arm64 kvm: add more handling of el0_exceptions

Add more comments and more handling for exceptions.

Signed-off-by: Robin Luk <lubin.lu@antgroup.com>

1 files changed, 19 insertions, 4 deletions

diff --git a/pkg/sentry/platform/kvm/machine_arm64_unsafe.go b/pkg/sentry/platform/kvm/machine_arm64_unsafe.go
index 3f5be276b..f2459755b 100644
--- a/pkg/sentry/platform/kvm/machine_arm64_unsafe.go
+++ b/pkg/sentry/platform/kvm/machine_arm64_unsafe.go
@@ -235,12 +235,12 @@ func (c *vCPU) SwitchToUser(switchOpts ring0.SwitchOpts, info *arch.SignalInfo)
 	ttbr0App := switchOpts.PageTables.TTBR0_EL1(false, 0)
 	c.SetTtbr0App(uintptr(ttbr0App))
 
-	// TODO(gvisor.dev/issue/1238): full context-switch supporting for Arm64.
+	// Full context-switch supporting for Arm64.
 	// The Arm64 user-mode execution state consists of:
 	// x0-x30
 	// PC, SP, PSTATE
 	// V0-V31: 32 128-bit registers for floating point, and simd
-	// FPSR
+	// FPSR, FPCR
 	// TPIDR_EL0, used for TLS
 	appRegs := switchOpts.Registers
 	c.SetAppAddr(ring0.KernelStartAddress | uintptr(unsafe.Pointer(appRegs)))
@@ -254,15 +254,30 @@ func (c *vCPU) SwitchToUser(switchOpts ring0.SwitchOpts, info *arch.SignalInfo)
 	case ring0.Syscall:
 		// Fast path: system call executed.
 		return usermem.NoAccess, nil
-
 	case ring0.PageFault:
 		return c.fault(int32(syscall.SIGSEGV), info)
 	case ring0.El0ErrNMI:
 		return c.fault(int32(syscall.SIGBUS), info)
-	case ring0.Vector(bounce): // ring0.VirtualizationException
+	case ring0.Vector(bounce): // ring0.VirtualizationException.
 		return usermem.NoAccess, platform.ErrContextInterrupt
 	case ring0.El0SyncUndef:
 		return c.fault(int32(syscall.SIGILL), info)
+	case ring0.El0SyncDbg:
+		*info = arch.SignalInfo{
+			Signo: int32(syscall.SIGTRAP),
+			Code:  1, // TRAP_BRKPT (breakpoint).
+		}
+		info.SetAddr(switchOpts.Registers.Pc) // Include address.
+		return usermem.AccessType{}, platform.ErrContextSignal
+	case ring0.El0SyncSpPc:
+		*info = arch.SignalInfo{
+			Signo: int32(syscall.SIGBUS),
+			Code:  2, // BUS_ADRERR (physical address does not exist).
+		}
+		return usermem.NoAccess, platform.ErrContextSignal
+	case ring0.El0SyncSys,
+		ring0.El0SyncWfx:
+		return usermem.NoAccess, nil // skip for now.
 	default:
 		panic(fmt.Sprintf("unexpected vector: 0x%x", vector))
 	}