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, 14 insertions, 1 deletions

diff --git a/arch/x86_64/kernel/head.S b/arch/x86_64/kernel/head.S
index 1fab487dee86..941c84baecc8 100644
--- a/arch/x86_64/kernel/head.S
+++ b/arch/x86_64/kernel/head.S
@@ -73,7 +73,11 @@ startup_64:
         addq    %rbp, init_level4_pgt + (511*8)(%rip)
 
         addq    %rbp, level3_ident_pgt + 0(%rip)
+
         addq    %rbp, level3_kernel_pgt + (510*8)(%rip)
+        addq    %rbp, level3_kernel_pgt + (511*8)(%rip)
+
+        addq    %rbp, level2_fixmap_pgt + (506*8)(%rip)
 
         /* Add an Identity mapping if I am above 1G */
         leaq    _text(%rip), %rdi
@@ -314,7 +318,16 @@ NEXT_PAGE(level3_kernel_pgt)
         .fill   510,8,0
         /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
         .quad   level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
-        .fill   1,8,0
+        .quad   level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
+
+NEXT_PAGE(level2_fixmap_pgt)
+        .fill   506,8,0
+        .quad   level1_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE
+        /* 8MB reserved for vsyscalls + a 2MB hole = 4 + 1 entries */
+        .fill   5,8,0
+
+NEXT_PAGE(level1_fixmap_pgt)
+        .fill   512,8,0
 
 NEXT_PAGE(level2_ident_pgt)
         /* Since I easily can, map the first 1G.