x86-64: Move kernelstack from PDA to per-cpu.

Also clean up PER_CPU_VAR usage in xen-asm_64.S

tj: * remove now unused stack_thread_info()
    * s/kernelstack/kernel_stack/
    * added FIXME comment in xen-asm_64.S

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 11 insertions, 12 deletions

diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
index 05794c566e87..5a23e8993678 100644
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -17,6 +17,7 @@
 #include <asm/processor-flags.h>
 #include <asm/errno.h>
 #include <asm/segment.h>
+#include <asm/percpu.h>
 
 #include <xen/interface/xen.h>
 
@@ -28,12 +29,10 @@
 
 #if 1
 /*
-        x86-64 does not yet support direct access to percpu variables
-        via a segment override, so we just need to make sure this code
-        never gets used
+        FIXME: x86_64 now can support direct access to percpu variables
+        via a segment override.  Update xen accordingly.
  */
 #define BUG                     ud2a
-#define PER_CPU_VAR(var, off)   0xdeadbeef
 #endif
 
 /*
@@ -45,14 +44,14 @@ ENTRY(xen_irq_enable_direct)
         BUG
 
         /* Unmask events */
-        movb $0, PER_CPU_VAR(xen_vcpu_info, XEN_vcpu_info_mask)
+        movb $0, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
 
         /* Preempt here doesn't matter because that will deal with
            any pending interrupts.  The pending check may end up being
            run on the wrong CPU, but that doesn't hurt. */
 
         /* Test for pending */
-        testb $0xff, PER_CPU_VAR(xen_vcpu_info, XEN_vcpu_info_pending)
+        testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending
         jz 1f
 
 2:      call check_events
@@ -69,7 +68,7 @@ ENDPATCH(xen_irq_enable_direct)
 ENTRY(xen_irq_disable_direct)
         BUG
 
-        movb $1, PER_CPU_VAR(xen_vcpu_info, XEN_vcpu_info_mask)
+        movb $1, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
 ENDPATCH(xen_irq_disable_direct)
         ret
         ENDPROC(xen_irq_disable_direct)
@@ -87,7 +86,7 @@ ENDPATCH(xen_irq_disable_direct)
 ENTRY(xen_save_fl_direct)
         BUG
 
-        testb $0xff, PER_CPU_VAR(xen_vcpu_info, XEN_vcpu_info_mask)
+        testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
         setz %ah
         addb %ah,%ah
 ENDPATCH(xen_save_fl_direct)
@@ -107,13 +106,13 @@ ENTRY(xen_restore_fl_direct)
         BUG
 
         testb $X86_EFLAGS_IF>>8, %ah
-        setz PER_CPU_VAR(xen_vcpu_info, XEN_vcpu_info_mask)
+        setz PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask
         /* Preempt here doesn't matter because that will deal with
            any pending interrupts.  The pending check may end up being
            run on the wrong CPU, but that doesn't hurt. */
 
         /* check for unmasked and pending */
-        cmpw $0x0001, PER_CPU_VAR(xen_vcpu_info, XEN_vcpu_info_pending)
+        cmpw $0x0001, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending
         jz 1f
 2:      call check_events
 1:
@@ -196,7 +195,7 @@ ENTRY(xen_sysret64)
         /* We're already on the usermode stack at this point, but still
            with the kernel gs, so we can easily switch back */
         movq %rsp, %gs:pda_oldrsp
-        movq %gs:pda_kernelstack,%rsp
+        movq PER_CPU_VAR(kernel_stack),%rsp
 
         pushq $__USER_DS
         pushq %gs:pda_oldrsp
@@ -213,7 +212,7 @@ ENTRY(xen_sysret32)
         /* We're already on the usermode stack at this point, but still
            with the kernel gs, so we can easily switch back */
         movq %rsp, %gs:pda_oldrsp
-        movq %gs:pda_kernelstack, %rsp
+        movq PER_CPU_VAR(kernel_stack), %rsp
 
         pushq $__USER32_DS
         pushq %gs:pda_oldrsp