Date: Tue, 15 Aug 2017 12:10:32 +0100 From: Catalin Marinas <catalin.marinas@....com> To: Mark Rutland <mark.rutland@....com> Cc: linux-arm-kernel@...ts.infradead.org, keescook@...omium.org, ard.biesheuvel@...aro.org, matt@...eblueprint.co.uk, kernel-hardening@...ts.openwall.com, will.deacon@....com, linux-kernel@...r.kernel.org, luto@...capital.net, james.morse@....com, labbott@...hat.com Subject: Re: [PATCH 14/14] arm64: add VMAP_STACK overflow detection On Mon, Aug 07, 2017 at 07:36:05PM +0100, Mark Rutland wrote: > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index e5aa866..44a27c3 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -72,6 +72,37 @@ > .macro kernel_ventry label > .align 7 > sub sp, sp, #S_FRAME_SIZE > +#ifdef CONFIG_VMAP_STACK > + add sp, sp, x0 // sp' = sp + x0 > + sub x0, sp, x0 // x0' = sp' - x0 = (sp + x0) - x0 = sp > + tbnz x0, #THREAD_SHIFT, 0f > + sub x0, sp, x0 // sp' - x0' = (sp + x0) - sp = x0 > + sub sp, sp, x0 // sp' - x0 = (sp + x0) - x0 = sp > + b \label Maybe a small comment before this hunk just to tell the user that it's trying to test a bit in SP without corrupting a gpr. It's obvious once you read it but not you see it for the first time ;). > + > + /* Stash the original SP value in tpidr_el0 */ > +0: msr tpidr_el0, x0 And a comment here that on this path we no longer care about the user tpidr_el0 as we are never returning there. Otherwise I'm fine with the series (I'm not a fan of the complexity it adds but I don't have a better suggestion). -- Catalin
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.