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Message-Id: <20230609183632.48706-11-alexander.shishkin@linux.intel.com>
Date: Fri, 9 Jun 2023 21:36:30 +0300
From: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To: linux-kernel@...r.kernel.org, x86@...nel.org,
Andy Lutomirski <luto@...nel.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Ravi Shankar <ravi.v.shankar@...el.com>,
Tony Luck <tony.luck@...el.com>,
Sohil Mehta <sohil.mehta@...el.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Dave Hansen <dave.hansen@...el.com>
Subject: [PATCH v3 10/12] x86/vsyscall: Document the fact that vsyscall=emulate disables LASS
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@...nel.org>
Suggested-by: Dave Hansen <dave.hansen@...el.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.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
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