From: Marc Zyngier Date: Mon, 17 Oct 2016 12:47:34 +0000 (+0100) Subject: arm64: kernel: Init MDCR_EL2 even in the absence of a PMU X-Git-Tag: firefly_0821_release~176^2~4^2~22^2~12 X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=08cd19c602145b75e2782831e1822f6fe7f560c9;p=firefly-linux-kernel-4.4.55.git arm64: kernel: Init MDCR_EL2 even in the absence of a PMU commit 850540351bb1a4fa5f192e5ce55b89928cc57f42 upstream. Commit f436b2ac90a0 ("arm64: kernel: fix architected PMU registers unconditional access") made sure we wouldn't access unimplemented PMU registers, but also left MDCR_EL2 uninitialized in that case, leading to trap bits being potentially left set. Make sure we always write something in that register. Fixes: f436b2ac90a0 ("arm64: kernel: fix architected PMU registers unconditional access") Cc: Lorenzo Pieralisi Cc: Will Deacon Signed-off-by: Marc Zyngier Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index b685257926f0..20ceb5edf7b8 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -518,8 +518,9 @@ CPU_LE( movk x0, #0x30d0, lsl #16 ) // Clear EE and E0E on LE systems b.lt 4f // Skip if no PMU present mrs x0, pmcr_el0 // Disable debug access traps ubfx x0, x0, #11, #5 // to EL2 and allow access to - msr mdcr_el2, x0 // all PMU counters from EL1 4: + csel x0, xzr, x0, lt // all PMU counters from EL1 + msr mdcr_el2, x0 // (if they exist) /* Stage-2 translation */ msr vttbr_el2, xzr