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// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package pkginit
import (
"strings"
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types"
"cmd/internal/src"
)
// instrumentGlobals declares a global array of _asan_global structures and initializes it.
func instrumentGlobals(fn *ir.Func) *ir.Name {
asanGlobalStruct, asanLocationStruct, defStringstruct := createtypes()
lname := typecheck.Lookup
tconv := typecheck.ConvNop
// Make a global array of asanGlobalStruct type.
// var asanglobals []asanGlobalStruct
arraytype := types.NewArray(asanGlobalStruct, int64(len(InstrumentGlobalsMap)))
symG := lname(".asanglobals")
globals := typecheck.NewName(symG)
globals.SetType(arraytype)
globals.Class = ir.PEXTERN
symG.Def = globals
typecheck.Target.Externs = append(typecheck.Target.Externs, globals)
// Make a global array of asanLocationStruct type.
// var asanL []asanLocationStruct
arraytype = types.NewArray(asanLocationStruct, int64(len(InstrumentGlobalsMap)))
symL := lname(".asanL")
asanlocation := typecheck.NewName(symL)
asanlocation.SetType(arraytype)
asanlocation.Class = ir.PEXTERN
symL.Def = asanlocation
typecheck.Target.Externs = append(typecheck.Target.Externs, asanlocation)
// Make three global string variables to pass the global name and module name
// and the name of the source file that defines it.
// var asanName string
// var asanModulename string
// var asanFilename string
symL = lname(".asanName")
asanName := typecheck.NewName(symL)
asanName.SetType(types.Types[types.TSTRING])
asanName.Class = ir.PEXTERN
symL.Def = asanName
typecheck.Target.Externs = append(typecheck.Target.Externs, asanName)
symL = lname(".asanModulename")
asanModulename := typecheck.NewName(symL)
asanModulename.SetType(types.Types[types.TSTRING])
asanModulename.Class = ir.PEXTERN
symL.Def = asanModulename
typecheck.Target.Externs = append(typecheck.Target.Externs, asanModulename)
symL = lname(".asanFilename")
asanFilename := typecheck.NewName(symL)
asanFilename.SetType(types.Types[types.TSTRING])
asanFilename.Class = ir.PEXTERN
symL.Def = asanFilename
typecheck.Target.Externs = append(typecheck.Target.Externs, asanFilename)
var init ir.Nodes
var c ir.Node
// globals[i].odrIndicator = 0 is the default, no need to set it explicitly here.
for i, n := range InstrumentGlobalsSlice {
setField := func(f string, val ir.Node, i int) {
r := ir.NewAssignStmt(base.Pos, ir.NewSelectorExpr(base.Pos, ir.ODOT,
ir.NewIndexExpr(base.Pos, globals, ir.NewInt(int64(i))), lname(f)), val)
init.Append(typecheck.Stmt(r))
}
// globals[i].beg = uintptr(unsafe.Pointer(&n))
c = tconv(typecheck.NodAddr(n), types.Types[types.TUNSAFEPTR])
c = tconv(c, types.Types[types.TUINTPTR])
setField("beg", c, i)
// Assign globals[i].size.
g := n.(*ir.Name)
size := g.Type().Size()
c = tconv(ir.NewInt(size), types.Types[types.TUINTPTR])
setField("size", c, i)
// Assign globals[i].sizeWithRedzone.
rzSize := GetRedzoneSizeForGlobal(size)
sizeWithRz := rzSize + size
c = tconv(ir.NewInt(sizeWithRz), types.Types[types.TUINTPTR])
setField("sizeWithRedzone", c, i)
// The C string type is terminated by a null charactor "\0", Go should use three-digit
// octal "\000" or two-digit hexadecimal "\x00" to create null terminated string.
// asanName = symbol's linkname + "\000"
// globals[i].name = (*defString)(unsafe.Pointer(&asanName)).data
name := g.Linksym().Name
init.Append(typecheck.Stmt(ir.NewAssignStmt(base.Pos, asanName, ir.NewString(name+"\000"))))
c = tconv(typecheck.NodAddr(asanName), types.Types[types.TUNSAFEPTR])
c = tconv(c, types.NewPtr(defStringstruct))
c = ir.NewSelectorExpr(base.Pos, ir.ODOT, c, lname("data"))
setField("name", c, i)
// Set the name of package being compiled as a unique identifier of a module.
// asanModulename = pkgName + "\000"
init.Append(typecheck.Stmt(ir.NewAssignStmt(base.Pos, asanModulename, ir.NewString(types.LocalPkg.Name+"\000"))))
c = tconv(typecheck.NodAddr(asanModulename), types.Types[types.TUNSAFEPTR])
c = tconv(c, types.NewPtr(defStringstruct))
c = ir.NewSelectorExpr(base.Pos, ir.ODOT, c, lname("data"))
setField("moduleName", c, i)
// Assign asanL[i].filename, asanL[i].line, asanL[i].column
// and assign globals[i].location = uintptr(unsafe.Pointer(&asanL[i]))
asanLi := ir.NewIndexExpr(base.Pos, asanlocation, ir.NewInt(int64(i)))
filename := ir.NewString(base.Ctxt.PosTable.Pos(n.Pos()).Filename() + "\000")
init.Append(typecheck.Stmt(ir.NewAssignStmt(base.Pos, asanFilename, filename)))
c = tconv(typecheck.NodAddr(asanFilename), types.Types[types.TUNSAFEPTR])
c = tconv(c, types.NewPtr(defStringstruct))
c = ir.NewSelectorExpr(base.Pos, ir.ODOT, c, lname("data"))
init.Append(typecheck.Stmt(ir.NewAssignStmt(base.Pos, ir.NewSelectorExpr(base.Pos, ir.ODOT, asanLi, lname("filename")), c)))
line := ir.NewInt(int64(n.Pos().Line()))
init.Append(typecheck.Stmt(ir.NewAssignStmt(base.Pos, ir.NewSelectorExpr(base.Pos, ir.ODOT, asanLi, lname("line")), line)))
col := ir.NewInt(int64(n.Pos().Col()))
init.Append(typecheck.Stmt(ir.NewAssignStmt(base.Pos, ir.NewSelectorExpr(base.Pos, ir.ODOT, asanLi, lname("column")), col)))
c = tconv(typecheck.NodAddr(asanLi), types.Types[types.TUNSAFEPTR])
c = tconv(c, types.Types[types.TUINTPTR])
setField("sourceLocation", c, i)
}
fn.Body.Append(init...)
return globals
}
// createtypes creates the asanGlobal, asanLocation and defString struct type.
// Go compiler does not refer to the C types, we represent the struct field
// by a uintptr, then use type conversion to make copies of the data.
// E.g., (*defString)(asanGlobal.name).data to C string.
//
// Keep in sync with src/runtime/asan/asan.go.
// type asanGlobal struct {
// beg uintptr
// size uintptr
// size_with_redzone uintptr
// name uintptr
// moduleName uintptr
// hasDynamicInit uintptr
// sourceLocation uintptr
// odrIndicator uintptr
// }
//
// type asanLocation struct {
// filename uintptr
// line int32
// column int32
// }
//
// defString is synthesized struct type meant to capture the underlying
// implementations of string.
// type defString struct {
// data uintptr
// len uintptr
// }
func createtypes() (*types.Type, *types.Type, *types.Type) {
up := types.Types[types.TUINTPTR]
i32 := types.Types[types.TINT32]
fname := typecheck.Lookup
nxp := src.NoXPos
nfield := types.NewField
asanGlobal := types.NewStruct(types.NoPkg, []*types.Field{
nfield(nxp, fname("beg"), up),
nfield(nxp, fname("size"), up),
nfield(nxp, fname("sizeWithRedzone"), up),
nfield(nxp, fname("name"), up),
nfield(nxp, fname("moduleName"), up),
nfield(nxp, fname("hasDynamicInit"), up),
nfield(nxp, fname("sourceLocation"), up),
nfield(nxp, fname("odrIndicator"), up),
})
types.CalcSize(asanGlobal)
asanLocation := types.NewStruct(types.NoPkg, []*types.Field{
nfield(nxp, fname("filename"), up),
nfield(nxp, fname("line"), i32),
nfield(nxp, fname("column"), i32),
})
types.CalcSize(asanLocation)
defString := types.NewStruct(types.NoPkg, []*types.Field{
types.NewField(nxp, fname("data"), up),
types.NewField(nxp, fname("len"), up),
})
types.CalcSize(defString)
return asanGlobal, asanLocation, defString
}
// Calculate redzone for globals.
func GetRedzoneSizeForGlobal(size int64) int64 {
maxRZ := int64(1 << 18)
minRZ := int64(32)
redZone := (size / minRZ / 4) * minRZ
switch {
case redZone > maxRZ:
redZone = maxRZ
case redZone < minRZ:
redZone = minRZ
}
// Round up to multiple of minRZ.
if size%minRZ != 0 {
redZone += minRZ - (size % minRZ)
}
return redZone
}
// InstrumentGlobalsMap contains only package-local (and unlinknamed from somewhere else)
// globals.
// And the key is the object name. For example, in package p, a global foo would be in this
// map as "foo".
// Consider range over maps is nondeterministic, make a slice to hold all the values in the
// InstrumentGlobalsMap and iterate over the InstrumentGlobalsSlice.
var InstrumentGlobalsMap = make(map[string]ir.Node)
var InstrumentGlobalsSlice = make([]ir.Node, 0, 0)
func canInstrumentGlobal(g ir.Node) bool {
if g.Op() != ir.ONAME {
return false
}
n := g.(*ir.Name)
if n.Class == ir.PFUNC {
return false
}
if n.Sym().Pkg != types.LocalPkg {
return false
}
// Do not instrument any _cgo_ related global variables, because they are declared in C code.
if strings.Contains(n.Sym().Name, "cgo") {
return false
}
// Do not instrument globals that are linknamed, because their home package will do the work.
if n.Sym().Linkname != "" {
return false
}
return true
}
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