cmd/link, runtime: arm64 implementation of addmoduledata

Change-Id: I62fb5b20d7caa51b77560a4bfb74a39f17089805
Reviewed-on: https://go-review.googlesource.com/13999
Reviewed-by: Russ Cox <rsc@golang.org>

diff --git a/src/cmd/link/internal/arm64/asm.go b/src/cmd/link/internal/arm64/asm.go
index 8517a900049461fd3c0f3dfa14c9296befaf4e7a..2e974cc3f43e45eb9a916c1981aa0e4691d5e56e 100644 (file)
--- a/src/cmd/link/internal/arm64/asm.go
+++ b/src/cmd/link/internal/arm64/asm.go
@@ -38,7 +38,58 @@ import (
        "log"
 )
 
-func gentext() {}
+func gentext() {
+       if !ld.DynlinkingGo() {
+               return
+       }
+       addmoduledata := ld.Linklookup(ld.Ctxt, "runtime.addmoduledata", 0)
+       if addmoduledata.Type == obj.STEXT {
+               // we're linking a module containing the runtime -> no need for
+               // an init function
+               return
+       }
+       addmoduledata.Reachable = true
+       initfunc := ld.Linklookup(ld.Ctxt, "go.link.addmoduledata", 0)
+       initfunc.Type = obj.STEXT
+       initfunc.Local = true
+       initfunc.Reachable = true
+       o := func(op uint32) {
+               ld.Adduint32(ld.Ctxt, initfunc, op)
+       }
+       // 0000000000000000 <local.dso_init>:
+       // 0:   90000000        adrp    x0, 0 <runtime.firstmoduledata>
+       //      0: R_AARCH64_ADR_PREL_PG_HI21   local.moduledata
+       // 4:   91000000        add     x0, x0, #0x0
+       //      4: R_AARCH64_ADD_ABS_LO12_NC    local.moduledata
+       o(0x90000000)
+       o(0x91000000)
+       rel := ld.Addrel(initfunc)
+       rel.Off = 0
+       rel.Siz = 8
+       rel.Sym = ld.Ctxt.Moduledata
+       rel.Type = obj.R_ADDRARM64
+
+       // 8:   14000000        bl      0 <runtime.addmoduledata>
+       //      8: R_AARCH64_CALL26     runtime.addmoduledata
+       o(0x14000000)
+       rel = ld.Addrel(initfunc)
+       rel.Off = 8
+       rel.Siz = 4
+       rel.Sym = ld.Linklookup(ld.Ctxt, "runtime.addmoduledata", 0)
+       rel.Type = obj.R_CALLARM64 // Really should be R_AARCH64_JUMP26 but doesn't seem to make any difference
+
+       if ld.Ctxt.Etextp != nil {
+               ld.Ctxt.Etextp.Next = initfunc
+       } else {
+               ld.Ctxt.Textp = initfunc
+       }
+       ld.Ctxt.Etextp = initfunc
+       initarray_entry := ld.Linklookup(ld.Ctxt, "go.link.addmoduledatainit", 0)
+       initarray_entry.Reachable = true
+       initarray_entry.Local = true
+       initarray_entry.Type = obj.SINITARR
+       ld.Addaddr(ld.Ctxt, initarray_entry, initfunc)
+}
 
 func adddynrela(rel *ld.LSym, s *ld.LSym, r *ld.Reloc) {
        log.Fatalf("adddynrela not implemented")

diff --git a/src/runtime/asm_arm64.s b/src/runtime/asm_arm64.s
index 4c964c0b2d295720c2ca73b456d71272f9cbf2ed..80309868f4a1d5f226381803876f59ca271d90ae 100644 (file)
--- a/src/runtime/asm_arm64.s
+++ b/src/runtime/asm_arm64.s
@@ -1030,3 +1030,14 @@ TEXT runtime·prefetchnta(SB),NOSPLIT,$0-8
 
 TEXT runtime·sigreturn(SB),NOSPLIT,$0-8
         RET
+
+// This is called from .init_array and follows the platform, not Go, ABI.
+TEXT runtime·addmoduledata(SB),NOSPLIT,$0-0
+       SUB     $0x10, RSP
+       MOVD    R27, 8(RSP) // The access to global variables below implicitly uses R27, which is callee-save
+       MOVD    runtime·lastmoduledatap(SB), R1
+       MOVD    R0, moduledata_next(R1)
+       MOVD    R0, runtime·lastmoduledatap(SB)
+       MOVD    8(RSP), R27
+       ADD     $0x10, RSP
+       RET