There are no users of fpu__restore() so it is time to remove it. The
comment regarding fpu__restore() and TS bit is stale since commit
b3b0870ef3 ("i387: do not preload FPU state at task switch time")
and has no meaning since.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aubrey Li <aubrey.li@intel.com>
Cc: Babu Moger <Babu.Moger@amd.com>
Cc: "Chang S. Bae" <chang.seok.bae@intel.com>
Cc: Dmitry Safonov <dima@arista.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: kvm ML <kvm@vger.kernel.org>
Cc: linux-doc@vger.kernel.org
Cc: Nicolai Stange <nstange@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190403164156.19645-3-bigeasy@linutronix.de
User space tools which do automated task placement need information
about AVX-512 usage of tasks, because AVX-512 usage could cause core
turbo frequency drop and impact the running task on the sibling CPU.
The XSAVE hardware structure has bits that indicate when valid state
is present in registers unique to AVX-512 use. Use these bits to
indicate when AVX-512 has been in use and add per-task AVX-512 state
timestamp tracking to context switch.
Well-written AVX-512 applications are expected to clear the AVX-512
state when not actively using AVX-512 registers, so the tracking
mechanism is imprecise and can theoretically miss AVX-512 usage during
context switch. But it has been measured to be precise enough to be
useful under real-world workloads like tensorflow and linpack.
If higher precision is required, suggest user space tools to use the
PMU-based mechanisms in combination.
Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
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: Tim Chen <tim.c.chen@linux.intel.com>
Cc: aubrey.li@intel.com
Link: http://lkml.kernel.org/r/20190117183822.31333-1-aubrey.li@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This was a "workaround" to probe for binutils which could generate
FXSAVEQ, apparently gas with min version 2.16. In the meantime, minimal
required gas version is 2.20 so all those workarounds for older binutils
can be dropped.
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20190117232408.GH5023@zn.tnic
Every user of user_insn() passes an user memory pointer to this macro.
Add might_fault() to user_insn() so we can spot users which are using
this macro in sections where page faulting is not allowed.
[ bp: Space it out to make it more visible. ]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm ML <kvm@vger.kernel.org>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20181128222035.2996-6-bigeasy@linutronix.de
Commit
75045f77f7 ("x86/extable: Introduce _ASM_EXTABLE_UA for uaccess fixups")
incorrectly replaced the fixup entry for XSTATE_OP with a user-#PF-only
fixup. XRSTOR can also raise #GP if the xstate content is invalid,
and _ASM_EXTABLE_UA doesn't expect that. Change this fixup back to
_ASM_EXTABLE so that #GP gets fixed up.
Fixes: 75045f77f7 ("x86/extable: Introduce _ASM_EXTABLE_UA for uaccess fixups")
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-hardening@lists.openwall.com
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20181126165957.xhsyu2dhyy45mrjo@linutronix.de
Link: https://lkml.kernel.org/r/20181127133200.38322-1-jannh@google.com
Pull locking and misc x86 updates from Ingo Molnar:
"Lots of changes in this cycle - in part because locking/core attracted
a number of related x86 low level work which was easier to handle in a
single tree:
- Linux Kernel Memory Consistency Model updates (Alan Stern, Paul E.
McKenney, Andrea Parri)
- lockdep scalability improvements and micro-optimizations (Waiman
Long)
- rwsem improvements (Waiman Long)
- spinlock micro-optimization (Matthew Wilcox)
- qspinlocks: Provide a liveness guarantee (more fairness) on x86.
(Peter Zijlstra)
- Add support for relative references in jump tables on arm64, x86
and s390 to optimize jump labels (Ard Biesheuvel, Heiko Carstens)
- Be a lot less permissive on weird (kernel address) uaccess faults
on x86: BUG() when uaccess helpers fault on kernel addresses (Jann
Horn)
- macrofy x86 asm statements to un-confuse the GCC inliner. (Nadav
Amit)
- ... and a handful of other smaller changes as well"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (57 commits)
locking/lockdep: Make global debug_locks* variables read-mostly
locking/lockdep: Fix debug_locks off performance problem
locking/pvqspinlock: Extend node size when pvqspinlock is configured
locking/qspinlock_stat: Count instances of nested lock slowpaths
locking/qspinlock, x86: Provide liveness guarantee
x86/asm: 'Simplify' GEN_*_RMWcc() macros
locking/qspinlock: Rework some comments
locking/qspinlock: Re-order code
locking/lockdep: Remove duplicated 'lock_class_ops' percpu array
x86/defconfig: Enable CONFIG_USB_XHCI_HCD=y
futex: Replace spin_is_locked() with lockdep
locking/lockdep: Make class->ops a percpu counter and move it under CONFIG_DEBUG_LOCKDEP=y
x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs
x86/cpufeature: Macrofy inline assembly code to work around GCC inlining bugs
x86/extable: Macrofy inline assembly code to work around GCC inlining bugs
x86/paravirt: Work around GCC inlining bugs when compiling paravirt ops
x86/bug: Macrofy the BUG table section handling, to work around GCC inlining bugs
x86/alternatives: Macrofy lock prefixes to work around GCC inlining bugs
x86/refcount: Work around GCC inlining bug
x86/objtool: Use asm macros to work around GCC inlining bugs
...
Booting an i486 with "no387 nofxsr" ends with with the following crash:
math_emulate: 0060:c101987d
Kernel panic - not syncing: Math emulation needed in kernel
on the first context switch in user land.
The reason is that copy_fpregs_to_fpstate() tries FNSAVE which does not work
as the FPU is turned off.
This bug was introduced in:
f1c8cd0176 ("x86/fpu: Change fpu->fpregs_active users to fpu->fpstate_active")
Add a check for X86_FEATURE_FPU before trying to save FPU registers (we
have such a check in switch_fpu_finish() already).
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Fixes: f1c8cd0176 ("x86/fpu: Change fpu->fpregs_active users to fpu->fpstate_active")
Link: http://lkml.kernel.org/r/20181016202525.29437-4-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, most fixups for attempting to access userspace memory are
handled using _ASM_EXTABLE, which is also used for various other types of
fixups (e.g. safe MSR access, IRET failures, and a bunch of other things).
In order to make it possible to add special safety checks to uaccess fixups
(in particular, checking whether the fault address is actually in
userspace), introduce a new exception table handler ex_handler_uaccess()
and wire it up to all the user access fixups (excluding ones that
already use _ASM_EXTABLE_EX).
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: dvyukov@google.com
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lkml.kernel.org/r/20180828201421.157735-5-jannh@google.com
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As per the new nomenclature we don't 'activate' the FPU state
anymore, we initialize it. So drop the _activate_fpstate name
from these functions, which were a bit of a mouthful anyway,
and name them:
fpu__prepare_read()
fpu__prepare_write()
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Eric Biggers <ebiggers3@gmail.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: Ingo Molnar <mingo@kernel.org>
Rename this function to better express that it's all about
initializing the FPU state of a task which goes hand in hand
with the fpu::initialized field.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
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/20170923130016.21448-33-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The x86 FPU code used to have a complex state machine where both the FPU
registers and the FPU state context could be 'active' (or inactive)
independently of each other - which enabled features like lazy FPU restore.
Much of this complexity is gone in the current code: now we basically can
have FPU-less tasks (kernel threads) that don't use (and save/restore) FPU
state at all, plus full FPU users that save/restore directly with no laziness
whatsoever.
But the fpu::fpstate_active still carries bits of the old complexity - meanwhile
this flag has become a simple flag that shows whether the FPU context saving
area in the thread struct is initialized and used, or not.
Rename it to fpu::initialized to express this simplicity in the name as well.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
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/20170923130016.21448-30-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Userspace can change the FPU state of a task using the ptrace() or
rt_sigreturn() system calls. Because reserved bits in the FPU state can
cause the XRSTOR instruction to fail, the kernel has to carefully
validate that no reserved bits or other invalid values are being set.
Unfortunately, there have been bugs in this validation code. For
example, we were not checking that the 'xcomp_bv' field in the
xstate_header was 0. As-is, such bugs are exploitable to read the FPU
registers of other processes on the system. To do so, an attacker can
create a task, assign to it an invalid FPU state, then spin in a loop
and monitor the values of the FPU registers. Because the task's FPU
registers are not being restored, sometimes the FPU registers will have
the values from another process.
This is likely to continue to be a problem in the future because the
validation done by the CPU instructions like XRSTOR is not immediately
visible to kernel developers. Nor will invalid FPU states ever be
encountered during ordinary use --- they will only be seen during
fuzzing or exploits. There can even be reserved bits outside the
xstate_header which are easy to forget about. For example, the MXCSR
register contains reserved bits, which were not validated by the
KVM_SET_XSAVE ioctl until commit a575813bfe ("KVM: x86: Fix load
damaged SSEx MXCSR register").
Therefore, mitigate this class of vulnerability by restoring the FPU
registers from init_fpstate if restoring from the task's state fails.
We actually used to do this, but it was (perhaps unwisely) removed by
commit 9ccc27a5d2 ("x86/fpu: Remove error return values from
copy_kernel_to_*regs() functions"). This new patch is also a bit
different. First, it only clears the registers, not also the bad
in-memory state; this is simpler and makes it easier to make the
mitigation cover all callers of __copy_kernel_to_fpregs(). Second, it
does the register clearing in an exception handler so that no extra
instructions are added to context switches. In fact, we *remove*
instructions, since previously we were always zeroing the register
containing 'err' even if CONFIG_X86_DEBUG_FPU was disabled.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Kevin Hao <haokexin@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Halcrow <mhalcrow@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: kernel-hardening@lists.openwall.com
Link: http://lkml.kernel.org/r/20170922174156.16780-4-ebiggers3@gmail.com
Link: http://lkml.kernel.org/r/20170923130016.21448-27-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
copy_xregs_to_kernel checks if the alternatives have been already
patched.
This WARN_ON() is always executed in every context switch.
All the other checks in fpu internal.h are WARN_ON_FPU(), but
this one is plain WARN_ON(). I assume it was forgotten to switch it.
So switch it to WARN_ON_FPU() too to avoid some unnecessary code
in the context switch, and a potentially expensive cache line miss for the
global variable.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
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/20170329062605.4970-1-andi@firstfloor.org
Link: http://lkml.kernel.org/r/20170923130016.21448-24-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The previous changes paved the way for the removal of the
fpu::fpregs_active state flag - we now only have the
fpu::fpstate_active and fpu::last_cpu fields left.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
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/20170923130016.21448-21-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The fpregs_activate()/fpregs_deactivate() are currently called in such a pattern:
if (!fpu->fpregs_active)
fpregs_activate(fpu);
...
if (fpu->fpregs_active)
fpregs_deactivate(fpu);
But note that it's actually safe to call them without checking the flag first.
This further decouples the fpu->fpregs_active flag from actual FPU logic.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
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/20170923130016.21448-20-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We want to simplify the FPU state machine by eliminating fpu->fpregs_active,
and we can do that because the two state flags (::fpregs_active and
::fpstate_active) are set essentially together.
The old lazy FPU switching code used to make a distinction - but there's
no lazy switching code anymore, we always switch in an 'eager' fashion.
Do this by first changing all substantial uses of fpu->fpregs_active
to fpu->fpstate_active and adding a few debug checks to double check
our assumption is correct.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
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/20170923130016.21448-19-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The fpregs_active() inline function is pretty pointless - in almost
all the callsites it can be replaced with a direct fpu->fpregs_active
access.
Do so and eliminate the extra layer of obfuscation.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
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/20170923130016.21448-16-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The host pkru is restored right after vcpu exit (commit 1be0e61), so
KVM_GET_XSAVE will return the host PKRU value instead. Fix this by
using the guest PKRU explicitly in fill_xsave and load_xsave. This
part is based on a patch by Junkang Fu.
The host PKRU data may also not match the value in vcpu->arch.guest_fpu.state,
because it could have been changed by userspace since the last time
it was saved, so skip loading it in kvm_load_guest_fpu.
Reported-by: Junkang Fu <junkang.fjk@alibaba-inc.com>
Cc: Yang Zhang <zy107165@alibaba-inc.com>
Fixes: 1be0e61c1f
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Make XSTATE init similar to existing code; move it to a separate function.
There is no functionality change.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
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: Ravi V. Shankar <ravi.v.shankar@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1485282346-15437-1-git-send-email-yu-cheng.yu@intel.com
[ Minor cleanliness edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
By moving all of the new_fpu state handling into switch_fpu_finish(),
the code can be simplified some more.
This gets rid of the prefetch, but given the size of the FPU register
state on modern CPUs, and the amount of work done by __switch_to()
inbetween both functions, the value of a single cache line prefetch
seems somewhat dubious anyway.
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Dave Hansen <dave.hansen@intel.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: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1476447331-21566-3-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The __{fpu,cpu}_invalidate_fpregs_state() functions can only be used
to invalidate a resource they control. Document that, and change
the API a little bit to reflect that.
Go back to open coding the fpu_fpregs_owner_ctx write in the CPU
hotplug code, which should be the exception, and move __kernel_fpu_begin()
to this API.
This patch has no functional changes to the current code.
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Dave Hansen <dave.hansen@intel.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: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1476447331-21566-2-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that CR0.TS is no longer being manipulated, we can simplify
switch_fpu_prepare() by no longer nesting the handling of new_fpu
inside the two branches for the old_fpu.
Signed-off-by: Rik van Riel <riel@redhat.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: Thomas Gleixner <tglx@linutronix.de>
Cc: pbonzini@redhat.com
Link: http://lkml.kernel.org/r/1475627678-20788-10-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that fpregs_activate() and fpregs_deactivate() do nothing except
call the double underscored versions of themselves, we can get
rid of the double underscore version.
Signed-off-by: Rik van Riel <riel@redhat.com>
Reviewed-by: 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: Thomas Gleixner <tglx@linutronix.de>
Cc: pbonzini@redhat.com
Link: http://lkml.kernel.org/r/1475627678-20788-9-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Name the functions after the state they track, rather than the function
they currently enable. This should make it more obvious when we use the
fpu_register_state_valid() function for something else in the future.
Signed-off-by: Rik van Riel <riel@redhat.com>
Reviewed-by: 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: Thomas Gleixner <tglx@linutronix.de>
Cc: pbonzini@redhat.com
Link: http://lkml.kernel.org/r/1475627678-20788-8-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With the lazy FPU code gone, we no longer use the counter field
in struct fpu for anything. Get rid it.
Signed-off-by: Rik van Riel <riel@redhat.com>
Reviewed-by: 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: Thomas Gleixner <tglx@linutronix.de>
Cc: pbonzini@redhat.com
Link: http://lkml.kernel.org/r/1475627678-20788-6-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since commit:
58122bf1d8 ("x86/fpu: Default eagerfpu=on on all CPUs")
... in Linux 4.6, eager FPU mode has been the default on all x86
systems, and no one has reported any regressions.
This patch removes the ability to enable lazy mode: use_eager_fpu()
becomes "return true" and all of the FPU mode selection machinery is
removed.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Rik van Riel <riel@redhat.com>
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: Thomas Gleixner <tglx@linutronix.de>
Cc: pbonzini@redhat.com
Link: http://lkml.kernel.org/r/1475627678-20788-3-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The use of config_enabled() against config options is ambiguous. In
practical terms, config_enabled() is equivalent to IS_BUILTIN(), but the
author might have used it for the meaning of IS_ENABLED(). Using
IS_ENABLED(), IS_BUILTIN(), IS_MODULE() etc. makes the intention
clearer.
This commit replaces config_enabled() with IS_ENABLED() where possible.
This commit is only touching bool config options.
I noticed two cases where config_enabled() is used against a tristate
option:
- config_enabled(CONFIG_HWMON)
[ drivers/net/wireless/ath/ath10k/thermal.c ]
- config_enabled(CONFIG_BACKLIGHT_CLASS_DEVICE)
[ drivers/gpu/drm/gma500/opregion.c ]
I did not touch them because they should be converted to IS_BUILTIN()
in order to keep the logic, but I was not sure it was the authors'
intention.
Link: http://lkml.kernel.org/r/1465215656-20569-1-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Stas Sergeev <stsp@list.ru>
Cc: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Joshua Kinard <kumba@gentoo.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: "Dmitry V. Levin" <ldv@altlinux.org>
Cc: yu-cheng yu <yu-cheng.yu@intel.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Will Drewry <wad@chromium.org>
Cc: Nikolay Martynov <mar.kolya@gmail.com>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: Rafal Milecki <zajec5@gmail.com>
Cc: James Cowgill <James.Cowgill@imgtec.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Alex Smith <alex.smith@imgtec.com>
Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Mikko Rapeli <mikko.rapeli@iki.fi>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: "Luis R. Rodriguez" <mcgrof@do-not-panic.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Tony Wu <tung7970@gmail.com>
Cc: Huaitong Han <huaitong.han@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrea Gelmini <andrea.gelmini@gelma.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Rabin Vincent <rabin@rab.in>
Cc: "Maciej W. Rozycki" <macro@imgtec.com>
Cc: David Daney <david.daney@cavium.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I've been carrying this patch around for a bit and it's helped me
solve at least a couple FPU-related bugs. In addition to using
it for debugging, I also drug it out because using AVX (and
AVX2/AVX-512) can have serious power consequences for a modern
core. It's very important to be able to figure out who is using
it.
It's also insanely useful to go out and see who is using a given
feature, like MPX or Memory Protection Keys. If you, for
instance, want to find all processes using protection keys, you
can do:
echo 'xfeatures & 0x200' > filter
Since 0x200 is the protection keys feature bit.
Note that this touches the KVM code. KVM did a CREATE_TRACE_POINTS
and then included a bunch of random headers. If anyone one of
those included other tracepoints, it would have defined the *OTHER*
tracepoints. That's bogus, so move it to the right place.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.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: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160601174220.3CDFB90E@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We want to modify the Protection Key rights inside the kernel, so
we need to change PKRU's contents. But, if we do a plain
'wrpkru', when we return to userspace we might do an XRSTOR and
wipe out the kernel's 'wrpkru'. So, we need to go after PKRU in
the xsave buffer.
We do this by:
1. Ensuring that we have the XSAVE registers (fpregs) in the
kernel FPU buffer (fpstate)
2. Looking up the location of a given state in the buffer
3. Filling in the stat
4. Ensuring that the hardware knows that state is present there
(basically that the 'init optimization' is not in place).
5. Copying the newly-modified state back to the registers if
necessary.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.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: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160212210235.5A3139BF@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Systems without an FPU are generally old and therefore use lazy FPU
switching. Unsurprisingly, math emulation in eager FPU mode is a
bit buggy. Fix it.
There were two bugs involving kernel code trying to use the FPU
registers in eager mode even if they didn't exist and one BUG_ON()
that was incorrect.
Signed-off-by: Andy Lutomirski <luto@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: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: yu-cheng yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/b4b8d112436bd6fab866e1b4011131507e8d7fbe.1453675014.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So the old one didn't work properly before alternatives had run.
And it was supposed to provide an optimized JMP because the
assumption was that the offset it is jumping to is within a
signed byte and thus a two-byte JMP.
So I did an x86_64 allyesconfig build and dumped all possible
sites where static_cpu_has() was used. The optimization amounted
to all in all 12(!) places where static_cpu_has() had generated
a 2-byte JMP. Which has saved us a whopping 36 bytes!
This clearly is not worth the trouble so we can remove it. The
only place where the optimization might count - in __switch_to()
- we will handle differently. But that's not subject of this
patch.
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1453842730-28463-6-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Move them to a separate header and have the following
dependency:
x86/cpufeatures.h <- x86/processor.h <- x86/cpufeature.h
This makes it easier to use the header in asm code and not
include the whole cpufeature.h and add guards for asm.
Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1453842730-28463-5-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This issue is a fallout from the command-line parsing move.
When "eagerfpu=off" is given as a command-line input, the kernel
should disable MPX support. The decision for turning off MPX was
made in fpu__init_system_ctx_switch(), which is after the
selection of the XSAVE format. This patch fixes it by getting
that decision done earlier in fpu__init_system_xstate().
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.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: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Ravi V. Shankar <ravi.v.shankar@intel.com>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: yu-cheng yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/1452119094-7252-4-git-send-email-yu-cheng.yu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add macros for the alternative XSAVE*/XRSTOR* operations which
contain the fault handling and use them. Kill xstate_fault().
Also, copy_xregs_to_kernel() didn't have the extended state as
memory reference in the asm.
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
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: 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>
Link: http://lkml.kernel.org/r/1447932326-4371-3-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add an XSTATE_OP() macro which contains the XSAVE* fault handling
and replace all non-alternatives users of xstate_fault() with
it.
This fixes also the buglet in copy_xregs_to_user() and
copy_user_to_xregs() where the inline asm didn't have @xstate as
memory reference and thus potentially causing unwanted
reordering of accesses to the extended state.
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
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: 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>
Link: http://lkml.kernel.org/r/1447932326-4371-2-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Make sure the WARN_ON_FPU() macro consumes the macro argument,
to avoid 'unused variable' build warnings if the only use of
a variable is in debugging code.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
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: Ingo Molnar <mingo@kernel.org>
copy_kernel_to_xregs_booting() has a second parameter that is the mask
of xfeatures that should be copied - but this parameter is always -1.
Simplify the call site of this function, this also makes it more
similar to the function call signature of other copy_kernel_to*regs()
functions.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
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: Ingo Molnar <mingo@kernel.org>
Bring the __copy_fpstate_to_fpregs() and copy_fpstate_to_fpregs() functions
in line with the parameter passing convention of other kernel-to-FPU-registers
copying functions: pass around an in-memory FPU register state pointer,
instead of struct fpu *.
NOTE: This patch also changes the assembly constraint of the FXSAVE-leak
workaround from 'fpu->fpregs_active' to 'fpstate' - but that is fine,
as we only need a valid memory address there for the FILDL instruction.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
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: Ingo Molnar <mingo@kernel.org>
None of the copy_kernel_to_*regs() FPU register copying functions are
supposed to fail, and all of them have debugging checks that enforce
this.
Remove their return values and simplify their call sites, which have
redundant error checks and error handling code paths.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
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: Ingo Molnar <mingo@kernel.org>
Bring the __copy_fpstate_to_fpregs() and copy_fpstate_to_fpregs() functions
in line with the naming of other kernel-to-FPU-registers copying functions.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
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: Ingo Molnar <mingo@kernel.org>
Copying from in-kernel FPU context buffers to FPU registers are
never supposed to fault.
Add debugging checks to copy_kernel_to_fxregs() and copy_kernel_to_fregs()
to double check this assumption.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
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: Ingo Molnar <mingo@kernel.org>
Remaining users of fpu__activate_fpstate() are all places that want to modify
FPU registers, rename the function to fpu__activate_fpstate_write() according
to this usage.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
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: Ingo Molnar <mingo@kernel.org>
Currently fpu__activate_fpstate() is used for two distinct purposes:
- read access by ptrace and core dumping, where in the core dumping
case the current task's FPU state may be examined as well.
- write access by ptrace, which modifies FPU registers and expects
the modified registers to be reloaded on the next context switch.
Split out the reading side into fpu__activate_fpstate_read().
( Note that this is just a pure duplication of fpu__activate_fpstate()
for the time being, we'll optimize the new function in the next patch. )
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
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: Ingo Molnar <mingo@kernel.org>
Bobby Powers reported the following FPU warning during ELF coredumping:
WARNING: CPU: 0 PID: 27452 at arch/x86/kernel/fpu/core.c:324 fpu__activate_stopped+0x8a/0xa0()
This warning unearthed an invalid assumption about fpu__activate_stopped()
that I added in:
67e97fc2ec ("x86/fpu: Rename init_fpu() to fpu__unlazy_stopped() and add debugging check")
the old init_fpu() function had an (intentional but obscure) side effect:
when FPU registers are accessed for the current task, for reading, then
it synchronized live in-register FPU state with the fpstate by saving it.
So fix this bug by saving the FPU if we are the current task. We'll
still warn in fpu__save() if this is called for not yet stopped
child tasks, so the debugging check is still preserved.
Also rename the function to fpu__activate_fpstate(), because it's not
exclusively used for stopped tasks, but for the current task as well.
( Note that this bug calls for a cleaner separation of access-for-read
and access-for-modification FPU methods, but we'll do that in separate
patches. )
Reported-by: Bobby Powers <bobbypowers@gmail.com>
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: Ingo Molnar <mingo@kernel.org>
The copy_xregs_to_kernel*() and copy_kernel_to_xregs*() functions are used
to copy FPU registers to kernel memory and vice versa.
They are never expected to fail, yet they have a return code, mostly because
that way they can share the assembly macros with the copy*user*() functions.
This error code is then silently ignored by the context switching
and other code - which made the bug in:
b8c1b8ea7b ("x86/fpu: Fix FPU state save area alignment bug")
harder to fix than necessary.
So remove the return values and check for no faults when FPU debugging
is enabled in the .config.
This improves the eagerfpu context switching fast path by a couple of
instructions, when FPU debugging is disabled:
ffffffff810407fa: 89 c2 mov %eax,%edx
ffffffff810407fc: 48 0f ae 2f xrstor64 (%rdi)
ffffffff81040800: 31 c0 xor %eax,%eax
-ffffffff81040802: eb 0a jmp ffffffff8104080e <__switch_to+0x321>
+ffffffff81040802: eb 16 jmp ffffffff8104081a <__switch_to+0x32d>
ffffffff81040804: 31 c0 xor %eax,%eax
ffffffff81040806: 48 0f ae 8b c0 05 00 fxrstor64 0x5c0(%rbx)
ffffffff8104080d: 00
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: Ingo Molnar <mingo@kernel.org>
There's a confusing aspect of how xstate_fault() constraints are
handled by the FPU register/memory copying functions in
fpu/internal.h: they use "0" (0) to signal that the asm code
will not always set 'err' to a valid value.
But 'err' is already initialized to 0 in C code, which is duplicated
by the asm() constraint. Should the initialization value ever be
changed, it might become subtly inconsistent with the not too clear
asm() constraint.
Use 'err' as the value of the input variable instead, to clarify
this all.
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: Ingo Molnar <mingo@kernel.org>
Sebastian Andrzej Siewior