mirror of
https://github.com/golang/go
synced 2024-11-24 09:50:17 -07:00
runtime: factor amd64 specifics from vdso_linux.go
This is a preparation step for adding vDSO support on linux/386. This change relocates the elf64 and amd64 specifics from vdso_linux.go to a new vdso_linux_amd64.go. This should enable vdso_linux.go to be used for vDSO support on linux architectures other than amd64. - Relocate the elf64X structure definitions appropriate to amd64, and change their names to elfX so that the code in vdso_linux.go is ELFnn-agnostic. - Relocate the sym_keys and corresponding __vdso_* variables appropriate to amd64. - Provide an amd64-specific constant for the maximum byte size of an array, and use this in vdso_linux.go to compute constants for sizing the elf structure arrays traversed in the loaded vDSO. Change-Id: I1edb4e4ec9f2d79b7533aa95fbd09f771fa4edef Reviewed-on: https://go-review.googlesource.com/69391 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Frank Somers
Ian Lance Taylor
parent
c58b98b2d6
commit
c14dcfda6b
@ -46,86 +46,23 @@ const (
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_STB_WEAK = 2 /* Weak symbol */
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_EI_NIDENT = 16
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// Maximum indices for the array types used when traversing the vDSO ELF structures.
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// Computed from architecture-specific max provided by vdso_linux_*.go
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vdsoSymTabSize = vdsoArrayMax / unsafe.Sizeof(elfSym{})
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vdsoDynSize = vdsoArrayMax / unsafe.Sizeof(elfDyn{})
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vdsoSymStringsSize = vdsoArrayMax // byte
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vdsoVerSymSize = vdsoArrayMax / 2 // uint16
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vdsoHashSize = vdsoArrayMax / 4 // uint32
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// vdsoBloomSizeScale is a scaling factor for gnuhash tables which are uint32 indexed,
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// but contain uintptrs
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vdsoBloomSizeScale = unsafe.Sizeof(uintptr(0)) / 4 // uint32
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)
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/* How to extract and insert information held in the st_info field. */
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func _ELF64_ST_BIND(val byte) byte { return val >> 4 }
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func _ELF64_ST_TYPE(val byte) byte { return val & 0xf }
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type elf64Sym struct {
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st_name uint32
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st_info byte
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st_other byte
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st_shndx uint16
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st_value uint64
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st_size uint64
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}
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type elf64Verdef struct {
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vd_version uint16 /* Version revision */
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vd_flags uint16 /* Version information */
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vd_ndx uint16 /* Version Index */
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vd_cnt uint16 /* Number of associated aux entries */
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vd_hash uint32 /* Version name hash value */
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vd_aux uint32 /* Offset in bytes to verdaux array */
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vd_next uint32 /* Offset in bytes to next verdef entry */
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}
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type elf64Ehdr struct {
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e_ident [_EI_NIDENT]byte /* Magic number and other info */
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e_type uint16 /* Object file type */
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e_machine uint16 /* Architecture */
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e_version uint32 /* Object file version */
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e_entry uint64 /* Entry point virtual address */
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e_phoff uint64 /* Program header table file offset */
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e_shoff uint64 /* Section header table file offset */
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e_flags uint32 /* Processor-specific flags */
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e_ehsize uint16 /* ELF header size in bytes */
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e_phentsize uint16 /* Program header table entry size */
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e_phnum uint16 /* Program header table entry count */
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e_shentsize uint16 /* Section header table entry size */
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e_shnum uint16 /* Section header table entry count */
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e_shstrndx uint16 /* Section header string table index */
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}
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type elf64Phdr struct {
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p_type uint32 /* Segment type */
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p_flags uint32 /* Segment flags */
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p_offset uint64 /* Segment file offset */
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p_vaddr uint64 /* Segment virtual address */
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p_paddr uint64 /* Segment physical address */
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p_filesz uint64 /* Segment size in file */
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p_memsz uint64 /* Segment size in memory */
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p_align uint64 /* Segment alignment */
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}
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type elf64Shdr struct {
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sh_name uint32 /* Section name (string tbl index) */
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sh_type uint32 /* Section type */
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sh_flags uint64 /* Section flags */
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sh_addr uint64 /* Section virtual addr at execution */
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sh_offset uint64 /* Section file offset */
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sh_size uint64 /* Section size in bytes */
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sh_link uint32 /* Link to another section */
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sh_info uint32 /* Additional section information */
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sh_addralign uint64 /* Section alignment */
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sh_entsize uint64 /* Entry size if section holds table */
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}
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type elf64Dyn struct {
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d_tag int64 /* Dynamic entry type */
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d_val uint64 /* Integer value */
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}
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type elf64Verdaux struct {
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vda_name uint32 /* Version or dependency names */
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vda_next uint32 /* Offset in bytes to next verdaux entry */
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}
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type elf64Auxv struct {
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a_type uint64 /* Entry type */
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a_val uint64 /* Integer value */
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}
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func _ELF_ST_BIND(val byte) byte { return val >> 4 }
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func _ELF_ST_TYPE(val byte) byte { return val & 0xf }
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type symbol_key struct {
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name string
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@ -147,34 +84,23 @@ type vdso_info struct {
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load_offset uintptr /* load_addr - recorded vaddr */
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/* Symbol table */
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symtab *[1 << 32]elf64Sym
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symstrings *[1 << 32]byte
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symtab *[vdsoSymTabSize]elfSym
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symstrings *[vdsoSymStringsSize]byte
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chain []uint32
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bucket []uint32
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symOff uint32
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isGNUHash bool
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/* Version table */
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versym *[1 << 32]uint16
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verdef *elf64Verdef
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versym *[vdsoVerSymSize]uint16
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verdef *elfVerdef
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}
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var linux26 = version_key{"LINUX_2.6", 0x3ae75f6}
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var sym_keys = []symbol_key{
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{"__vdso_time", 0xa33c485, 0x821e8e0d, &__vdso_time_sym},
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{"__vdso_gettimeofday", 0x315ca59, 0xb01bca00, &__vdso_gettimeofday_sym},
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{"__vdso_clock_gettime", 0xd35ec75, 0x6e43a318, &__vdso_clock_gettime_sym},
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}
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// see vdso_linux_*.go for sym_keys[] and __vdso_* vars
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// initialize with vsyscall fallbacks
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var (
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__vdso_time_sym uintptr = 0xffffffffff600400
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__vdso_gettimeofday_sym uintptr = 0xffffffffff600000
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__vdso_clock_gettime_sym uintptr = 0
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)
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func vdso_init_from_sysinfo_ehdr(info *vdso_info, hdr *elf64Ehdr) {
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func vdso_init_from_sysinfo_ehdr(info *vdso_info, hdr *elfEhdr) {
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info.valid = false
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info.load_addr = uintptr(unsafe.Pointer(hdr))
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@ -183,9 +109,9 @@ func vdso_init_from_sysinfo_ehdr(info *vdso_info, hdr *elf64Ehdr) {
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// We need two things from the segment table: the load offset
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// and the dynamic table.
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var found_vaddr bool
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var dyn *[1 << 20]elf64Dyn
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var dyn *[vdsoDynSize]elfDyn
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for i := uint16(0); i < hdr.e_phnum; i++ {
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pt := (*elf64Phdr)(add(pt, uintptr(i)*unsafe.Sizeof(elf64Phdr{})))
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pt := (*elfPhdr)(add(pt, uintptr(i)*unsafe.Sizeof(elfPhdr{})))
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switch pt.p_type {
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case _PT_LOAD:
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if !found_vaddr {
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@ -194,7 +120,7 @@ func vdso_init_from_sysinfo_ehdr(info *vdso_info, hdr *elf64Ehdr) {
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}
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case _PT_DYNAMIC:
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dyn = (*[1 << 20]elf64Dyn)(unsafe.Pointer(info.load_addr + uintptr(pt.p_offset)))
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dyn = (*[vdsoDynSize]elfDyn)(unsafe.Pointer(info.load_addr + uintptr(pt.p_offset)))
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}
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}
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@ -204,7 +130,7 @@ func vdso_init_from_sysinfo_ehdr(info *vdso_info, hdr *elf64Ehdr) {
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// Fish out the useful bits of the dynamic table.
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var hash, gnuhash *[1 << 30]uint32
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var hash, gnuhash *[vdsoHashSize]uint32
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info.symstrings = nil
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info.symtab = nil
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info.versym = nil
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@ -214,17 +140,17 @@ func vdso_init_from_sysinfo_ehdr(info *vdso_info, hdr *elf64Ehdr) {
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p := info.load_offset + uintptr(dt.d_val)
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switch dt.d_tag {
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case _DT_STRTAB:
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info.symstrings = (*[1 << 32]byte)(unsafe.Pointer(p))
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info.symstrings = (*[vdsoSymStringsSize]byte)(unsafe.Pointer(p))
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case _DT_SYMTAB:
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info.symtab = (*[1 << 32]elf64Sym)(unsafe.Pointer(p))
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info.symtab = (*[vdsoSymTabSize]elfSym)(unsafe.Pointer(p))
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case _DT_HASH:
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hash = (*[1 << 30]uint32)(unsafe.Pointer(p))
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hash = (*[vdsoHashSize]uint32)(unsafe.Pointer(p))
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case _DT_GNU_HASH:
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gnuhash = (*[1 << 30]uint32)(unsafe.Pointer(p))
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gnuhash = (*[vdsoHashSize]uint32)(unsafe.Pointer(p))
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case _DT_VERSYM:
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info.versym = (*[1 << 32]uint16)(unsafe.Pointer(p))
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info.versym = (*[vdsoVerSymSize]uint16)(unsafe.Pointer(p))
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case _DT_VERDEF:
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info.verdef = (*elf64Verdef)(unsafe.Pointer(p))
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info.verdef = (*elfVerdef)(unsafe.Pointer(p))
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}
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}
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@ -241,8 +167,8 @@ func vdso_init_from_sysinfo_ehdr(info *vdso_info, hdr *elf64Ehdr) {
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nbucket := gnuhash[0]
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info.symOff = gnuhash[1]
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bloomSize := gnuhash[2]
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info.bucket = gnuhash[4+bloomSize*2:][:nbucket]
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info.chain = gnuhash[4+bloomSize*2+nbucket:]
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info.bucket = gnuhash[4+bloomSize*uint32(vdsoBloomSizeScale):][:nbucket]
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info.chain = gnuhash[4+bloomSize*uint32(vdsoBloomSizeScale)+nbucket:]
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info.isGNUHash = true
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} else {
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// Parse the hash table header.
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@ -264,7 +190,7 @@ func vdso_find_version(info *vdso_info, ver *version_key) int32 {
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def := info.verdef
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for {
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if def.vd_flags&_VER_FLG_BASE == 0 {
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aux := (*elf64Verdaux)(add(unsafe.Pointer(def), uintptr(def.vd_aux)))
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aux := (*elfVerdaux)(add(unsafe.Pointer(def), uintptr(def.vd_aux)))
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if def.vd_hash == ver.ver_hash && ver.version == gostringnocopy(&info.symstrings[aux.vda_name]) {
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return int32(def.vd_ndx & 0x7fff)
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}
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@ -273,7 +199,7 @@ func vdso_find_version(info *vdso_info, ver *version_key) int32 {
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if def.vd_next == 0 {
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break
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}
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def = (*elf64Verdef)(add(unsafe.Pointer(def), uintptr(def.vd_next)))
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def = (*elfVerdef)(add(unsafe.Pointer(def), uintptr(def.vd_next)))
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}
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return -1 // cannot match any version
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@ -286,8 +212,8 @@ func vdso_parse_symbols(info *vdso_info, version int32) {
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apply := func(symIndex uint32, k symbol_key) bool {
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sym := &info.symtab[symIndex]
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typ := _ELF64_ST_TYPE(sym.st_info)
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bind := _ELF64_ST_BIND(sym.st_info)
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typ := _ELF_ST_TYPE(sym.st_info)
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bind := _ELF_ST_BIND(sym.st_info)
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if typ != _STT_FUNC || bind != _STB_GLOBAL && bind != _STB_WEAK || sym.st_shndx == _SHN_UNDEF {
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return false
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}
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@ -349,7 +275,7 @@ func archauxv(tag, val uintptr) {
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// TODO(rsc): I don't understand why the compiler thinks info escapes
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// when passed to the three functions below.
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info1 := (*vdso_info)(noescape(unsafe.Pointer(&info)))
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vdso_init_from_sysinfo_ehdr(info1, (*elf64Ehdr)(unsafe.Pointer(val)))
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vdso_init_from_sysinfo_ehdr(info1, (*elfEhdr)(unsafe.Pointer(val)))
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vdso_parse_symbols(info1, vdso_find_version(info1, &linux26))
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}
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}
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96
src/runtime/vdso_linux_amd64.go
Normal file
96
src/runtime/vdso_linux_amd64.go
Normal file
@ -0,0 +1,96 @@
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// Copyright 2012 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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// ELF64 structure definitions for use by the Linux vDSO loader
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type elfSym struct {
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st_name uint32
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st_info byte
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st_other byte
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st_shndx uint16
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st_value uint64
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st_size uint64
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}
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type elfVerdef struct {
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vd_version uint16 /* Version revision */
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vd_flags uint16 /* Version information */
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vd_ndx uint16 /* Version Index */
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vd_cnt uint16 /* Number of associated aux entries */
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vd_hash uint32 /* Version name hash value */
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vd_aux uint32 /* Offset in bytes to verdaux array */
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vd_next uint32 /* Offset in bytes to next verdef entry */
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}
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type elfEhdr struct {
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e_ident [_EI_NIDENT]byte /* Magic number and other info */
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e_type uint16 /* Object file type */
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e_machine uint16 /* Architecture */
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e_version uint32 /* Object file version */
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e_entry uint64 /* Entry point virtual address */
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e_phoff uint64 /* Program header table file offset */
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e_shoff uint64 /* Section header table file offset */
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e_flags uint32 /* Processor-specific flags */
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e_ehsize uint16 /* ELF header size in bytes */
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e_phentsize uint16 /* Program header table entry size */
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e_phnum uint16 /* Program header table entry count */
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e_shentsize uint16 /* Section header table entry size */
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e_shnum uint16 /* Section header table entry count */
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e_shstrndx uint16 /* Section header string table index */
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}
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type elfPhdr struct {
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p_type uint32 /* Segment type */
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p_flags uint32 /* Segment flags */
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p_offset uint64 /* Segment file offset */
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p_vaddr uint64 /* Segment virtual address */
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p_paddr uint64 /* Segment physical address */
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p_filesz uint64 /* Segment size in file */
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p_memsz uint64 /* Segment size in memory */
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p_align uint64 /* Segment alignment */
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}
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type elfShdr struct {
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sh_name uint32 /* Section name (string tbl index) */
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sh_type uint32 /* Section type */
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sh_flags uint64 /* Section flags */
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sh_addr uint64 /* Section virtual addr at execution */
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sh_offset uint64 /* Section file offset */
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sh_size uint64 /* Section size in bytes */
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sh_link uint32 /* Link to another section */
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sh_info uint32 /* Additional section information */
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sh_addralign uint64 /* Section alignment */
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sh_entsize uint64 /* Entry size if section holds table */
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}
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type elfDyn struct {
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d_tag int64 /* Dynamic entry type */
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d_val uint64 /* Integer value */
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}
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type elfVerdaux struct {
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vda_name uint32 /* Version or dependency names */
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vda_next uint32 /* Offset in bytes to next verdaux entry */
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}
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const (
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// vdsoArrayMax is the byte-size of a maximally sized array on this architecture.
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// See cmd/compile/internal/amd64/galign.go arch.MAXWIDTH initialization.
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vdsoArrayMax = 1<<50 - 1
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)
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var sym_keys = []symbol_key{
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{"__vdso_time", 0xa33c485, 0x821e8e0d, &__vdso_time_sym},
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{"__vdso_gettimeofday", 0x315ca59, 0xb01bca00, &__vdso_gettimeofday_sym},
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{"__vdso_clock_gettime", 0xd35ec75, 0x6e43a318, &__vdso_clock_gettime_sym},
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}
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// initialize with vsyscall fallbacks
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var (
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__vdso_time_sym uintptr = 0xffffffffff600400
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__vdso_gettimeofday_sym uintptr = 0xffffffffff600000
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__vdso_clock_gettime_sym uintptr = 0
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)
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