x86: use stack_start in x86_64

call x86_64's init_rsp stack_start, just as i386 does.
Put a zeroed stack segment for consistency. With this,
we can eliminate one ugly ifdef in smpboot.c.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 5 insertions, 9 deletions

diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index 36af01f029ed..a81f468ab410 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -86,7 +86,7 @@ int acpi_save_state_mem(void)
         saved_magic = 0x12345678;
 #else /* CONFIG_64BIT */
         header->trampoline_segment = setup_trampoline() >> 4;
-        init_rsp = (unsigned long)temp_stack + 4096;
+        stack_start.sp = temp_stack + 4096;
         initial_code = (unsigned long)wakeup_long64;
         saved_magic = 0x123456789abcdef0;
 #endif /* CONFIG_64BIT */
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 263b9d14753e..918a2711aff6 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -191,7 +191,7 @@ ENTRY(secondary_startup_64)
         movq    %rax, %cr0
 
         /* Setup a boot time stack */
-        movq init_rsp(%rip),%rsp
+        movq stack_start(%rip),%rsp
 
         /* zero EFLAGS after setting rsp */
         pushq $0
@@ -252,8 +252,9 @@ ENTRY(secondary_startup_64)
         .quad   x86_64_start_kernel
         __FINITDATA
 
-        ENTRY(init_rsp)
+        ENTRY(stack_start)
         .quad  init_thread_union+THREAD_SIZE-8
+        .word  0
 
 bad_address:
         jmp bad_address
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index d3ad4e09455b..a71e3cad5470 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -714,11 +714,7 @@ wakeup_secondary_cpu(int phys_apicid, unsigned long start_eip)
          * target processor state.
          */
         startup_ipi_hook(phys_apicid, (unsigned long) start_secondary,
-#ifdef CONFIG_X86_64
-                         (unsigned long)init_rsp);
-#else
                          (unsigned long)stack_start.sp);
-#endif
 
         /*
          * Run STARTUP IPI loop.
@@ -905,15 +901,14 @@ do_rest:
         early_gdt_descr.address = (unsigned long)get_cpu_gdt_table(cpu);
         c_idle.idle->thread.ip = (unsigned long) start_secondary;
         /* Stack for startup_32 can be just as for start_secondary onwards */
-        stack_start.sp = (void *) c_idle.idle->thread.sp;
         irq_ctx_init(cpu);
 #else
         cpu_pda(cpu)->pcurrent = c_idle.idle;
-        init_rsp = c_idle.idle->thread.sp;
         load_sp0(&per_cpu(init_tss, cpu), &c_idle.idle->thread);
         initial_code = (unsigned long)start_secondary;
         clear_tsk_thread_flag(c_idle.idle, TIF_FORK);
 #endif
+        stack_start.sp = (void *) c_idle.idle->thread.sp;
 
         /* start_ip had better be page-aligned! */
         start_ip = setup_trampoline();