Move the code that manages floating-point state to a separate package

This change is inspired by Adin's cl/355256448.

PiperOrigin-RevId: 364695931

1 files changed, 9 insertions, 62 deletions

diff --git a/pkg/sentry/arch/arch_aarch64.go b/pkg/sentry/arch/arch_aarch64.go
index fd73751e7..08789f517 100644
--- a/pkg/sentry/arch/arch_aarch64.go
+++ b/pkg/sentry/arch/arch_aarch64.go
@@ -23,6 +23,7 @@ import (
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/cpuid"
 	"gvisor.dev/gvisor/pkg/log"
+	"gvisor.dev/gvisor/pkg/sentry/arch/fpu"
 	rpb "gvisor.dev/gvisor/pkg/sentry/arch/registers_go_proto"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
@@ -40,65 +41,11 @@ type Registers struct {
 const (
 	// SyscallWidth is the width of insturctions.
 	SyscallWidth = 4
-
-	// fpsimdMagic is the magic number which is used in fpsimd_context.
-	fpsimdMagic = 0x46508001
-
-	// fpsimdContextSize is the size of fpsimd_context.
-	fpsimdContextSize = 0x210
 )
 
 // ARMTrapFlag is the mask for the trap flag.
 const ARMTrapFlag = uint64(1) << 21
 
-// aarch64FPState is aarch64 floating point state.
-type aarch64FPState []byte
-
-// initAarch64FPState sets up initial state.
-//
-// Related code in Linux kernel: fpsimd_flush_thread().
-// FPCR = FPCR_RM_RN (0x0 << 22).
-//
-// Currently, aarch64FPState is only a space of 0x210 length for fpstate.
-// The fp head is useless in sentry/ptrace/kvm.
-//
-func initAarch64FPState(data aarch64FPState) {
-}
-
-func newAarch64FPStateSlice() []byte {
-	return alignedBytes(4096, 16)[:fpsimdContextSize]
-}
-
-// newAarch64FPState returns an initialized floating point state.
-//
-// The returned state is large enough to store all floating point state
-// supported by host, even if the app won't use much of it due to a restricted
-// FeatureSet.
-func newAarch64FPState() aarch64FPState {
-	f := aarch64FPState(newAarch64FPStateSlice())
-	initAarch64FPState(f)
-	return f
-}
-
-// fork creates and returns an identical copy of the aarch64 floating point state.
-func (f aarch64FPState) fork() aarch64FPState {
-	n := aarch64FPState(newAarch64FPStateSlice())
-	copy(n, f)
-	return n
-}
-
-// FloatingPointData returns the raw data pointer.
-func (f aarch64FPState) FloatingPointData() *FloatingPointData {
-	return (*FloatingPointData)(&f[0])
-}
-
-// NewFloatingPointData returns a new floating point data blob.
-//
-// This is primarily for use in tests.
-func NewFloatingPointData() *FloatingPointData {
-	return (*FloatingPointData)(&(newAarch64FPState()[0]))
-}
-
 // State contains the common architecture bits for aarch64 (the build tag of this
 // file ensures it's only built on aarch64).
 //
@@ -108,7 +55,7 @@ type State struct {
 	Regs Registers
 
 	// Our floating point state.
-	aarch64FPState `state:"wait"`
+	fpState fpu.State `state:"wait"`
 
 	// FeatureSet is a pointer to the currently active feature set.
 	FeatureSet *cpuid.FeatureSet
@@ -162,10 +109,10 @@ func (s State) Proto() *rpb.Registers {
 // Fork creates and returns an identical copy of the state.
 func (s *State) Fork() State {
 	return State{
-		Regs:           s.Regs,
-		aarch64FPState: s.aarch64FPState.fork(),
-		FeatureSet:     s.FeatureSet,
-		OrigR0:         s.OrigR0,
+		Regs:       s.Regs,
+		fpState:    s.fpState.Fork(),
+		FeatureSet: s.FeatureSet,
+		OrigR0:     s.OrigR0,
 	}
 }
 
@@ -318,10 +265,10 @@ func New(arch Arch, fs *cpuid.FeatureSet) Context {
 	case ARM64:
 		return &context64{
 			State{
-				aarch64FPState: newAarch64FPState(),
-				FeatureSet:     fs,
+				fpState:    fpu.NewState(),
+				FeatureSet: fs,
 			},
-			[]aarch64FPState(nil),
+			[]fpu.State(nil),
 		}
 	}
 	panic(fmt.Sprintf("unknown architecture %v", arch))