This is a note to let you know that I've just added the patch titled
x86/fpu: Set the xcomp_bv when we fake up a XSAVES area
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-fpu-set-the-xcomp_bv-when-we-fake-up-a-xsaves-area.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Wed Dec 6 17:39:55 CET 2017
From: Kevin Hao <haokexin@xxxxxxxxx>
Date: Sun, 22 Jan 2017 16:50:23 +0800
Subject: x86/fpu: Set the xcomp_bv when we fake up a XSAVES area
From: Kevin Hao <haokexin@xxxxxxxxx>
[ Upstream commit 4c833368f0bf748d4147bf301b1f95bc8eccb3c0 ]
I got the following calltrace on a Apollo Lake SoC with 32-bit kernel:
WARNING: CPU: 2 PID: 261 at arch/x86/include/asm/fpu/internal.h:363 fpu__restore+0x1f5/0x260
[...]
Hardware name: Intel Corp. Broxton P/NOTEBOOK, BIOS APLIRVPA.X64.0138.B35.1608091058 08/09/2016
Call Trace:
dump_stack()
__warn()
? fpu__restore()
warn_slowpath_null()
fpu__restore()
__fpu__restore_sig()
fpu__restore_sig()
restore_sigcontext.isra.9()
sys_sigreturn()
do_int80_syscall_32()
entry_INT80_32()
The reason is that a #GP occurs when executing XRSTORS. The root cause
is that we forget to set the xcomp_bv when we fake up the XSAVES area
in the copyin_to_xsaves() function.
Signed-off-by: Kevin Hao <haokexin@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Quentin Casasnovas <quentin.casasnovas@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1485075023-30161-1-git-send-email-haokexin@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/fpu/xstate.c | 1 +
1 file changed, 1 insertion(+)
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1077,6 +1077,7 @@ int copyin_to_xsaves(const void *kbuf, c
* Add back in the features that came in from userspace:
*/
xsave->header.xfeatures |= xfeatures;
+ xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xsave->header.xfeatures;
return 0;
}
Patches currently in stable-queue which might be from haokexin@xxxxxxxxx are
queue-4.9/x86-fpu-set-the-xcomp_bv-when-we-fake-up-a-xsaves-area.patch