[PATCH] i386: Omit pmap workaround on i486 or later.

[Masanori Ogino]

As described in XXX comments, the workaround for memory mapping is
implemented for 80386 and it is unnecessary on i486 or later.  Thus, it
is safe to omit that if the kernel is built for the recent (1989~)
processors.

Fuhito Inagawa pointed out the problem to me.

* i386/i386/trap.c (kernel_trap): Disable the workaround when the kernel
is built for i[456]86.
* i386/intel/pmap.c (pmap_protect, pmap_enter): Ditto.
* i386/intel/read_fault.c: Define intel_read_fault if and only if it is
necessary.
---
 i386/i386/trap.c        | 2 ++
 i386/intel/pmap.c       | 9 +++++----
 i386/intel/read_fault.c | 2 ++
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/i386/i386/trap.c b/i386/i386/trap.c
index 6470504..77aa6db 100644
--- a/i386/i386/trap.c
+++ b/i386/i386/trap.c
@@ -250,6 +250,7 @@ dump_ss(regs);
                }
                else
 #endif /* MACH_KDB */
+#if !(__486__ || __586__ || __686__)
                if ((code & T_PF_WRITE) == 0 &&
                    result == KERN_PROTECTION_FAILURE)
                {
@@ -261,6 +262,7 @@ dump_ss(regs);
                    result = intel_read_fault(map,
                                          trunc_page((vm_offset_t)subcode));
                }
+#endif
 
                if (result == KERN_SUCCESS) {
                    /*
diff --git a/i386/intel/pmap.c b/i386/intel/pmap.c
index e362b45..9a3a7ac 100644
--- a/i386/intel/pmap.c
+++ b/i386/intel/pmap.c
@@ -1711,17 +1711,17 @@ void pmap_protect(
                return;
        }
 
+#if !(__486__ || __586__ || __686__)
        /*
         * If write-protecting in the kernel pmap,
         * remove the mappings; the i386 ignores
         * the write-permission bit in kernel mode.
-        *
-        * XXX should be #if'd for i386
         */
        if (map == kernel_pmap) {
            pmap_remove(map, s, e);
            return;
        }
+#endif
 
        SPLVM(spl);
        simple_lock(&map->lock);
@@ -1812,14 +1812,14 @@ if (pmap_debug) printf("pmap(%lx, %lx)\n", v, pa);
        if (pmap == kernel_pmap && (v < kernel_virtual_start || v >= 
kernel_virtual_end))
                panic("pmap_enter(%p, %p) falls in physical memory area!\n", v, 
pa);
 #endif
+
+#if !(__486__ || __586__ || __686__)
        if (pmap == kernel_pmap && (prot & VM_PROT_WRITE) == 0
            && !wired /* hack for io_wire */ ) {
            /*
             *  Because the 386 ignores write protection in kernel mode,
             *  we cannot enter a read-only kernel mapping, and must
             *  remove an existing mapping if changing it.
-            *
-            *  XXX should be #if'd for i386
             */
            PMAP_READ_LOCK(pmap, spl);
 
@@ -1836,6 +1836,7 @@ if (pmap_debug) printf("pmap(%lx, %lx)\n", v, pa);
            PMAP_READ_UNLOCK(pmap, spl);
            return;
        }
+#endif
 
        /*
         *      Must allocate a new pvlist entry while we're unlocked;
diff --git a/i386/intel/read_fault.c b/i386/intel/read_fault.c
index 4b1edce..f28cbbc 100644
--- a/i386/intel/read_fault.c
+++ b/i386/intel/read_fault.c
@@ -33,6 +33,7 @@
 
 #include <kern/macros.h>
 
+#if !(__486__ || __586__ || __686__)
 /*
  *     Expansion of vm_fault for read fault in kernel mode.
  *     Must enter the mapping as writable, since the i386
@@ -174,3 +175,4 @@ intel_read_fault(
 
        return (KERN_SUCCESS);
 }
+#endif
-- 
2.7.3