x86-64: Convert irqstacks to per-cpu

Move the irqstackptr variable from the PDA to per-cpu.  Make the
stacks themselves per-cpu, removing some specific allocation code.
Add a seperate flag (is_boot_cpu) to simplify the per-cpu boot
adjustments.

tj: * sprinkle some underbars around.

    * irq_stack_ptr is not used till traps_init(), no reason to
      initialize it early.  On SMP, just leaving it NULL till proper
      initialization in setup_per_cpu_areas() works.  Dropped
      is_boot_cpu and early irq_stack_ptr initialization.

    * do DECLARE/DEFINE_PER_CPU(char[IRQ_STACK_SIZE], irq_stack)
      instead of (char, irq_stack[IRQ_STACK_SIZE]).

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

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 4833f3a19650..d22677a66438 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -345,7 +345,7 @@ ENTRY(save_args)
 1:      incl %gs:pda_irqcount
         jne 2f
         popq_cfi %rax                   /* move return address... */
-        mov %gs:pda_irqstackptr,%rsp
+        mov PER_CPU_VAR(irq_stack_ptr),%rsp
         EMPTY_FRAME 0
         pushq_cfi %rax                  /* ... to the new stack */
         /*
@@ -1261,7 +1261,7 @@ ENTRY(call_softirq)
         mov  %rsp,%rbp
         CFI_DEF_CFA_REGISTER rbp
         incl %gs:pda_irqcount
-        cmove %gs:pda_irqstackptr,%rsp
+        cmove PER_CPU_VAR(irq_stack_ptr),%rsp
         push  %rbp                      # backlink for old unwinder
         call __do_softirq
         leaveq
@@ -1300,7 +1300,7 @@ ENTRY(xen_do_hypervisor_callback)   # do_hypervisor_callback(struct *pt_regs)
 11:     incl %gs:pda_irqcount
         movq %rsp,%rbp
         CFI_DEF_CFA_REGISTER rbp
-        cmovzq %gs:pda_irqstackptr,%rsp
+        cmovzq PER_CPU_VAR(irq_stack_ptr),%rsp
         pushq %rbp                      # backlink for old unwinder
         call xen_evtchn_do_upcall
         popq %rsp