From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
To: linux-kernel@vger.kernel.org, x86@kernel.org,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Ravi Shankar <ravi.v.shankar@intel.com>,
Tony Luck <tony.luck@intel.com>,
Sohil Mehta <sohil.mehta@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>
Subject: [PATCH v3 10/12] x86/vsyscall: Document the fact that vsyscall=emulate disables LASS
Date: Fri, 9 Jun 2023 21:36:30 +0300 [thread overview]
Message-ID: <20230609183632.48706-11-alexander.shishkin@linux.intel.com> (raw)
In-Reply-To: <20230609183632.48706-1-alexander.shishkin@linux.intel.com>
Since EMULATE mode of vsyscall disables LASS, because fixing the LASS
violations during the EMULATE mode would need complex instruction
decoding, document this fact in kernel-parameters.txt.
Cc: Andy Lutomirski <luto@kernel.org>
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
---
Documentation/admin-guide/kernel-parameters.txt | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9e5bab29685f..efed9193107e 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6850,7 +6850,9 @@
emulate Vsyscalls turn into traps and are emulated
reasonably safely. The vsyscall page is
- readable.
+ readable. This also disables the LASS
+ feature to allow userspace to poke around
+ the vsyscall page.
xonly [default] Vsyscalls turn into traps and are
emulated reasonably safely. The vsyscall
--
2.39.2
next prev parent reply other threads:[~2023-06-09 18:38 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-09 18:36 [PATCH v3 00/12] Enable Linear Address Space Separation support Alexander Shishkin
2023-06-09 18:36 ` [PATCH v3 01/12] x86/cpu: Enumerate the LASS feature bits Alexander Shishkin
2023-06-09 18:36 ` [PATCH v3 02/12] x86/asm: Introduce inline memcpy and memset Alexander Shishkin
2023-06-09 18:36 ` [PATCH v3 03/12] x86/alternatives: Disable LASS when patching kernel alternatives Alexander Shishkin
2023-07-31 22:41 ` Edgecombe, Rick P
2023-08-01 21:10 ` Sohil Mehta
2023-08-01 21:50 ` Edgecombe, Rick P
2023-06-09 18:36 ` [PATCH v3 04/12] x86/cpu: Enable LASS during CPU initialization Alexander Shishkin
2023-06-09 18:36 ` [PATCH v3 05/12] x86/cpu: Remove redundant comment during feature setup Alexander Shishkin
2023-06-09 18:36 ` [PATCH v3 06/12] x86/vsyscall: Reorganize the #PF emulation code Alexander Shishkin
2023-06-09 18:36 ` [PATCH v3 07/12] x86/traps: Consolidate user fixups in exc_general_protection() Alexander Shishkin
2023-06-09 18:36 ` [PATCH v3 08/12] x86/vsyscall: Add vsyscall emulation for #GP Alexander Shishkin
2023-06-09 18:36 ` [PATCH v3 09/12] x86/vsyscall: Disable LASS if vsyscall mode is set to EMULATE Alexander Shishkin
2023-06-09 18:36 ` Alexander Shishkin [this message]
2023-06-09 18:36 ` [PATCH v3 11/12] x86/cpu: Set LASS CR4 bit as pinning sensitive Alexander Shishkin
2023-06-09 18:36 ` [RFC v3 12/12] x86/efi: Disable LASS enforcement when switching to EFI MM Alexander Shishkin
2023-07-31 18:00 ` [PATCH v3 00/12] Enable Linear Address Space Separation support Alexander Shishkin
2023-07-31 22:36 ` Edgecombe, Rick P
2023-08-01 19:50 ` Sohil Mehta
2023-08-01 20:38 ` Edgecombe, Rick P
2023-08-04 23:52 ` Edgecombe, Rick P
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