x86, espfix: Make espfix64 a Kconfig option, fix UML

Make espfix64 a hidden Kconfig option.  This fixes the x86-64 UML
build which had broken due to the non-existence of init_espfix_bsp()
in UML: since UML uses its own Kconfig, this option does not appear in
the UML build.

This also makes it possible to make support for 16-bit segments a
configuration option, for the people who want to minimize the size of
the kernel.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Richard Weinberger <richard@nod.at>
Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com

4 files changed, 7 insertions, 3 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 25d2c6f7325e..9a952a572585 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -914,6 +914,10 @@ config VM86
           XFree86 to initialize some video cards via BIOS. Disabling this
           option saves about 6k.
 
+config X86_ESPFIX64
+        def_bool y
+        depends on X86_64
+
 config TOSHIBA
         tristate "Toshiba Laptop support"
         depends on X86_32
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 1cc3789d99d9..491ef3e59850 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -29,7 +29,7 @@ obj-$(CONFIG_X86_64)	+= sys_x86_64.o x8664_ksyms_64.o
 obj-y                   += syscall_$(BITS).o vsyscall_gtod.o
 obj-$(CONFIG_X86_64)    += vsyscall_64.o
 obj-$(CONFIG_X86_64)    += vsyscall_emu_64.o
-obj-$(CONFIG_X86_64)    += espfix_64.o
+obj-$(CONFIG_X86_ESPFIX64)      += espfix_64.o
 obj-$(CONFIG_SYSFS)     += ksysfs.o
 obj-y                   += bootflag.o e820.o
 obj-y                   += pci-dma.o quirks.o topology.o kdebugfs.o
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 61a5350850fb..5d93ac1b72db 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -246,7 +246,7 @@ static void notrace start_secondary(void *unused)
         /*
          * Enable the espfix hack for this CPU
          */
-#ifdef CONFIG_X86_64
+#ifdef CONFIG_X86_ESPFIX64
         init_espfix_ap();
 #endif
 
diff --git a/init/main.c b/init/main.c
index 70fc00e7db06..58c132d7de4b 100644
--- a/init/main.c
+++ b/init/main.c
@@ -617,7 +617,7 @@ asmlinkage void __init start_kernel(void)
         if (efi_enabled(EFI_RUNTIME_SERVICES))
                 efi_enter_virtual_mode();
 #endif
-#ifdef CONFIG_X86_64
+#ifdef CONFIG_X86_ESPFIX64
         /* Should be run before the first non-init thread is created */
         init_espfix_bsp();
 #endif