mirror of
https://github.com/taigrr/gopher-os
synced 2025-01-18 04:43:13 -08:00
Support parsing of 64-bit ELF section tags off from the multiboot data
This commit is contained in:
Achilleas Anagnostopoulos
parent
af9613e336
commit
a79be7c268
@ -6,6 +6,12 @@ import (
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"unsafe"
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)
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var (
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infoData uintptr
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cmdLineKV map[string]string
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elfSectionList []*ElfSection
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)
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type tagType uint32
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// nolint
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@ -140,11 +146,6 @@ const (
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memUnknown
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)
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var (
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infoData uintptr
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cmdLineKV map[string]string
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)
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// MemRegionVisitor defies a visitor function that gets invoked by VisitMemRegions
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// for each memory region provided by the boot loader. The visitor must return true
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// to continue or false to abort the scan.
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@ -179,6 +180,115 @@ func (t MemoryEntryType) String() string {
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}
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}
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type elfSections struct {
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numSections uint16
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sectionSize uint32
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strtabSectionIndex uint32
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sectionData [0]byte
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}
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/*
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type elfSection32 struct {
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nameIndex uint32
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sectionType uint32
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flags uint32
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address uint32
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offset uint32
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size uint32
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link uint32
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info uint32
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addrAlign uint32
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entSize uint32
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}
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*/
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type elfSection64 struct {
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nameIndex uint32
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sectionType uint32
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flags uint64
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address uint64
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offset uint64
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size uint64
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link uint32
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info uint32
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addrAlign uint64
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entSize uint64
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}
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// ElfSectionFlag defines an OR-able flag associated with an ElfSection.
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type ElfSectionFlag uint32
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const (
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// ElfSectionWritable marks the section as writable.
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ElfSectionWritable ElfSectionFlag = 1 << iota
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// ElfSectionAllocated means that the section is allocated in memory
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// when the image is loaded (e.g .bss sections)
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ElfSectionAllocated
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// ElfSectionExecutable marks the section as executable.
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ElfSectionExecutable
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)
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// ElfSection deefines the name, flags and virtual address of an ELF section
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// which is part of the kernel image.
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type ElfSection struct {
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// The section name.
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Name string
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// The list of flags associated with this section
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Flags ElfSectionFlag
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// The virtual address of this section.
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Address uintptr
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}
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// GetElfSections returns a slice of ElfSections for the loaded kernel image.
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func GetElfSections() []*ElfSection {
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if elfSectionList != nil {
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return elfSectionList
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}
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curPtr, size := findTagByType(tagElfSymbols)
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if size == 0 {
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return nil
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}
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ptrElfSections := (*elfSections)(unsafe.Pointer(curPtr))
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sectionData := *(*[]elfSection64)(unsafe.Pointer(&reflect.SliceHeader{
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Len: int(ptrElfSections.numSections),
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Cap: int(ptrElfSections.numSections),
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Data: uintptr(unsafe.Pointer(&ptrElfSections.sectionData)),
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}))
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var (
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strTable = *(*[]byte)(unsafe.Pointer(&reflect.SliceHeader{
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Len: int(sectionData[ptrElfSections.strtabSectionIndex].size),
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Cap: int(sectionData[ptrElfSections.strtabSectionIndex].size),
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Data: uintptr(sectionData[ptrElfSections.strtabSectionIndex].address),
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}))
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)
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for _, secData := range sectionData {
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if secData.size == 0 {
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continue
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}
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// String table entries are C-style NULL-terminated strings
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end := secData.nameIndex
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for ; strTable[end] != 0; end++ {
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}
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elfSectionList = append(elfSectionList, &ElfSection{
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Name: string(strTable[secData.nameIndex:end]),
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Flags: ElfSectionFlag(secData.flags),
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Address: uintptr(secData.address),
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})
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}
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return elfSectionList
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}
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// SetInfoPtr updates the internal multiboot information pointer to the given
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// value. This function must be invoked before invoking any other function
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// exported by this package.
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@ -1,6 +1,8 @@
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package multiboot
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import (
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"bytes"
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"encoding/binary"
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"reflect"
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"testing"
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"unsafe"
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@ -191,6 +193,62 @@ func TestGetBootCmdLine(t *testing.T) {
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}
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}
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func TestGetElfSections(t *testing.T) {
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SetInfoPtr(uintptr(unsafe.Pointer(&emptyInfoData[0])))
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if GetElfSections() != nil {
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t.Fatalf("expected GetElfSections() to return nil when no elf sections tag is present")
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}
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SetInfoPtr(uintptr(unsafe.Pointer(&multibootInfoTestData[0])))
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// Patch the strtab address to point to out mock data
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var buf bytes.Buffer
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binary.Write(&buf, binary.LittleEndian, uint64(uintptr(unsafe.Pointer(&mockStrTable[0]))))
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for i, b := range buf.Bytes() {
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multibootInfoTestData[1660+i] = b
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}
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sections := GetElfSections()
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specs := []struct {
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secName string
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expFlags ElfSectionFlag
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}{
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{".text", ElfSectionAllocated | ElfSectionExecutable},
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{".bss", ElfSectionAllocated | ElfSectionWritable},
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{".noptrbss", ElfSectionAllocated | ElfSectionWritable},
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{".data", ElfSectionAllocated | ElfSectionWritable},
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{".rodata", ElfSectionAllocated},
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{".strtab", 0},
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}
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for specIndex, spec := range specs {
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var found *ElfSection
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for _, sec := range sections {
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if sec.Name == spec.secName {
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found = sec
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break
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}
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}
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if found == nil {
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t.Errorf("[spec %d] missing section %q", specIndex, spec.secName)
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continue
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}
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if found.Flags != spec.expFlags {
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t.Errorf("[spec %d] expected section flags to be: 0x%x; got 0x%x", specIndex, spec.expFlags, found.Flags)
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}
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}
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// Second call should return the memoized data
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sections[0].Name = "foo"
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if sections2 := GetElfSections(); !reflect.DeepEqual(sections2, sections) {
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t.Error("expected second call to GetElfSections() to return the memoized section list")
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}
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}
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var (
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emptyInfoData = []byte{
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0, 0, 0, 0, // size
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@ -374,4 +432,23 @@ var (
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0x59, 0x42, 0x4f, 0x43, 0x48, 0x53, 0x20, 0x00, 0xdc, 0x18, 0xfe, 0x07, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00,
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}
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mockStrTable = []byte{
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0x00, 0x2e, 0x73, 0x79, 0x6d, 0x74, 0x61, 0x62, 0x00, 0x2e, 0x73, 0x74, 0x72, 0x74, 0x61, 0x62, // ..symtab..strtab
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0x00, 0x2e, 0x73, 0x68, 0x73, 0x74, 0x72, 0x74, 0x61, 0x62, 0x00, 0x2e, 0x74, 0x65, 0x78, 0x74, // ..shstrtab..text
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0x00, 0x2e, 0x72, 0x6f, 0x64, 0x61, 0x74, 0x61, 0x00, 0x2e, 0x74, 0x79, 0x70, 0x65, 0x6c, 0x69, // ..rodata..typeli
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0x6e, 0x6b, 0x00, 0x2e, 0x69, 0x74, 0x61, 0x62, 0x6c, 0x69, 0x6e, 0x6b, 0x00, 0x2e, 0x67, 0x6f, // nk..itablink..go
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0x70, 0x63, 0x6c, 0x6e, 0x74, 0x61, 0x62, 0x00, 0x2e, 0x64, 0x61, 0x74, 0x61, 0x00, 0x2e, 0x6e, // pclntab..data..n
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0x6f, 0x70, 0x74, 0x72, 0x64, 0x61, 0x74, 0x61, 0x00, 0x2e, 0x62, 0x73, 0x73, 0x00, 0x2e, 0x6e, // optrdata..bss..n
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0x6f, 0x70, 0x74, 0x72, 0x62, 0x73, 0x73, 0x00, 0x2e, 0x67, 0x6f, 0x72, 0x65, 0x64, 0x69, 0x72, // optrbss..goredir
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0x65, 0x63, 0x74, 0x73, 0x74, 0x62, 0x6c, 0x00, 0x2e, 0x6e, 0x6f, 0x74, 0x65, 0x2e, 0x67, 0x6f, // ectstbl..note.go
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0x2e, 0x62, 0x75, 0x69, 0x6c, 0x64, 0x69, 0x64, 0x00, 0x2e, 0x74, 0x62, 0x73, 0x73, 0x00, 0x2e, // .buildid..tbss..
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0x64, 0x65, 0x62, 0x75, 0x67, 0x5f, 0x61, 0x72, 0x61, 0x6e, 0x67, 0x65, 0x73, 0x00, 0x2e, 0x64, // debug_aranges..d
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0x65, 0x62, 0x75, 0x67, 0x5f, 0x70, 0x75, 0x62, 0x6e, 0x61, 0x6d, 0x65, 0x73, 0x00, 0x2e, 0x64, // ebug_pubnames..d
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0x65, 0x62, 0x75, 0x67, 0x5f, 0x69, 0x6e, 0x66, 0x6f, 0x00, 0x2e, 0x64, 0x65, 0x62, 0x75, 0x67, // ebug_info..debug
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0x5f, 0x61, 0x62, 0x62, 0x72, 0x65, 0x76, 0x00, 0x2e, 0x64, 0x65, 0x62, 0x75, 0x67, 0x5f, 0x6c, // _abbrev..debug_l
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0x69, 0x6e, 0x65, 0x00, 0x2e, 0x64, 0x65, 0x62, 0x75, 0x67, 0x5f, 0x66, 0x72, 0x61, 0x6d, 0x65, // ine..debug_frame
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0x00, 0x2e, 0x64, 0x65, 0x62, 0x75, 0x67, 0x5f, 0x6c, 0x6f, 0x63, 0x00, 0x2e, 0x64, 0x65, 0x62, // ..debug_loc..deb
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0x75, 0x67, 0x5f, 0x70, 0x75, 0x62, 0x74, 0x79, 0x70, 0x65, 0x73, 0x00, // ug_pubtypes.
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}
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)
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