linux-toradex.git/arch/x86/kernel/i387.c, branch v3.4.55

i387: ptrace breaks the lazy-fpu-restore logic

2012-04-16T23:23:59+00:00

Starting from 7e16838d "i387: support lazy restore of FPU state"
we assume that fpu_owner_task doesn't need restore_fpu_checking()
on the context switch, its FPU state should match what we already
have in the FPU on this CPU.

However, debugger can change the tracee's FPU state, in this case
we should reset fpu.last_cpu to ensure fpu_lazy_restore() can't
return true.

Change init_fpu() to do this, it is called by user_regset->set()
methods.

Reported-by: Jan Kratochvil 
Suggested-by: Linus Torvalds 
Signed-off-by: Oleg Nesterov 
Link: http://lkml.kernel.org/r/20120416204815.GB24884@redhat.com
Cc:  v3.3
Signed-off-by: H. Peter Anvin

i387: Split up into exported and internal interfaces

2012-02-21T22:12:54+00:00

While various modules include  to get access to things we
actually *intend* for them to use, most of that header file was really
pretty low-level internal stuff that we really don't want to expose to
others.

So split the header file into two: the small exported interfaces remain
in , while the internal definitions that are only used by
core architecture code are now in .

The guiding principle for this was to expose functions that we export to
modules, and leave them in , while stuff that is used by
task switching or was marked GPL-only is in .

The fpu-internal.h file could be further split up too, especially since
arch/x86/kvm/ uses some of the remaining stuff for its module.  But that
kvm usage should probably be abstracted out a bit, and at least now the
internal FPU accessor functions are much more contained.  Even if it
isn't perhaps as contained as it _could_ be.

Signed-off-by: Linus Torvalds 
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1202211340330.5354@i5.linux-foundation.org
Signed-off-by: H. Peter Anvin

i387: Uninline the generic FP helpers that we expose to kernel modules

2012-02-21T22:12:46+00:00

Instead of exporting the very low-level internals of the FPU state
save/restore code (ie things like 'fpu_owner_task'), we should export
the higher-level interfaces.

Inlining these things is pointless anyway: sure, sometimes the end
result is small, but while 'stts()' can result in just three x86
instructions, those are not cheap instructions (writing %cr0 is a
serializing instruction and a very slow one at that).

So the overhead of a function call is not noticeable, and we really
don't want random modules mucking about with our internal state save
logic anyway.

So this unexports 'fpu_owner_task', and instead uninlines and exports
the actual functions that modules can use: fpu_kernel_begin/end() and
unlazy_fpu().

Signed-off-by: Linus Torvalds 
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1202211339590.5354@i5.linux-foundation.org
Signed-off-by: H. Peter Anvin

treewide: fix potentially dangerous trailing ';' in #defined values/expressions

2011-07-21T12:10:00+00:00

All these are instances of
  #define NAME value;
or
  #define NAME(params_opt) value;

These of course fail to build when used in contexts like
  if(foo $OP NAME)
  while(bar $OP NAME)
and may silently generate the wrong code in contexts such as
  foo = NAME + 1;    /* foo = value; + 1; */
  bar = NAME - 1;    /* bar = value; - 1; */
  baz = NAME & quux; /* baz = value; & quux; */

Reported on comp.lang.c,
Message-ID: 
Initial analysis of the dangers provided by Keith Thompson in that thread.

There are many more instances of more complicated macros having unnecessary
trailing semicolons, but this pile seems to be all of the cases of simple
values suffering from the problem. (Thus things that are likely to be found
in one of the contexts above, more complicated ones aren't.)

Signed-off-by: Phil Carmody 
Signed-off-by: Jiri Kosina

x86: Fix common misspellings

2011-03-18T09:39:30+00:00

They were generated by 'codespell' and then manually reviewed.

Signed-off-by: Lucas De Marchi 
Cc: trivial@kernel.org
LKML-Reference: <1300389856-1099-3-git-send-email-lucas.demarchi@profusion.mobi>
Signed-off-by: Ingo Molnar

KVM: Initialize fpu state in preemptible context

2011-01-12T10:02:26+00:00

init_fpu() (which is indirectly called by the fpu switching code) assumes
it is in process context.  Rather than makeing init_fpu() use an atomic
allocation, which can cause a task to be killed, make sure the fpu is
already initialized when we enter the run loop.

KVM-Stable-Tag.
Reported-and-tested-by: Kirill A. Shutemov 
Acked-by: Pekka Enberg 
Reviewed-by: Christoph Lameter 
Signed-off-by: Avi Kivity

Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2010-10-21T20:34:32+00:00

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, fpu: Merge fpu_save_init()
  x86-32, fpu: Rewrite fpu_save_init()
  x86, fpu: Remove PSHUFB_XMM5_* macros
  x86, fpu: Remove unnecessary ifdefs from i387 code.
  x86-32, fpu: Remove math_emulate stub
  x86-64, fpu: Simplify constraints for fxsave/fxtstor
  x86-64, fpu: Fix %cs value in convert_from_fxsr()
  x86-64, fpu: Disable preemption when using TS_USEDFPU
  x86, fpu: Merge __save_init_fpu()
  x86, fpu: Merge tolerant_fwait()
  x86, fpu: Merge fpu_init()
  x86: Use correct type for %cr4
  x86, xsave: Disable xsave in i387 emulation mode

Fixed up fxsaveq-induced conflict in arch/x86/include/asm/i387.h

x86, fpu: Remove unnecessary ifdefs from i387 code.

2010-09-09T21:17:18+00:00

Remove ifdefs for code that the compiler can optimize away on 64-bit.

Signed-off-by: Brian Gerst 
Acked-by: Pekka Enberg 
Cc: Suresh Siddha 
LKML-Reference: <1283563039-3466-10-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin

x86-64, fpu: Fix %cs value in convert_from_fxsr()

2010-09-09T21:16:58+00:00

While %ds still contains the userspace selector, %cs is KERNEL_CS at
this point.  Always get %cs from pt_regs even for the current task.

Signed-off-by: Brian Gerst 
Acked-by: Pekka Enberg 
Cc: Suresh Siddha 
LKML-Reference: <1283563039-3466-7-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin

x86, fpu: Merge fpu_init()

2010-09-09T21:16:20+00:00

Make fpu_init() handle 32-bit setup.

Signed-off-by: Brian Gerst 
Acked-by: Pekka Enberg 
Cc: Suresh Siddha 
LKML-Reference: <1283563039-3466-3-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin