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 arm64be alpha sparc64 ia64
   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         // In Linux the user address space for each architecture is limited as
  15         // follows (taken from the processor.h file for the architecture):
  16         //
  17         // Architecture  Name              Maximum Value (exclusive)
  18         // ---------------------------------------------------------------------
  19         // arm64         TASK_SIZE_64      Depends on configuration.
  20         // ppc64{,le}    TASK_SIZE_USER64  0x400000000000UL (46 bit addresses)
  21         // mips64{,le}   TASK_SIZE64       0x010000000000UL (40 bit addresses)
  22         // s390x         TASK_SIZE         0x020000000000UL (41 bit addresses)
  23         //
  24         // These values may increase over time.
  25         //
  26         // On AMD64, virtual addresses are 48-bit numbers sign extended to 64.
  27         // We shift the address left 16 to eliminate the sign extended part and make
  28         // room in the bottom for the count.
  29         addrBits = 48
  30
  31         // In addition to the 16 bits taken from the top, we can take 3 from the
  32         // bottom, because node must be pointer-aligned, giving a total of 19 bits
  33         // of count.
  34         cntBits = 64 - addrBits + 3
  35
  36         // On sparc64-linux, user addresses are 52-bit numbers sign extended to 64.
  37         // We shift the address left 12 to eliminate the sign extended part and make
  38         // room in the bottom for the count.
  39         sparcLinuxAddrBits = 52
  40         sparcLinuxCntBits  = 64 - sparcLinuxAddrBits + 3
  41
  42         // On IA64, the virtual address space is devided into 8 regions, with
  43         // 52 address bits each (with 64k page size).
  44         ia64AddrBits = 55
  45         ia64CntBits  = 64 - ia64AddrBits + 3
  46
  47         // On AIX, 64-bit addresses are split into 36-bit segment number and 28-bit
  48         // offset in segment.  Segment numbers in the range 0x070000000-0x07FFFFFFF
  49         // and 0x0A0000000-0x0AFFFFFFF(LSA) are available for mmap.
  50         // We assume all lfnode addresses are from memory allocated with mmap.
  51         // We use one bit to distinguish between the two ranges.
  52         aixAddrBits = 57
  53         aixCntBits  = 64 - aixAddrBits + 3
  54 )
  55
  56 func lfstackPack(node *lfnode, cnt uintptr) uint64 {
  57         if GOARCH == "sparc64" && GOOS == "linux" {
  58                 return uint64(uintptr(unsafe.Pointer(node)))<<(64-sparcLinuxAddrBits) | uint64(cnt&(1<<sparcLinuxCntBits-1))
  59         }
  60         if GOARCH == "ia64" {
  61                 // Top three bits are the region number
  62                 val := uint64(uintptr(unsafe.Pointer(node)))
  63                 return (val<<(64-ia64AddrBits))&(1<<(64-3)-1) | val&^(1<<(64-3)-1) | uint64(cnt&(1<<ia64CntBits-1))
  64         }
  65         if GOARCH == "ppc64" && GOOS == "aix" {
  66                 return uint64(uintptr(unsafe.Pointer(node)))<<(64-aixAddrBits) | uint64(cnt&(1<<aixCntBits-1))
  67         }
  68         return uint64(uintptr(unsafe.Pointer(node)))<<(64-addrBits) | uint64(cnt&(1<<cntBits-1))
  69 }
  70
  71 func lfstackUnpack(val uint64) *lfnode {
  72         if GOARCH == "amd64" || GOOS == "solaris" {
  73                 // amd64 or Solaris systems can place the stack above the VA hole, so we need to sign extend
  74                 // val before unpacking.
  75                 return (*lfnode)(unsafe.Pointer(uintptr(int64(val) >> cntBits << 3)))
  76         }
  77         if GOARCH == "sparc64" && GOOS == "linux" {
  78                 return (*lfnode)(unsafe.Pointer(uintptr(int64(val) >> sparcLinuxCntBits << 3)))
  79         }
  80         if GOARCH == "ia64" {
  81                 return (*lfnode)(unsafe.Pointer(uintptr((val>>ia64CntBits<<3)&(1<<(64-3)-1) | val&^(1<<(64-3)-1))))
  82         }
  83         if GOARCH == "ppc64" && GOOS == "aix" {
  84                 if val&(1<<63) != 0 {
  85                         return (*lfnode)(unsafe.Pointer(uintptr((val >> aixCntBits << 3) | 0x7<<56)))
  86                 } else {
  87                         return (*lfnode)(unsafe.Pointer(uintptr((val >> aixCntBits << 3) | 0xa<<56)))
  88                 }
  89         }
  90         return (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
  91 }