osdep: introduce qemu_mprotect_rwx/none

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

include/qemu/osdep.h

@@ -371,6 +371,8 @@ void sigaction_invoke(struct sigaction *action,
 #endif
 
 int qemu_madvise(void *addr, size_t len, int advice);
+int qemu_mprotect_rwx(void *addr, size_t size);
+int qemu_mprotect_none(void *addr, size_t size);
 
 int qemu_open(const char *name, int flags, ...);
 int qemu_close(int fd);

util/osdep.c

@@ -73,6 +73,47 @@ int qemu_madvise(void *addr, size_t len, int advice)
 #endif
 }
 
+static int qemu_mprotect__osdep(void *addr, size_t size, int prot)
+{
+    g_assert(!((uintptr_t)addr & ~qemu_real_host_page_mask));
+    g_assert(!(size & ~qemu_real_host_page_mask));
+
+#ifdef _WIN32
+    DWORD old_protect;
+
+    if (!VirtualProtect(addr, size, prot, &old_protect)) {
+        error_report("%s: VirtualProtect failed with error code %ld",
+                     __func__, GetLastError());
+        return -1;
+    }
+    return 0;
+#else
+    if (mprotect(addr, size, prot)) {
+        error_report("%s: mprotect failed: %s", __func__, strerror(errno));
+        return -1;
+    }
+    return 0;
+#endif
+}
+
+int qemu_mprotect_rwx(void *addr, size_t size)
+{
+#ifdef _WIN32
+    return qemu_mprotect__osdep(addr, size, PAGE_EXECUTE_READWRITE);
+#else
+    return qemu_mprotect__osdep(addr, size, PROT_READ | PROT_WRITE | PROT_EXEC);
+#endif
+}
+
+int qemu_mprotect_none(void *addr, size_t size)
+{
+#ifdef _WIN32
+    return qemu_mprotect__osdep(addr, size, PAGE_NOACCESS);
+#else
+    return qemu_mprotect__osdep(addr, size, PROT_NONE);
+#endif
+}
+
 #ifndef _WIN32
 
 static int fcntl_op_setlk = -1;