nintendoswitch: Add dynamic loader for runtime loading PIE sections

src/runtime/dynamic_arm64.go

@@ -0,0 +1,55 @@
+package runtime
+
+import (
+	"debug/elf"
+	"unsafe"
+)
+
+const debugLoader = false
+
+//export __dynamic_loader
+func dynamicLoader(base uintptr, dyn *elf.Dyn64) {
+	var rela *elf.Rela64
+	relasz := uint64(0)
+
+	if debugLoader {
+		println("ASLR Base: ", base)
+	}
+
+	for dyn.Tag != int64(elf.DT_NULL) {
+		switch elf.DynTag(dyn.Tag) {
+		case elf.DT_RELA:
+			rela = (*elf.Rela64)(unsafe.Pointer(base + uintptr(dyn.Val)))
+		case elf.DT_RELASZ:
+			relasz = uint64(dyn.Val) / uint64(unsafe.Sizeof(elf.Rela64{}))
+		}
+
+		ptr := uintptr(unsafe.Pointer(dyn))
+		ptr += unsafe.Sizeof(elf.Dyn64{})
+		dyn = (*elf.Dyn64)(unsafe.Pointer(ptr))
+	}
+
+	if rela == nil {
+		runtimePanic("bad reloc")
+	}
+	if rela == nil {
+		runtimePanic("bad reloc")
+	}
+
+	if debugLoader {
+		println("Sections to load: ", relasz)
+	}
+
+	for relasz > 0 && rela != nil {
+		switch elf.R_AARCH64(rela.Info) {
+		case elf.R_AARCH64_RELATIVE:
+			ptr := (*uint64)(unsafe.Pointer(base + uintptr(rela.Off)))
+			*ptr = uint64(base + uintptr(rela.Addend))
+		}
+
+		rptr := uintptr(unsafe.Pointer(rela))
+		rptr += unsafe.Sizeof(elf.Rela64{})
+		rela = (*elf.Rela64)(unsafe.Pointer(rptr))
+		relasz--
+	}
+}

src/runtime/runtime_nintendoswitch.go

@@ -2,6 +2,8 @@
 
 package runtime
 
+import "unsafe"
+
 type timeUnit int64
 
 const asyncScheduler = false
@@ -60,6 +62,16 @@ func abort() {
 	}
 }
 
+//export write
+func write(fd int32, buf *byte, count int) int {
+	// TODO: Proper handling write
+	for i := 0; i < count; i++ {
+		putchar(*buf)
+		buf = (*byte)(unsafe.Pointer(uintptr(unsafe.Pointer(buf)) + 1))
+	}
+	return count
+}
+
 //export sleepThread
 func sleepThread(nanos uint64)