[VOYAGER] Use modern techniques to setup and teardown low identiy mappings.

This is a trivial and hopefully obviously correct patch to setup
and teardown the identity mappings the way the rest of arch/i386
does.

My new page table setup code will break some assumptions below so
this is my attempt to keep voyager working.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 6 insertions, 32 deletions

diff --git a/arch/i386/mach-voyager/voyager_smp.c b/arch/i386/mach-voyager/voyager_smp.c
index a126baeaa423..535fb9e754fb 100644
--- a/arch/i386/mach-voyager/voyager_smp.c
+++ b/arch/i386/mach-voyager/voyager_smp.c
@@ -536,15 +536,6 @@ do_boot_cpu(__u8 cpu)
                 & ~( voyager_extended_vic_processors
                      & voyager_allowed_boot_processors);
 
-        /* For the 486, we can't use the 4Mb page table trick, so
-         * must map a region of memory */
-#ifdef CONFIG_M486
-        int i;
-        unsigned long *page_table_copies = (unsigned long *)
-                __get_free_page(GFP_KERNEL);
-#endif
-        pgd_t orig_swapper_pg_dir0;
-
         /* This is an area in head.S which was used to set up the
          * initial kernel stack.  We need to alter this to give the
          * booting CPU a new stack (taken from its idle process) */
@@ -595,24 +586,11 @@ do_boot_cpu(__u8 cpu)
         VDEBUG(("VOYAGER SMP: Booting CPU%d at 0x%lx[%x:%x], stack %p\n", cpu, 
                 (unsigned long)hijack_source.val, hijack_source.idt.Segment,
                 hijack_source.idt.Offset, stack_start.esp));
-        /* set the original swapper_pg_dir[0] to map 0 to 4Mb transparently
-         * (so that the booting CPU can find start_32 */
-        orig_swapper_pg_dir0 = swapper_pg_dir[0];
-#ifdef CONFIG_M486
-        if(page_table_copies == NULL)
-                panic("No free memory for 486 page tables\n");
-        for(i = 0; i < PAGE_SIZE/sizeof(unsigned long); i++)
-                page_table_copies[i] = (i * PAGE_SIZE) 
-                        | _PAGE_RW | _PAGE_USER | _PAGE_PRESENT;
-
-        ((unsigned long *)swapper_pg_dir)[0] = 
-                ((virt_to_phys(page_table_copies)) & PAGE_MASK)
-                | _PAGE_RW | _PAGE_USER | _PAGE_PRESENT;
-#else
-        ((unsigned long *)swapper_pg_dir)[0] = 
-                (virt_to_phys(pg0) & PAGE_MASK)
-                | _PAGE_RW | _PAGE_USER | _PAGE_PRESENT;
-#endif
+
+        /* init lowmem identity mapping */
+        clone_pgd_range(swapper_pg_dir, swapper_pg_dir + USER_PGD_PTRS,
+                        min_t(unsigned long, KERNEL_PGD_PTRS, USER_PGD_PTRS));
+        flush_tlb_all();
 
         if(quad_boot) {
                 printk("CPU %d: non extended Quad boot\n", cpu);
@@ -655,11 +633,7 @@ do_boot_cpu(__u8 cpu)
                 udelay(100);
         }
         /* reset the page table */
-        swapper_pg_dir[0] = orig_swapper_pg_dir0;
-        local_flush_tlb();
-#ifdef CONFIG_M486
-        free_page((unsigned long)page_table_copies);
-#endif
+        zap_low_mappings();
           
         if (cpu_booted_map) {
                 VDEBUG(("CPU%d: Booted successfully, back in CPU %d\n",