From 1557153cadb260706bc9721e50dc0797a2a8c48b Mon Sep 17 00:00:00 2001
From: Bin Lu <bin.lu@arm.com>
Date: Wed, 30 Sep 2020 10:16:02 +0800
Subject: arm64 kvm: add tls-usr support

The tls of guest-el1-sentry and host-el0-sentry may be different on Arm64.
I added a solution for it.

Signed-off-by: Bin Lu <bin.lu@arm.com>
---
 pkg/sentry/platform/kvm/bluepill_arm64.go | 13 +++++++++++++
 pkg/sentry/platform/kvm/bluepill_arm64.s  | 12 ++++++++++++
 2 files changed, 25 insertions(+)

(limited to 'pkg/sentry/platform/kvm')

diff --git a/pkg/sentry/platform/kvm/bluepill_arm64.go b/pkg/sentry/platform/kvm/bluepill_arm64.go
index ed5ae03d3..58f3d6fdd 100644
--- a/pkg/sentry/platform/kvm/bluepill_arm64.go
+++ b/pkg/sentry/platform/kvm/bluepill_arm64.go
@@ -39,6 +39,16 @@ var (
 	}
 )
 
+// getTLS returns the value of TPIDR_EL0 register.
+//
+//go:nosplit
+func getTLS() (value uint64)
+
+// setTLS writes the TPIDR_EL0 value.
+//
+//go:nosplit
+func setTLS(value uint64)
+
 // bluepillArchEnter is called during bluepillEnter.
 //
 //go:nosplit
@@ -51,6 +61,8 @@ func bluepillArchEnter(context *arch.SignalContext64) (c *vCPU) {
 	regs.Pstate = context.Pstate
 	regs.Pstate &^= uint64(ring0.PsrFlagsClear)
 	regs.Pstate |= ring0.KernelFlagsSet
+	regs.TPIDR_EL0 = getTLS()
+
 	return
 }
 
@@ -65,6 +77,7 @@ func bluepillArchExit(c *vCPU, context *arch.SignalContext64) {
 	context.Pstate = regs.Pstate
 	context.Pstate &^= uint64(ring0.PsrFlagsClear)
 	context.Pstate |= ring0.UserFlagsSet
+	setTLS(regs.TPIDR_EL0)
 
 	lazyVfp := c.GetLazyVFP()
 	if lazyVfp != 0 {
diff --git a/pkg/sentry/platform/kvm/bluepill_arm64.s b/pkg/sentry/platform/kvm/bluepill_arm64.s
index 04efa0147..09c7e88e5 100644
--- a/pkg/sentry/platform/kvm/bluepill_arm64.s
+++ b/pkg/sentry/platform/kvm/bluepill_arm64.s
@@ -32,6 +32,18 @@
 #define CONTEXT_PC  0x1B8
 #define CONTEXT_R0 0xB8
 
+// getTLS returns the value of TPIDR_EL0 register.
+TEXT ·getTLS(SB),NOSPLIT,$0-8
+	MRS TPIDR_EL0, R1
+	MOVD R1, ret+0(FP)
+	RET
+
+// setTLS writes the TPIDR_EL0 value.
+TEXT ·setTLS(SB),NOSPLIT,$0-8
+	MOVD addr+0(FP), R1
+	MSR R1, TPIDR_EL0
+	RET
+
 // See bluepill.go.
 TEXT ·bluepill(SB),NOSPLIT,$0
 begin:
-- 
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