x86: initial fixmap support

Needed to get fixed virtual address for USB debug and earlycon with mmio.

Signed-off-by: Eric W. Biderman <ebiderman@xmisson.com>
Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Gerd Hoffmann <kraxel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S
index f74dfc419b56..82714668d43b 100644
--- a/arch/i386/kernel/head.S
+++ b/arch/i386/kernel/head.S
@@ -168,6 +168,12 @@ page_pde_offset = (__PAGE_OFFSET >> 20);
 .section .init.text,"ax",@progbits
 #endif
 
+        /* Do an early initialization of the fixmap area */
+        movl $(swapper_pg_dir - __PAGE_OFFSET), %edx
+        movl $(swapper_pg_pmd - __PAGE_OFFSET), %eax
+        addl $0x007, %eax                       /* 0x007 = PRESENT+RW+USER */
+        movl %eax, 4092(%edx)
+
 #ifdef CONFIG_SMP
 ENTRY(startup_32_smp)
         cld
@@ -507,6 +513,8 @@ ENTRY(_stext)
 .section ".bss.page_aligned","w"
 ENTRY(swapper_pg_dir)
         .fill 1024,4,0
+ENTRY(swapper_pg_pmd)
+        .fill 1024,4,0
 ENTRY(empty_zero_page)
         .fill 4096,1,0