lkml.org 
[lkml]   [2018]   [Jun]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 02/10] x86/cet: Introduce WRUSS instruction
From
Date
On Mon, 2018-06-11 at 10:17 +0200, Peter Zijlstra wrote:
> On Thu, Jun 07, 2018 at 09:40:02AM -0700, Andy Lutomirski wrote:
> > On Thu, Jun 7, 2018 at 7:41 AM Yu-cheng Yu <yu-cheng.yu@intel.com> wrote:
>
> > Peterz, isn't there some fancy better way we're supposed to handle the
> > error return these days?
>
> > > + asm volatile("1:.byte 0x66, 0x0f, 0x38, 0xf5, 0x37\n"
> > > + "xor %[err],%[err]\n"
> > > + "2:\n"
> > > + ".section .fixup,\"ax\"\n"
> > > + "3: mov $-1,%[err]; jmp 2b\n"
> > > + ".previous\n"
> > > + _ASM_EXTABLE(1b, 3b)
> > > + : [err] "=a" (err)
> > > + : [val] "S" (val), [addr] "D" (addr)
> > > + : "memory");
>
> So the alternative is something like:
>
> __visible bool ex_handler_wuss(const struct exception_table_entry *fixup,
> struct pt_regs *regs, int trapnr)
> {
> regs->ip = ex_fixup_addr(fixup);
> regs->ax = -1L;
>
> return true;
> }
>
>
> int err = 0;
>
> asm volatile("1: INSN_WUSS\n"
> "2:\n"
> _ASM_EXTABLE_HANDLE(1b, 2b, ex_handler_wuss)
> : "=a" (err)
> : "S" (val), "D" (addr));
>
> But I'm not at all sure that's actually better.

Thanks! I will fix it.

Yu-cheng


\
 
 \ /
  Last update: 2018-06-11 17:06    [W:0.101 / U:2.660 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site