[PATCH] x86_64 machine_kexec: Cleanup inline assembly.

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>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 16 insertions, 18 deletions

diff --git a/arch/x86_64/kernel/machine_kexec.c b/arch/x86_64/kernel/machine_kexec.c
index 60d1eff41567..717f7db4b532 100644
--- 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 *image, unsigned long start_pgtable)
 
 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,