[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <1a6c4d3a8a4e7be79ba448b42685e0321d50c14c.1461698311.git.luto@kernel.org>
Date: Tue, 26 Apr 2016 12:23:27 -0700
From: Andy Lutomirski <luto@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>,
Brian Gerst <brgerst@...il.com>,
Andi Kleen <andi@...stfloor.org>,
Andy Lutomirski <luto@...nel.org>
Subject: [PATCH 4/8] x86/segments/64: When load_gs_index fails, clear the base
On AMD CPUs, a failed load_gs_base currently may not clear the FS
base. Fix it.
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
arch/x86/entry/entry_64.S | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 1693c17dbf81..6344629ae1ce 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -794,6 +794,12 @@ END(native_load_gs_index)
/* running with kernelgs */
bad_gs:
SWAPGS /* switch back to user gs */
+.macro ZAP_GS
+ /* This can't be a string because the preprocessor needs to see it. */
+ movl $__USER_DS, %eax
+ movl %eax, %gs
+.endm
+ ALTERNATIVE "", "ZAP_GS", X86_BUG_NULL_SEG
xorl %eax, %eax
movl %eax, %gs
jmp 2b
--
2.5.5
Powered by blists - more mailing lists