cmd/link: on PPC64, put plt stubs at beginning of Textp

Put call stubs at the beginning (instead of the end). So the
trampoline pass knows the addresses of the stubs, and it can
insert trampolines when necessary.

Fixes #19425.

Change-Id: I1e06529ef837a6130df58917315610d45a6819ca
Reviewed-on: https://go-review.googlesource.com/38131
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>

diff --git a/src/cmd/link/internal/ppc64/asm.go b/src/cmd/link/internal/ppc64/asm.go
index 97107b9e5235629fbaeb40f024420f7d5a8e3215..cf2c532f9e894ce32d6c8f02c05c82cacd235f87 100644 (file)
--- a/src/cmd/link/internal/ppc64/asm.go
+++ b/src/cmd/link/internal/ppc64/asm.go
@@ -87,6 +87,7 @@ func genplt(ctxt *ld.Link) {
        //
        // This assumes "case 1" from the ABI, where the caller needs
        // us to save and restore the TOC pointer.
+       var stubs []*ld.Symbol
        for _, s := range ctxt.Textp {
                for i := range s.R {
                        r := &s.R[i]
@@ -108,7 +109,7 @@ func genplt(ctxt *ld.Link) {
                        if stub.Size == 0 {
                                // Need outer to resolve .TOC.
                                stub.Outer = s
-                               ctxt.Textp = append(ctxt.Textp, stub)
+                               stubs = append(stubs, stub)
                                gencallstub(ctxt, 1, stub, r.Sym)
                        }
 
@@ -121,6 +122,11 @@ func genplt(ctxt *ld.Link) {
                        ctxt.Arch.ByteOrder.PutUint32(s.P[r.Off+4:], o1)
                }
        }
+       // Put call stubs at the beginning (instead of the end).
+       // So when resolving the relocations to calls to the stubs,
+       // the addresses are known and trampolines can be inserted
+       // when necessary.
+       ctxt.Textp = append(stubs, ctxt.Textp...)
 }
 
 func genaddmoduledata(ctxt *ld.Link) {