linux-kernel - [PATCH v4 0/4] x86/mm: Fix some issues with using trampoline

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20211202153226.22946-1-joro@8bytes.org>
Date:   Thu,  2 Dec 2021 16:32:22 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     x86@...nel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        hpa@...or.com, Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Mike Rapoport <rppt@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Brijesh Singh <brijesh.singh@....com>,
        linux-kernel@...r.kernel.org, Joerg Roedel <jroedel@...e.de>,
        Joerg Roedel <joro@...tes.org>
Subject: [PATCH v4 0/4] x86/mm: Fix some issues with using trampoline_pgd

From: Joerg Roedel <jroedel@...e.de>

Hi

here are a couple of fixes and documentation improvements for the use of
the trampoline_pgd in the kernel. Most importantly it fixes the issue
that switching to the trampoline_pgd will unmap the kernel stack and
real_mode_header, making crashes likely before the code can actually
jump to real mode.

The first patch adds a comment to document that the trampoline_pgd
aliases kernel page-tables in the user address range, establishing
global TLB entries for these addresses. The next two patches add
global TLB flushes when switching to and from the trampoline_pgd.

The last patch extends the trampoline_pgd to cover the whole kernel
address range. This is needed to make sure the stack and the
real_mode_header are still mapped after the switch and that the code
flow can safely reach real-mode.

Please review.

Thanks,

	Joerg

Changes v3->v4:

	- Rebased to latest tip/master
	- Addressed Boris' review comments

Link to v3: https://lore.kernel.org/all/20211001154817.29225-1-joro@8bytes.org/

Joerg Roedel (4):
  x86/realmode: Add comment for Global bit usage in trampline_pgd
  x86/mm/64: Flush global TLB on boot and AP bringup
  x86/mm: Flush global TLB when switching to trampoline page-table
  x86/64/mm: Map all kernel memory into trampoline_pgd

 arch/x86/include/asm/realmode.h |  1 +
 arch/x86/include/asm/tlbflush.h |  5 +++++
 arch/x86/kernel/head64.c        |  2 ++
 arch/x86/kernel/head_64.S       | 19 ++++++++++++++++-
 arch/x86/kernel/reboot.c        | 12 ++---------
 arch/x86/mm/init.c              |  5 +++++
 arch/x86/mm/tlb.c               |  8 ++-----
 arch/x86/realmode/init.c        | 38 ++++++++++++++++++++++++++++++++-
 8 files changed, 72 insertions(+), 18 deletions(-)

base-commit: b6c28e3cc445bf451a516ac075ec27b4619e4f5f
-- 
2.34.0