diff options
Diffstat (limited to 'src/cmd')
| -rw-r--r-- | src/cmd/link/internal/loader/loader.go | 29 | ||||
| -rw-r--r-- | src/cmd/link/link_test.go | 50 | ||||
| -rw-r--r-- | src/cmd/link/testdata/linkname/sched.go | 19 |
3 files changed, 90 insertions, 8 deletions
diff --git a/src/cmd/link/internal/loader/loader.go b/src/cmd/link/internal/loader/loader.go index 0c234e8975..182379f0df 100644 --- a/src/cmd/link/internal/loader/loader.go +++ b/src/cmd/link/internal/loader/loader.go @@ -432,16 +432,16 @@ func (st *loadState) addSym(name string, ver int, r *oReader, li uint32, kind in return i } // symbol already exists + // Fix for issue #47185 -- given two dupok or BSS symbols with + // different sizes, favor symbol with larger size. See also + // issue #46653 and #72032. + oldsz := l.SymSize(oldi) + sz := int64(r.Sym(li).Siz()) if osym.Dupok() { if l.flags&FlagStrictDups != 0 { l.checkdup(name, r, li, oldi) } - // Fix for issue #47185 -- given two dupok symbols with - // different sizes, favor symbol with larger size. See - // also issue #46653. - szdup := l.SymSize(oldi) - sz := int64(r.Sym(li).Siz()) - if szdup < sz { + if oldsz < sz { // new symbol overwrites old symbol. l.objSyms[oldi] = objSym{r.objidx, li} } @@ -452,11 +452,24 @@ func (st *loadState) addSym(name string, ver int, r *oReader, li uint32, kind in if oldsym.Dupok() { return oldi } - overwrite := r.DataSize(li) != 0 + // If one is a DATA symbol (i.e. has content, DataSize != 0) + // and the other is BSS, the one with content wins. + // If both are BSS, the one with larger size wins. + // Specifically, the "overwrite" variable and the final result are + // + // new sym old sym overwrite + // --------------------------------------------- + // DATA DATA true => ERROR + // DATA lg/eq BSS sm/eq true => new wins + // DATA small BSS large true => ERROR + // BSS large DATA small true => ERROR + // BSS large BSS small true => new wins + // BSS sm/eq D/B lg/eq false => old wins + overwrite := r.DataSize(li) != 0 || oldsz < sz if overwrite { // new symbol overwrites old symbol. oldtyp := sym.AbiSymKindToSymKind[objabi.SymKind(oldsym.Type())] - if !(oldtyp.IsData() && oldr.DataSize(oldli) == 0) { + if !(oldtyp.IsData() && oldr.DataSize(oldli) == 0) || oldsz > sz { log.Fatalf("duplicated definition of symbol %s, from %s and %s", name, r.unit.Lib.Pkg, oldr.unit.Lib.Pkg) } l.objSyms[oldi] = objSym{r.objidx, li} diff --git a/src/cmd/link/link_test.go b/src/cmd/link/link_test.go index ab56b49e15..5f265c4c2b 100644 --- a/src/cmd/link/link_test.go +++ b/src/cmd/link/link_test.go @@ -20,6 +20,7 @@ import ( "testing" imacho "cmd/internal/macho" + "cmd/internal/objfile" "cmd/internal/sys" ) @@ -1541,3 +1542,52 @@ func TestCheckLinkname(t *testing.T) { }) } } + +func TestLinknameBSS(t *testing.T) { + // Test that the linker chooses the right one as the definition + // for linknamed variables. See issue #72032. + testenv.MustHaveGoBuild(t) + t.Parallel() + + tmpdir := t.TempDir() + + src := filepath.Join("testdata", "linkname", "sched.go") + exe := filepath.Join(tmpdir, "sched.exe") + cmd := testenv.Command(t, testenv.GoToolPath(t), "build", "-o", exe, src) + out, err := cmd.CombinedOutput() + if err != nil { + t.Fatalf("build failed unexpectedly: %v:\n%s", err, out) + } + + // Check the symbol size. + f, err := objfile.Open(exe) + if err != nil { + t.Fatalf("fail to open executable: %v", err) + } + syms, err := f.Symbols() + if err != nil { + t.Fatalf("fail to get symbols: %v", err) + } + found := false + for _, s := range syms { + if s.Name == "runtime.sched" || s.Name == "_runtime.sched" { + found = true + if s.Size < 100 { + // As of Go 1.25 (Mar 2025), runtime.sched has 6848 bytes on + // darwin/arm64. It should always be larger than 100 bytes on + // all platforms. + t.Errorf("runtime.sched symbol size too small: want > 100, got %d", s.Size) + } + } + } + if !found { + t.Errorf("runtime.sched symbol not found") + } + + // Executable should run. + cmd = testenv.Command(t, exe) + out, err = cmd.CombinedOutput() + if err != nil { + t.Errorf("executable failed to run: %v\n%s", err, out) + } +} diff --git a/src/cmd/link/testdata/linkname/sched.go b/src/cmd/link/testdata/linkname/sched.go new file mode 100644 index 0000000000..7a9d66f495 --- /dev/null +++ b/src/cmd/link/testdata/linkname/sched.go @@ -0,0 +1,19 @@ +// Copyright 2025 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package main + +import _ "unsafe" + +type schedt struct{} + +//go:linkname sched runtime.sched +var sched schedt + +func main() { + select { + default: + println("hello") + } +} |