perf: Remove the nmi parameter from the swevent and overflow interface

The nmi parameter indicated if we could do wakeups from the current
context, if not, we would set some state and self-IPI and let the
resulting interrupt do the wakeup.

For the various event classes:

  - hardware: nmi=0; PMI is in fact an NMI or we run irq_work_run from
    the PMI-tail (ARM etc.)
  - tracepoint: nmi=0; since tracepoint could be from NMI context.
  - software: nmi=[0,1]; some, like the schedule thing cannot
    perform wakeups, and hence need 0.

As one can see, there is very little nmi=1 usage, and the down-side of
not using it is that on some platforms some software events can have a
jiffy delay in wakeup (when arch_irq_work_raise isn't implemented).

The up-side however is that we can remove the nmi parameter and save a
bunch of conditionals in fast paths.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Michael Cree <mcree@orcon.net.nz>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Don Zickus <dzickus@redhat.com>
Link: http://lkml.kernel.org/n/tip-agjev8eu666tvknpb3iaj0fg@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
static int set_segment_reg(struct task_struct *task,
			   unsigned long offset, u16 value)
{
	/*
	 * The value argument was already truncated to 16 bits.
	 */
	if (invalid_selector(value))
		return -EIO;

	switch (offset) {
	case offsetof(struct user_regs_struct,fs):
		/*
		 * If this is setting fs as for normal 64-bit use but
		 * setting fs_base has implicitly changed it, leave it.
		 */
		if ((value == FS_TLS_SEL && task->thread.fsindex == 0 &&
		     task->thread.fs != 0) ||
		    (value == 0 && task->thread.fsindex == FS_TLS_SEL &&
		     task->thread.fs == 0))
			break;
		task->thread.fsindex = value;
		if (task == current)
			loadsegment(fs, task->thread.fsindex);
		break;
	case offsetof(struct user_regs_struct,gs):
		/*
		 * If this is setting gs as for normal 64-bit use but
		 * setting gs_base has implicitly changed it, leave it.
		 */
		if ((value == GS_TLS_SEL && task->thread.gsindex == 0 &&
		     task->thread.gs != 0) ||
		    (value == 0 && task->thread.gsindex == GS_TLS_SEL &&
		     task->thread.gs == 0))
			break;
		task->thread.gsindex = value;
		if (task == current)
			load_gs_index(task->thread.gsindex);
		break;
	case offsetof(struct user_regs_struct,ds):
		task->thread.ds = value;
		if (task == current)
			loadsegment(ds, task->thread.ds);
		break;
	case offsetof(struct user_regs_struct,es):
		task->thread.es = value;
		if (task == current)
			loadsegment(es, task->thread.es);
		break;

		/*
		 * Can't actually change these in 64-bit mode.
		 */
	case offsetof(struct user_regs_struct,cs):
		if (unlikely(value == 0))
			return -EIO;
#ifdef CONFIG_IA32_EMULATION
		if (test_tsk_thread_flag(task, TIF_IA32))
			task_pt_regs(task)->cs = value;
#endif
		break;
	case offsetof(struct user_regs_struct,ss):
		if (unlikely(value == 0))
			return -EIO;
#ifdef CONFIG_IA32_EMULATION
		if (test_tsk_thread_flag(task, TIF_IA32))
			task_pt_regs(task)->ss = value;
#endif
		break;
	}

	return 0;
}

static int set_segment_reg(struct task_struct *task,
			   unsigned long offset, u16 value)
{
	/*
	 * The value argument was already truncated to 16 bits.
	 */
	if (invalid_selector(value))
		return -EIO;

	switch (offset) {
	case offsetof(struct user_regs_struct,fs):
		/*
		 * If this is setting fs as for normal 64-bit use but
		 * setting fs_base has implicitly changed it, leave it.
		 */
		if ((value == FS_TLS_SEL && task->thread.fsindex == 0 &&
		     task->thread.fs != 0) ||
		    (value == 0 && task->thread.fsindex == FS_TLS_SEL &&
		     task->thread.fs == 0))
			break;
		task->thread.fsindex = value;
		if (task == current)
			loadsegment(fs, task->thread.fsindex);
		break;
	case offsetof(struct user_regs_struct,gs):
		/*
		 * If this is setting gs as for normal 64-bit use but
		 * setting gs_base has implicitly changed it, leave it.
		 */
		if ((value == GS_TLS_SEL && task->thread.gsindex == 0 &&
		     task->thread.gs != 0) ||
		    (value == 0 && task->thread.gsindex == GS_TLS_SEL &&
		     task->thread.gs == 0))
			break;
		task->thread.gsindex = value;
		if (task == current)
			load_gs_index(task->thread.gsindex);
		break;
	case offsetof(struct user_regs_struct,ds):
		task->thread.ds = value;
		if (task == current)
			loadsegment(ds, task->thread.ds);
		break;
	case offsetof(struct user_regs_struct,es):
		task->thread.es = value;
		if (task == current)
			loadsegment(es, task->thread.es);
		break;

		/*
		 * Can't actually change these in 64-bit mode.
		 */
	case offsetof(struct user_regs_struct,cs):
		if (unlikely(value == 0))
			return -EIO;
#ifdef CONFIG_IA32_EMULATION
		if (test_tsk_thread_flag(task, TIF_IA32))
			task_pt_regs(task)->cs = value;
#endif
		break;
	case offsetof(struct user_regs_struct,ss):
		if (unlikely(value == 0))
			return -EIO;
#ifdef CONFIG_IA32_EMULATION
		if (test_tsk_thread_flag(task, TIF_IA32))
			task_pt_regs(task)->ss = value;
#endif
		break;
	}

	return 0;
}
