linux/arch/x86
Oleg Nesterov 33a3ebdc07 x86, fpu: Don't abuse has_fpu in __kernel_fpu_begin/end()
Now that we have in_kernel_fpu we can remove __thread_clear_has_fpu()
in __kernel_fpu_begin(). And this allows to replace the asymmetrical
and nontrivial use_eager_fpu + tsk_used_math check in kernel_fpu_end()
with the same __thread_has_fpu() check.

The logic becomes really simple; if _begin() does save() then _end()
needs restore(), this is controlled by __thread_has_fpu(). Otherwise
they do clts/stts unless use_eager_fpu().

Not only this makes begin/end symmetrical and imo more understandable,
potentially this allows to change irq_fpu_usable() to avoid all other
checks except "in_kernel_fpu".

Also, with this patch __kernel_fpu_end() does restore_fpu_checking()
and WARNs if it fails instead of math_state_restore(). I think this
looks better because we no longer need __thread_fpu_begin(), and it
would be better to report the failure in this case.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: matt.fleming@intel.com
Cc: bp@suse.de
Cc: pbonzini@redhat.com
Cc: luto@amacapital.net
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Link: http://lkml.kernel.org/r/20150115192005.GC27332@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-01-20 13:53:07 +01:00
..
boot Merge branch 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 12:42:16 -08:00
configs x86/kconfig/defconfig: Enable CONFIG_FHANDLE=y 2014-12-08 12:04:17 +01:00
crypto crypto: sha - replace memset by memzero_explicit 2014-12-02 22:55:49 +08:00
ia32 x86: hook up execveat system call 2014-12-13 12:42:51 -08:00
include x86, fpu: Introduce per-cpu in_kernel_fpu state 2015-01-20 13:53:07 +01:00
kernel x86, fpu: Don't abuse has_fpu in __kernel_fpu_begin/end() 2015-01-20 13:53:07 +01:00
kvm 3.19 changes for KVM: 2014-12-18 16:05:28 -08:00
lguest x86: Avoid building unused IRQ entry stubs 2014-12-16 14:08:14 +01:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-12-11 14:27:06 -08:00
math-emu
mm kernel: Provide READ_ONCE and ASSIGN_ONCE 2014-12-20 16:48:59 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-12-10 15:48:20 -05:00
oprofile percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t 2014-08-28 08:58:57 -04:00
pci Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-19 14:02:02 -08:00
platform Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-19 14:02:02 -08:00
power nosave: consolidate __nosave_{begin,end} in <asm/sections.h> 2014-10-09 22:26:04 -04:00
purgatory Merge branches 'x86-build-for-linus', 'x86-cleanups-for-linus' and 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 12:35:46 -08:00
realmode
syscalls x86: hook up execveat system call 2014-12-13 12:42:51 -08:00
tools Merge branch 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 12:10:24 -08:00
um Merge branch 'akpm' (second patch-bomb from Andrew) 2014-12-13 13:00:36 -08:00
vdso x86,vdso: Use LSL unconditionally for vgetcpu 2014-11-03 13:41:53 +01:00
video
xen xen: additional features for 3.19-rc0 2014-12-16 13:23:03 -08:00
.gitignore x86/build: Add arch/x86/purgatory/ make generated files to gitignore 2014-10-09 09:29:46 +02:00
Kbuild kexec: create a new config option CONFIG_KEXEC_FILE for new syscall 2014-08-29 16:28:16 -07:00
Kconfig Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-19 14:02:02 -08:00
Kconfig.cpu
Kconfig.debug
Makefile Merge branch 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 18:17:33 +02:00
Makefile_32.cpu
Makefile.um