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Add the AMX state components in XFEATURE_MASK_USER_SUPPORTED and the
TILE_DATA component to the dynamic states and update the permission check
table accordingly.
This is only effective on 64 bit kernels as for 32bit kernels
XFEATURE_MASK_TILE is defined as 0.
TILE_DATA is caller-saved state and the only dynamic state. Add build time
sanity check to ensure the assumption that every dynamic feature is caller-
saved.
Make AMX state depend on XFD as it is dynamic feature.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211021225527.10184-24-chang.seok.bae@intel.com
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To handle the dynamic sizing of buffers on first use the XFD MSR has to be
armed. Store the delta between the maximum available and the default
feature bits in init_fpstate where it can be retrieved for task creation.
If the delta is non zero then dynamic features are enabled. This needs also
to enable the static key which guards the XFD updates. This is delayed to
an initcall because the FPU setup runs before jump labels are initialized.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211021225527.10184-23-chang.seok.bae@intel.com
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When dynamically enabled states are supported the maximum and default sizes
for the kernel buffers and user space interfaces are not longer identical.
Put the necessary calculations in place which only take the default enabled
features into account.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211021225527.10184-22-chang.seok.bae@intel.com
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The XSTATE initialization uses check_xstate_against_struct() to sanity
check the size of XSTATE-enabled features. AMX is a XSAVE-enabled feature,
and its size is not hard-coded but discoverable at run-time via CPUID.
The AMX state is composed of state components 17 and 18, which are all user
state components. The first component is the XTILECFG state of a 64-byte
tile-related control register. The state component 18, called XTILEDATA,
contains the actual tile data, and the state size varies on
implementations. The architectural maximum, as defined in the CPUID(0x1d,
1): EAX[15:0], is a byte less than 64KB. The first implementation supports
8KB.
Check the XTILEDATA state size dynamically. The feature introduces the new
tile register, TMM. Define one register struct only and read the number of
registers from CPUID. Cross-check the overall size with CPUID again.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211021225527.10184-21-chang.seok.bae@intel.com
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The kernel checks at boot time which features are available by walking a
XSAVE feature table which contains the CPUID feature bit numbers which need
to be checked whether a feature is available on a CPU or not. So far the
feature numbers have been linear, but AMX will create a gap which the
current code cannot handle.
Make the table entries explicitly indexed and adjust the loop code
accordingly to prepare for that.
No functional change.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Len Brown <len.brown@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211021225527.10184-20-chang.seok.bae@intel.com
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The fpstate embedded in struct fpu is the default state for storing the FPU
registers. It's sized so that the default supported features can be stored.
For dynamically enabled features the register buffer is too small.
The #NM handler detects first use of a feature which is disabled in the
XFD MSR. After handling permission checks it recalculates the size for
kernel space and user space state and invokes fpstate_realloc() which
tries to reallocate fpstate and install it.
Provide the allocator function which checks whether the current buffer size
is sufficient and if not allocates one. If allocation is successful the new
fpstate is initialized with the new features and sizes and the now enabled
features is removed from the task's XFD mask.
realloc_fpstate() uses vzalloc(). If use of this mechanism grows to
re-allocate buffers larger than 64KB, a more sophisticated allocation
scheme that includes purpose-built reclaim capability might be justified.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211021225527.10184-19-chang.seok.bae@intel.com
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If the XFD MSR has feature bits set then #NM will be raised when user space
attempts to use an instruction related to one of these features.
When the task has no permissions to use that feature, raise SIGILL, which
is the same behavior as #UD.
If the task has permissions, calculate the new buffer size for the extended
feature set and allocate a larger fpstate. In the unlikely case that
vzalloc() fails, SIGSEGV is raised.
The allocation function will be added in the next step. Provide a stub
which fails for now.
[ tglx: Updated serialization ]
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211021225527.10184-18-chang.seok.bae@intel.com
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The IA32_XFD_MSR allows to arm #NM traps for XSTATE components which are
enabled in XCR0. The register has to be restored before the tasks XSTATE is
restored. The life time rules are the same as for FPU state.
XFD is updated on return to userspace only when the FPU state of the task
is not up to date in the registers. It's updated before the XRSTORS so
that eventually enabled dynamic features are restored as well and not
brought into init state.
Also in signal handling for restoring FPU state from user space the
correctness of the XFD state has to be ensured.
Add it to CPU initialization and resume as well.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211021225527.10184-17-chang.seok.bae@intel.com
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Add debug functionality to ensure that the XFD MSR is up to date for XSAVE*
and XRSTOR* operations.
[ tglx: Improve comment. ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211021225527.10184-16-chang.seok.bae@intel.com
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The software reserved portion of the fxsave frame in the signal frame
is copied from structures which have been set up at boot time. With
dynamically enabled features the content of these structures is no
longer correct because the xfeatures and size can be different per task.
Calculate the software reserved portion at runtime and fill in the
xfeatures and size values from the tasks active fpstate.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211021225527.10184-10-chang.seok.bae@intel.com
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Dynamically enabled XSTATE features are by default disabled for all
processes. A process has to request permission to use such a feature.
To support this implement a architecture specific prctl() with the options:
- ARCH_GET_XCOMP_SUPP
Copies the supported feature bitmap into the user space provided
u64 storage. The pointer is handed in via arg2
- ARCH_GET_XCOMP_PERM
Copies the process wide permitted feature bitmap into the user space
provided u64 storage. The pointer is handed in via arg2
- ARCH_REQ_XCOMP_PERM
Request permission for a feature set. A feature set can be mapped to a
facility, e.g. AMX, and can require one or more XSTATE components to
be enabled.
The feature argument is the number of the highest XSTATE component
which is required for a facility to work.
The request argument is not a user supplied bitmap because that makes
filtering harder (think seccomp) and even impossible because to
support 32bit tasks the argument would have to be a pointer.
The permission mechanism works this way:
Task asks for permission for a facility and kernel checks whether that's
supported. If supported it does:
1) Check whether permission has already been granted
2) Compute the size of the required kernel and user space buffer
(sigframe) size.
3) Validate that no task has a sigaltstack installed
which is smaller than the resulting sigframe size
4) Add the requested feature bit(s) to the permission bitmap of
current->group_leader->fpu and store the sizes in the group
leaders fpu struct as well.
If that is successful then the feature is still not enabled for any of the
tasks. The first usage of a related instruction will result in a #NM
trap. The trap handler validates the permission bit of the tasks group
leader and if permitted it installs a larger kernel buffer and transfers
the permission and size info to the new fpstate container which makes all
the FPU functions which require per task information aware of the extended
feature set.
[ tglx: Adopted to new base code, added missing serialization,
massaged namings, comments and changelog ]
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211021225527.10184-7-chang.seok.bae@intel.com
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Split out the size calculation from the paranoia check so it can be used
for recalculating buffer sizes when dynamically enabled features are
supported.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
[ tglx: Adopted to changed base code ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211021225527.10184-4-chang.seok.bae@intel.com
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xfeatures_mask_fpstate() is no longer valid when dynamically enabled
features come into play.
Rework restore_regs_from_fpstate() so it takes a constant mask which will
then be applied against the maximum feature set so that the restore
operation brings all features which are not in the xsave buffer xfeature
bitmap into init state.
This ensures that if the previous task used a dynamically enabled feature
that the task which restores has all unused components properly initialized.
Cleanup the last user of xfeatures_mask_fpstate() as well and remove it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211014230739.461348278@linutronix.de
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Use the new fpu_user_cfg to retrieve the information instead of
xfeatures_mask_uabi() which will be no longer correct when dynamically
enabled features become available.
Using fpu_user_cfg is appropriate when setting XCOMP_BV in the
init_fpstate since it has space allocated for "max_features". But,
normal fpstates might only have space for default xfeatures. Since
XRSTOR* derives the format of the XSAVE buffer from XCOMP_BV, this can
lead to XRSTOR reading out of bounds.
So when copying actively used fpstate, simply read the XCOMP_BV features
bits directly out of the fpstate instead.
This correction courtesy of Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211014230739.408879849@linutronix.de
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Move the feature mask storage to the kernel and user config
structs. Default and maximum feature set are the same for now.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211014230739.352041752@linutronix.de
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Use the new kernel and user space config storage to store and retrieve the
XSTATE buffer sizes. The default and the maximum size are the same for now,
but will change when support for dynamically enabled features is added.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211014230739.296830097@linutronix.de
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The size calculations are partially unreadable gunk. Clean them up.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211014230739.241223689@linutronix.de
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Prepare for dynamically enabled states per task. The function needs to
retrieve the features and sizes which are valid in a fpstate
context. Retrieve them from fpstate.
Move the function declarations to the core header as they are not
required anywhere else.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211013145323.233529986@linutronix.de
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With dynamically enabled features the copy function must know the features
and the size which is valid for the task. Retrieve them from fpstate.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211013145323.181495492@linutronix.de
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Add state size and feature mask information to the fpstate container. This
will be used for runtime checks with the upcoming support for dynamically
enabled features and dynamically sized buffers. That avoids conditionals
all over the place as the required information is accessible for both
default and extended buffers.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211013145322.921388806@linutronix.de
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Convert the rest of the core code to the new register storage mechanism in
preparation for dynamically sized buffers.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211013145322.659456185@linutronix.de
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In order to prepare for the support of dynamically enabled FPU features,
move the clearing of xstate components to the FPU core code.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: kvm@vger.kernel.org
Link: https://lkml.kernel.org/r/20211013145322.399567049@linutronix.de
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Convert fpstate_init() and related code to the new register storage
mechanism in preparation for dynamically sized buffers.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211013145322.292157401@linutronix.de
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Now that the file is empty, fixup all references with the proper includes
and delete the former kitchen sink.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011540.001197214@linutronix.de
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No need to expose that to code which only needs the XCR0 accessors.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011539.740012411@linutronix.de
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Nothing outside the core code requires them.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011539.572439164@linutronix.de
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It's only required in the xstate init code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011539.455836597@linutronix.de
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No need to keep it around.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011539.296435736@linutronix.de
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Prepare for replacing the KVM copy xstate to user function by extending
copy_xstate_to_uabi_buf() with a pkru argument which allows the caller to
hand in the pkru value, which is required for KVM because the guest PKRU is
not accessible via current. Fixup all callsites accordingly.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011539.191902137@linutronix.de
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Copying a user space buffer to the memory buffer is already available in
the FPU core. The copy mechanism in KVM lacks sanity checks and needs to
use cpuid() to lookup the offset of each component, while the FPU core has
this information cached.
Make the FPU core variant accessible for KVM and replace the home brewed
mechanism.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: kvm@vger.kernel.org
Link: https://lkml.kernel.org/r/20211015011539.134065207@linutronix.de
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Swapping the host/guest FPU is directly fiddling with FPU internals which
requires 5 exports. The upcoming support of dynamically enabled states
would even need more.
Implement a swap function in the FPU core code and export that instead.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Link: https://lkml.kernel.org/r/20211015011539.076072399@linutronix.de
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No point to keep them around after boot.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011539.017919252@linutronix.de
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These loops evaluating xfeature bits are really hard to read. Create an
iterator and use for_each_set_bit_from() inside which already does the right
thing.
No functional changes.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011538.958107505@linutronix.de
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No point in having this duplicated all over the place with needlessly
different defines.
Provide a proper initialization function which initializes user buffers
properly and make KVM use it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011538.897664678@linutronix.de
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Defensive programming is useful, but this on_boot_cpu debug is really
silly.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011538.665080855@linutronix.de
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These interfaces are really only valid for features which are independently
managed and not part of the task context state for various reasons.
Tighten the checks and adjust the misleading comments.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211015011538.608492174@linutronix.de
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The change which made copy_xstate_to_uabi_buf() usable for
[x]fpregs_get() removed the zeroing of the header which means the
header, which is copied to user space later, contains except for the
xfeatures member, random stack content.
Add the memset() back to zero it before usage.
Fixes: eb6f51723f03 ("x86/fpu: Make copy_xstate_to_kernel() usable for [x]fpregs_get()")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/875yy3wb8h.ffs@nanos.tec.linutronix.de
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As the PKRU state is managed separately restoring it from the xstate
buffer would be counterproductive as it might either restore a stale
value or reinit the PKRU state to 0.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121456.606745195@linutronix.de
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One nice thing about having PKRU be XSAVE-managed is that it gets naturally
exposed into the XSAVE-using ABIs. Now that XSAVE will not be used to
manage PKRU, these ABIs need to be manually enabled to deal with PKRU.
ptrace() uses copy_uabi_xstate_to_kernel() to collect the tracee's
XSTATE. As PKRU is not in the task's XSTATE buffer, use task->thread.pkru
for filling in up the ptrace buffer.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121456.508770763@linutronix.de
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Rename it so it's clear that this is about user ABI features which can
differ from the feature set which the kernel saves and restores because the
kernel handles e.g. PKRU differently. But the user ABI (ptrace, signal
frame) expects it to be there.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121456.211585137@linutronix.de
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X86_FEATURE_OSPKE is enabled first on the boot CPU and the feature flag is
set. Secondary CPUs have to enable CR4.PKE as well and set their per CPU
feature flag. That's ineffective because all call sites have checks for
boot_cpu_data.
Make it smarter and force the feature flag when PKU is enabled on the boot
cpu which allows then to use cpu_feature_enabled(X86_FEATURE_OSPKE) all
over the place. That either compiles the code out when PKEY support is
disabled in Kconfig or uses a static_cpu_has() for the feature check which
makes a significant difference in hotpaths, e.g. context switch.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121455.305113644@linutronix.de
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The copy functions for the independent features are horribly named and the
supervisor and independent part is just overengineered.
The point is that the supplied mask has either to be a subset of the
independent features or a subset of the task->fpu.xstate managed features.
Rewrite it so it checks for invalid overlaps of these areas in the caller
supplied feature mask. Rename it so it follows the new naming convention
for these operations. Mop up the function documentation.
This allows to use that function for other purposes as well.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lkml.kernel.org/r/20210623121455.004880675@linutronix.de
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The salient feature of "dynamic" XSTATEs is that they are not part of the
main task XSTATE buffer. The fact that they are dynamically allocated is
irrelevant and will become quite confusing when user math XSTATEs start
being dynamically allocated. Rename them to "independent" because they
are independent of the main XSTATE code.
This is just a search-and-replace with some whitespace updates to keep
things aligned.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/1eecb0e4f3e07828ebe5d737ec77dc3b708fad2d.1623388344.git.luto@kernel.org
Link: https://lkml.kernel.org/r/20210623121454.911450390@linutronix.de
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copy_uabi_from_user_to_xstate() and copy_uabi_from_kernel_to_xstate() are
almost identical except for the copy function.
Unify them.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20210623121454.414215896@linutronix.de
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Rename them to reflect that these functions deal with user space format
XSAVE buffers.
copy_kernel_to_xstate() -> copy_uabi_from_kernel_to_xstate()
copy_user_to_xstate() -> copy_sigframe_from_user_to_xstate()
Again a clear statement that these functions deal with user space ABI.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121454.318485015@linutronix.de
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The function names for xsave[s]/xrstor[s] operations are horribly named and
a permanent source of confusion.
Rename:
copy_xregs_to_kernel() to os_xsave()
copy_kernel_to_xregs() to os_xrstor()
These are truly low level wrappers around the actual instructions
XSAVE[OPT]/XRSTOR and XSAVES/XRSTORS with the twist that the selection
based on the available CPU features happens with an alternative to avoid
conditionals all over the place and to provide the best performance for hot
paths.
The os_ prefix tells that this is the OS selected mechanism.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.830239347@linutronix.de
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If the fast path of restoring the FPU state on sigreturn fails or is not
taken and the current task's FPU is active then the FPU has to be
deactivated for the slow path to allow a safe update of the tasks FPU
memory state.
With supervisor states enabled, this requires to save the supervisor state
in the memory state first. Supervisor states require XSAVES so saving only
the supervisor state requires to reshuffle the memory buffer because XSAVES
uses the compacted format and therefore stores the supervisor states at the
beginning of the memory state. That's just an overengineered optimization.
Get rid of it and save the full state for this case.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.734561971@linutronix.de
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The function does a sanity check with a WARN_ON_ONCE() but happily proceeds
when the pkey argument is out of range.
Clean it up.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.635764326@linutronix.de
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This function is pointlessly global and a complete misnomer because it's
usage is related to both supervisor state checks and compacted format
checks. Remove it and just make the conditions check the XSAVES feature.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.425493349@linutronix.de
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No more users.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.124819167@linutronix.de
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