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, 4 insertions, 12 deletions

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 63a1a5596ac0..e63bb5185855 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -298,22 +298,16 @@ notrace static void __cpuinit start_secondary(void *unused)
          * fragile that we want to limit the things done here to the
          * most necessary things.
          */
+        cpu_init();
+        preempt_disable();
+        smp_callin();
 
 #ifdef CONFIG_X86_32
-        /*
-         * Switch away from the trampoline page-table
-         *
-         * Do this before cpu_init() because it needs to access per-cpu
-         * data which may not be mapped in the trampoline page-table.
-         */
+        /* switch away from the initial page table */
         load_cr3(swapper_pg_dir);
         __flush_tlb_all();
 #endif
 
-        cpu_init();
-        preempt_disable();
-        smp_callin();
-
         /* otherwise gcc will move up smp_processor_id before the cpu_init */
         barrier();
         /*
@@ -772,7 +766,6 @@ do_rest:
 #ifdef CONFIG_X86_32
         /* Stack for startup_32 can be just as for start_secondary onwards */
         irq_ctx_init(cpu);
-        initial_page_table = __pa(&trampoline_pg_dir);
 #else
         clear_tsk_thread_flag(c_idle.idle, TIF_FORK);
         initial_gs = per_cpu_offset(cpu);
@@ -921,7 +914,6 @@ int __cpuinit native_cpu_up(unsigned int cpu)
         per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
 
         err = do_boot_cpu(apicid, cpu);
-
         if (err) {
                 pr_debug("do_boot_cpu failed %d\n", err);
                 return -EIO;