x86/boot: Update construct_dom0() to take a const char *cmdline

With hvm_copy_to_guest_*() able to use const sources, update construct_dom0()
and friends to pass a const cmdline pointer.  Nothing in these paths have a
reason to be modifying the command line passed in.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/dom0_build.c

@@ -564,7 +564,7 @@ int __init dom0_setup_permissions(struct domain *d)
 
 int __init construct_dom0(struct domain *d, const module_t *image,
                           unsigned long image_headroom, module_t *initrd,
-                          char *cmdline)
+                          const char *cmdline)
 {
     int rc;
 

xen/arch/x86/hvm/dom0_build.c

@@ -532,7 +532,7 @@ static paddr_t __init find_memory(
 static int __init pvh_load_kernel(struct domain *d, const module_t *image,
                                   unsigned long image_headroom,
                                   module_t *initrd, void *image_base,
-                                  char *cmdline, paddr_t *entry,
+                                  const char *cmdline, paddr_t *entry,
                                   paddr_t *start_info_addr)
 {
     void *image_start = image_base + image_headroom;
@@ -1177,7 +1177,7 @@ static void __hwdom_init pvh_setup_mmcfg(struct domain *d)
 int __init dom0_construct_pvh(struct domain *d, const module_t *image,
                               unsigned long image_headroom,
                               module_t *initrd,
-                              char *cmdline)
+                              const char *cmdline)
 {
     paddr_t entry, start_info;
     int rc;

xen/arch/x86/include/asm/dom0_build.h

@@ -16,12 +16,12 @@ int dom0_setup_permissions(struct domain *d);
 int dom0_construct_pv(struct domain *d, const module_t *image,
                       unsigned long image_headroom,
                       module_t *initrd,
-                      char *cmdline);
+                      const char *cmdline);
 
 int dom0_construct_pvh(struct domain *d, const module_t *image,
                        unsigned long image_headroom,
                        module_t *initrd,
-                       char *cmdline);
+                       const char *cmdline);
 
 unsigned long dom0_paging_pages(const struct domain *d,
                                 unsigned long nr_pages);

xen/arch/x86/include/asm/setup.h

@@ -35,7 +35,7 @@ int construct_dom0(
     struct domain *d,
     const module_t *kernel, unsigned long kernel_headroom,
     module_t *initrd,
-    char *cmdline);
+    const char *cmdline);
 void setup_io_bitmap(struct domain *d);
 
 unsigned long initial_images_nrpages(nodeid_t node);

xen/arch/x86/pv/dom0_build.c

@@ -358,7 +358,7 @@ int __init dom0_construct_pv(struct domain *d,
                              const module_t *image,
                              unsigned long image_headroom,
                              module_t *initrd,
-                             char *cmdline)
+                             const char *cmdline)
 {
     int i, rc, order, machine;
     bool compatible, compat;