diff options
Diffstat (limited to 'src/cmd/link/internal/ppc64/asm.go')
| -rw-r--r-- | src/cmd/link/internal/ppc64/asm.go | 73 |
1 files changed, 56 insertions, 17 deletions
diff --git a/src/cmd/link/internal/ppc64/asm.go b/src/cmd/link/internal/ppc64/asm.go index cf2c532f9e..9f2925fc51 100644 --- a/src/cmd/link/internal/ppc64/asm.go +++ b/src/cmd/link/internal/ppc64/asm.go @@ -522,13 +522,22 @@ func archrelocaddr(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol, val *int64) int { // resolve direct jump relocation r in s, and add trampoline if necessary func trampoline(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol) { + // Trampolines are created if the branch offset is too large and the linker cannot insert a call stub to handle it. + // For internal linking, trampolines are always created for long calls. + // For external linking, the linker can insert a call stub to handle a long call, but depends on having the TOC address in + // r2. For those build modes with external linking where the TOC address is not maintained in r2, trampolines must be created. + if ld.Linkmode == ld.LinkExternal && (ctxt.DynlinkingGo() || ld.Buildmode == ld.BuildmodeCArchive || ld.Buildmode == ld.BuildmodeCShared || ld.Buildmode == ld.BuildmodePIE) { + // No trampolines needed since r2 contains the TOC + return + } + t := ld.Symaddr(r.Sym) + r.Add - (s.Value + int64(r.Off)) switch r.Type { case obj.R_CALLPOWER: // If branch offset is too far then create a trampoline. - if int64(int32(t<<6)>>6) != t || (*ld.FlagDebugTramp > 1 && s.File != r.Sym.File) { + if (ld.Linkmode == ld.LinkExternal && s.Sect != r.Sym.Sect) || (ld.Linkmode == ld.LinkInternal && int64(int32(t<<6)>>6) != t) || (*ld.FlagDebugTramp > 1 && s.File != r.Sym.File) { var tramp *ld.Symbol for i := 0; ; i++ { @@ -552,26 +561,20 @@ func trampoline(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol) { t = ld.Symaddr(tramp) + r.Add - (s.Value + int64(r.Off)) - // If the offset of the trampoline that has been found is within range, use it. - if int64(int32(t<<6)>>6) == t { + // With internal linking, the trampoline can be used if it is not too far. + // With external linking, the trampoline must be in this section for it to be reused. + if (ld.Linkmode == ld.LinkInternal && int64(int32(t<<6)>>6) == t) || (ld.Linkmode == ld.LinkExternal && s.Sect == tramp.Sect) { break } } if tramp.Type == 0 { - ctxt.AddTramp(tramp) - tramp.Size = 16 // 4 instructions - tramp.P = make([]byte, tramp.Size) - t = ld.Symaddr(r.Sym) + r.Add - f := t & 0xffff0000 - o1 := uint32(0x3fe00000 | (f >> 16)) // lis r31,trampaddr hi (r31 is temp reg) - f = t & 0xffff - o2 := uint32(0x63ff0000 | f) // ori r31,trampaddr lo - o3 := uint32(0x7fe903a6) // mtctr - o4 := uint32(0x4e800420) // bctr - ld.SysArch.ByteOrder.PutUint32(tramp.P, o1) - ld.SysArch.ByteOrder.PutUint32(tramp.P[4:], o2) - ld.SysArch.ByteOrder.PutUint32(tramp.P[8:], o3) - ld.SysArch.ByteOrder.PutUint32(tramp.P[12:], o4) + if ctxt.DynlinkingGo() || ld.Buildmode == ld.BuildmodeCArchive || ld.Buildmode == ld.BuildmodeCShared || ld.Buildmode == ld.BuildmodePIE { + // Should have returned for above cases + ld.Errorf(s, "unexpected trampoline for shared or dynamic linking\n") + } else { + ctxt.AddTramp(tramp) + gentramp(tramp, r.Sym, int64(r.Add)) + } } r.Sym = tramp r.Add = 0 // This was folded into the trampoline target address @@ -582,6 +585,42 @@ func trampoline(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol) { } } +func gentramp(tramp, target *ld.Symbol, offset int64) { + // Used for default build mode for an executable + // Address of the call target is generated using + // relocation and doesn't depend on r2 (TOC). + tramp.Size = 16 // 4 instructions + tramp.P = make([]byte, tramp.Size) + t := ld.Symaddr(target) + offset + o1 := uint32(0x3fe00000) // lis r31,targetaddr hi + o2 := uint32(0x3bff0000) // addi r31,targetaddr lo + // With external linking, the target address must be + // relocated using LO and HA + if ld.Linkmode == ld.LinkExternal { + tr := ld.Addrel(tramp) + tr.Off = 0 + tr.Type = obj.R_ADDRPOWER + tr.Siz = 8 // generates 2 relocations: HA + LO + tr.Sym = target + tr.Add = offset + } else { + // adjustment needed if lo has sign bit set + // when using addi to compute address + val := uint32((t & 0xffff0000) >> 16) + if t&0x8000 != 0 { + val += 1 + } + o1 |= val // hi part of addr + o2 |= uint32(t & 0xffff) // lo part of addr + } + o3 := uint32(0x7fe903a6) // mtctr r31 + o4 := uint32(0x4e800420) // bctr + ld.SysArch.ByteOrder.PutUint32(tramp.P, o1) + ld.SysArch.ByteOrder.PutUint32(tramp.P[4:], o2) + ld.SysArch.ByteOrder.PutUint32(tramp.P[8:], o3) + ld.SysArch.ByteOrder.PutUint32(tramp.P[12:], o4) +} + func archreloc(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol, val *int64) int { if ld.Linkmode == ld.LinkExternal { switch r.Type { |