From: "Marvin Häuser" <mhaeuser@posteo.de>
To: Yuanhao Xie <yuanhao.xie@intel.com>,devel@edk2.groups.io
Subject: Re: [edk2-devel] [PATCH 2/5] UefiCpuPkg: Contiguous memory allocation and code clean-up.
Date: Tue, 07 Feb 2023 08:40:41 -0800 [thread overview]
Message-ID: <32073.1675788041796635561@groups.io> (raw)
In-Reply-To: <20230207134939.273-3-yuanhao.xie@intel.com>
[-- Attachment #1: Type: text/plain, Size: 951 bytes --]
Hi Yuanhao,
1) The code comments and copy code suggest that the stacks are located low and the function is located high (good). However, the SetMemorySpaceAttributes() call un-XP's Address, which is the low address. So, do I misunderstand the changes, or are you un-XP'ing the first stack (and keep the function XP'd)?
2) The same SetMemorySpaceAttributes() call, you now pass ApLoopFuncSize over ApSafeBufferSize. The latter was explicitly page-aligned, while the former is not. How is it guaranteed it is indeed aligned? If it is not, I don't think this is supported, at least universally.
3) Similar to 2), the stack size is much smaller than the page size, no? How do you guarantee the function is on a page boundary for memory protection?
4) A proper W^X flow should be to wait with un-XP till the CopyMem() for the function code has returned. Right before that, the copied code should be marked read-only.
Best regards,
Marvin
[-- Attachment #2: Type: text/html, Size: 1268 bytes --]
next prev parent reply other threads:[~2023-02-07 16:40 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-07 13:49 [PATCH 0/5] Put APs in 64 bit mode before handoff to OS Yuanhao Xie
2023-02-07 13:49 ` [PATCH 1/5] UefiCpuPkg: Duplicate RelocateApLoop for Amd x64 processors Yuanhao Xie
2023-02-07 13:49 ` [PATCH 2/5] UefiCpuPkg: Contiguous memory allocation and code clean-up Yuanhao Xie
2023-02-07 16:40 ` Marvin Häuser [this message]
2023-02-07 16:43 ` [edk2-devel] " Marvin Häuser
2023-02-08 10:36 ` Yuanhao Xie
2023-02-08 11:09 ` Gerd Hoffmann
2023-02-10 9:12 ` Yuanhao Xie
2023-02-10 11:09 ` Gerd Hoffmann
2023-02-10 12:52 ` Ni, Ray
2023-02-07 13:49 ` [PATCH 3/5] OvmfPkg: Add CpuPageTableLib required by MpInitLib Yuanhao Xie
2023-02-08 10:53 ` Gerd Hoffmann
2023-02-09 16:30 ` [edk2-devel] " Ard Biesheuvel
2023-02-07 13:49 ` [PATCH 4/5] UefiPayloadPkg: " Yuanhao Xie
2023-02-08 5:38 ` Guo, Gua
2023-02-08 17:02 ` Guo Dong
2023-02-07 13:49 ` [PATCH 5/5] UefiCpuPkg: Put APs in 64 bit mode before handoff to OS Yuanhao Xie
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-list from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=32073.1675788041796635561@groups.io \
--to=devel@edk2.groups.io \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox