cmd/link: skip gaps between PT_LOAD segments in TestPIESize

There may be gaps between non-writeable and writeable PT_LOAD
segments, and the gaps may be large as the segments may have
large alignment. Don't count those gaps in file size comparison.

Fixes #36023.

Change-Id: I68582bdd0f385ac5c6f87d485d476d06bc96db19
Reviewed-on: https://go-review.googlesource.com/c/go/+/210180
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/cmd/link/elf_test.go b/src/cmd/link/elf_test.go
index f0c787223672659430abad5c978a5cd5eea6b666..11a7730796bd33ea3d4b875232d26224cf80702a 100644 (file)
--- a/src/cmd/link/elf_test.go
+++ b/src/cmd/link/elf_test.go
@@ -348,6 +348,9 @@ func TestPIESize(t *testing.T) {
                        // difference in size of the .got and .plt
                        // sections if they exist.
                        // We ignore unallocated sections.
+                       // There may be gaps between non-writeable and
+                       // writable PT_LOAD segments. We also skip those
+                       // gaps (see issue #36023).
 
                        textsize := func(ef *elf.File, name string) uint64 {
                                for _, s := range ef.Sections {
@@ -383,11 +386,23 @@ func TestPIESize(t *testing.T) {
 
                        extrasize := func(ef *elf.File) uint64 {
                                var ret uint64
+                               // skip unallocated sections
                                for _, s := range ef.Sections {
                                        if s.Flags&elf.SHF_ALLOC == 0 {
                                                ret += s.Size
                                        }
                                }
+                               // also skip gaps between PT_LOAD segments
+                               for i := range ef.Progs {
+                                       if i == 0 {
+                                               continue
+                                       }
+                                       p1 := ef.Progs[i-1]
+                                       p2 := ef.Progs[i]
+                                       if p1.Type == elf.PT_LOAD && p2.Type == elf.PT_LOAD {
+                                               ret += p2.Off - p1.Off - p1.Filesz
+                                       }
+                               }
                                return ret
                        }