On Mon, 2012-02-20 at 10:03 -0800, Linus Torvalds wrote: > On Mon, Feb 20, 2012 at 3:47 AM, tip-bot for Steven Rostedt > <rostedt@xxxxxxxxxxx> wrote: > > /* > > + * If %cs was not the kernel segment, then the NMI triggered in user > > + * space, which means it is definitely not nested. > > + */ > > + cmp $__KERNEL_CS, 16(%rsp) > > + jne first_nmi > > I don't like how you wrote 'cmp' without a size, especially with none > of the arguments then giving a size either. Usually there's a register > name or something that gives you the size, but not here. > > I guess there is some default size that gas will use, but at least > some versions of gas have traditionally errored out instead of > guessing on sizes. Maybe x86-64 doesn't use those gas versions any > more, but still.. OK, I'll send an update fix to use cmpq. >From HPA's email: "User space can change %cs, but it can never set it to __KERNEL_CS; specifically user space can never set the bottom two bits in CS to zero." I'm not sure it matters, but I'll change it anyway since we are comparing an 8 byte word on the stack. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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