Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip (625037cc) · Commits · e / devices / android_kernel_oneplus_sm7250

arch/x86/include/asm/i387.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -26,6 +26,7 @@ extern void fpu_init(void);
		extern void mxcsr_feature_mask_init(void);
		extern int init_fpu(struct task_struct *child);
		extern asmlinkage void math_state_restore(void);
		extern void __math_state_restore(void);
		extern void init_thread_xstate(void);
		extern int dump_fpu(struct pt_regs , struct user_i387_struct );

arch/x86/kernel/process_32.c

+16 −11

Original line number	Diff line number	Diff line
		@@ -350,14 +350,21 @@ __switch_to(struct task_struct prev_p, struct task_struct next_p)
		*next = &next_p->thread;
		int cpu = smp_processor_id();
		struct tss_struct *tss = &per_cpu(init_tss, cpu);
		bool preload_fpu;

		/* never put a printk in __switch_to... printk() calls wake_up() indirectly /

		__unlazy_fpu(prev_p);
		/*
		* If the task has used fpu the last 5 timeslices, just do a full
		* restore of the math state immediately to avoid the trap; the
		* chances of needing FPU soon are obviously high now
		*/
		preload_fpu = tsk_used_math(next_p) && next_p->fpu_counter > 5;

		__unlazy_fpu(prev_p);

		/* we're going to use this soon, after a few expensive things */
		if (next_p->fpu_counter > 5)
		if (preload_fpu)
		prefetch(next->xstate);

		/*
		@@ -398,6 +405,11 @@ __switch_to(struct task_struct prev_p, struct task_struct next_p)
		task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
		__switch_to_xtra(prev_p, next_p, tss);

		/* If we're going to preload the fpu context, make sure clts
		is run while we're batching the cpu state updates. */
		if (preload_fpu)
		clts();

		/*
		* Leave lazy mode, flushing any hypercalls made here.
		* This must be done before restoring TLS segments so
		@@ -407,15 +419,8 @@ __switch_to(struct task_struct prev_p, struct task_struct next_p)
		*/
		arch_end_context_switch(next_p);

		/* If the task has used fpu the last 5 timeslices, just do a full
		* restore of the math state immediately to avoid the trap; the
		* chances of needing FPU soon are obviously high now
		*
		* tsk_used_math() checks prevent calling math_state_restore(),
		* which can sleep in the case of !tsk_used_math()
		*/
		if (tsk_used_math(next_p) && next_p->fpu_counter > 5)
		math_state_restore();
		if (preload_fpu)
		__math_state_restore();

		/*
		* Restore %gs if needed (which is common)

arch/x86/kernel/process_64.c

+21 −12

Original line number	Diff line number	Diff line
		@@ -386,9 +386,17 @@ __switch_to(struct task_struct prev_p, struct task_struct next_p)
		int cpu = smp_processor_id();
		struct tss_struct *tss = &per_cpu(init_tss, cpu);
		unsigned fsindex, gsindex;
		bool preload_fpu;

		/*
		* If the task has used fpu the last 5 timeslices, just do a full
		* restore of the math state immediately to avoid the trap; the
		* chances of needing FPU soon are obviously high now
		*/
		preload_fpu = tsk_used_math(next_p) && next_p->fpu_counter > 5;

		/* we're going to use this soon, after a few expensive things */
		if (next_p->fpu_counter > 5)
		if (preload_fpu)
		prefetch(next->xstate);

		/*
		@@ -419,6 +427,13 @@ __switch_to(struct task_struct prev_p, struct task_struct next_p)

		load_TLS(next, cpu);

		/* Must be after DS reload */
		unlazy_fpu(prev_p);

		/* Make sure cpu is ready for new context */
		if (preload_fpu)
		clts();

		/*
		* Leave lazy mode, flushing any hypercalls made here.
		* This must be done before restoring TLS segments so
		@@ -459,9 +474,6 @@ __switch_to(struct task_struct prev_p, struct task_struct next_p)
		wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
		prev->gsindex = gsindex;

		/* Must be after DS reload */
		unlazy_fpu(prev_p);

		/*
		* Switch the PDA and FPU contexts.
		*/
		@@ -480,15 +492,12 @@ __switch_to(struct task_struct prev_p, struct task_struct next_p)
		task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV))
		__switch_to_xtra(prev_p, next_p, tss);

		/* If the task has used fpu the last 5 timeslices, just do a full
		* restore of the math state immediately to avoid the trap; the
		* chances of needing FPU soon are obviously high now
		*
		* tsk_used_math() checks prevent calling math_state_restore(),
		* which can sleep in the case of !tsk_used_math()
		/*
		* Preload the FPU context, now that we've determined that the
		* task is likely to be using it.
		*/
		if (tsk_used_math(next_p) && next_p->fpu_counter > 5)
		math_state_restore();
		if (preload_fpu)
		__math_state_restore();
		return prev_p;
		}

arch/x86/kernel/traps.c

+23 −10

Original line number	Diff line number	Diff line
		@@ -794,6 +794,28 @@ asmlinkage void __attribute__((weak)) smp_threshold_interrupt(void)
		{
		}

		/*
		* __math_state_restore assumes that cr0.TS is already clear and the
		* fpu state is all ready for use. Used during context switch.
		*/
		void __math_state_restore(void)
		{
		struct thread_info *thread = current_thread_info();
		struct task_struct *tsk = thread->task;

		/*
		* Paranoid restore. send a SIGSEGV if we fail to restore the state.
		*/
		if (unlikely(restore_fpu_checking(tsk))) {
		stts();
		force_sig(SIGSEGV, tsk);
		return;
		}

		thread->status \|= TS_USEDFPU; /* So we fnsave on switch_to() */
		tsk->fpu_counter++;
		}

		/*
		* 'math_state_restore()' saves the current math information in the
		* old math state array, and gets the new ones from the current task
		@@ -825,17 +847,8 @@ asmlinkage void math_state_restore(void)
		}

		clts(); /* Allow maths ops (or we recurse) */
		/*
		* Paranoid restore. send a SIGSEGV if we fail to restore the state.
		*/
		if (unlikely(restore_fpu_checking(tsk))) {
		stts();
		force_sig(SIGSEGV, tsk);
		return;
		}

		thread->status \|= TS_USEDFPU; /* So we fnsave on switch_to() */
		tsk->fpu_counter++;
		__math_state_restore();
		}
		EXPORT_SYMBOL_GPL(math_state_restore);