vdso

Documentation

Overview

Package vdso provides the binary level virtual dynamic shared object (vDSO).

Index

• Constants
• Variables
• func Auxv(tag, val uintptr)
• func FindVersion(vdso *VDSO, ver *VersionKey) int32
• func InVDSOPage(pc uintptr) bool
• func InitFromSysinfoELFHeader(vdso *VDSO, hdr *elfdef.Header)
• func ParseSymbols(vdso *VDSO, version int32)
• type SymbolKey
• type VDSO
• type VersionKey

Constants

const (
	// ArrayMax is the byte-size of a maximally sized array on this architecture.
	ArrayMax = 1<<50 - 1

	// Maximum indices for the array types used when traversing the vDSO ELF structures.
	SymTabSize     = ArrayMax / unsafe.Sizeof(elfdef.Sym{})
	DynSize        = ArrayMax / unsafe.Sizeof(elfdef.Dyn{})
	SymStringsSize = ArrayMax     // byte
	VerSymSize     = ArrayMax / 2 // uint16
	HashSize       = ArrayMax / 4 // uint32

	// BloomSizeScale is a scaling factor for gnuhash tables which are uint32 indexed, but contain uintptrs.
	BloomSizeScale = unsafe.Sizeof(uintptr(0)) / 4 // uint32
)

Variables

var (
	GettimeofdaySym uintptr = 0xffffffffff600000
	ClockgettimeSym uintptr = 0
)

initialize with vsyscall fallbacks.

var LinuxVersion = VersionKey{"LINUX_2.6", 0x3ae75f6}

LinuxVersion version of Linux Kernel in vDSO object.

var SymbolKeys = []SymbolKey{
	{"__vdso_gettimeofday", 0x315ca59, 0xb01bca00, &GettimeofdaySym},
	{"__vdso_clock_gettime", 0xd35ec75, 0x6e43a318, &ClockgettimeSym},
}

SymbolKeys is the Linux amd64 vDSO symbol keys.

Functions

func Auxv

func Auxv(tag, val uintptr)

Auxv parses auxv by tag and allocate elfdef.Header to val.

func FindVersion

func FindVersion(vdso *VDSO, ver *VersionKey) int32

FindVersion finds version from vDSO.

func InVDSOPage

func InVDSOPage(pc uintptr) bool

InVDSOPage reports whether the pc is on the VDSO page.

func InitFromSysinfoELFHeader

func InitFromSysinfoELFHeader(vdso *VDSO, hdr *elfdef.Header)

InitFromSysinfoELFHeader init vDSO from hdr.

func ParseSymbols

func ParseSymbols(vdso *VDSO, version int32)

ParseSymbols parses and allocates symbols from vDSO.

Types

type SymbolKey

type SymbolKey struct {
	Name    string
	SymHash uint32
	GnuHash uint32
	Ptr     *uintptr
}

SymbolKey represents a vDSO symbol key entries.

type VDSO

type VDSO struct {
	Valid bool

	// Load information
	LoadAddr   uintptr
	LoadOffset uintptr // LoadAddr - recorded vaddr

	// Symbol table
	Symtab     *[SymTabSize]elfdef.Sym
	Symstrings *[SymStringsSize]byte
	Chain      []uint32
	Bucket     []uint32
	SymOff     uint32
	IsGNUHash  bool

	// Version table
	Versym *[VerSymSize]uint16
	Verdef *elfdef.Verdef
}

VDSO represents a vDSO object.

type VersionKey

type VersionKey struct {
	Version string
	VerHash uint32
}

VersionKey represents a vDSO Version key entries.