liblink: add leaf bit to object file format

Without the leaf bit, the linker cannot record
the correct frame size in the symbol table, and
then stack traces get mangled. (Only for ARM.)

Fixes #7338.
Fixes #7347.

LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/88550043

diff --git a/src/cmd/ld/pcln.c b/src/cmd/ld/pcln.c
index bdb139f7a48f383f86ab64389c6f9d37c87e8636..b2370f2a91542cde5c119181e96c5098e6209e38 100644 (file)
--- a/src/cmd/ld/pcln.c
+++ b/src/cmd/ld/pcln.c
@@ -112,7 +112,7 @@ pclntab(void)
 {
        int32 i, nfunc, start, funcstart;
        LSym *ftab, *s;
-       int32 off, end;
+       int32 off, end, frameptrsize;
        int64 funcdata_bytes;
        Pcln *pcln;
        Pciter it;
@@ -173,7 +173,10 @@ pclntab(void)
                // when a called function doesn't have argument information.
                // We need to make sure everything has argument information
                // and then remove this.
-               off = setuint32(ctxt, ftab, off, ctxt->cursym->locals + PtrSize);
+               frameptrsize = PtrSize;
+               if(ctxt->cursym->leaf)
+                       frameptrsize = 0;
+               off = setuint32(ctxt, ftab, off, ctxt->cursym->locals + frameptrsize);
                
                if(pcln != &zpcln) {
                        renumberfiles(pcln->file, pcln->nfile, &pcln->pcfile);

diff --git a/src/cmd/link/testdata/autosection.6 b/src/cmd/link/testdata/autosection.6
index 3a2e35a5b227ebca6093cb358a0762e802a51680..f392e416808f3a92e59faf51628911f57b0d4d1f 100644 (file)
Binary files a/src/cmd/link/testdata/autosection.6 and b/src/cmd/link/testdata/autosection.6 differ

diff --git a/src/cmd/link/testdata/autoweak.6 b/src/cmd/link/testdata/autoweak.6
index 1fd54ed7e60d52f1247958df3b85dadb9369d70f..a694e4729180ac7096dcbff6ef9393357b05e2b8 100644 (file)
Binary files a/src/cmd/link/testdata/autoweak.6 and b/src/cmd/link/testdata/autoweak.6 differ

diff --git a/src/cmd/link/testdata/dead.6 b/src/cmd/link/testdata/dead.6
index e0cdecea96b934cdb54ef1416a675cd3d4dca273..270416f0b6c6bc5ed628cdbab77cd7bdbdfb6d55 100644 (file)
Binary files a/src/cmd/link/testdata/dead.6 and b/src/cmd/link/testdata/dead.6 differ

diff --git a/src/cmd/link/testdata/hello.6 b/src/cmd/link/testdata/hello.6
index 9ec799b4f39e5c1f2944573a46c7f7a091cbe895..448d40f76b8ecf08d4b0418e17e66c055484e244 100644 (file)
Binary files a/src/cmd/link/testdata/hello.6 and b/src/cmd/link/testdata/hello.6 differ

diff --git a/src/cmd/link/testdata/layout.6 b/src/cmd/link/testdata/layout.6
index c5121ff154a5b12ba4f13ff087a3d8c37ef4f345..56d416a1a0a62316d4c47109bfbd111b6f91d4b0 100644 (file)
Binary files a/src/cmd/link/testdata/layout.6 and b/src/cmd/link/testdata/layout.6 differ

diff --git a/src/cmd/link/testdata/pclntab.6 b/src/cmd/link/testdata/pclntab.6
index 0f7ab6dd78b59ff505d186408427dc18c909d305..91583a3fd471460d06b111a20e87a41207c8ee79 100644 (file)
Binary files a/src/cmd/link/testdata/pclntab.6 and b/src/cmd/link/testdata/pclntab.6 differ

diff --git a/src/liblink/objfile.c b/src/liblink/objfile.c
index b52b29ca59ebd55856f6340022e21c85f22e7d41..0c51e795f5582acdfe79cbdcb60265e593760c6b 100644 (file)
--- a/src/liblink/objfile.c
+++ b/src/liblink/objfile.c
@@ -49,6 +49,7 @@
 //
 //     - args [int]
 //     - locals [int]
+//     - leaf [int]
 //     - nlocal [int]
 //     - local [nlocal automatics]
 //     - pcln [pcln table]
@@ -291,8 +292,11 @@ writesym(Link *ctxt, Biobuf *b, LSym *s)
                if(s->dupok)
                        Bprint(ctxt->bso, "dupok ");
                Bprint(ctxt->bso, "size=%lld value=%lld", (vlong)s->size, (vlong)s->value);
-               if(s->type == STEXT)
+               if(s->type == STEXT) {
                        Bprint(ctxt->bso, " args=%#llux locals=%#llux", (uvlong)s->args, (uvlong)s->locals);
+                       if(s->leaf)
+                               Bprint(ctxt->bso, " leaf");
+               }
                Bprint(ctxt->bso, "\n");
                for(p=s->text; p != nil; p = p->link)
                        Bprint(ctxt->bso, "\t%#06ux %P\n", (int)p->pc, p);
@@ -346,6 +350,7 @@ writesym(Link *ctxt, Biobuf *b, LSym *s)
        if(s->type == STEXT) {
                wrint(b, s->args);
                wrint(b, s->locals);
+               wrint(b, s->leaf);
                n = 0;
                for(a = s->autom; a != nil; a = a->link)
                        n++;
@@ -566,6 +571,7 @@ readsym(Link *ctxt, Biobuf *f, char *pkg, char *pn)
        if(s->type == STEXT) {
                s->args = rdint(f);
                s->locals = rdint(f);
+               s->leaf = rdint(f);
                n = rdint(f);
                for(i=0; i<n; i++) {
                        a = emallocz(sizeof *a);

diff --git a/src/pkg/debug/goobj/read.go b/src/pkg/debug/goobj/read.go
index 8882eae53496e27aae41a72ea67b66d0e80b2485..c2e6fa09274f86516d52c584c8b9c6bf718b5dd3 100644 (file)
--- a/src/pkg/debug/goobj/read.go
+++ b/src/pkg/debug/goobj/read.go
@@ -190,6 +190,7 @@ type Var struct {
 type Func struct {
        Args     int        // size in bytes of of argument frame: inputs and outputs
        Frame    int        // size in bytes of local variable frame
+       Leaf     bool       // function omits save of link register (ARM)
        Var      []Var      // detail about local variables
        PCSP     Data       // PC → SP offset map
        PCFile   Data       // PC → file number map (index into File)
@@ -621,6 +622,7 @@ func (r *objReader) parseObject(prefix []byte) error {
                        s.Func = f
                        f.Args = r.readInt()
                        f.Frame = r.readInt()
+                       f.Leaf = r.readInt() != 0
                        f.Var = make([]Var, r.readInt())
                        for i := range f.Var {
                                v := &f.Var[i]