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%3Ba=su...
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@vger.kernel.org know about it.
From foo@baz Wed Dec 6 17:39:55 CET 2017
From: Kevin Hao haokexin@gmail.com 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@gmail.com
[ 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@gmail.com Cc: Andy Lutomirski luto@kernel.org Cc: Borislav Petkov bp@alien8.de Cc: Brian Gerst brgerst@gmail.com Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Denys Vlasenko dvlasenk@redhat.com Cc: Fenghua Yu fenghua.yu@intel.com Cc: H. Peter Anvin hpa@zytor.com Cc: Josh Poimboeuf jpoimboe@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Oleg Nesterov oleg@redhat.com Cc: Peter Zijlstra peterz@infradead.org Cc: Quentin Casasnovas quentin.casasnovas@oracle.com Cc: Rik van Riel riel@redhat.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Yu-cheng Yu yu-cheng.yu@intel.com Link: http://lkml.kernel.org/r/1485075023-30161-1-git-send-email-haokexin@gmail.co... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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@gmail.com are
queue-4.9/x86-fpu-set-the-xcomp_bv-when-we-fake-up-a-xsaves-area.patch