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>

1 files changed, 96 insertions, 0 deletions

diff --git a/src/runtime/vdso_linux_amd64.go b/src/runtime/vdso_linux_amd64.go
new file mode 100644
index 0000000000..0bbe5c2e8f
--- /dev/null
+++ b/src/runtime/vdso_linux_amd64.go
@@ -0,0 +1,96 @@
+// Copyright 2012 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 runtime
+
+// ELF64 structure definitions for use by the Linux vDSO loader
+
+type elfSym struct {
+	st_name  uint32
+	st_info  byte
+	st_other byte
+	st_shndx uint16
+	st_value uint64
+	st_size  uint64
+}
+
+type elfVerdef struct {
+	vd_version uint16 /* Version revision */
+	vd_flags   uint16 /* Version information */
+	vd_ndx     uint16 /* Version Index */
+	vd_cnt     uint16 /* Number of associated aux entries */
+	vd_hash    uint32 /* Version name hash value */
+	vd_aux     uint32 /* Offset in bytes to verdaux array */
+	vd_next    uint32 /* Offset in bytes to next verdef entry */
+}
+
+type elfEhdr struct {
+	e_ident     [_EI_NIDENT]byte /* Magic number and other info */
+	e_type      uint16           /* Object file type */
+	e_machine   uint16           /* Architecture */
+	e_version   uint32           /* Object file version */
+	e_entry     uint64           /* Entry point virtual address */
+	e_phoff     uint64           /* Program header table file offset */
+	e_shoff     uint64           /* Section header table file offset */
+	e_flags     uint32           /* Processor-specific flags */
+	e_ehsize    uint16           /* ELF header size in bytes */
+	e_phentsize uint16           /* Program header table entry size */
+	e_phnum     uint16           /* Program header table entry count */
+	e_shentsize uint16           /* Section header table entry size */
+	e_shnum     uint16           /* Section header table entry count */
+	e_shstrndx  uint16           /* Section header string table index */
+}
+
+type elfPhdr struct {
+	p_type   uint32 /* Segment type */
+	p_flags  uint32 /* Segment flags */
+	p_offset uint64 /* Segment file offset */
+	p_vaddr  uint64 /* Segment virtual address */
+	p_paddr  uint64 /* Segment physical address */
+	p_filesz uint64 /* Segment size in file */
+	p_memsz  uint64 /* Segment size in memory */
+	p_align  uint64 /* Segment alignment */
+}
+
+type elfShdr struct {
+	sh_name      uint32 /* Section name (string tbl index) */
+	sh_type      uint32 /* Section type */
+	sh_flags     uint64 /* Section flags */
+	sh_addr      uint64 /* Section virtual addr at execution */
+	sh_offset    uint64 /* Section file offset */
+	sh_size      uint64 /* Section size in bytes */
+	sh_link      uint32 /* Link to another section */
+	sh_info      uint32 /* Additional section information */
+	sh_addralign uint64 /* Section alignment */
+	sh_entsize   uint64 /* Entry size if section holds table */
+}
+
+type elfDyn struct {
+	d_tag int64  /* Dynamic entry type */
+	d_val uint64 /* Integer value */
+}
+
+type elfVerdaux struct {
+	vda_name uint32 /* Version or dependency names */
+	vda_next uint32 /* Offset in bytes to next verdaux entry */
+}
+
+const (
+	// vdsoArrayMax is the byte-size of a maximally sized array on this architecture.
+	// See cmd/compile/internal/amd64/galign.go arch.MAXWIDTH initialization.
+	vdsoArrayMax = 1<<50 - 1
+)
+
+var sym_keys = []symbol_key{
+	{"__vdso_time", 0xa33c485, 0x821e8e0d, &__vdso_time_sym},
+	{"__vdso_gettimeofday", 0x315ca59, 0xb01bca00, &__vdso_gettimeofday_sym},
+	{"__vdso_clock_gettime", 0xd35ec75, 0x6e43a318, &__vdso_clock_gettime_sym},
+}
+
+// initialize with vsyscall fallbacks
+var (
+	__vdso_time_sym          uintptr = 0xffffffffff600400
+	__vdso_gettimeofday_sym  uintptr = 0xffffffffff600000
+	__vdso_clock_gettime_sym uintptr = 0
+)