From: Heiko Carstens <hca@linux.ibm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Kees Cook <keescook@chromium.org>,
Alexander Popov <alex.popov@linux.com>,
Vasily Gorbik <gor@linux.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] stackleak: allow to specify arch specific stackleak poison function
Date: Wed, 12 Apr 2023 11:58:07 +0200 [thread overview]
Message-ID: <ZDaAr0Tg5DPJM9BY@osiris> (raw)
In-Reply-To: <ZDZz8QvPdpGJqMd6@FVFF77S0Q05N>
On Wed, Apr 12, 2023 at 10:03:46AM +0100, Mark Rutland wrote:
> On Wed, Apr 05, 2023 at 03:08:40PM +0200, Heiko Carstens wrote:
> > Factor out the code that fills the stack with the stackleak poison value
> > in order to allow architectures to provide a faster implementation.
> >
> > Acked-by: Vasily Gorbik <gor@linux.ibm.com>
> > Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
>
> As on patch 2, it might be nicer to have a noinstr-safe memset64() and use that
> directly, but I don't have strong feelings either way, and I'll defer to Kees's
> judgement:
Wouldn't that enforce that memset64() wouldn't be allowed to have an own
stackframe, since otherwise it would write poison values to it, since we
have
if (on_task_stack)
erase_high = current_stack_pointer;
in __stackleak_erase()?
That was actually my motiviation to make this s390 optimization an always
inline asm.
Besides that this wouldn't be a problem for at least s390, since memset64()
is an asm function which comes whithout the need for a stackframe, but on
the other hand this would add a quite subtle requirement to memset64(), if
I'm not mistaken.
next prev parent reply other threads:[~2023-04-12 9:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-05 13:08 [PATCH 0/2] stackleak: allow to specify arch specific stackleak poison function Heiko Carstens
2023-04-05 13:08 ` [PATCH 1/2] " Heiko Carstens
2023-04-12 9:03 ` Mark Rutland
2023-04-12 9:58 ` Heiko Carstens [this message]
2023-04-12 10:06 ` Mark Rutland
2023-04-05 13:08 ` [PATCH 2/2] s390/stackleak: provide fast __stackleak_poison() implementation Heiko Carstens
2023-04-12 9:02 ` Mark Rutland
2023-04-18 17:21 ` [PATCH 0/2] stackleak: allow to specify arch specific stackleak poison function Heiko Carstens
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