cmd/link: fix AIX builds after recent linker changes

This updates XCOFF-specific code for the recent addition
of funcdata to pclntab.

Because XCOFF puts separate symbols into separate csects,
each with their own alignment, it's important to tell the
external linker the expected alignment of each part of pclntab.
Otherwise the offsets within pclntab may change as the external
linker aligns symbols. This CL sets the correct alignment for
each pclntab child symbol, and sets pclntab's alignment to the
max of that of its children.

Tested on the GCC compile farm.

Fixes #76486

Change-Id: I77d8a90c4b4b79d80ca11ede8d9a2aa9cc89f53f
Reviewed-on: https://go-review.googlesource.com/c/go/+/725603
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/src/cmd/link/internal/ld/xcoff.go b/src/cmd/link/internal/ld/xcoff.go
index 77ae1236c9..5f01eb2507 100644
--- a/src/cmd/link/internal/ld/xcoff.go
+++ b/src/cmd/link/internal/ld/xcoff.go
@@ -603,14 +603,20 @@ func xcoffUpdateOuterSize(ctxt *Link, size int64, stype sym.SymKind) {
 		outerSymSize["go:string.*"] = size
 	case sym.SGOFUNC:
 		if !ctxt.DynlinkingGo() {
-			outerSymSize["go:func.*"] = size
+			outerSymSize["go:funcdesc"] = size
 		}
 	case sym.SGOFUNCRELRO:
-		outerSymSize["go:funcrel.*"] = size
+		outerSymSize["go:funcdescrel"] = size
 	case sym.SGCBITS:
 		outerSymSize["runtime.gcbits.*"] = size
 	case sym.SPCLNTAB:
-		outerSymSize["runtime.pclntab"] = size
+		// go:func.* size must be removed from pclntab,
+		// as it's a real symbol. Same for runtime.findfunctab.
+		fsize := ldr.SymSize(ldr.Lookup("go:func.*", 0))
+		fft := ldr.Lookup("runtime.findfunctab", 0)
+		fsize = Rnd(fsize, int64(symalign(ldr, fft)))
+		tsize := ldr.SymSize(fft)
+		outerSymSize["runtime.pclntab"] = size - (fsize + tsize)
 	}
 }