cmd/ld: decode local entry offset from ppc64 symbols

ppc64 function symbols have both a global entry point and a local
entry point, where the difference is stashed in sym.other.  We'll need
this information to generate calls to ELF ABI functions.

Change-Id: Ibe343923f56801de7ebec29946c79690a9ffde57
Reviewed-on: https://go-review.googlesource.com/2002Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>

include/link.h

@@ -141,6 +141,7 @@ struct	LSym
 	uchar	hide;
 	uchar	leaf;	// arm only
 	uchar	fnptr;	// arm only
+	uchar	localentry;	// ppc64: instrs between global & local entry
 	uchar	seenglobl;
 	uchar	onlist;	// on the textp or datap lists
 	int16	symid;	// for writing .5/.6/.8 files

src/cmd/ld/ldelf.c

@@ -327,7 +327,7 @@ ldelf(Biobuf *f, char *pkg, int64 len, char *pn)
 	int32 base;
 	uint64 add, info;
 	char *name;
-	int i, j, rela, is64, n;
+	int i, j, rela, is64, n, flag;
 	uchar hdrbuf[64];
 	uchar *p;
 	ElfHdrBytes *hdr;
@@ -616,6 +616,13 @@ ldelf(Biobuf *f, char *pkg, int64 len, char *pn)
 					diag("%s: duplicate definition of %s", pn, s->name);
 			s->external = 1;
 		}
+		if(obj->machine == ElfMachPower64) {
+			flag = sym.other >> 5;
+			if(2 <= flag && flag <= 6)
+				s->localentry = 1 << (flag - 2);
+			else if(flag == 7)
+				diag("%s: invalid sym.other 0x%x for %s", pn, sym.other, s->name);
+		}
 	}
 	
 	// Sort outer lists by address, adding to textp.