liblink: use pc-relative addressing for all memory references in amd64 code

LGTM=rminnich, iant
R=golang-codereviews, rminnich, iant
CC=golang-codereviews, r
https://golang.org/cl/125140043

diff --git a/src/cmd/6l/asm.c b/src/cmd/6l/asm.c
index e251e32ca906aad3749c41f03e991d06cae3f83d..c7f6c65d00e54042b4fead6a2b3b11763db709fa 100644 (file)
--- a/src/cmd/6l/asm.c
+++ b/src/cmd/6l/asm.c
@@ -290,7 +290,6 @@ elfreloc1(Reloc *r, vlong sectoff)
                break;
                
        case R_CALL:
-       case R_PCREL:
                if(r->siz == 4) {
                        if(r->xsym->type == SDYNIMPORT)
                                VPUT(R_X86_64_GOTPCREL | (uint64)elfsym<<32);
@@ -299,7 +298,14 @@ elfreloc1(Reloc *r, vlong sectoff)
                } else
                        return -1;
                break;
-       
+
+       case R_PCREL:
+               if(r->siz == 4) {
+                       VPUT(R_X86_64_PC32 | (uint64)elfsym<<32);
+               } else
+                       return -1;
+               break;
+
        case R_TLS:
                if(r->siz == 4) {
                        if(flag_shared)
@@ -323,7 +329,7 @@ machoreloc1(Reloc *r, vlong sectoff)
        
        rs = r->xsym;
 
-       if(rs->type == SHOSTOBJ) {
+       if(rs->type == SHOSTOBJ || r->type == R_PCREL) {
                if(rs->dynid < 0) {
                        diag("reloc %d to non-macho symbol %s type=%d", r->type, rs->name, rs->type);
                        return -1;
@@ -345,10 +351,13 @@ machoreloc1(Reloc *r, vlong sectoff)
                v |= MACHO_X86_64_RELOC_UNSIGNED<<28;
                break;
        case R_CALL:
-       case R_PCREL:
                v |= 1<<24; // pc-relative bit
                v |= MACHO_X86_64_RELOC_BRANCH<<28;
                break;
+       case R_PCREL:
+               // NOTE: Only works with 'external' relocation. Forced above.
+               v |= 1<<24; // pc-relative bit
+               v |= MACHO_X86_64_RELOC_SIGNED<<28;
        }
        
        switch(r->siz) {

diff --git a/src/cmd/ld/data.c b/src/cmd/ld/data.c
index f76ac0129cd892e00984377aebc956815d4f2304..a988e807e6e749322bd4550634f8086bbfaf5845 100644 (file)
--- a/src/cmd/ld/data.c
+++ b/src/cmd/ld/data.c
@@ -281,9 +281,13 @@ relocsym(LSym *s)
                                        if(thechar == '6')
                                                o = 0;
                                } else if(HEADTYPE == Hdarwin) {
-                                       if(rs->type != SHOSTOBJ)
-                                               o += symaddr(rs) - rs->sect->vaddr;
-                                       o -= r->off; // WTF?
+                                       if(r->type == R_CALL) {
+                                               if(rs->type != SHOSTOBJ)
+                                                       o += symaddr(rs) - rs->sect->vaddr;
+                                               o -= r->off; // relative to section offset, not symbol
+                                       } else {
+                                               o += r->siz;
+                                       }
                                } else {
                                        diag("unhandled pcrel relocation for %s", headstring);
                                }

diff --git a/src/liblink/asm6.c b/src/liblink/asm6.c
index fa329777d03fcc450ef0b7726d2992e7586a6411..e25c85053ac8f055ce8425716846e6baca350eb7 100644 (file)
--- a/src/liblink/asm6.c
+++ b/src/liblink/asm6.c
@@ -1932,10 +1932,7 @@ oclass(Link *ctxt, Addr *a)
                                switch(a->index) {
                                case D_EXTERN:
                                case D_STATIC:
-                                       if(ctxt->flag_shared || ctxt->headtype == Hnacl)
-                                               return Yiauto;
-                                       else
-                                               return Yi32;    /* TO DO: Yi64 */
+                                       return Yiauto; // use pc-relative addressing
                                case D_AUTO:
                                case D_PARAM:
                                        return Yiauto;
@@ -2290,15 +2287,12 @@ vaddr(Link *ctxt, Addr *a, Reloc *r)
                r->sym = s;
                r->add = v;
                v = 0;
-               if(ctxt->flag_shared || ctxt->headtype == Hnacl) {
-                       if(s->type == STLSBSS) {
-                               r->xadd = r->add - r->siz;
-                               r->type = R_TLS;
-                               r->xsym = s;
-                       } else
-                               r->type = R_PCREL;
-               } else
-                       r->type = R_ADDR;
+               r->type = R_PCREL;
+               if(s->type == STLSBSS) {
+                       r->xadd = r->add - r->siz;
+                       r->type = R_TLS;
+                       r->xsym = s;
+               }
                break;
        
        case D_INDIR+D_TLS:
@@ -2333,13 +2327,6 @@ asmandsz(Link *ctxt, Addr *a, int r, int rex, int m64)
                        switch(t) {
                        default:
                                goto bad;
-                       case D_STATIC:
-                       case D_EXTERN:
-                               if(ctxt->flag_shared || ctxt->headtype == Hnacl)
-                                       goto bad;
-                               t = D_NONE;
-                               v = vaddr(ctxt, a, &rel);
-                               break;
                        case D_AUTO:
                        case D_PARAM:
                                t = D_SP;
@@ -2399,7 +2386,7 @@ asmandsz(Link *ctxt, Addr *a, int r, int rex, int m64)
 
        ctxt->rexflag |= (regrex[t] & Rxb) | rex;
        if(t == D_NONE || (D_CS <= t && t <= D_GS) || t == D_TLS) {
-               if((ctxt->flag_shared || ctxt->headtype == Hnacl) && t == D_NONE && (a->type == D_STATIC || a->type == D_EXTERN) || ctxt->asmode != 64) {
+               if(t == D_NONE && (a->type == D_STATIC || a->type == D_EXTERN) || ctxt->asmode != 64) {
                        *ctxt->andptr++ = (0 << 6) | (5 << 0) | (r << 3);
                        goto putrelv;
                }