From 40521f86261f0cf3cc83bd321dc310b75301bf97 Mon Sep 17 00:00:00 2001
From: Achilleas Anagnostopoulos <achilleas.imap.mbox@gmail.com>
Date: Wed, 5 Jul 2017 16:50:59 +0100
Subject: [PATCH] Ensure that the memory returned by sysAlloc is always zeroed

---
 src/gopheros/kernel/goruntime/bootstrap.go      | 13 +++++++++++++
 src/gopheros/kernel/goruntime/bootstrap_test.go | 15 +++++++++++++--
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/gopheros/kernel/goruntime/bootstrap.go b/src/gopheros/kernel/goruntime/bootstrap.go
index e43e279..06d06b4 100644
--- a/src/gopheros/kernel/goruntime/bootstrap.go
+++ b/src/gopheros/kernel/goruntime/bootstrap.go
@@ -13,12 +13,14 @@ import (
 var (
 	mapFn                = vmm.Map
 	earlyReserveRegionFn = vmm.EarlyReserveRegion
+	memsetFn             = mem.Memset
 	frameAllocFn         = allocator.AllocFrame
 	mallocInitFn         = mallocInit
 	algInitFn            = algInit
 	modulesInitFn        = modulesInit
 	typeLinksInitFn      = typeLinksInit
 	itabsInitFn          = itabsInit
+	initGoPackagesFn     = initGoPackages
 
 	// A seed for the pseudo-random number generator used by getRandomData
 	prngSeed = 0xdeadc0de
@@ -42,6 +44,13 @@ func mallocInit()
 //go:linkname mSysStatInc runtime.mSysStatInc
 func mSysStatInc(*uint64, uintptr)
 
+// initGoPackages is an alias to main.init which recursively calls the init()
+// methods in all imported packages. Unless this function is called, things like
+// package errors will not be properly initialized causing various problems when
+// we try to use the stdlib.
+//go:linkname initGoPackages main.init
+func initGoPackages()
+
 // sysReserve reserves address space without allocating any memory or
 // establishing any page mappings.
 //
@@ -117,6 +126,8 @@ func sysAlloc(size uintptr, sysStat *uint64) unsafe.Pointer {
 		if err = mapFn(page, frame, mapFlags); err != nil {
 			return unsafe.Pointer(uintptr(0))
 		}
+
+		memsetFn(page.Address(), 0, mem.PageSize)
 	}
 
 	mSysStatInc(sysStat, uintptr(regionSize))
@@ -163,6 +174,8 @@ func Init() *kernel.Error {
 	typeLinksInitFn() // uses maps, activeModules
 	itabsInitFn()     // uses activeModules
 
+	initGoPackagesFn()
+
 	return nil
 }
 
diff --git a/src/gopheros/kernel/goruntime/bootstrap_test.go b/src/gopheros/kernel/goruntime/bootstrap_test.go
index 298c5d0..cec83a7 100644
--- a/src/gopheros/kernel/goruntime/bootstrap_test.go
+++ b/src/gopheros/kernel/goruntime/bootstrap_test.go
@@ -136,6 +136,7 @@ func TestSysAlloc(t *testing.T) {
 	defer func() {
 		earlyReserveRegionFn = vmm.EarlyReserveRegion
 		mapFn = vmm.Map
+		memsetFn = mem.Memset
 		frameAllocFn = allocator.AllocFrame
 	}()
 
@@ -161,10 +162,15 @@ func TestSysAlloc(t *testing.T) {
 
 		for specIndex, spec := range specs {
 			var (
-				sysStat      uint64
-				mapCallCount int
+				sysStat         uint64
+				mapCallCount    int
+				memsetCallCount int
 			)
 
+			memsetFn = func(_ uintptr, _ byte, _ mem.Size) {
+				memsetCallCount++
+			}
+
 			mapFn = func(_ vmm.Page, _ pmm.Frame, flags vmm.PageTableEntryFlag) *kernel.Error {
 				expFlags := vmm.FlagPresent | vmm.FlagNoExecute | vmm.FlagRW
 				if flags != expFlags {
@@ -182,6 +188,11 @@ func TestSysAlloc(t *testing.T) {
 				t.Errorf("[spec %d] expected vmm.Map call count to be %d; got %d", specIndex, spec.expMapCallCount, mapCallCount)
 			}
 
+			// sysAlloc should perform the same number of memset calls as map calls
+			if memsetCallCount != spec.expMapCallCount {
+				t.Errorf("[spec %d] expected mem.Memset call count to be %d; got %d", specIndex, spec.expMapCallCount, memsetCallCount)
+			}
+
 			if exp := uint64(spec.expMapCallCount << mem.PageShift); sysStat != exp {
 				t.Errorf("[spec %d] expected stat counter to be %d; got %d", specIndex, exp, sysStat)
 			}