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Diffstat (limited to 'pkg/sentry/mm/syscalls.go')
-rw-r--r--pkg/sentry/mm/syscalls.go423
1 files changed, 367 insertions, 56 deletions
diff --git a/pkg/sentry/mm/syscalls.go b/pkg/sentry/mm/syscalls.go
index daaae4da1..383703ec3 100644
--- a/pkg/sentry/mm/syscalls.go
+++ b/pkg/sentry/mm/syscalls.go
@@ -20,6 +20,7 @@ import (
"gvisor.googlesource.com/gvisor/pkg/abi/linux"
"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+ "gvisor.googlesource.com/gvisor/pkg/sentry/kernel/auth"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/futex"
"gvisor.googlesource.com/gvisor/pkg/sentry/limits"
"gvisor.googlesource.com/gvisor/pkg/sentry/memmap"
@@ -128,16 +129,24 @@ func (mm *MemoryManager) MMap(ctx context.Context, opts memmap.MMapOpts) (userme
// Get the new vma.
mm.mappingMu.Lock()
+ if opts.MLockMode < mm.defMLockMode {
+ opts.MLockMode = mm.defMLockMode
+ }
vseg, ar, err := mm.createVMALocked(ctx, opts)
if err != nil {
mm.mappingMu.Unlock()
return 0, err
}
+ // TODO: In Linux, VM_LOCKONFAULT (which may be set on the new
+ // vma by mlockall(MCL_FUTURE|MCL_ONFAULT) => mm_struct::def_flags) appears
+ // to effectively disable MAP_POPULATE by unsetting FOLL_POPULATE in
+ // mm/util.c:vm_mmap_pgoff() => mm/gup.c:__mm_populate() =>
+ // populate_vma_page_range(). Confirm this behavior.
switch {
- case opts.Precommit:
+ case opts.Precommit || opts.MLockMode == memmap.MLockEager:
// Get pmas and map with precommit as requested.
- mm.populateAndUnlock(ctx, vseg, ar, true)
+ mm.populateVMAAndUnlock(ctx, vseg, ar, true)
case opts.Mappable == nil && length <= privateAllocUnit:
// NOTE: Get pmas and map eagerly in the hope
@@ -146,7 +155,7 @@ func (mm *MemoryManager) MMap(ctx context.Context, opts memmap.MMapOpts) (userme
// memmap.Mappable.Translate is unknown; and only for small mappings,
// to avoid needing to allocate large amounts of memory that we may
// subsequently need to checkpoint.
- mm.populateAndUnlock(ctx, vseg, ar, false)
+ mm.populateVMAAndUnlock(ctx, vseg, ar, false)
default:
mm.mappingMu.Unlock()
@@ -155,31 +164,29 @@ func (mm *MemoryManager) MMap(ctx context.Context, opts memmap.MMapOpts) (userme
return ar.Start, nil
}
-// Preconditions: mm.mappingMu must be locked for writing.
+// populateVMA obtains pmas for addresses in ar in the given vma, and maps them
+// into mm.as if it is active.
//
-// Postconditions: mm.mappingMu will be unlocked.
-func (mm *MemoryManager) populateAndUnlock(ctx context.Context, vseg vmaIterator, ar usermem.AddrRange, precommit bool) {
+// Preconditions: mm.mappingMu must be locked. vseg.Range().IsSupersetOf(ar).
+func (mm *MemoryManager) populateVMA(ctx context.Context, vseg vmaIterator, ar usermem.AddrRange, precommit bool) {
if !vseg.ValuePtr().effectivePerms.Any() {
// Linux doesn't populate inaccessible pages. See
// mm/gup.c:populate_vma_page_range.
- mm.mappingMu.Unlock()
return
}
mm.activeMu.Lock()
+ // Can't defer mm.activeMu.Unlock(); see below.
- // Even if we get a new pma, we can't actually map it if we don't have an
+ // Even if we get new pmas, we can't actually map them if we don't have an
// AddressSpace.
if mm.as == nil {
mm.activeMu.Unlock()
- mm.mappingMu.Unlock()
return
}
// Ensure that we have usable pmas.
- mm.mappingMu.DowngradeLock()
pseg, _, err := mm.getPMAsLocked(ctx, vseg, ar, pmaOpts{})
- mm.mappingMu.RUnlock()
if err != nil {
// mm/util.c:vm_mmap_pgoff() ignores the error, if any, from
// mm/gup.c:mm_populate(). If it matters, we'll get it again when
@@ -197,6 +204,45 @@ func (mm *MemoryManager) populateAndUnlock(ctx context.Context, vseg vmaIterator
mm.activeMu.RUnlock()
}
+// populateVMAAndUnlock is equivalent to populateVMA, but also unconditionally
+// unlocks mm.mappingMu. In cases where populateVMAAndUnlock is usable, it is
+// preferable to populateVMA since it unlocks mm.mappingMu before performing
+// expensive operations that don't require it to be locked.
+//
+// Preconditions: mm.mappingMu must be locked for writing.
+// vseg.Range().IsSupersetOf(ar).
+//
+// Postconditions: mm.mappingMu will be unlocked.
+func (mm *MemoryManager) populateVMAAndUnlock(ctx context.Context, vseg vmaIterator, ar usermem.AddrRange, precommit bool) {
+ // See populateVMA above for commentary.
+ if !vseg.ValuePtr().effectivePerms.Any() {
+ mm.mappingMu.Unlock()
+ return
+ }
+
+ mm.activeMu.Lock()
+
+ if mm.as == nil {
+ mm.activeMu.Unlock()
+ mm.mappingMu.Unlock()
+ return
+ }
+
+ // mm.mappingMu doesn't need to be write-locked for getPMAsLocked, and it
+ // isn't needed at all for mapASLocked.
+ mm.mappingMu.DowngradeLock()
+ pseg, _, err := mm.getPMAsLocked(ctx, vseg, ar, pmaOpts{})
+ mm.mappingMu.RUnlock()
+ if err != nil {
+ mm.activeMu.Unlock()
+ return
+ }
+
+ mm.activeMu.DowngradeLock()
+ mm.mapASLocked(pseg, ar, precommit)
+ mm.activeMu.RUnlock()
+}
+
// MapStack allocates the initial process stack.
func (mm *MemoryManager) MapStack(ctx context.Context) (usermem.AddrRange, error) {
// maxStackSize is the maximum supported process stack size in bytes.
@@ -236,6 +282,7 @@ func (mm *MemoryManager) MapStack(ctx context.Context) (usermem.AddrRange, error
MaxPerms: usermem.AnyAccess,
Private: true,
GrowsDown: true,
+ MLockMode: mm.defMLockMode,
Hint: "[stack]",
})
return ar, err
@@ -334,6 +381,19 @@ func (mm *MemoryManager) MRemap(ctx context.Context, oldAddr usermem.Addr, oldSi
// occupies at least part of the destination. Thus the NoMove case always
// fails and the MayMove case always falls back to copying.
+ if vma := vseg.ValuePtr(); newSize > oldSize && vma.mlockMode != memmap.MLockNone {
+ // Check against RLIMIT_MEMLOCK. Unlike mmap, mlock, and mlockall,
+ // mremap in Linux does not check mm/mlock.c:can_do_mlock() and
+ // therefore does not return EPERM if RLIMIT_MEMLOCK is 0 and
+ // !CAP_IPC_LOCK.
+ mlockLimit := limits.FromContext(ctx).Get(limits.MemoryLocked).Cur
+ if creds := auth.CredentialsFromContext(ctx); !creds.HasCapabilityIn(linux.CAP_IPC_LOCK, creds.UserNamespace.Root()) {
+ if newLockedAS := mm.lockedAS - oldSize + newSize; newLockedAS > mlockLimit {
+ return 0, syserror.EAGAIN
+ }
+ }
+ }
+
if opts.Move != MRemapMustMove {
// Handle no-ops and in-place shrinking. These cases don't care if
// [oldAddr, oldEnd) maps to a single vma, or is even mapped at all
@@ -360,7 +420,7 @@ func (mm *MemoryManager) MRemap(ctx context.Context, oldAddr usermem.Addr, oldSi
if vma.mappable != nil {
newOffset = vseg.mappableRange().End
}
- _, _, err := mm.createVMALocked(ctx, memmap.MMapOpts{
+ vseg, ar, err := mm.createVMALocked(ctx, memmap.MMapOpts{
Length: newSize - oldSize,
MappingIdentity: vma.id,
Mappable: vma.mappable,
@@ -371,9 +431,13 @@ func (mm *MemoryManager) MRemap(ctx context.Context, oldAddr usermem.Addr, oldSi
MaxPerms: vma.maxPerms,
Private: vma.private,
GrowsDown: vma.growsDown,
+ MLockMode: vma.mlockMode,
Hint: vma.hint,
})
if err == nil {
+ if vma.mlockMode == memmap.MLockEager {
+ mm.populateVMA(ctx, vseg, ar, true)
+ }
return oldAddr, nil
}
// In-place growth failed. In the MRemapMayMove case, fall through to
@@ -462,8 +526,14 @@ func (mm *MemoryManager) MRemap(ctx context.Context, oldAddr usermem.Addr, oldSi
if vma.id != nil {
vma.id.IncRef()
}
- mm.vmas.Add(newAR, vma)
+ vseg := mm.vmas.Insert(mm.vmas.FindGap(newAR.Start), newAR, vma)
mm.usageAS += uint64(newAR.Length())
+ if vma.mlockMode != memmap.MLockNone {
+ mm.lockedAS += uint64(newAR.Length())
+ if vma.mlockMode == memmap.MLockEager {
+ mm.populateVMA(ctx, vseg, newAR, true)
+ }
+ }
return newAR.Start, nil
}
@@ -485,8 +555,11 @@ func (mm *MemoryManager) MRemap(ctx context.Context, oldAddr usermem.Addr, oldSi
vseg = mm.vmas.Isolate(vseg, oldAR)
vma := vseg.Value()
mm.vmas.Remove(vseg)
- mm.vmas.Add(newAR, vma)
+ vseg = mm.vmas.Insert(mm.vmas.FindGap(newAR.Start), newAR, vma)
mm.usageAS = mm.usageAS - uint64(oldAR.Length()) + uint64(newAR.Length())
+ if vma.mlockMode != memmap.MLockNone {
+ mm.lockedAS = mm.lockedAS - uint64(oldAR.Length()) + uint64(newAR.Length())
+ }
// Move pmas. This is technically optional for non-private pmas, which
// could just go through memmap.Mappable.Translate again, but it's required
@@ -501,6 +574,10 @@ func (mm *MemoryManager) MRemap(ctx context.Context, oldAddr usermem.Addr, oldSi
vma.mappable.RemoveMapping(ctx, mm, oldAR, vma.off, vma.isMappableAsWritable())
}
+ if vma.mlockMode == memmap.MLockEager {
+ mm.populateVMA(ctx, vseg, newAR, true)
+ }
+
return newAR.Start, nil
}
@@ -611,9 +688,10 @@ func (mm *MemoryManager) BrkSetup(ctx context.Context, addr usermem.Addr) {
// error on failure.
func (mm *MemoryManager) Brk(ctx context.Context, addr usermem.Addr) (usermem.Addr, error) {
mm.mappingMu.Lock()
- defer mm.mappingMu.Unlock()
+ // Can't defer mm.mappingMu.Unlock(); see below.
if addr < mm.brk.Start {
+ mm.mappingMu.Unlock()
return mm.brk.End, syserror.EINVAL
}
@@ -623,21 +701,24 @@ func (mm *MemoryManager) Brk(ctx context.Context, addr usermem.Addr) (usermem.Ad
// heap + data + bss. The segment sizes need to be plumbed from the
// loader package to fully enforce RLIMIT_DATA.
if uint64(addr-mm.brk.Start) > limits.FromContext(ctx).Get(limits.Data).Cur {
+ mm.mappingMu.Unlock()
return mm.brk.End, syserror.ENOMEM
}
oldbrkpg, _ := mm.brk.End.RoundUp()
newbrkpg, ok := addr.RoundUp()
if !ok {
+ mm.mappingMu.Unlock()
return mm.brk.End, syserror.EFAULT
}
switch {
case newbrkpg < oldbrkpg:
mm.unmapLocked(ctx, usermem.AddrRange{newbrkpg, oldbrkpg})
+ mm.mappingMu.Unlock()
case oldbrkpg < newbrkpg:
- _, _, err := mm.createVMALocked(ctx, memmap.MMapOpts{
+ vseg, ar, err := mm.createVMALocked(ctx, memmap.MMapOpts{
Length: uint64(newbrkpg - oldbrkpg),
Addr: oldbrkpg,
Fixed: true,
@@ -646,17 +727,221 @@ func (mm *MemoryManager) Brk(ctx context.Context, addr usermem.Addr) (usermem.Ad
Perms: usermem.ReadWrite,
MaxPerms: usermem.AnyAccess,
Private: true,
- Hint: "[heap]",
+ // Linux: mm/mmap.c:sys_brk() => do_brk_flags() includes
+ // mm->def_flags.
+ MLockMode: mm.defMLockMode,
+ Hint: "[heap]",
})
if err != nil {
+ mm.mappingMu.Unlock()
return mm.brk.End, err
}
+ if mm.defMLockMode == memmap.MLockEager {
+ mm.populateVMAAndUnlock(ctx, vseg, ar, true)
+ } else {
+ mm.mappingMu.Unlock()
+ }
+
+ default:
+ // Nothing to do.
+ mm.mappingMu.Unlock()
}
mm.brk.End = addr
return addr, nil
}
+// MLock implements the semantics of Linux's mlock()/mlock2()/munlock(),
+// depending on mode.
+func (mm *MemoryManager) MLock(ctx context.Context, addr usermem.Addr, length uint64, mode memmap.MLockMode) error {
+ // Linux allows this to overflow.
+ la, _ := usermem.Addr(length + addr.PageOffset()).RoundUp()
+ ar, ok := addr.RoundDown().ToRange(uint64(la))
+ if !ok {
+ return syserror.EINVAL
+ }
+
+ mm.mappingMu.Lock()
+ // Can't defer mm.mappingMu.Unlock(); see below.
+
+ if mode != memmap.MLockNone {
+ // Check against RLIMIT_MEMLOCK.
+ if creds := auth.CredentialsFromContext(ctx); !creds.HasCapabilityIn(linux.CAP_IPC_LOCK, creds.UserNamespace.Root()) {
+ mlockLimit := limits.FromContext(ctx).Get(limits.MemoryLocked).Cur
+ if mlockLimit == 0 {
+ mm.mappingMu.Unlock()
+ return syserror.EPERM
+ }
+ if newLockedAS := mm.lockedAS + uint64(ar.Length()) - mm.mlockedBytesRangeLocked(ar); newLockedAS > mlockLimit {
+ mm.mappingMu.Unlock()
+ return syserror.ENOMEM
+ }
+ }
+ }
+
+ // Check this after RLIMIT_MEMLOCK for consistency with Linux.
+ if ar.Length() == 0 {
+ mm.mappingMu.Unlock()
+ return nil
+ }
+
+ // Apply the new mlock mode to vmas.
+ var unmapped bool
+ vseg := mm.vmas.FindSegment(ar.Start)
+ for {
+ if !vseg.Ok() {
+ unmapped = true
+ break
+ }
+ vseg = mm.vmas.Isolate(vseg, ar)
+ vma := vseg.ValuePtr()
+ prevMode := vma.mlockMode
+ vma.mlockMode = mode
+ if mode != memmap.MLockNone && prevMode == memmap.MLockNone {
+ mm.lockedAS += uint64(vseg.Range().Length())
+ } else if mode == memmap.MLockNone && prevMode != memmap.MLockNone {
+ mm.lockedAS -= uint64(vseg.Range().Length())
+ }
+ if ar.End <= vseg.End() {
+ break
+ }
+ vseg, _ = vseg.NextNonEmpty()
+ }
+ mm.vmas.MergeRange(ar)
+ mm.vmas.MergeAdjacent(ar)
+ if unmapped {
+ mm.mappingMu.Unlock()
+ return syserror.ENOMEM
+ }
+
+ if mode == memmap.MLockEager {
+ // Ensure that we have usable pmas. Since we didn't return ENOMEM
+ // above, ar must be fully covered by vmas, so we can just use
+ // NextSegment below.
+ mm.activeMu.Lock()
+ mm.mappingMu.DowngradeLock()
+ for vseg := mm.vmas.FindSegment(ar.Start); vseg.Ok() && vseg.Start() < ar.End; vseg = vseg.NextSegment() {
+ if !vseg.ValuePtr().effectivePerms.Any() {
+ // Linux: mm/gup.c:__get_user_pages() returns EFAULT in this
+ // case, which is converted to ENOMEM by mlock.
+ mm.activeMu.Unlock()
+ mm.mappingMu.RUnlock()
+ return syserror.ENOMEM
+ }
+ _, _, err := mm.getPMAsLocked(ctx, vseg, vseg.Range().Intersect(ar), pmaOpts{})
+ if err != nil {
+ mm.activeMu.Unlock()
+ mm.mappingMu.RUnlock()
+ // Linux: mm/mlock.c:__mlock_posix_error_return()
+ if err == syserror.EFAULT {
+ return syserror.ENOMEM
+ }
+ if err == syserror.ENOMEM {
+ return syserror.EAGAIN
+ }
+ return err
+ }
+ }
+
+ // Map pmas into the active AddressSpace, if we have one.
+ mm.mappingMu.RUnlock()
+ if mm.as != nil {
+ mm.activeMu.DowngradeLock()
+ err := mm.mapASLocked(mm.pmas.LowerBoundSegment(ar.Start), ar, true /* precommit */)
+ mm.activeMu.RUnlock()
+ if err != nil {
+ return err
+ }
+ } else {
+ mm.activeMu.Unlock()
+ }
+ } else {
+ mm.mappingMu.Unlock()
+ }
+
+ return nil
+}
+
+// MLockAllOpts holds options to MLockAll.
+type MLockAllOpts struct {
+ // If Current is true, change the memory-locking behavior of all mappings
+ // to Mode. If Future is true, upgrade the memory-locking behavior of all
+ // future mappings to Mode. At least one of Current or Future must be true.
+ Current bool
+ Future bool
+ Mode memmap.MLockMode
+}
+
+// MLockAll implements the semantics of Linux's mlockall()/munlockall(),
+// depending on opts.
+func (mm *MemoryManager) MLockAll(ctx context.Context, opts MLockAllOpts) error {
+ if !opts.Current && !opts.Future {
+ return syserror.EINVAL
+ }
+
+ mm.mappingMu.Lock()
+ // Can't defer mm.mappingMu.Unlock(); see below.
+
+ if opts.Current {
+ if opts.Mode != memmap.MLockNone {
+ // Check against RLIMIT_MEMLOCK.
+ if creds := auth.CredentialsFromContext(ctx); !creds.HasCapabilityIn(linux.CAP_IPC_LOCK, creds.UserNamespace.Root()) {
+ mlockLimit := limits.FromContext(ctx).Get(limits.MemoryLocked).Cur
+ if mlockLimit == 0 {
+ mm.mappingMu.Unlock()
+ return syserror.EPERM
+ }
+ if uint64(mm.vmas.Span()) > mlockLimit {
+ mm.mappingMu.Unlock()
+ return syserror.ENOMEM
+ }
+ }
+ }
+ for vseg := mm.vmas.FirstSegment(); vseg.Ok(); vseg = vseg.NextSegment() {
+ vma := vseg.ValuePtr()
+ prevMode := vma.mlockMode
+ vma.mlockMode = opts.Mode
+ if opts.Mode != memmap.MLockNone && prevMode == memmap.MLockNone {
+ mm.lockedAS += uint64(vseg.Range().Length())
+ } else if opts.Mode == memmap.MLockNone && prevMode != memmap.MLockNone {
+ mm.lockedAS -= uint64(vseg.Range().Length())
+ }
+ }
+ }
+
+ if opts.Future {
+ mm.defMLockMode = opts.Mode
+ }
+
+ if opts.Current && opts.Mode == memmap.MLockEager {
+ // Linux: mm/mlock.c:sys_mlockall() => include/linux/mm.h:mm_populate()
+ // ignores the return value of __mm_populate(), so all errors below are
+ // ignored.
+ //
+ // Try to get usable pmas.
+ mm.activeMu.Lock()
+ mm.mappingMu.DowngradeLock()
+ for vseg := mm.vmas.FirstSegment(); vseg.Ok(); vseg = vseg.NextSegment() {
+ if vseg.ValuePtr().effectivePerms.Any() {
+ mm.getPMAsLocked(ctx, vseg, vseg.Range(), pmaOpts{})
+ }
+ }
+
+ // Map all pmas into the active AddressSpace, if we have one.
+ mm.mappingMu.RUnlock()
+ if mm.as != nil {
+ mm.activeMu.DowngradeLock()
+ mm.mapASLocked(mm.pmas.FirstSegment(), mm.applicationAddrRange(), true /* precommit */)
+ mm.activeMu.RUnlock()
+ } else {
+ mm.activeMu.Unlock()
+ }
+ } else {
+ mm.mappingMu.Unlock()
+ }
+ return nil
+}
+
// Decommit implements the semantics of Linux's madvise(MADV_DONTNEED).
func (mm *MemoryManager) Decommit(addr usermem.Addr, length uint64) error {
ar, ok := addr.ToRange(length)
@@ -680,46 +965,49 @@ func (mm *MemoryManager) Decommit(addr usermem.Addr, length uint64) error {
// ensures that Decommit immediately reduces host memory usage.
var didUnmapAS bool
pseg := mm.pmas.LowerBoundSegment(ar.Start)
- vseg := mm.vmas.LowerBoundSegment(ar.Start)
mem := mm.p.Memory()
- for pseg.Ok() && pseg.Start() < ar.End {
- pma := pseg.ValuePtr()
- if pma.private && !mm.isPMACopyOnWriteLocked(pseg) {
- psegAR := pseg.Range().Intersect(ar)
- vseg = vseg.seekNextLowerBound(psegAR.Start)
- if checkInvariants {
- if !vseg.Ok() {
- panic(fmt.Sprintf("no vma after %#x", psegAR.Start))
- }
- if psegAR.Start < vseg.Start() {
- panic(fmt.Sprintf("no vma in [%#x, %#x)", psegAR.Start, vseg.Start()))
- }
+ for vseg := mm.vmas.LowerBoundSegment(ar.Start); vseg.Ok() && vseg.Start() < ar.End; vseg = vseg.NextSegment() {
+ vma := vseg.ValuePtr()
+ if vma.mlockMode != memmap.MLockNone {
+ return syserror.EINVAL
+ }
+ vsegAR := vseg.Range().Intersect(ar)
+ // pseg should already correspond to either this vma or a later one,
+ // since there can't be a pma without a corresponding vma.
+ if checkInvariants {
+ if pseg.Ok() && pseg.End() <= vsegAR.Start {
+ panic(fmt.Sprintf("pma %v precedes vma %v", pseg.Range(), vsegAR))
}
- if vseg.Range().IsSupersetOf(psegAR) && vseg.ValuePtr().mappable == nil {
- if err := mem.Decommit(pseg.fileRangeOf(psegAR)); err == nil {
- pseg = pseg.NextSegment()
- continue
+ }
+ for pseg.Ok() && pseg.Start() < vsegAR.End {
+ pma := pseg.ValuePtr()
+ if pma.private && !mm.isPMACopyOnWriteLocked(pseg) {
+ psegAR := pseg.Range().Intersect(ar)
+ if vsegAR.IsSupersetOf(psegAR) && vma.mappable == nil {
+ if err := mem.Decommit(pseg.fileRangeOf(psegAR)); err == nil {
+ pseg = pseg.NextSegment()
+ continue
+ }
+ // If an error occurs, fall through to the general
+ // invalidation case below.
}
- // If an error occurs, fall through to the general
- // invalidation case below.
}
+ pseg = mm.pmas.Isolate(pseg, vsegAR)
+ pma = pseg.ValuePtr()
+ if !didUnmapAS {
+ // Unmap all of ar, not just pseg.Range(), to minimize host
+ // syscalls. AddressSpace mappings must be removed before
+ // mm.decPrivateRef().
+ mm.unmapASLocked(ar)
+ didUnmapAS = true
+ }
+ if pma.private {
+ mm.decPrivateRef(pseg.fileRange())
+ }
+ pma.file.DecRef(pseg.fileRange())
+ mm.removeRSSLocked(pseg.Range())
+ pseg = mm.pmas.Remove(pseg).NextSegment()
}
- pseg = mm.pmas.Isolate(pseg, ar)
- pma = pseg.ValuePtr()
- if !didUnmapAS {
- // Unmap all of ar, not just pseg.Range(), to minimize host
- // syscalls. AddressSpace mappings must be removed before
- // mm.decPrivateRef().
- mm.unmapASLocked(ar)
- didUnmapAS = true
- }
- if pma.private {
- mm.decPrivateRef(pseg.fileRange())
- }
- pma.file.DecRef(pseg.fileRange())
- mm.removeRSSLocked(pseg.Range())
-
- pseg = mm.pmas.Remove(pseg).NextSegment()
}
// "If there are some parts of the specified address space that are not
@@ -732,9 +1020,28 @@ func (mm *MemoryManager) Decommit(addr usermem.Addr, length uint64) error {
return nil
}
-// Sync implements the semantics of Linux's msync(MS_SYNC).
-func (mm *MemoryManager) Sync(ctx context.Context, addr usermem.Addr, length uint64) error {
- ar, ok := addr.ToRange(length)
+// MSyncOpts holds options to MSync.
+type MSyncOpts struct {
+ // Sync has the semantics of MS_SYNC.
+ Sync bool
+
+ // Invalidate has the semantics of MS_INVALIDATE.
+ Invalidate bool
+}
+
+// MSync implements the semantics of Linux's msync().
+func (mm *MemoryManager) MSync(ctx context.Context, addr usermem.Addr, length uint64, opts MSyncOpts) error {
+ if addr != addr.RoundDown() {
+ return syserror.EINVAL
+ }
+ if length == 0 {
+ return nil
+ }
+ la, ok := usermem.Addr(length).RoundUp()
+ if !ok {
+ return syserror.ENOMEM
+ }
+ ar, ok := addr.ToRange(uint64(la))
if !ok {
return syserror.ENOMEM
}
@@ -759,10 +1066,14 @@ func (mm *MemoryManager) Sync(ctx context.Context, addr usermem.Addr, length uin
}
lastEnd = vseg.End()
vma := vseg.ValuePtr()
+ if opts.Invalidate && vma.mlockMode != memmap.MLockNone {
+ mm.mappingMu.RUnlock()
+ return syserror.EBUSY
+ }
// It's only possible to have dirtied the Mappable through a shared
// mapping. Don't check if the mapping is writable, because mprotect
// may have changed this, and also because Linux doesn't.
- if id := vma.id; id != nil && vma.mappable != nil && !vma.private {
+ if id := vma.id; opts.Sync && id != nil && vma.mappable != nil && !vma.private {
// We can't call memmap.MappingIdentity.Msync while holding
// mm.mappingMu since it may take fs locks that precede it in the
// lock order.
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 22:30:45 +0000