[op] Move SignalStack to abi/linux package.

Updates #214

PiperOrigin-RevId: 378594929

6 files changed, 12 insertions, 117 deletions

diff --git a/pkg/sentry/arch/BUILD b/pkg/sentry/arch/BUILD
index d8253ecbe..1f467b7c9 100644
--- a/pkg/sentry/arch/BUILD
+++ b/pkg/sentry/arch/BUILD
@@ -18,7 +18,6 @@ go_library(
         "signal_amd64.go",
         "signal_arm64.go",
         "signal_info.go",
-        "signal_stack.go",
         "stack.go",
         "stack_unsafe.go",
         "syscalls_amd64.go",
diff --git a/pkg/sentry/arch/arch.go b/pkg/sentry/arch/arch.go
index 9db228bab..d765d8374 100644
--- a/pkg/sentry/arch/arch.go
+++ b/pkg/sentry/arch/arch.go
@@ -134,10 +134,6 @@ type Context interface {
 	// RegisterMap returns a map of all registers.
 	RegisterMap() (map[string]uintptr, error)
 
-	// NewSignalStack returns a new object that is equivalent to stack_t in the
-	// guest architecture.
-	NewSignalStack() NativeSignalStack
-
 	// SignalSetup modifies the context in preparation for handling the
 	// given signal.
 	//
@@ -153,7 +149,7 @@ type Context interface {
 	// stack is not going to be used).
 	//
 	// sigset is the signal mask before entering the signal handler.
-	SignalSetup(st *Stack, act *linux.SigAction, info *SignalInfo, alt *SignalStack, sigset linux.SignalSet) error
+	SignalSetup(st *Stack, act *linux.SigAction, info *SignalInfo, alt *linux.SignalStack, sigset linux.SignalSet) error
 
 	// SignalRestore restores context after returning from a signal
 	// handler.
@@ -163,7 +159,7 @@ type Context interface {
 	// rt is true if SignalRestore is being entered from rt_sigreturn and
 	// false if SignalRestore is being entered from sigreturn.
 	// SignalRestore returns the thread's new signal mask.
-	SignalRestore(st *Stack, rt bool) (linux.SignalSet, SignalStack, error)
+	SignalRestore(st *Stack, rt bool) (linux.SignalSet, linux.SignalStack, error)
 
 	// CPUIDEmulate emulates a CPUID instruction according to current register state.
 	CPUIDEmulate(l log.Logger)
diff --git a/pkg/sentry/arch/signal.go b/pkg/sentry/arch/signal.go
index 3e601b17e..b9fd14d10 100644
--- a/pkg/sentry/arch/signal.go
+++ b/pkg/sentry/arch/signal.go
@@ -19,28 +19,6 @@ import (
 	"gvisor.dev/gvisor/pkg/hostarch"
 )
 
-// SignalStack represents information about a user stack, and is equivalent to
-// stack_t.
-//
-// +marshal
-// +stateify savable
-type SignalStack struct {
-	Addr  uint64
-	Flags uint32
-	_     uint32
-	Size  uint64
-}
-
-// SerializeFrom implements NativeSignalStack.SerializeFrom.
-func (s *SignalStack) SerializeFrom(other *SignalStack) {
-	*s = *other
-}
-
-// DeserializeTo implements NativeSignalStack.DeserializeTo.
-func (s *SignalStack) DeserializeTo(other *SignalStack) {
-	*other = *s
-}
-
 // SignalInfo represents information about a signal being delivered, and is
 // equivalent to struct siginfo in linux kernel(linux/include/uapi/asm-generic/siginfo.h).
 //
diff --git a/pkg/sentry/arch/signal_amd64.go b/pkg/sentry/arch/signal_amd64.go
index 0bf272e16..fa74a2551 100644
--- a/pkg/sentry/arch/signal_amd64.go
+++ b/pkg/sentry/arch/signal_amd64.go
@@ -76,16 +76,11 @@ const (
 type UContext64 struct {
 	Flags    uint64
 	Link     uint64
-	Stack    SignalStack
+	Stack    linux.SignalStack
 	MContext SignalContext64
 	Sigset   linux.SignalSet
 }
 
-// NewSignalStack implements Context.NewSignalStack.
-func (c *context64) NewSignalStack() NativeSignalStack {
-	return &SignalStack{}
-}
-
 // From Linux 'arch/x86/include/uapi/asm/sigcontext.h' the following is the
 // size of the magic cookie at the end of the xsave frame.
 //
@@ -105,7 +100,7 @@ func (c *context64) fpuFrameSize() (size int, useXsave bool) {
 
 // SignalSetup implements Context.SignalSetup. (Compare to Linux's
 // arch/x86/kernel/signal.c:__setup_rt_frame().)
-func (c *context64) SignalSetup(st *Stack, act *linux.SigAction, info *SignalInfo, alt *SignalStack, sigset linux.SignalSet) error {
+func (c *context64) SignalSetup(st *Stack, act *linux.SigAction, info *SignalInfo, alt *linux.SignalStack, sigset linux.SignalSet) error {
 	sp := st.Bottom
 
 	// "The 128-byte area beyond the location pointed to by %rsp is considered
@@ -232,15 +227,15 @@ func (c *context64) SignalSetup(st *Stack, act *linux.SigAction, info *SignalInf
 
 // SignalRestore implements Context.SignalRestore. (Compare to Linux's
 // arch/x86/kernel/signal.c:sys_rt_sigreturn().)
-func (c *context64) SignalRestore(st *Stack, rt bool) (linux.SignalSet, SignalStack, error) {
+func (c *context64) SignalRestore(st *Stack, rt bool) (linux.SignalSet, linux.SignalStack, error) {
 	// Copy out the stack frame.
 	var uc UContext64
 	if _, err := uc.CopyIn(st, StackBottomMagic); err != nil {
-		return 0, SignalStack{}, err
+		return 0, linux.SignalStack{}, err
 	}
 	var info SignalInfo
 	if _, err := info.CopyIn(st, StackBottomMagic); err != nil {
-		return 0, SignalStack{}, err
+		return 0, linux.SignalStack{}, err
 	}
 
 	// Restore registers.
diff --git a/pkg/sentry/arch/signal_arm64.go b/pkg/sentry/arch/signal_arm64.go
index cc3c6ce62..3d632e7fd 100644
--- a/pkg/sentry/arch/signal_arm64.go
+++ b/pkg/sentry/arch/signal_arm64.go
@@ -61,7 +61,7 @@ type FpsimdContext struct {
 type UContext64 struct {
 	Flags  uint64
 	Link   uint64
-	Stack  SignalStack
+	Stack  linux.SignalStack
 	Sigset linux.SignalSet
 	// glibc uses a 1024-bit sigset_t
 	_pad [120]byte // (1024 - 64) / 8 = 120
@@ -71,13 +71,8 @@ type UContext64 struct {
 	MContext SignalContext64
 }
 
-// NewSignalStack implements Context.NewSignalStack.
-func (c *context64) NewSignalStack() NativeSignalStack {
-	return &SignalStack{}
-}
-
 // SignalSetup implements Context.SignalSetup.
-func (c *context64) SignalSetup(st *Stack, act *linux.SigAction, info *SignalInfo, alt *SignalStack, sigset linux.SignalSet) error {
+func (c *context64) SignalSetup(st *Stack, act *linux.SigAction, info *SignalInfo, alt *linux.SignalStack, sigset linux.SignalSet) error {
 	sp := st.Bottom
 
 	// Construct the UContext64 now since we need its size.
@@ -142,15 +137,15 @@ func (c *context64) SignalSetup(st *Stack, act *linux.SigAction, info *SignalInf
 }
 
 // SignalRestore implements Context.SignalRestore.
-func (c *context64) SignalRestore(st *Stack, rt bool) (linux.SignalSet, SignalStack, error) {
+func (c *context64) SignalRestore(st *Stack, rt bool) (linux.SignalSet, linux.SignalStack, error) {
 	// Copy out the stack frame.
 	var uc UContext64
 	if _, err := uc.CopyIn(st, StackBottomMagic); err != nil {
-		return 0, SignalStack{}, err
+		return 0, linux.SignalStack{}, err
 	}
 	var info SignalInfo
 	if _, err := info.CopyIn(st, StackBottomMagic); err != nil {
-		return 0, SignalStack{}, err
+		return 0, linux.SignalStack{}, err
 	}
 
 	// Restore registers.
diff --git a/pkg/sentry/arch/signal_stack.go b/pkg/sentry/arch/signal_stack.go
deleted file mode 100644
index c732c7503..000000000
--- a/pkg/sentry/arch/signal_stack.go
+++ /dev/null
@@ -1,68 +0,0 @@
-// Copyright 2018 The gVisor Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// +build 386 amd64 arm64
-
-package arch
-
-import (
-	"gvisor.dev/gvisor/pkg/hostarch"
-	"gvisor.dev/gvisor/pkg/marshal"
-)
-
-const (
-	// SignalStackFlagOnStack is possible set on return from getaltstack,
-	// in order to indicate that the thread is currently on the alt stack.
-	SignalStackFlagOnStack = 1
-
-	// SignalStackFlagDisable is a flag to indicate the stack is disabled.
-	SignalStackFlagDisable = 2
-)
-
-// IsEnabled returns true iff this signal stack is marked as enabled.
-func (s SignalStack) IsEnabled() bool {
-	return s.Flags&SignalStackFlagDisable == 0
-}
-
-// Top returns the stack's top address.
-func (s SignalStack) Top() hostarch.Addr {
-	return hostarch.Addr(s.Addr + s.Size)
-}
-
-// SetOnStack marks this signal stack as in use.
-//
-// Note that there is no corresponding ClearOnStack, and that this should only
-// be called on copies that are serialized to userspace.
-func (s *SignalStack) SetOnStack() {
-	s.Flags |= SignalStackFlagOnStack
-}
-
-// Contains checks if the stack pointer is within this stack.
-func (s *SignalStack) Contains(sp hostarch.Addr) bool {
-	return hostarch.Addr(s.Addr) < sp && sp <= hostarch.Addr(s.Addr+s.Size)
-}
-
-// NativeSignalStack is a type that is equivalent to stack_t in the guest
-// architecture.
-type NativeSignalStack interface {
-	marshal.Marshallable
-
-	// SerializeFrom copies the data in the host SignalStack s into this
-	// object.
-	SerializeFrom(s *SignalStack)
-
-	// DeserializeTo copies the data in this object into the host SignalStack
-	// s.
-	DeserializeTo(s *SignalStack)
-}