From b574c715a799e476ac788e5f5b2c68f1a00b3538 Mon Sep 17 00:00:00 2001
From: Haibo Xu <haibo.xu@arm.com>
Date: Wed, 4 Mar 2020 05:44:46 +0000
Subject: Move pagetables.limitPCID to arch-specific file.
X86 provide 12 bits for PCID while arm64 support
8/16 bits ASID.
Signed-off-by: Haibo Xu <haibo.xu@arm.com>
Change-Id: I0bd9236e44e6b6c4c88eb6e9adc5ac27b918bf6c
---
pkg/sentry/platform/ring0/pagetables/BUILD | 3 ++
pkg/sentry/platform/ring0/pagetables/pcids.go | 5 +--
.../platform/ring0/pagetables/pcids_aarch64.go | 32 +++++++++++++++
.../platform/ring0/pagetables/pcids_aarch64.s | 45 ++++++++++++++++++++++
pkg/sentry/platform/ring0/pagetables/pcids_x86.go | 20 ++++++++++
5 files changed, 101 insertions(+), 4 deletions(-)
create mode 100644 pkg/sentry/platform/ring0/pagetables/pcids_aarch64.go
create mode 100644 pkg/sentry/platform/ring0/pagetables/pcids_aarch64.s
create mode 100644 pkg/sentry/platform/ring0/pagetables/pcids_x86.go
(limited to 'pkg/sentry/platform')
diff --git a/pkg/sentry/platform/ring0/pagetables/BUILD b/pkg/sentry/platform/ring0/pagetables/BUILD
index 581841555..16d5f478b 100644
--- a/pkg/sentry/platform/ring0/pagetables/BUILD
+++ b/pkg/sentry/platform/ring0/pagetables/BUILD
@@ -81,6 +81,9 @@ go_library(
"pagetables_arm64.go",
"pagetables_x86.go",
"pcids.go",
+ "pcids_aarch64.go",
+ "pcids_aarch64.s",
+ "pcids_x86.go",
"walker_amd64.go",
"walker_arm64.go",
"walker_empty.go",
diff --git a/pkg/sentry/platform/ring0/pagetables/pcids.go b/pkg/sentry/platform/ring0/pagetables/pcids.go
index 9206030bf..964496aac 100644
--- a/pkg/sentry/platform/ring0/pagetables/pcids.go
+++ b/pkg/sentry/platform/ring0/pagetables/pcids.go
@@ -18,9 +18,6 @@ import (
"gvisor.dev/gvisor/pkg/sync"
)
-// limitPCID is the number of valid PCIDs.
-const limitPCID = 4096
-
// PCIDs is a simple PCID database.
//
// This is not protected by locks and is thus suitable for use only with a
@@ -44,7 +41,7 @@ type PCIDs struct {
//
// Nil is returned iff the start and size are out of range.
func NewPCIDs(start, size uint16) *PCIDs {
- if start+uint16(size) >= limitPCID {
+ if start+uint16(size) > limitPCID {
return nil // See comment.
}
p := &PCIDs{
diff --git a/pkg/sentry/platform/ring0/pagetables/pcids_aarch64.go b/pkg/sentry/platform/ring0/pagetables/pcids_aarch64.go
new file mode 100644
index 000000000..fbfd41d83
--- /dev/null
+++ b/pkg/sentry/platform/ring0/pagetables/pcids_aarch64.go
@@ -0,0 +1,32 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build arm64
+
+package pagetables
+
+// limitPCID is the maximum value of PCIDs.
+//
+// In VMSAv8-64, the PCID(ASID) size is an IMPLEMENTATION DEFINED choice
+// of 8 bits or 16 bits, and ID_AA64MMFR0_EL1.ASIDBits identifies the
+// supported size. When an implementation supports a 16-bit ASID, TCR_ELx.AS
+// selects whether the top 8 bits of the ASID are used.
+var limitPCID uint16
+
+// GetASIDBits return the system ASID bits, 8 or 16 bits.
+func GetASIDBits() uint8
+
+func init() {
+ limitPCID = uint16(1)<<GetASIDBits() - 1
+}
diff --git a/pkg/sentry/platform/ring0/pagetables/pcids_aarch64.s b/pkg/sentry/platform/ring0/pagetables/pcids_aarch64.s
new file mode 100644
index 000000000..e9d62d768
--- /dev/null
+++ b/pkg/sentry/platform/ring0/pagetables/pcids_aarch64.s
@@ -0,0 +1,45 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build arm64
+
+#include "funcdata.h"
+#include "textflag.h"
+
+#define ID_AA64MMFR0_ASIDBITS_SHIFT 4
+#define ID_AA64MMFR0_ASIDBITS_16 2
+#define TCR_EL1_AS_BIT 36
+
+// GetASIDBits return the system ASID bits, 8 or 16 bits.
+//
+// func GetASIDBits() uint8
+TEXT ·GetASIDBits(SB),NOSPLIT,$0-1
+ // First, check whether 16bits ASID is supported.
+ // ID_AA64MMFR0_EL1.ASIDBITS[7:4] == 0010.
+ WORD $0xd5380700 // MRS ID_AA64MMFR0_EL1, R0
+ UBFX $ID_AA64MMFR0_ASIDBITS_SHIFT, R0, $4, R0
+ CMPW $ID_AA64MMFR0_ASIDBITS_16, R0
+ BNE bits_8
+
+ // Second, check whether 16bits ASID is enabled.
+ // TCR_EL1.AS[36] == 1.
+ WORD $0xd5382040 // MRS TCR_EL1, R0
+ TBZ $TCR_EL1_AS_BIT, R0, bits_8
+ MOVD $16, R0
+ B done
+bits_8:
+ MOVD $8, R0
+done:
+ MOVB R0, ret+0(FP)
+ RET
diff --git a/pkg/sentry/platform/ring0/pagetables/pcids_x86.go b/pkg/sentry/platform/ring0/pagetables/pcids_x86.go
new file mode 100644
index 000000000..91fc5e8dd
--- /dev/null
+++ b/pkg/sentry/platform/ring0/pagetables/pcids_x86.go
@@ -0,0 +1,20 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build i386 amd64
+
+package pagetables
+
+// limitPCID is the maximum value of valid PCIDs.
+const limitPCID = 4095
--
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