[PATCH] x86_64 machine_kexec: Cleanup inline assembly.

[PATCH] x86_64 machine_kexec: Cleanup inline assembly.

[Eric W. Biederman]

In an uncensored copy of code from i386 to x86_64 I wound up
with inline assembly with the wrong constraints.  Use input
constraints instead of output constraints.

So I know the assembler will do the right thing specify the size
of the operand lidtq and lgdtq instead of just lidt and lgdt.

Make load_segments use an input constraint, and delete the macro fun.
Without having to reload %cs like I do on i386 this code is noticeably
simpler.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---

 arch/x86_64/kernel/machine_kexec.c |   34 ++++++++++++++++------------------
 1 files changed, 16 insertions(+), 18 deletions(-)

d5f1c67bf3b1c8ebfd146ea2782af48a6c6a9bbc
diff --git a/arch/x86_64/kernel/machine_kexec.c b/arch/x86_64/kernel/machine_kexec.c
--- a/arch/x86_64/kernel/machine_kexec.c
+++ b/arch/x86_64/kernel/machine_kexec.c
@@ -122,45 +122,43 @@ static int init_pgtable(struct kimage *i
 
 static void set_idt(void *newidt, u16 limit)
 {
-	unsigned char curidt[10];
+	struct desc_ptr curidt;
 
 	/* x86-64 supports unaliged loads & stores */
-	(*(u16 *)(curidt)) = limit;
-	(*(u64 *)(curidt +2)) = (unsigned long)(newidt);
+	curidt.size    = limit;
+	curidt.address = (unsigned long)newidt;
 
 	__asm__ __volatile__ (
-		"lidt %0\n"
-		: "=m" (curidt)
+		"lidtq %0\n"
+		:: "m" (curidt)
 		);
 };
 
 
 static void set_gdt(void *newgdt, u16 limit)
 {
-	unsigned char curgdt[10];
+	struct desc_ptr curgdt;
 
 	/* x86-64 supports unaligned loads & stores */
-	(*(u16 *)(curgdt)) = limit;
-	(*(u64 *)(curgdt +2)) = (unsigned long)(newgdt);
+	curgdt.size    = limit;
+	curgdt.address = (unsigned long)newgdt;
 
 	__asm__ __volatile__ (
-		"lgdt %0\n"
-		: "=m" (curgdt)
+		"lgdtq %0\n"
+		:: "m" (curgdt)
 		);
 };
 
 static void load_segments(void)
 {
 	__asm__ __volatile__ (
-		"\tmovl $"STR(__KERNEL_DS)",%eax\n"
-		"\tmovl %eax,%ds\n"
-		"\tmovl %eax,%es\n"
-		"\tmovl %eax,%ss\n"
-		"\tmovl %eax,%fs\n"
-		"\tmovl %eax,%gs\n"
+		"\tmovl %0,%%ds\n"
+		"\tmovl %0,%%es\n"
+		"\tmovl %0,%%ss\n"
+		"\tmovl %0,%%fs\n"
+		"\tmovl %0,%%gs\n"
+		:: "a" (__KERNEL_DS)
 		);
-#undef STR
-#undef __STR
 }
 
 typedef NORET_TYPE void (*relocate_new_kernel_t)(unsigned long indirection_page,