[PATCH] x86_64: Align and pad x86_64 GDT on page boundary

This patch is on the same lines as Zachary Amsden's i386 GDT page alignemnt
patch in -mm, but for x86_64.

Patch to align and pad x86_64 GDT on page boundries.

[AK: some minor cleanups and fixed incorrect TLS initialization
in CPU init.]

Signed-off-by: Nippun Goel <nippung@calsoftinc.com>
Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Shai Fultheim <shai@scalex86.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 16 insertions, 10 deletions

diff --git a/arch/x86_64/kernel/head.S b/arch/x86_64/kernel/head.S
index 15290968e49d..1d216a9fc6d8 100644
--- a/arch/x86_64/kernel/head.S
+++ b/arch/x86_64/kernel/head.S
@@ -379,7 +379,7 @@ gdt:
  * Also sysret mandates a special GDT layout 
  */
                                 
-.align L1_CACHE_BYTES
+.align PAGE_SIZE
 
 /* The TLS descriptors are currently at a different place compared to i386.
    Hopefully nobody expects them at a fixed place (Wine?) */
@@ -401,10 +401,11 @@ ENTRY(cpu_gdt_table)
 gdt_end:        
         /* asm/segment.h:GDT_ENTRIES must match this */ 
         /* This should be a multiple of the cache line size */
-        /* GDTs of other CPUs: */       
-        .fill (GDT_SIZE * NR_CPUS) - (gdt_end - cpu_gdt_table)
+        /* GDTs of other CPUs are now dynamically allocated */
+
+        /* zero the remaining page */
+        .fill PAGE_SIZE / 8 - GDT_ENTRIES,8,0
 
-        .align  L1_CACHE_BYTES
 ENTRY(idt_table)        
         .rept   256
         .quad   0
diff --git a/arch/x86_64/kernel/setup64.c b/arch/x86_64/kernel/setup64.c
index 39e728cfe6a0..972f5d4ce823 100644
--- a/arch/x86_64/kernel/setup64.c
+++ b/arch/x86_64/kernel/setup64.c
@@ -213,16 +213,14 @@ void __cpuinit cpu_init (void)
          * Initialize the per-CPU GDT with the boot GDT,
          * and set up the GDT descriptor:
          */
-        if (cpu) {
-                memcpy(cpu_gdt_table[cpu], cpu_gdt_table[0], GDT_SIZE);
-        }       
+        if (cpu)
+                memcpy(cpu_gdt(cpu), cpu_gdt_table, GDT_SIZE);
 
         cpu_gdt_descr[cpu].size = GDT_SIZE;
-        cpu_gdt_descr[cpu].address = (unsigned long)cpu_gdt_table[cpu];
         asm volatile("lgdt %0" :: "m" (cpu_gdt_descr[cpu]));
         asm volatile("lidt %0" :: "m" (idt_descr));
 
-        memcpy(me->thread.tls_array, cpu_gdt_table[cpu], GDT_ENTRY_TLS_ENTRIES * 8);
+        memset(me->thread.tls_array, 0, GDT_ENTRY_TLS_ENTRIES * 8);
         syscall_init();
 
         wrmsrl(MSR_FS_BASE, 0);
diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c
index f513dacc177f..e6af93b51dce 100644
--- a/arch/x86_64/kernel/smpboot.c
+++ b/arch/x86_64/kernel/smpboot.c
@@ -744,6 +744,13 @@ static int __cpuinit do_boot_cpu(int cpu, int apicid)
         };
         DECLARE_WORK(work, do_fork_idle, &c_idle);
 
+        /* allocate memory for gdts of secondary cpus. Hotplug is considered */
+        if (!cpu_gdt_descr[cpu].address &&
+                !(cpu_gdt_descr[cpu].address = get_zeroed_page(GFP_KERNEL))) {
+                printk(KERN_ERR "Failed to allocate GDT for CPU %d\n", cpu);
+                return -1;
+        }
+
         c_idle.idle = get_idle_for_cpu(cpu);
 
         if (c_idle.idle) {
diff --git a/arch/x86_64/kernel/suspend.c b/arch/x86_64/kernel/suspend.c
index fd2bef780882..ecbd34c1093d 100644
--- a/arch/x86_64/kernel/suspend.c
+++ b/arch/x86_64/kernel/suspend.c
@@ -120,7 +120,7 @@ void fix_processor_context(void)
 
         set_tss_desc(cpu,t);    /* This just modifies memory; should not be neccessary. But... This is neccessary, because 386 hardware has concept of busy TSS or some similar stupidity. */
 
-        cpu_gdt_table[cpu][GDT_ENTRY_TSS].type = 9;
+        cpu_gdt(cpu)[GDT_ENTRY_TSS].type = 9;
 
         syscall_init();                         /* This sets MSR_*STAR and related */
         load_TR_desc();                         /* This does ltr */