From 6bad4851d4a04b5f56ade1f8ba68bd9c16471533 Mon Sep 17 00:00:00 2001
From: Jamie Liu <jamieliu@google.com>
Date: Thu, 8 Oct 2020 16:21:14 -0700
Subject: Implement MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ.

cf. 2a36ab717e8f "rseq/membarrier: Add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ"

PiperOrigin-RevId: 336186795
---
 pkg/sentry/mm/mm.go       |  6 ++++++
 pkg/sentry/mm/syscalls.go | 12 ++++++++++++
 2 files changed, 18 insertions(+)

(limited to 'pkg/sentry/mm')

diff --git a/pkg/sentry/mm/mm.go b/pkg/sentry/mm/mm.go
index 43567b92c..92cc87d84 100644
--- a/pkg/sentry/mm/mm.go
+++ b/pkg/sentry/mm/mm.go
@@ -243,6 +243,12 @@ type MemoryManager struct {
 	//
 	// membarrierPrivateEnabled is accessed using atomic memory operations.
 	membarrierPrivateEnabled uint32
+
+	// membarrierRSeqEnabled is non-zero if EnableMembarrierRSeq has previously
+	// been called.
+	//
+	// membarrierRSeqEnabled is accessed using atomic memory operations.
+	membarrierRSeqEnabled uint32
 }
 
 // vma represents a virtual memory area.
diff --git a/pkg/sentry/mm/syscalls.go b/pkg/sentry/mm/syscalls.go
index 0a66b1cdd..675efdc7c 100644
--- a/pkg/sentry/mm/syscalls.go
+++ b/pkg/sentry/mm/syscalls.go
@@ -1287,3 +1287,15 @@ func (mm *MemoryManager) EnableMembarrierPrivate() {
 func (mm *MemoryManager) IsMembarrierPrivateEnabled() bool {
 	return atomic.LoadUint32(&mm.membarrierPrivateEnabled) != 0
 }
+
+// EnableMembarrierRSeq causes future calls to IsMembarrierRSeqEnabled to
+// return true.
+func (mm *MemoryManager) EnableMembarrierRSeq() {
+	atomic.StoreUint32(&mm.membarrierRSeqEnabled, 1)
+}
+
+// IsMembarrierRSeqEnabled returns true if mm.EnableMembarrierRSeq() has
+// previously been called.
+func (mm *MemoryManager) IsMembarrierRSeqEnabled() bool {
+	return atomic.LoadUint32(&mm.membarrierRSeqEnabled) != 0
+}
-- 
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