libgo/go/runtime/lfstack_64bit.go

   1 // Copyright 2014 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // +build amd64 arm64 mips64 mips64le ppc64 ppc64le s390x wasm arm64be alpha sparc64 ia64 riscv64
   6
   7 package runtime
   8
   9 import "unsafe"
  10
  11 const (
  12         // addrBits is the number of bits needed to represent a virtual address.
  13         //
  14         // See heapAddrBits for a table of address space sizes on
  15         // various architectures. 48 bits is enough for all
  16         // architectures except s390x.
  17         //
  18         // On AMD64, virtual addresses are 48-bit (or 57-bit) numbers sign extended to 64.
  19         // We shift the address left 16 to eliminate the sign extended part and make
  20         // room in the bottom for the count.
  21         //
  22         // On s390x, virtual addresses are 64-bit. There's not much we
  23         // can do about this, so we just hope that the kernel doesn't
  24         // get to really high addresses and panic if it does.
  25         addrBits = 48
  26
  27         // In addition to the 16 bits taken from the top, we can take 3 from the
  28         // bottom, because node must be pointer-aligned, giving a total of 19 bits
  29         // of count.
  30         cntBits = 64 - addrBits + 3
  31
  32         // On sparc64-linux, user addresses are 52-bit numbers sign extended to 64.
  33         // We shift the address left 12 to eliminate the sign extended part and make
  34         // room in the bottom for the count.
  35         sparcLinuxAddrBits = 52
  36         sparcLinuxCntBits  = 64 - sparcLinuxAddrBits + 3
  37
  38         // On IA64, the virtual address space is devided into 8 regions, with
  39         // 52 address bits each (with 64k page size).
  40         ia64AddrBits = 55
  41         ia64CntBits  = 64 - ia64AddrBits + 3
  42
  43         // On AIX, 64-bit addresses are split into 36-bit segment number and 28-bit
  44         // offset in segment.  Segment numbers in the range 0x070000000-0x07FFFFFFF
  45         // and 0x0A0000000-0x0AFFFFFFF(LSA) are available for mmap.
  46         // We assume all lfnode addresses are from memory allocated with mmap.
  47         // We use one bit to distinguish between the two ranges.
  48         aixAddrBits = 57
  49         aixCntBits  = 64 - aixAddrBits + 3
  50 )
  51
  52 func lfstackPack(node *lfnode, cnt uintptr) uint64 {
  53         if GOARCH == "sparc64" && GOOS == "linux" {
  54                 return uint64(uintptr(unsafe.Pointer(node)))<<(64-sparcLinuxAddrBits) | uint64(cnt&(1<<sparcLinuxCntBits-1))
  55         }
  56         if GOARCH == "ia64" {
  57                 // Top three bits are the region number
  58                 val := uint64(uintptr(unsafe.Pointer(node)))
  59                 return (val<<(64-ia64AddrBits))&(1<<(64-3)-1) | val&^(1<<(64-3)-1) | uint64(cnt&(1<<ia64CntBits-1))
  60         }
  61         if GOARCH == "ppc64" && GOOS == "aix" {
  62                 return uint64(uintptr(unsafe.Pointer(node)))<<(64-aixAddrBits) | uint64(cnt&(1<<aixCntBits-1))
  63         }
  64         return uint64(uintptr(unsafe.Pointer(node)))<<(64-addrBits) | uint64(cnt&(1<<cntBits-1))
  65 }
  66
  67 func lfstackUnpack(val uint64) *lfnode {
  68         if GOARCH == "amd64" || GOOS == "solaris" {
  69                 // amd64 or Solaris systems can place the stack above the VA hole, so we need to sign extend
  70                 // val before unpacking.
  71                 return (*lfnode)(unsafe.Pointer(uintptr(int64(val) >> cntBits << 3)))
  72         }
  73         if GOARCH == "sparc64" && GOOS == "linux" {
  74                 return (*lfnode)(unsafe.Pointer(uintptr(int64(val) >> sparcLinuxCntBits << 3)))
  75         }
  76         if GOARCH == "ia64" {
  77                 return (*lfnode)(unsafe.Pointer(uintptr(((val & (1<<(64-3) - 1)) >> ia64CntBits << 3) | val&^(1<<(64-3)-1))))
  78         }
  79         if GOARCH == "ppc64" && GOOS == "aix" {
  80                 if val&(1<<63) != 0 {
  81                         return (*lfnode)(unsafe.Pointer(uintptr((val >> aixCntBits << 3) | 0x7<<56)))
  82                 } else {
  83                         return (*lfnode)(unsafe.Pointer(uintptr((val >> aixCntBits << 3) | 0xa<<56)))
  84                 }
  85         }
  86         return (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
  87 }