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From: "H. Peter Anvin" <hpa@zytor.com>
To: Xiang Mei <xmei5@asu.edu>, Pedro Falcato <pfalcato@suse.de>
Cc: Kees Cook <kees@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, linux-hardening@vger.kernel.org,
	Uladzislau Rezki <urezki@gmail.com>,
	"Gustavo A . R . Silva" <gustavoars@kernel.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Jennifer Miller <jmill@asu.edu>, Tiffany Bao <tbao@asu.edu>,
	Ruoyu Wang <fishw@asu.edu>, Adam Doupe <doupe@asu.edu>,
	Kyle Zeng <zengyhkyle@asu.edu>,
	Yan Shoshitaishvili <yans@asu.edu>
Subject: Re: [PATCH] mm/vmalloc: widen guard region to defeat ENTER-based stack pivot
Date: Sun, 28 Jun 2026 19:09:37 -0700	[thread overview]
Message-ID: <499a4e15-34a4-421b-946a-c855199fdbf9@zytor.com> (raw)
In-Reply-To: <CAPpSM+RVFDOYJFT2iwgNYdjbwqF-MmrbYizpLYksd1SLb5bT9g@mail.gmail.com>

On 2026-06-26 13:05, Xiang Mei wrote:
> 
> Thanks for your questions and attention.
> 
> 1) `enter` can do big enough stack pivoting (where we can't find many
> `add/sub/adc/sbb rsp, ` doing so)

Say what?

Using add/sub/lea on %rsp is probably more common than enter, because enter is
considered kind of slow.

gcc, I believe, will generate "leave" but not "enter" as a result.


> 2) `enter` is not rare since we can take part in the instruction.

This sentence doesn't parse.

	-hpa



  reply	other threads:[~2026-06-29  2:10 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-26 17:34 [PATCH] mm/vmalloc: widen guard region to defeat ENTER-based stack pivot Xiang Mei
2026-06-26 17:46 ` Xiang Mei
2026-06-26 17:48   ` Xiang Mei
2026-06-30  7:12     ` Peter Zijlstra
2026-06-30  8:09       ` Xiang Mei
2026-06-26 19:39 ` Pedro Falcato
2026-06-26 20:05   ` Xiang Mei
2026-06-29  2:09     ` H. Peter Anvin [this message]
2026-06-29  4:43       ` Matthew Wilcox
2026-06-29 12:50         ` H. Peter Anvin
2026-06-29 17:21           ` Xiang Mei
2026-06-29 21:50             ` Xiang Mei
2026-06-29 21:51               ` Xiang Mei

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