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authorIngo Molnar <mingo@kernel.org>2017-09-23 16:00:00 +0300
committerIngo Molnar <mingo@kernel.org>2017-09-24 14:04:34 +0300
commitb6aa85558d7e7b18fc3470d2bc1731d2205dd275 (patch)
tree36f8fdcaa749ba225152a88e946fe9e5c19d7683 /arch/x86/kernel/fpu
parenta10b6a16cdad88170f546d008c77453cddf918e6 (diff)
downloadlinux-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.c19
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 == &current->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;