linux-user: fix build on hosts not using guest base

Commit 68a1c816 broke qemu on hosts not
using guest base. It uses reserved_va unconditionally in mmap.c. To
avoid to many #ifdef #endif blocks, define RESERVED_VA as either
reserved_va or 0ul, and use it instead of reserved_va, similarly to what
has been done with guest_base/GUEST_BASE.
(cherry picked from commit 18e9ea8a)

cpu-all.h

@@ -629,8 +629,10 @@ extern unsigned long guest_base;
 extern int have_guest_base;
 extern unsigned long reserved_va;
 #define GUEST_BASE guest_base
+#define RESERVED_VA reserved_va
 #else
 #define GUEST_BASE 0ul
+#define RESERVED_VA 0ul
 #endif
 
 /* All direct uses of g2h and h2g need to go away for usermode softmmu.  */

linux-user/mmap.c

@@ -225,13 +225,13 @@ static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size)
     int prot;
     int looped = 0;
 
-    if (size > reserved_va) {
+    if (size > RESERVED_VA) {
         return (abi_ulong)-1;
     }
 
     last_addr = start;
     for (addr = start; last_addr + size != addr; addr += qemu_host_page_size) {
-        if (last_addr + size >= reserved_va
+        if (last_addr + size >= RESERVED_VA
             || (abi_ulong)(last_addr + size) < last_addr) {
             if (looped) {
                 return (abi_ulong)-1;
@@ -271,7 +271,7 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size)
 
     size = HOST_PAGE_ALIGN(size);
 
-    if (reserved_va) {
+    if (RESERVED_VA) {
         return mmap_find_vma_reserved(start, size);
     }
 
@@ -651,7 +651,7 @@ int target_munmap(abi_ulong start, abi_ulong len)
     ret = 0;
     /* unmap what we can */
     if (real_start < real_end) {
-        if (reserved_va) {
+        if (RESERVED_VA) {
             mmap_reserve(real_start, real_end - real_start);
         } else {
             ret = munmap(g2h(real_start), real_end - real_start);
@@ -679,7 +679,7 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size,
                                      flags,
                                      g2h(new_addr));
 
-        if (reserved_va && host_addr != MAP_FAILED) {
+        if (RESERVED_VA && host_addr != MAP_FAILED) {
             /* If new and old addresses overlap then the above mremap will
                already have failed with EINVAL.  */
             mmap_reserve(old_addr, old_size);
@@ -701,7 +701,7 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size,
         }
     } else {
         int prot = 0;
-        if (reserved_va && old_size < new_size) {
+        if (RESERVED_VA && old_size < new_size) {
             abi_ulong addr;
             for (addr = old_addr + old_size;
                  addr < old_addr + new_size;
@@ -711,7 +711,7 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size,
         }
         if (prot == 0) {
             host_addr = mremap(g2h(old_addr), old_size, new_size, flags);
-            if (host_addr != MAP_FAILED && reserved_va && old_size > new_size) {
+            if (host_addr != MAP_FAILED && RESERVED_VA && old_size > new_size) {
                 mmap_reserve(old_addr + old_size, new_size - old_size);
             }
         } else {