From: Vasily Gorbik <gor@linux.ibm.com>
To: Heiko Carstens <hca@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Christoph Hellwig <hch@lst.de>,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org
Subject: Re: [PATCH 3/3] s390/stackleak: Fix __stackleak_poison() inline assembly constraint
Date: Mon, 2 Mar 2026 16:40:45 +0100 [thread overview]
Message-ID: <your-ad-here.call-01772466045-ext-9689@work.hours> (raw)
In-Reply-To: <20260302133500.1560531-4-hca@linux.ibm.com>
On Mon, Mar 02, 2026 at 02:35:00PM +0100, Heiko Carstens wrote:
> The __stackleak_poison() inline assembly comes with a "count" operand where
> the "d" constraint is used. "count" is used with the exrl instruction and
> "d" means that the compiler may allocate any register from 0 to 15.
>
> If the compiler would allocate register 0 then the exrl instruction would
> not or the value of "count" into the executed instruction - resulting in a
> stackframe which is only partially poisoned.
>
> Use the correct "a" constraint, which excludes register 0 from register
> allocation.
>
> Fixes: 2a405f6bb3a5 ("s390/stackleak: provide fast __stackleak_poison() implementation")
> Cc: stable@vger.kernel.org
> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
> ---
> arch/s390/include/asm/processor.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
next prev parent reply other threads:[~2026-03-02 15:40 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-02 13:34 [PATCH 0/3] s390: Fix and improve inline assembly constraints Heiko Carstens
2026-03-02 13:34 ` [PATCH 1/3] s390/xor: Fix xor_xc_2() " Heiko Carstens
2026-03-02 15:41 ` Vasily Gorbik
2026-03-02 13:34 ` [PATCH 2/3] s390/xor: Improve " Heiko Carstens
2026-03-02 16:02 ` Vasily Gorbik
2026-03-02 13:35 ` [PATCH 3/3] s390/stackleak: Fix __stackleak_poison() inline assembly constraint Heiko Carstens
2026-03-02 15:40 ` Vasily Gorbik [this message]
2026-03-02 13:47 ` [PATCH 0/3] s390: Fix and improve inline assembly constraints Christoph Hellwig
2026-03-02 14:40 ` Heiko Carstens
2026-03-02 16:13 ` Vasily Gorbik
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