i386: fix dubious segment register clear in cpu_init() From: Jeremy Fitzhardinge Fix a very dubious piece of code in arch/i386/kernel/cpu/common.c:cpu_init(). This clears out %fs and %gs, but clobbers %eax in the process without telling gcc. It turns out that gcc happens to be not using %eax at that point anyway so it doesn't matter much, but it looks like a bomb waiting to go off. This does end up saving an instruction, because gcc wants %eax==0 for the set_debugreg()s below. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Andi Kleen --- arch/i386/kernel/cpu/common.c | 2 +- 1 files changed, 1 insertion(+), 1 deletion(-) Index: linux/arch/i386/kernel/cpu/common.c =================================================================== --- linux.orig/arch/i386/kernel/cpu/common.c +++ linux/arch/i386/kernel/cpu/common.c @@ -675,7 +675,7 @@ old_gdt: #endif /* Clear %fs and %gs. */ - asm volatile ("xorl %eax, %eax; movl %eax, %fs; movl %eax, %gs"); + asm volatile ("movl %0, %%fs; movl %0, %%gs" : : "r" (0)); /* Clear all 6 debug registers: */ set_debugreg(0, 0);