diff options
author | Ingo Molnar <mingo@kernel.org> | 2017-09-23 16:00:00 +0300 |
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committer | Ingo Molnar <mingo@kernel.org> | 2017-09-24 14:04:34 +0300 |
commit | b6aa85558d7e7b18fc3470d2bc1731d2205dd275 (patch) | |
tree | 36f8fdcaa749ba225152a88e946fe9e5c19d7683 /arch/x86/kernel/fpu | |
parent | a10b6a16cdad88170f546d008c77453cddf918e6 (diff) | |
download | linux-b6aa85558d7e7b18fc3470d2bc1731d2205dd275.tar.xz |
x86/fpu: Split the state handling in fpu__drop()
Prepare fpu__drop() to use fpu->fpregs_active.
There are two distinct usecases for fpu__drop() in this context:
exit_thread() when called for 'current' in exit(), and when called
for another task in fork().
This patch does not change behavior, it only adds a couple of
debug checks and structures the code to make the ->fpregs_active
change more obviously correct.
All the complications will be removed later on.
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/20170923130016.21448-18-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/fpu')
-rw-r--r-- | arch/x86/kernel/fpu/core.c | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index b7dc3833d41a..815dfba7781a 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -414,12 +414,19 @@ void fpu__drop(struct fpu *fpu) { preempt_disable(); - if (fpu->fpregs_active) { - /* Ignore delayed exceptions from user space */ - asm volatile("1: fwait\n" - "2:\n" - _ASM_EXTABLE(1b, 2b)); - fpregs_deactivate(fpu); + if (fpu == ¤t->thread.fpu) { + WARN_ON_FPU(fpu->fpstate_active != fpu->fpregs_active); + + if (fpu->fpregs_active) { + /* Ignore delayed exceptions from user space */ + asm volatile("1: fwait\n" + "2:\n" + _ASM_EXTABLE(1b, 2b)); + if (fpu->fpregs_active) + fpregs_deactivate(fpu); + } + } else { + WARN_ON_FPU(fpu->fpregs_active); } fpu->fpstate_active = 0; |