMER_MASK @ test arch timer bits
movne r0, #0
mcrrne p15, 4, r0, r0, c14 @ Reset CNTVOFF to zero
movs pc, lr @ return to non-secure SVC
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