keep user vdso base addr in task.mm

we need a convient method to get the userspace addr of the loaded vdso
page. For example, vdso is required for aarch64 to set up the return
trampoline for sigreturn. This is a mockup and may need refactoring.

Signed-off-by: Tianhao Wang <[email protected]>

Author: shrik3

qlib/kernel/loader/loader.rs

@@ -279,6 +279,7 @@ pub fn Load(
     extraAuxv: &[AuxEntry],
 ) -> Result<(u64, u64, u64)> {
     let vdsoAddr = LoadVDSO(task)?;
+    task.mm.SetUserVDSOBase(vdsoAddr);
 
     let (loaded, executable, tmpArgv) = LoadExecutable(task, filename, argv)?;
     let argv = tmpArgv;

qlib/kernel/memmgr/mm.rs

@@ -158,6 +158,7 @@ pub struct MemoryManagerInternal {
     pub vcpuMapping: AtomicU64,
     pub tlbShootdownMask: AtomicU64,
 
+    pub userVDSOBase: AtomicU64,
     pub mappingLock: QUpgradableLock,
     pub mapping: QMutex<MMMapping>,
 
@@ -284,6 +285,7 @@ impl MemoryManager {
             inited: true,
             vcpuMapping: AtomicU64::new(0),
             tlbShootdownMask: AtomicU64::new(0),
+            userVDSOBase: AtomicU64::new(0),
             mappingLock: QUpgradableLock::default(),
             mapping: QMutex::new(mapping),
             pagetable: QRwLock::new(pagetable),
@@ -299,6 +301,14 @@ impl MemoryManager {
         return mm;
     }
 
+    pub fn SetUserVDSOBase(&self, addr: u64) {
+        return self.userVDSOBase.store(addr, Ordering::Release);
+    }
+
+    pub fn GetUserVDSOBase(&self) -> u64 {
+        return self.userVDSOBase.load(Ordering::Acquire);
+    }
+
     pub fn EnableMembarrierPrivate(&self) {
         return self.membarrierPrivateEnabled.store(true, Ordering::Release);
     }
@@ -1526,6 +1536,9 @@ impl MemoryManager {
             let ptInternal1 = self.pagetable.write();
             let mut ptInternal2 = mm2.pagetable.write();
 
+            let vdsoAddr = self.GetUserVDSOBase();
+            mm2.SetUserVDSOBase(vdsoAddr);
+
             ptInternal2.sharedLoadsOffset = ptInternal1.sharedLoadsOffset;
             ptInternal2.curRSS = ptInternal1.curRSS;
             ptInternal2.maxRSS = ptInternal1.maxRSS;