s390/percpu: Use new percpu code section for arch_this_cpu_add()

s390/percpu: Use new percpu code section for arch_this_cpu_add()

Convert arch_this_cpu_add() to make use of the new percpu code section
infrastructure.

With this the text size of the kernel image is reduced by ~76kb
(defconfig). Also more than 5300 generated preempt_schedule_notrace()
function calls within the kernel image (modules not counted) are removed.

With:

DEFINE_PER_CPU(long, foo);
void bar(long a) { this_cpu_add(foo, a); }

Old arch_this_cpu_add() looks like this:

00000000000000c0 <bar>:
  c0:   c0 04 00 00 00 00       jgnop   c0 <bar>
  c6:   eb 01 03 a8 00 6a       asi     936,1
  cc:   c4 18 00 00 00 00       lgrl    %r1,cc <bar+0xc>
                        ce: R_390_GOTENT        foo+0x2
  d2:   e3 10 03 b8 00 08       ag      %r1,952
  d8:   eb 22 10 00 00 e8       laag    %r2,%r2,0(%r1)
  de:   eb ff 03 a8 00 6e       alsi    936,-1
  e4:   a7 a4 00 05             jhe     ee <bar+0x2e>
  e8:   c0 f4 00 00 00 00       jg      e8 <bar+0x28>
                        ea: R_390_PC32DBL       __s390_indirect_jump_r14+0x2
  ee:   c0 f4 00 00 00 00       jg      ee <bar+0x2e>
                        f0: R_390_PLT32DBL      preempt_schedule_notrace+0x2

New arch_this_cpu_add() looks like this:

00000000000000c0 <bar>:
  c0:   c0 04 00 00 00 00       jgnop   c0 <bar>
  c6:   c4 38 00 00 00 00       lgrl    %r3,c6 <bar+0x6>
                        c8: R_390_GOTENT        foo+0x2
  cc:   b9 04 00 43             lgr     %r4,%r3
  d0:   eb 00 43 c0 00 52       mviy    960(%r0),4
  d6:   e3 40 03 b8 00 08       ag      %r4,952
  dc:   eb 52 40 00 00 e8       laag    %r5,%r2,0(%r4)
  e2:   eb 00 03 c0 00 52       mviy    960,0
  e8:   c0 f4 00 00 00 00       jg      e8 <bar+0x28>
                        ea: R_390_PC32DBL       __s390_indirect_jump_r14+0x2

Note that the conditional function call is removed.

Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>