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Commit 2f2984eb authored by Zachary Amsden's avatar Zachary Amsden Committed by Linus Torvalds
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[PATCH] i386: generate better code around descriptor update and access functions 



GCC can generate better code around descriptor update and access functions
when there is not an explicit "eax" register constraint.

Testing: You won't boot if this is messed up, since the TSS descriptor will be
corrupted.  Verified the assembler and booted.

Signed-off-by: default avatarZachary Amsden <zach@vmware.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 4d37e7e3

include/asm-i386/desc.h

+8 −8
Original line number Diff line number Diff line
@@ -27,8 +27,8 @@ struct Xgt_desc_struct { 


extern struct Xgt_desc_struct idt_descr, cpu_gdt_descr[NR_CPUS];



#define load_TR_desc() __asm__ __volatile__("ltr %%ax"::"a" (GDT_ENTRY_TSS*8))

#define load_LDT_desc() __asm__ __volatile__("lldt %%ax"::"a" (GDT_ENTRY_LDT*8))

#define load_TR_desc() __asm__ __volatile__("ltr %w0"::"q" (GDT_ENTRY_TSS*8))

#define load_LDT_desc() __asm__ __volatile__("lldt %w0"::"q" (GDT_ENTRY_LDT*8))



#define load_gdt(dtr) __asm__ __volatile("lgdt %0"::"m" (*dtr))

#define load_idt(dtr) __asm__ __volatile("lidt %0"::"m" (*dtr))
@@ -49,14 +49,14 @@ extern void set_intr_gate(unsigned int irq, void * addr); 


#define _set_tssldt_desc(n,addr,limit,type) \

__asm__ __volatile__ ("movw %w3,0(%2)\n\t" \

	"movw %%ax,2(%2)\n\t" \

	"rorl $16,%%eax\n\t" \

	"movb %%al,4(%2)\n\t" \

	"movw %w1,2(%2)\n\t" \

	"rorl $16,%1\n\t" \

	"movb %b1,4(%2)\n\t" \

	"movb %4,5(%2)\n\t" \

	"movb $0,6(%2)\n\t" \

	"movb %%ah,7(%2)\n\t" \

	"rorl $16,%%eax" \

	: "=m"(*(n)) : "a" (addr), "r"(n), "ir"(limit), "i"(type))

	"movb %h1,7(%2)\n\t" \

	"rorl $16,%1" \

	: "=m"(*(n)) : "q" (addr), "r"(n), "ir"(limit), "i"(type))



static inline void __set_tss_desc(unsigned int cpu, unsigned int entry, void *addr)

{