Support CLONE_VFORK with CLONE_VM
Test: The affected app doesn't crash anymore
Test: CtsBionicTestCases
Bug: 323981318
Bug: 156400255
Change-Id: Iab5bb6da9e495e669f49dff39eda6eafd41b31ed
diff --git a/guest_os_primitives/guest_thread_clone.cc b/guest_os_primitives/guest_thread_clone.cc
index d569186..8c6c6ac 100644
--- a/guest_os_primitives/guest_thread_clone.cc
+++ b/guest_os_primitives/guest_thread_clone.cc
@@ -15,6 +15,7 @@
*/
#include <linux/unistd.h>
+#include <sched.h>
#include <semaphore.h>
#include "berberis/base/checks.h"
@@ -22,6 +23,7 @@
#include "berberis/guest_os_primitives/guest_thread.h"
#include "berberis/guest_os_primitives/guest_thread_manager.h" // ResetCurrentGuestThreadAfterFork
#include "berberis/guest_os_primitives/scoped_pending_signals.h"
+#include "berberis/guest_state/guest_addr.h"
#include "berberis/guest_state/guest_state_opaque.h"
#include "berberis/runtime/execute_guest.h"
#include "berberis/runtime_primitives/runtime_library.h"
@@ -76,20 +78,13 @@
} // namespace
+// go/berberis-guest-threads
pid_t CloneGuestThread(GuestThread* thread,
int flags,
GuestAddr guest_stack_top,
GuestAddr parent_tid,
GuestAddr new_tls,
GuestAddr child_tid) {
- // TODO(b/280551726): Legacy hack to handle vfork, investigate if still needed.
- if ((flags & CLONE_VFORK)) {
- if ((flags & CLONE_VM)) {
- TRACE("cleared CLONE_VM for CLONE_VFORK");
- flags &= ~CLONE_VM;
- }
- }
-
ThreadState& thread_state = *thread->state();
if (!(flags & CLONE_VM)) {
// Memory is *not* shared with the child.
@@ -117,11 +112,6 @@
// cannot use host local variables. For now, use clone function to pass parameters to the child.
// The child needs new instance of guest thread object.
- if (guest_stack_top == 0) {
- TRACE("CLONE_VM without new stack");
- return EINVAL;
- }
-
GuestThreadCloneInfo info;
info.thread = GuestThread::CreateClone(thread);
@@ -130,7 +120,6 @@
}
ThreadState& clone_thread_state = *info.thread->state();
- SetStackRegister(GetCPUState(clone_thread_state), guest_stack_top);
if ((flags & CLONE_SETTLS)) {
SetTlsAddr(clone_thread_state, new_tls);
@@ -141,7 +130,19 @@
CPUState& clone_cpu = GetCPUState(clone_thread_state);
AdvanceInsnAddrBeyondSyscall(clone_cpu);
SetReturnValueRegister(clone_cpu, 0); // Syscall return value
- SetLinkRegister(clone_cpu, 0); // Caller address
+
+ if (guest_stack_top != kNullGuestAddr) {
+ SetStackRegister(GetCPUState(clone_thread_state), guest_stack_top);
+ SetLinkRegister(clone_cpu, kNullGuestAddr);
+ } else {
+ if (!(flags & CLONE_VFORK)) {
+ TRACE("CLONE_VM with NULL guest stack and not in CLONE_VFORK mode, returning EINVAL");
+ return EINVAL;
+ }
+ // See b/323981318 and b/156400255.
+ TRACE("CLONE_VFORK with CLONE_VM and NULL guest stack, will share guest stack with parent");
+ // GuestThread::CreateClone has already copied stack and link pointers to new thread.
+ }
// Thread must start with pending signals while it's executing runtime code.
SetPendingSignalsStatusAtomic(clone_thread_state, kPendingSignalsEnabled);
