x86, realmode: Move SMP trampoline to unified realmode code

Migrated SMP trampoline code to the real mode blob.
SMP trampoline code is not yet removed from
.x86_trampoline because it is needed by the wakeup
code.

[ hpa: always enable compiling startup_32_smp in head_32.S... it is
  only a few instructions which go into .init on UP builds, and it makes
  the rest of the code less #ifdef ugly. ]

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-6-git-send-email-jarkko.sakkinen@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 86 insertions, 0 deletions

diff --git a/arch/x86/realmode/rm/trampoline_32.S b/arch/x86/realmode/rm/trampoline_32.S
new file mode 100644
index 0000000..18cb7fc
--- /dev/null
+++ b/arch/x86/realmode/rm/trampoline_32.S
@@ -0,0 +1,86 @@
+/*
+ *
+ *	Trampoline.S	Derived from Setup.S by Linus Torvalds
+ *
+ *	4 Jan 1997 Michael Chastain: changed to gnu as.
+ *
+ *	This is only used for booting secondary CPUs in SMP machine
+ *
+ *	Entry: CS:IP point to the start of our code, we are
+ *	in real mode with no stack, but the rest of the
+ *	trampoline page to make our stack and everything else
+ *	is a mystery.
+ *
+ *	We jump into arch/x86/kernel/head_32.S.
+ *
+ *	On entry to trampoline_data, the processor is in real mode
+ *	with 16-bit addressing and 16-bit data.  CS has some value
+ *	and IP is zero.  Thus, we load CS to the physical segment
+ *	of the real mode code before doing anything further.
+ *
+ *	The structure real_mode_header includes entries that need
+ *	to be set up before executing this code:
+ *
+ *	startup_32_smp
+ *	boot_gdt
+ */
+
+#include <linux/linkage.h>
+#include <linux/init.h>
+#include <asm/segment.h>
+#include <asm/page_types.h>
+
+	.text
+	.code16
+	.globl trampoline_data
+
+	.balign PAGE_SIZE
+trampoline_data:
+	wbinvd			# Needed for NUMA-Q should be harmless for others
+
+	.byte	0xea		# ljmpw
+	.word	1f		# Offset
+	.word	real_mode_seg	# Segment
+1:
+	mov	%cs, %ax	# Code and data in the same place
+	mov	%ax, %ds
+
+	cli			# We should be safe anyway
+
+	movl	$0xA5A5A5A5, trampoline_status
+				# write marker for master knows we're running
+
+	/* GDT tables in non default location kernel can be beyond 16MB and
+	 * lgdt will not be able to load the address as in real mode default
+	 * operand size is 16bit. Use lgdtl instead to force operand size
+	 * to 32 bit.
+	 */
+
+	lidtl	boot_idt_descr		# load idt with 0, 0
+	lgdtl	boot_gdt_descr		# load gdt with whatever is appropriate
+
+	xor	%ax, %ax
+	inc	%ax			# protected mode (PE) bit
+	lmsw	%ax			# into protected mode
+
+	# flush prefetch and jump to startup_32_smp in arch/i386/kernel/head.S
+	ljmpl	*(startup_32_smp)
+
+	.data
+	.globl startup_32_smp, boot_gdt, trampoline_status
+
+boot_gdt_descr:
+	.word	__BOOT_DS + 7			# gdt limit
+boot_gdt:
+	.long	0				# gdt base
+
+boot_idt_descr:
+	.word	0				# idt limit = 0
+	.long	0				# idt base = 0L
+
+trampoline_status:
+	.long	0
+
+startup_32_smp:
+	.long	0x00000000
+	.word	__BOOT_CS, 0