prog: rework address allocation

1. mmap all memory always, without explicit mmap calls in the program.
This makes lots of things much easier and removes lots of code.
Makes mmap not a special syscall and allows to fuzz without mmap enabled.

2. Change address assignment algorithm.
Current algorithm allocates unmapped addresses too frequently
and allows collisions between arguments of a single syscall.
The new algorithm analyzes actual allocations in the program
and places new arguments at unused locations.

1 files changed, 3 insertions, 23 deletions

diff --git a/sys/windows/init.go b/sys/windows/init.go
index 8e3761024..7729f3260 100644
--- a/sys/windows/init.go
+++ b/sys/windows/init.go
@@ -15,19 +15,9 @@ func initTarget(target *prog.Target) {
 		PAGE_EXECUTE_READWRITE: target.ConstMap["PAGE_EXECUTE_READWRITE"],
 	}
 
-	target.PageSize = pageSize
-	target.DataOffset = dataOffset
-	target.MmapSyscall = arch.virtualAllocSyscall
 	target.MakeMmap = arch.makeMmap
-	target.AnalyzeMmap = arch.analyzeMmap
 }
 
-const (
-	// TODO(dvyukov): what should we do about 4k vs 64k?
-	pageSize   = 4 << 10
-	dataOffset = 512 << 20
-)
-
 type arch struct {
 	virtualAllocSyscall *prog.Syscall
 
@@ -36,26 +26,16 @@ type arch struct {
 	PAGE_EXECUTE_READWRITE uint64
 }
 
-func (arch *arch) makeMmap(start, npages uint64) *prog.Call {
+func (arch *arch) makeMmap(addr, size uint64) *prog.Call {
 	meta := arch.virtualAllocSyscall
 	return &prog.Call{
 		Meta: meta,
 		Args: []prog.Arg{
-			prog.MakePointerArg(meta.Args[0], start, 0, npages, nil),
-			prog.MakeConstArg(meta.Args[1], npages*pageSize),
+			prog.MakeVmaPointerArg(meta.Args[0], addr, size),
+			prog.MakeConstArg(meta.Args[1], size),
 			prog.MakeConstArg(meta.Args[2], arch.MEM_COMMIT|arch.MEM_RESERVE),
 			prog.MakeConstArg(meta.Args[3], arch.PAGE_EXECUTE_READWRITE),
 		},
 		Ret: prog.MakeReturnArg(meta.Ret),
 	}
 }
-
-func (arch *arch) analyzeMmap(c *prog.Call) (start, npages uint64, mapped bool) {
-	switch c.Meta.Name {
-	case "VirtualAlloc":
-		npages = c.Args[1].(*prog.ConstArg).Val / pageSize
-		start = c.Args[0].(*prog.PointerArg).PageIndex
-		mapped = true
-	}
-	return
-}