So the xstate code was probably first copied from the fxregs code,
hence it carried over the 'fx' naming for the state pointer variable.

But this is slightly confusing, as we usually on call the (legacy)
MMX/SSE state 'fx', both in data structures and in the functions
build around FXSAVE/FXRSTOR.

So rename it to 'xstate' to make it more apparent what it is related to.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Remove obsolete comment about __init limitations: in the new code there aren't any.

Also standardize the comment style in the function while at it.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

All the other register<-> memory copying functions are defined
in fpu/internal.h, so move the xstate variants there too.

Beyond being more consistent, this also allows FPU debugging
checks to be added to them. (Because they can now use the
macros defined in fpu/internal.h.)

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

On most configs task-struct is cache line aligned, which makes
the XSAVE area's 64-byte required alignment work out fine.

But on some .config's task_struct is aligned only to 16 bytes
(enforced by ARCH_MIN_TASKALIGN), which makes things like
fpu__copy() (that XSAVEOPT uses) not work so well.

I broke this in:

  7366ed77 ("x86/fpu: Simplify FPU handling by embedding the fpstate in task_struct (again)")

which embedded the fpstate in the task_struct.

The alignment requirements of the FPU code were originally present
in ARCH_MIN_TASKALIGN, which still has a value of 16, which was the
alignment requirement of the FPU state area prior XSAVE. But this
link was not documented (and not required) and the link got lost
when the FPU state area was made dynamic years ago.

With XSAVEOPT the minimum alignment requirment went up to 64 bytes,
and the embedding of the FPU state area in task_struct exposed it
again - and '16' was not increased to '64'.

So fix this bug, but also try to address the underlying lost link
of information that made it easier to happen:

  - document ARCH_MIN_TASKALIGN a bit better

  - use alignof() to recover the current alignment requirements.
    This would work in the future as well, should the alignment
    requirements go up to 128 bytes with things like AVX512.

( We should probably also use the vSMP alignment rules for all
  of x86, but that's for another patch. )
Reported-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Use the new zynq binding for macb ethernet, since it will disable half
duplex gigabit like the Zynq TRM says to do.
Signed-off-by: NNathan Sullivan <nathan.sullivan@ni.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For some CPU models I broke the AVX2 feature detection in:

  7bc371fa ("x86/fpu, crypto x86/camellia_aesni_avx2: Simplify the camellia_aesni_init() xfeature checks")
  534ff06e ("x86/fpu, crypto x86/serpent_avx2: Simplify the init() xfeature checks")

... because I did not realize that it's possible for a CPU to support
the xstate necessary for AVX2 execution (XSTATE_YMM), but not have
the AVX2 instructions themselves.

Restore the necessary CPUID checks as well.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Multitheaded tests showed that the icv buffer in the current ghash
implementation is not handled correctly. A move of this working ghash
buffer value to the descriptor context fixed this. Code is tested and
verified with an multithreaded application via af_alg interface.

Cc: stable@vger.kernel.org
Signed-off-by: NHarald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: NGerald Schaefer <geraldsc@linux.vnet.ibm.com>
Reported-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

The MPX feature requires eager KVM FPU restore support. We have verified
that MPX cannot work correctly with the current lazy KVM FPU restore
mechanism. Eager KVM FPU restore should be enabled if the MPX feature is
exposed to VM.
Signed-off-by: NYang Zhang <yang.z.zhang@intel.com>
Signed-off-by: NLiang Li <liang.z.li@intel.com>
[Also activate the FPU on AMD processors. - Paolo]
Cc: stable@vger.kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This reverts commit 4473b570.  We'll
use the hook again.

Cc: stable@vger.kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

memslot->userfault_addr is set by the kernel with a mmap executed
from the kernel but the userland can still munmap it and lead to the
below oops after memslot->userfault_addr points to a host virtual
address that has no vma or mapping.

[  327.538306] BUG: unable to handle kernel paging request at fffffffffffffffe
[  327.538407] IP: [<ffffffff811a7b55>] put_page+0x5/0x50
[  327.538474] PGD 1a01067 PUD 1a03067 PMD 0
[  327.538529] Oops: 0000 [#1] SMP
[  327.538574] Modules linked in: macvtap macvlan xt_CHECKSUM iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT iptable_filter ip_tables tun bridge stp llc rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache xprtrdma ib_isert iscsi_target_mod ib_iser libiscsi scsi_transport_iscsi ib_srpt target_core_mod ib_srp scsi_transport_srp scsi_tgt ib_ipoib rdma_ucm ib_ucm ib_uverbs ib_umad rdma_cm ib_cm iw_cm ipmi_devintf iTCO_wdt iTCO_vendor_support intel_powerclamp coretemp dcdbas intel_rapl kvm_intel kvm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel lrw gf128mul glue_helper ablk_helper cryptd pcspkr sb_edac edac_core ipmi_si ipmi_msghandler acpi_pad wmi acpi_power_meter lpc_ich mfd_core mei_me
[  327.539488]  mei shpchp nfsd auth_rpcgss nfs_acl lockd grace sunrpc mlx4_ib ib_sa ib_mad ib_core mlx4_en vxlan ib_addr ip_tunnel xfs libcrc32c sd_mod crc_t10dif crct10dif_common crc32c_intel mgag200 syscopyarea sysfillrect sysimgblt i2c_algo_bit drm_kms_helper ttm drm ahci i2c_core libahci mlx4_core libata tg3 ptp pps_core megaraid_sas ntb dm_mirror dm_region_hash dm_log dm_mod
[  327.539956] CPU: 3 PID: 3161 Comm: qemu-kvm Not tainted 3.10.0-240.el7.userfault19.4ca4011.x86_64.debug #1
[  327.540045] Hardware name: Dell Inc. PowerEdge R420/0CN7CM, BIOS 2.1.2 01/20/2014
[  327.540115] task: ffff8803280ccf00 ti: ffff880317c58000 task.ti: ffff880317c58000
[  327.540184] RIP: 0010:[<ffffffff811a7b55>]  [<ffffffff811a7b55>] put_page+0x5/0x50
[  327.540261] RSP: 0018:ffff880317c5bcf8  EFLAGS: 00010246
[  327.540313] RAX: 00057ffffffff000 RBX: ffff880616a20000 RCX: 0000000000000000
[  327.540379] RDX: 0000000000002014 RSI: 00057ffffffff000 RDI: fffffffffffffffe
[  327.540445] RBP: ffff880317c5bd10 R08: 0000000000000103 R09: 0000000000000000
[  327.540511] R10: 0000000000000000 R11: 0000000000000000 R12: fffffffffffffffe
[  327.540576] R13: 0000000000000000 R14: ffff880317c5bd70 R15: ffff880317c5bd50
[  327.540643] FS:  00007fd230b7f700(0000) GS:ffff880630800000(0000) knlGS:0000000000000000
[  327.540717] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  327.540771] CR2: fffffffffffffffe CR3: 000000062a2c3000 CR4: 00000000000427e0
[  327.540837] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  327.540904] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  327.540974] Stack:
[  327.541008]  ffffffffa05d6d0c ffff880616a20000 0000000000000000 ffff880317c5bdc0
[  327.541093]  ffffffffa05ddaa2 0000000000000000 00000000002191bf 00000042f3feab2d
[  327.541177]  00000042f3feab2d 0000000000000002 0000000000000001 0321000000000000
[  327.541261] Call Trace:
[  327.541321]  [<ffffffffa05d6d0c>] ? kvm_vcpu_reload_apic_access_page+0x6c/0x80 [kvm]
[  327.543615]  [<ffffffffa05ddaa2>] vcpu_enter_guest+0x3f2/0x10f0 [kvm]
[  327.545918]  [<ffffffffa05e2f10>] kvm_arch_vcpu_ioctl_run+0x2b0/0x5a0 [kvm]
[  327.548211]  [<ffffffffa05e2d02>] ? kvm_arch_vcpu_ioctl_run+0xa2/0x5a0 [kvm]
[  327.550500]  [<ffffffffa05ca845>] kvm_vcpu_ioctl+0x2b5/0x680 [kvm]
[  327.552768]  [<ffffffff810b8d12>] ? creds_are_invalid.part.1+0x12/0x50
[  327.555069]  [<ffffffff810b8d71>] ? creds_are_invalid+0x21/0x30
[  327.557373]  [<ffffffff812d6066>] ? inode_has_perm.isra.49.constprop.65+0x26/0x80
[  327.559663]  [<ffffffff8122d985>] do_vfs_ioctl+0x305/0x530
[  327.561917]  [<ffffffff8122dc51>] SyS_ioctl+0xa1/0xc0
[  327.564185]  [<ffffffff816de829>] system_call_fastpath+0x16/0x1b
[  327.566480] Code: 0b 31 f6 4c 89 e7 e8 4b 7f ff ff 0f 0b e8 24 fd ff ff e9 a9 fd ff ff 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 <48> f7 07 00 c0 00 00 55 48 89 e5 75 2a 8b 47 1c 85 c0 74 1e f0
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The kernel's handling of 'compacted' xsave state layout is buggy:

    http://marc.info/?l=linux-kernel&m=142967852317199

I don't have such a system, and the description there is vague, but
from extrapolation I guess that there were two kinds of bugs
observed:

  - boot crashes, due to size calculations being wrong and the dynamic
    allocation allocating a too small xstate area. (This is now fixed
    in the new FPU code - but still present in stable kernels.)

  - FPU state corruption and ABI breakage: if signal handlers try to
    change the FPU state in standard format, which then the kernel
    tries to restore in the compacted format.

These breakages are scary, but they only occur on a small number of
systems that have XSAVES* CPU support. Yet we have had XSAVES support
in the upstream kernel for a large number of stable kernel releases,
and the fixes are involved and unproven.

So do the safe resolution first: disable XSAVES* support and only
use the standard xstate format. This makes the code work and is
easy to backport.

On top of this we can work on enabling (and testing!) proper
compacted format support, without backporting pressure, on top of the
new, cleaned up FPU code.

Cc: <stable@vger.kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Explain the functions and also standardize their style
and naming.

No change in functionality.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

We had a number of FPU init related boot option handlers
in arch/x86/kernel/cpu/common.c - move them over into
arch/x86/kernel/fpu/init.c to have them all in a
single place.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

While looking at xstate.h it took me some time to realize that
'xstate_fault' uses 'err' as a silent parameter. This is not
obvious at the call site, at all.

Make it an explicit macro argument, so that the syntactic
connection is easier to see. Also explain xstate_fault()
a bit.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

fpu/internal.h has grown organically, with not much high level structure,
which hurts its readability.

Organize the various definitions into 5 sections:

 - high level FPU state functions
 - FPU/CPU feature flag helpers
 - fpstate handling functions
 - FPU context switching helpers
 - misc helper functions

Other related changes:

 - Move MXCSR_DEFAULT to fpu/types.h.
 - drop the unused X87_FSW_ES define

No change in functionality.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

There are various internal FPU state debugging checks that never
trigger in practice, but which are useful for FPU code development.

Separate these out into CONFIG_X86_DEBUG_FPU=y, and also add a
couple of new ones.

The size difference is about 0.5K of code on defconfig:

   text        data     bss          filename
   15028906    2578816  1638400      vmlinux
   15029430    2578816  1638400      vmlinux

( Keep this enabled by default until the new FPU code is debugged. )

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

I tried to simulate an ancient CPU via this option, and
found that it still has fxsr_opt enabled, confusing the
FPU code.

Make the 'nofxsr' option also clear FXSR_OPT flag.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

This cleans up the call sites and the function a bit,
and also makes it more symmetric with the other high
level FPU state handling functions.

It's still only valid for the current task, as we copy
to the FPU registers of the current CPU.

No change in functionality.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Now that all the FPU init function call dependencies are
cleaned up we can propagate __init annotations deeper.

This shrinks the runtime size of the kernel a bit, and
also addresses a few section warnings.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

So call setup_xstate_comp() from the xstate init code, not
from the generic fpu__init_system() code.

This allows us to remove the protytype from xstate.h as well.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Put MPX support into its separate high level structure, and
also replace the fixed YMM, LWP and MPX structures in
xregs_state with just reservations - their exact offsets
in the structure will depend on the CPU and no code actually
relies on those fields.

No change in functionality.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

The current xstate code in setup_xstate_features() assumes that
the first zero bit means the end of xfeatures - but that is not
so, the SDM clearly states that an arbitrary set of xfeatures
might be enabled - and it is also clear from the description
of the compaction feature that holes are possible:

  "13-6 Vol. 1MANAGING STATE USING THE XSAVE FEATURE SET
  [...]

  Compacted format. Each state component i (i ≥ 2) is located at a byte
  offset from the base address of the XSAVE area based on the XCOMP_BV
  field in the XSAVE header:

  — If XCOMP_BV[i] = 0, state component i is not in the XSAVE area.

  — If XCOMP_BV[i] = 1, the following items apply:

  • If XCOMP_BV[j] = 0 for every j, 2 ≤ j < i, state component i is
    located at a byte offset 576 from the base address of the XSAVE
    area. (This item applies if i is the first bit set in bits 62:2 of
    the XCOMP_BV; it implies that state component i is located at the
    beginning of the extended region.)

  • Otherwise, let j, 2 ≤ j < i, be the greatest value such that
    XCOMP_BV[j] = 1. Then state component i is located at a byte offset
    X from the location of state component j, where X is the number of
    bytes required for state component j as enumerated in
    CPUID.(EAX=0DH,ECX=j):EAX. (This item implies that state component i
    immediately follows the preceding state component whose bit is set
    in XCOMP_BV.)"

So don't assume that the first zero xfeatures bit means the end of
all xfeatures - iterate through all of them.

I'm not aware of hardware that triggers this currently.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

kernel_fpu_begin() is __kernel_fpu_begin() with a preempt_disable().

Move the kernel_fpu_begin() debugging check into __kernel_fpu_begin(),
so that users of __kernel_fpu_begin() may benefit from it as well.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Document all the structures that make up 'struct fpu'.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Improve the memory layout of 'struct fpu':

 - change ->fpregs_active from 'int' to 'char' - it's just a single flag
   and modern x86 CPUs can do efficient byte accesses.

 - pack related fields closer to each other: often 'fpu->state' will not be
   touched, while the other fields will - so pack them into a group.

Also add comments to each field, describing their purpose, and add
some background information about lazy restores.

Also fix an obsolete, lazy switching related comment in fpu_copy()'s description.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Use these consistent names:

    struct fregs_state           # was: i387_fsave_struct
    struct fxregs_state          # was: i387_fxsave_struct
    struct swregs_state          # was: i387_soft_struct
    struct xregs_state           # was: xsave_struct
    union  fpregs_state          # was: thread_xstate

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

So much of fpu/core.c is the regset code, but it just obscures the generic
FPU state machine logic. Factor out the regset code into fpu/regset.c, where
it can be read in isolation.

This affects one API: fpu__activate_stopped() has to be made available
from the core to fpu/regset.c.

No change in functionality.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

fpu/xstate.c has a lot of generic FPU signal frame handling routines,
move them into a separate file: fpu/signal.c.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Standardize the naming of the various functions that copy register
content in specific FPU context formats:

  copy_fxregs_to_kernel()         # was: fpu_fxsave()
  copy_xregs_to_kernel()          # was: xsave_state()

  copy_kernel_to_fregs()          # was: frstor_checking()
  copy_kernel_to_fxregs()         # was: fxrstor_checking()
  copy_kernel_to_xregs()          # was: fpu_xrstor_checking()
  copy_kernel_to_xregs_booting()  # was: xrstor_state_booting()

  copy_fregs_to_user()            # was: fsave_user()
  copy_fxregs_to_user()           # was: fxsave_user()
  copy_xregs_to_user()            # was: xsave_user()

  copy_user_to_fregs()            # was: frstor_user()
  copy_user_to_fxregs()           # was: fxrstor_user()
  copy_user_to_xregs()            # was: xrestore_user()
  copy_user_to_fpregs_zeroing()   # was: restore_user_xstate()

Eliminate fpu_xrstor_checking(), because it was just a wrapper.

No change in functionality.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Move restore_init_xstate() next to its sole caller.

Also rename it to copy_init_fpstate_to_fpregs() and add
some comments about what it does.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

So the handling of init_xstate_ctx has a layering violation: both
'struct xsave_struct' and 'union thread_xstate' have a
'struct i387_fxsave_struct' member:

   xsave_struct::i387
   thread_xstate::fxsave

The handling of init_xstate_ctx is generic, it is used on all
CPUs, with or without XSAVE instruction. So it's confusing how
the generic code passes around and handles an XSAVE specific
format.

What we really want is for init_xstate_ctx to be a proper
fpstate and we use its ::fxsave and ::xsave members, as
appropriate.

Since the xsave_struct::i387 and thread_xstate::fxsave aliases
each other this is not a functional problem.

So implement this, and move init_xstate_ctx to the generic FPU
code in the process.

Also, since init_xstate_ctx is not XSAVE specific anymore,
rename it to init_fpstate, and mark it __read_mostly,
because it's only modified once during bootup, and used
as a reference fpstate later on.

There's no change in functionality.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

fpstate_init() only uses fpu->state, so pass that in to it.

This enables the cleanup we will do in the next patch.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Harmonize the inconsistent naming of these related functions:

                          fpstate_init()
  finit_soft_fpu()   =>   fpstate_init_fsoft()
  fx_finit()         =>   fpstate_init_fxstate()
  fx_finit()         =>   fpstate_init_fstate()       # split out

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Factor out the FPU error code handling code from traps.c and fpu/internal.h
and move them close to each other.

Also convert the helper functions to 'struct fpu *', which further simplifies
them.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Remove various boot quirks that came from the old code.

The new code is cleanly split up into per-system and per-cpu
init sequences, and system init functions are only called once.

Remove the run-once quirks.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Only a few places use the regset definitions, so factor them out.

Also fix related header dependency assumptions.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Most of the FPU does not use them, so split it out and include
them in signal.c and ia32_signal.c

Also fix header file dependency assumption in fpu/core.c.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Move them to their only user. This makes the code easier to read,
the header is less cluttered, and it also speeds up the build a bit.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

With recent cleanups and fixes the fpu__reset() and fpu__clear()
functions have become almost identical in functionality: the only
difference is that fpu__reset() assumed that the fpstate
was already active in the eagerfpu case, while fpu__clear()
activated it if it was inactive.

This distinction almost never matters, the only case where such
fpstate activation happens if if the init thread (PID 1) gets exec()-ed
for the first time.

So keep fpu__clear() and change all fpu__reset() uses to
fpu__clear() to simpify the logic.

( In a later patch we'll further simplify fpu__clear() by making
  sure that all contexts it is called on are already active. )

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Consolidate more signal frame related functions:

   text      data    bss     dec       filename
   14108070  2575280 1634304 18317654  vmlinux.before
   14107944  2575344 1634304 18317592  vmlinux.after

Also, while moving it, rename alloc_mathframe() to fpu__alloc_mathframe().

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>