cmd/link: set .ctors COFF section to writable and aligned

Without setting these flags, LLVM's LLD ignores the .ctors section when
merging objects.

Updates #44250.
Updates #39326.
Updates #38755.
Updates #36439.
Updates #43800.

Change-Id: I8766104508f7acd832088a590ee7d68afa0d6065
Reviewed-on: https://go-review.googlesource.com/c/go/+/291633
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

diff --git a/src/cmd/link/internal/ld/pe.go b/src/cmd/link/internal/ld/pe.go
index 46e3df5df18dc0886250b48bec229333924e4751..a0aba866dcb18aae9973d99628947cdbf3185c0d 100644 (file)
--- a/src/cmd/link/internal/ld/pe.go
+++ b/src/cmd/link/internal/ld/pe.go
@@ -66,6 +66,8 @@ const (
        IMAGE_SCN_MEM_WRITE              = 0x80000000
        IMAGE_SCN_MEM_DISCARDABLE        = 0x2000000
        IMAGE_SCN_LNK_NRELOC_OVFL        = 0x1000000
+       IMAGE_SCN_ALIGN_4BYTES           = 0x300000
+       IMAGE_SCN_ALIGN_8BYTES           = 0x400000
        IMAGE_SCN_ALIGN_32BYTES          = 0x600000
 )
 
@@ -478,20 +480,19 @@ func (f *peFile) addInitArray(ctxt *Link) *peSection {
        // However, the entire Go runtime is initialized from just one function, so it is unlikely
        // that this will need to grow in the future.
        var size int
+       var alignment uint32
        switch objabi.GOARCH {
        default:
                Exitf("peFile.addInitArray: unsupported GOARCH=%q\n", objabi.GOARCH)
-       case "386":
-               size = 4
-       case "amd64":
-               size = 8
-       case "arm":
+       case "386", "arm":
                size = 4
-       case "arm64":
+               alignment = IMAGE_SCN_ALIGN_4BYTES
+       case "amd64", "arm64":
                size = 8
+               alignment = IMAGE_SCN_ALIGN_8BYTES
        }
        sect := f.addSection(".ctors", size, size)
-       sect.characteristics = IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ
+       sect.characteristics = IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE | alignment
        sect.sizeOfRawData = uint32(size)
        ctxt.Out.SeekSet(int64(sect.pointerToRawData))
        sect.checkOffset(ctxt.Out.Offset())