perf/x86/core: Refactor hw->idx checks and cleanup

mainline inclusion
from mainline-v5.9-rc1
commit 027440b5
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I47H3V


CVE: NA

--------------------------------

For intel_pmu_en/disable_event(), reorder the branches checks for hw->idx
and make them sorted by probability: gp,fixed,bts,others.

Clean up the x86_assign_hw_event() by converting multiple if-else
statements to a switch statement.

To skip x86_perf_event_update() and x86_perf_event_set_period(),
it's generic to replace "idx == INTEL_PMC_IDX_FIXED_BTS" check with
'!hwc->event_base' because that should be 0 for all non-gp/fixed cases.

Wrap related bit operations into intel_set/clear_masks() and make the main
path more cleaner and readable.

No functional changes.

Signed-off-by: Like Xu <like.xu@linux.intel.com>
Original-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200613080958.132489-3-like.xu@linux.intel.com


Signed-off-by: Guoqing Jiang <jiangguoqing@kylinos.cn>
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>
Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>