[PATCH] x86-64: 64bit ACPI wakeup trampoline

o Moved wakeup_level4_pgt into the wakeup routine so we can
  run the kernel above 4G.

o Now we first go to 64bit mode and continue to run from trampoline and
  then then start accessing kernel symbols and restore processor context.
  This enables us to resume even in relocatable kernel context when
  kernel might not be loaded at physical addr it has been compiled for.

o Removed the need for modifying any existing kernel page table.

o Increased the size of the wakeup routine to 8K. This is required as
  wake page tables are on trampoline itself and they got to be at 4K
  boundary, hence one page is not sufficient.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 4 insertions, 20 deletions

diff --git a/arch/x86_64/kernel/acpi/sleep.c b/arch/x86_64/kernel/acpi/sleep.c
index e1548fbe95ae..195b7034a148 100644
--- a/arch/x86_64/kernel/acpi/sleep.c
+++ b/arch/x86_64/kernel/acpi/sleep.c
@@ -60,19 +60,6 @@ extern char wakeup_start, wakeup_end;
 
 extern unsigned long acpi_copy_wakeup_routine(unsigned long);
 
-static pgd_t low_ptr;
-
-static void init_low_mapping(void)
-{
-        pgd_t *slot0 = pgd_offset(current->mm, 0UL);
-        low_ptr = *slot0;
-        /* FIXME: We're playing with the current task's page tables here, which
-         * is potentially dangerous on SMP systems.
-         */
-        set_pgd(slot0, *pgd_offset(current->mm, PAGE_OFFSET));
-        local_flush_tlb();
-}
-
 /**
  * acpi_save_state_mem - save kernel state
  *
@@ -81,8 +68,6 @@ static void init_low_mapping(void)
  */
 int acpi_save_state_mem(void)
 {
-        init_low_mapping();
-
         memcpy((void *)acpi_wakeup_address, &wakeup_start,
                &wakeup_end - &wakeup_start);
         acpi_copy_wakeup_routine(acpi_wakeup_address);
@@ -95,8 +80,6 @@ int acpi_save_state_mem(void)
  */
 void acpi_restore_state_mem(void)
 {
-        set_pgd(pgd_offset(current->mm, 0UL), low_ptr);
-        local_flush_tlb();
 }
 
 /**
@@ -109,10 +92,11 @@ void acpi_restore_state_mem(void)
  */
 void __init acpi_reserve_bootmem(void)
 {
-        acpi_wakeup_address = (unsigned long)alloc_bootmem_low(PAGE_SIZE);
-        if ((&wakeup_end - &wakeup_start) > PAGE_SIZE)
+        acpi_wakeup_address = (unsigned long)alloc_bootmem_low(PAGE_SIZE*2);
+        if ((&wakeup_end - &wakeup_start) > (PAGE_SIZE*2))
                 printk(KERN_CRIT
-                       "ACPI: Wakeup code way too big, will crash on attempt to suspend\n");
+                       "ACPI: Wakeup code way too big, will crash on attempt"
+                       " to suspend\n");
 }
 
 static int __init acpi_sleep_setup(char *str)