Messages in this thread Patch in this message | | | From | Kevin Hao <> | Subject | [PATCH] x86/fpu: set the xcomp_bv when we fake up a XSAVES area | Date | Sun, 22 Jan 2017 16:50:23 +0800 |
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I got the following calltrace on a Apollo Lake SoC with 32bit kernel. WARNING: CPU: 2 PID: 261 at arch/x86/include/asm/fpu/internal.h:363 fpu__restore+0x1f5/0x260 Modules linked in: CPU: 2 PID: 261 Comm: check_hostname. Not tainted 4.10.0-rc4-next-20170120 #90 Hardware name: Intel Corp. Broxton P/NOTEBOOK, BIOS APLIRVPA.X64.0138.B35.1608091058 08/09/2016 Call Trace: dump_stack+0x47/0x5f __warn+0xea/0x110 ? fpu__restore+0x1f5/0x260 warn_slowpath_null+0x2a/0x30 fpu__restore+0x1f5/0x260 __fpu__restore_sig+0x165/0x6b0 fpu__restore_sig+0x2f/0x50 restore_sigcontext.isra.9+0xe0/0xf0 sys_sigreturn+0xaa/0xf0 do_int80_syscall_32+0x59/0xb0 entry_INT80_32+0x2a/0x2a EIP: 0xb77acc61 EFLAGS: 00000246 CPU: 2 EAX: 00000000 EBX: 00000003 ECX: 08151d38 EDX: 00000000 ESI: bfa9ce20 EDI: 08151d38 EBP: 0000000c ESP: bfa9cdbc DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b
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 function copyin_to_xsaves().
Signed-off-by: Kevin Hao <haokexin@gmail.com> --- arch/x86/kernel/fpu/xstate.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 35f7024aace5..2c0df2681481 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1071,6 +1071,8 @@ int copyin_to_xsaves(const void *kbuf, const void __user *ubuf, * 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; } -- 2.9.3
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