cmd/link: enable DWARF combining on macOS ARM64
It appears the machoCalcStart function is meant to align the
segment, but it doesn't. Replace it with an actual alignment
calculation. Also, use the alignment from the configuration,
instead of hardcode.
With this fix we could enable DWARF combining on macOS ARM64.
Change-Id: I19ec771b77d752b83a54c53b6ee65af78a31b8ae
Reviewed-on: https://go-review.googlesource.com/c/go/+/253558
Reviewed-by: Than McIntosh <thanm@google.com>
diff --git a/src/cmd/link/internal/arm64/obj.go b/src/cmd/link/internal/arm64/obj.go
index 37b72b6..a980cfe 100644
--- a/src/cmd/link/internal/arm64/obj.go
+++ b/src/cmd/link/internal/arm64/obj.go
@@ -105,7 +105,7 @@
*ld.FlagTextAddr = 4096 + int64(ld.HEADR)
}
if *ld.FlagRound == -1 {
- *ld.FlagRound = 4096
+ *ld.FlagRound = 16384 // 16K page alignment
}
}
}
diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index 54ac109..4295b2a 100644
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -1240,11 +1240,11 @@
// On darwin, whether to combine DWARF into executable.
// Only macOS supports unmapped segments such as our __DWARF segment.
- combineDwarf := ctxt.IsDarwin() && !*FlagS && !*FlagW && !debug_s && machoPlatform == PLATFORM_MACOS && ctxt.IsAMD64()
+ combineDwarf := ctxt.IsDarwin() && !*FlagS && !*FlagW && !debug_s && machoPlatform == PLATFORM_MACOS
switch ctxt.HeadType {
case objabi.Hdarwin:
- if machoPlatform == PLATFORM_MACOS && ctxt.IsAMD64() {
+ if combineDwarf {
// Leave room for DWARF combining.
// -headerpad is incompatible with -fembed-bitcode.
argv = append(argv, "-Wl,-headerpad,1144")
diff --git a/src/cmd/link/internal/ld/macho_combine_dwarf.go b/src/cmd/link/internal/ld/macho_combine_dwarf.go
index e43aeb1..77ee8a4 100644
--- a/src/cmd/link/internal/ld/macho_combine_dwarf.go
+++ b/src/cmd/link/internal/ld/macho_combine_dwarf.go
@@ -16,10 +16,6 @@
"unsafe"
)
-const (
- pageAlign = 12 // 4096 = 1 << 12
-)
-
type loadCmd struct {
Cmd macho.LoadCmd
Len uint32
@@ -138,7 +134,7 @@
// Now copy the dwarf data into the output.
// Kernel requires all loaded segments to be page-aligned in the file,
// even though we mark this one as being 0 bytes of virtual address space.
- dwarfstart := machoCalcStart(realdwarf.Offset, linkseg.Offset, pageAlign)
+ dwarfstart := Rnd(int64(linkseg.Offset), int64(*FlagRound))
if _, err := outf.Seek(dwarfstart, 0); err != nil {
return err
}
@@ -166,7 +162,7 @@
if _, err := exef.Seek(int64(linkseg.Offset), 0); err != nil {
return err
}
- linkstart := machoCalcStart(linkseg.Offset, uint64(dwarfstart)+dwarfsize, pageAlign)
+ linkstart := Rnd(dwarfstart+int64(dwarfsize), int64(*FlagRound))
if _, err := outf.Seek(linkstart, 0); err != nil {
return err
}
@@ -432,12 +428,3 @@
}
return nil
}
-
-func machoCalcStart(origAddr, newAddr uint64, alignExp uint32) int64 {
- align := uint64(1 << alignExp)
- origMod, newMod := origAddr%align, newAddr%align
- if origMod == newMod {
- return int64(newAddr)
- }
- return int64(newAddr + align + origMod - newMod)
-}
