From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Wed, 2 Mar 2016 13:55:36 +0000 Subject: [PATCHv2] arm64: kasan: clear stale stack poison In-Reply-To: <20160302124723.GA11086@e104818-lin.cambridge.arm.com> References: <1456862465-31505-1-git-send-email-mark.rutland@arm.com> <20160302105620.GB25547@red-moon> <20160302114833.GA11670@leverpostej> <20160302124723.GA11086@e104818-lin.cambridge.arm.com> Message-ID: <20160302135535.GE7637@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Mar 02, 2016 at 12:47:24PM +0000, Catalin Marinas wrote: > On Wed, Mar 02, 2016 at 11:48:34AM +0000, Mark Rutland wrote: > > On Wed, Mar 02, 2016 at 10:56:20AM +0000, Lorenzo Pieralisi wrote: > > > On Tue, Mar 01, 2016 at 08:01:05PM +0000, Mark Rutland wrote: > > > > > > [...] > > > > > > > diff --git a/arch/arm64/include/asm/kasan.h b/arch/arm64/include/asm/kasan.h > > > > index 2774fa3..6f00b76 100644 > > > > --- a/arch/arm64/include/asm/kasan.h > > > > +++ b/arch/arm64/include/asm/kasan.h > > > > @@ -1,10 +1,30 @@ > > > > #ifndef __ASM_KASAN_H > > > > #define __ASM_KASAN_H > > > > > > > > -#ifndef __ASSEMBLY__ > > > > - > > > > +#ifndef LINKER_SCRIPT > > > > #ifdef CONFIG_KASAN > > > > > > > > +#ifdef __ASSEMBLY__ > > > > + > > > > +#include > > > > +#include > > > > + > > > > + /* > > > > + * Remove stale shadow posion for the stack left over from a prior > > > > + * hot-unplug or idle exit, from the lowest stack address in the > > > > + * thread_union up to the covering up to the current stack pointer. > > > > + * Shadow poison above this is preserved. > > > > + */ > > > > + .macro kasan_unpoison_stack > > > > + mov x1, sp > > > > + and x0, x1, #~(THREAD_SIZE - 1) > > > > > > I suspect you did not use sp_el0 on purpose here (that contains a > > > pointer to thread_info), just asking. > > > > I worked on the assumption that the arithmetic was likely to be faster > > than a system register access, but I do not have numbers to back that > > up. > > > > I'm happy to use sp_el0 if that's preferrable. > > Since we need sp anyway, it is probably faster. But, I think the current > patch is more to the point - clearing from the bottom of the current > stack up to the current sp, we don't need any assumption about sp_el0 (I > guess we never call cpu_suspend() on an IRQ stack, though I'm not 100% > sure). > > I don't think Will wants to send this as a fix for 4.5, probably not > urgent but I'll let him decide. In any case: > > Reviewed-by: Catalin Marinas I wasn't rushing to queue this, especially with the hotplug case outstanding. Feel free to take it for 4.6. Will