x86-32, mm: Add an initial page table for core bootstrapping

This patch adds an initial page table with low mappings used exclusively
for booting APs/resuming after ACPI suspend/machine restart. After this,
there's no need to add low mappings to swapper_pg_dir and zap them later
or create own swsusp PGD page solely for ACPI sleep needs - we have
initial_page_table for that.

Signed-off-by: Borislav Petkov <bp@alien8.de>
LKML-Reference: <20101020070526.GA9588@liondog.tnic>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 2 insertions, 8 deletions

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 7a4cf14223ba..f7f53dcd3e0a 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -371,16 +371,10 @@ void machine_real_restart(const unsigned char *code, int length)
         CMOS_WRITE(0x00, 0x8f);
         spin_unlock(&rtc_lock);
 
-        /* Remap the kernel at virtual address zero, as well as offset zero
-           from the kernel segment.  This assumes the kernel segment starts at
-           virtual address PAGE_OFFSET. */
-        memcpy(swapper_pg_dir, swapper_pg_dir + KERNEL_PGD_BOUNDARY,
-                sizeof(swapper_pg_dir [0]) * KERNEL_PGD_PTRS);
-
         /*
-         * Use `swapper_pg_dir' as our page directory.
+         * Switch back to the initial page table.
          */
-        load_cr3(swapper_pg_dir);
+        load_cr3(initial_page_table);
 
         /* Write 0x1234 to absolute memory location 0x472.  The BIOS reads
            this on booting to tell it to "Bypass memory test (also warm