[PATCH] x86_64 machine_kexec: Cleanup inline assembly.

From: Eric W. Biederman
Date: Fri Jul 29 2005 - 14:08:52 EST



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@xxxxxxxxxxxx>
---

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,
-
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