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authorgVisor bot <gvisor-bot@google.com>2021-04-10 00:35:45 +0000
committergVisor bot <gvisor-bot@google.com>2021-04-10 00:35:45 +0000
commitb49ed2038a13acf391f26a6b4ef7e7808b53103d (patch)
treec1e2be0fa174d273cb68a5a858c301302749ac89
parent4c57ae1fda3e3ae786efc905665bd3aa7b09a730 (diff)
parent7420821a7b5fe15f3666bb4971796cd45fc5ff38 (diff)
Merge release-20210408.0-15-g7420821a7 (automated)
-rw-r--r--pkg/ring0/kernel_amd64.go19
-rw-r--r--pkg/ring0/kernel_arm64.go6
-rw-r--r--pkg/ring0/lib_amd64.go6
-rw-r--r--pkg/ring0/lib_amd64.s12
-rw-r--r--pkg/sentry/arch/fpu/fpu_amd64.go5
5 files changed, 48 insertions, 0 deletions
diff --git a/pkg/ring0/kernel_amd64.go b/pkg/ring0/kernel_amd64.go
index 92d2330cb..41dfd0bf9 100644
--- a/pkg/ring0/kernel_amd64.go
+++ b/pkg/ring0/kernel_amd64.go
@@ -250,6 +250,7 @@ func (c *CPU) SwitchToUser(switchOpts SwitchOpts) (vector Vector) {
}
SaveFloatingPoint(switchOpts.FloatingPointState.BytePointer()) // escapes: no. Copy out floating point.
WriteFS(uintptr(c.registers.Fs_base)) // escapes: no. Restore kernel FS.
+ RestoreKernelFPState() // escapes: no. Restore kernel MXCSR.
return
}
@@ -321,3 +322,21 @@ func SetCPUIDFaulting(on bool) bool {
func ReadCR2() uintptr {
return readCR2()
}
+
+// kernelMXCSR is the value of the mxcsr register in the Sentry.
+//
+// The MXCSR control configuration is initialized once and never changed. Look
+// at src/cmd/compile/abi-internal.md in the golang sources for more details.
+var kernelMXCSR uint32
+
+// RestoreKernelFPState restores the Sentry floating point state.
+//
+//go:nosplit
+func RestoreKernelFPState() {
+ // Restore the MXCSR control configuration.
+ ldmxcsr(&kernelMXCSR)
+}
+
+func init() {
+ stmxcsr(&kernelMXCSR)
+}
diff --git a/pkg/ring0/kernel_arm64.go b/pkg/ring0/kernel_arm64.go
index 0496c40b4..21db910a2 100644
--- a/pkg/ring0/kernel_arm64.go
+++ b/pkg/ring0/kernel_arm64.go
@@ -89,3 +89,9 @@ func (c *CPU) SwitchToUser(switchOpts SwitchOpts) (vector Vector) {
return
}
+
+// RestoreKernelFPState restores the Sentry floating point state.
+//
+//go:nosplit
+func RestoreKernelFPState() {
+}
diff --git a/pkg/ring0/lib_amd64.go b/pkg/ring0/lib_amd64.go
index 0ec5c3bc5..3e6bb9663 100644
--- a/pkg/ring0/lib_amd64.go
+++ b/pkg/ring0/lib_amd64.go
@@ -61,6 +61,12 @@ func wrgsbase(addr uintptr)
// wrgsmsr writes to the GS_BASE MSR.
func wrgsmsr(addr uintptr)
+// stmxcsr reads the MXCSR control and status register.
+func stmxcsr(addr *uint32)
+
+// ldmxcsr writes to the MXCSR control and status register.
+func ldmxcsr(addr *uint32)
+
// readCR2 reads the current CR2 value.
func readCR2() uintptr
diff --git a/pkg/ring0/lib_amd64.s b/pkg/ring0/lib_amd64.s
index 2fe83568a..70a43e79e 100644
--- a/pkg/ring0/lib_amd64.s
+++ b/pkg/ring0/lib_amd64.s
@@ -198,3 +198,15 @@ TEXT ·rdmsr(SB),NOSPLIT,$0-16
MOVL AX, ret+8(FP)
MOVL DX, ret+12(FP)
RET
+
+// stmxcsr reads the MXCSR control and status register.
+TEXT ·stmxcsr(SB),NOSPLIT,$0-8
+ MOVQ addr+0(FP), SI
+ STMXCSR (SI)
+ RET
+
+// ldmxcsr writes to the MXCSR control and status register.
+TEXT ·ldmxcsr(SB),NOSPLIT,$0-8
+ MOVQ addr+0(FP), SI
+ LDMXCSR (SI)
+ RET
diff --git a/pkg/sentry/arch/fpu/fpu_amd64.go b/pkg/sentry/arch/fpu/fpu_amd64.go
index 1e9625bee..f0ba26736 100644
--- a/pkg/sentry/arch/fpu/fpu_amd64.go
+++ b/pkg/sentry/arch/fpu/fpu_amd64.go
@@ -219,6 +219,11 @@ func (s *State) PtraceSetXstateRegs(src io.Reader, maxlen int, featureSet *cpuid
return copy(*s, f), nil
}
+// SetMXCSR sets the MXCSR control/status register in the state.
+func (s *State) SetMXCSR(mxcsr uint32) {
+ hostarch.ByteOrder.PutUint32((*s)[mxcsrOffset:], mxcsr)
+}
+
// BytePointer returns a pointer to the first byte of the state.
//
//go:nosplit