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

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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>
This commit is contained in:
Heiko Carstens 2026-05-26 07:56:58 +02:00 committed by Alexander Gordeev
parent b50403d4f3
commit 18ec6c5d7e
1 changed files with 43 additions and 22 deletions
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65
arch/s390/include/asm/percpu.h
View File

@ -135,28 +135,49 @@
#else /* MARCH_HAS_Z196_FEATURES */
#define arch_this_cpu_add(pcp, val, op1, op2, szcast) \
do { \
typedef typeof(pcp) pcp_op_T__; \
pcp_op_T__ val__ = (val); \
pcp_op_T__ old__, *ptr__; \
preempt_disable_notrace(); \
ptr__ = raw_cpu_ptr(&(pcp)); \
if (__builtin_constant_p(val__) && \
((szcast)val__ > -129) && ((szcast)val__ < 128)) { \
asm volatile( \
op2 " %[ptr__],%[val__]" \
: [ptr__] "+Q" (*ptr__) \
: [val__] "i" ((szcast)val__) \
: "cc"); \
} else { \
asm volatile( \
op1 " %[old__],%[val__],%[ptr__]" \
: [old__] "=d" (old__), [ptr__] "+Q" (*ptr__) \
: [val__] "d" (val__) \
: "cc"); \
} \
preempt_enable_notrace(); \
#define arch_this_cpu_add(pcp, val, op1, op2, szcast) \
do { \
unsigned long lc_pcpr, lc_pcpo; \
typedef typeof(pcp) pcp_op_T__; \
pcp_op_T__ val__ = (val); \
pcp_op_T__ old__, *ptr__; \
\
lc_pcpr = offsetof(struct lowcore, percpu_register); \
lc_pcpo = offsetof(struct lowcore, percpu_offset); \
ptr__ = PERCPU_PTR(&(pcp)); \
if (__builtin_constant_p(val__) && \
((szcast)val__ > -129) && ((szcast)val__ < 128)) { \
asm volatile( \
MVIY_PERCPU("%[disppcpr]", "%[dispaltpcpr]", "%[ptr__]")\
AG_ALT("%[disppcpo]", "%[dispaltpcpo]", "%[ptr__]") \
op2 " 0(%[ptr__]),%[val__]\n" \
MVIY_ALT("%[disppcpr]", "%[dispaltpcpr]") \
: [ptr__] "+&a" (ptr__), "+m" (*ptr__), \
"=m" (((struct lowcore *)0)->percpu_register) \
: [val__] "i" ((szcast)val__), \
[disppcpr] "i" (lc_pcpr), \
[disppcpo] "i" (lc_pcpo), \
[dispaltpcpr] "i" (lc_pcpr + LOWCORE_ALT_ADDRESS), \
[dispaltpcpo] "i" (lc_pcpo + LOWCORE_ALT_ADDRESS), \
"m" (((struct lowcore *)0)->percpu_offset) \
: "cc"); \
} else { \
asm volatile( \
MVIY_PERCPU("%[disppcpr]", "%[dispaltpcpr]", "%[ptr__]")\
AG_ALT("%[disppcpo]", "%[dispaltpcpo]", "%[ptr__]") \
op1 " %[old__],%[val__],0(%[ptr__])\n" \
MVIY_ALT("%[disppcpr]", "%[dispaltpcpr]") \
: [old__] "=&d" (old__), \
[ptr__] "+&a" (ptr__), "+m" (*ptr__), \
"=m" (((struct lowcore *)0)->percpu_register) \
: [val__] "d" (val__), \
[disppcpr] "i" (lc_pcpr), \
[disppcpo] "i" (lc_pcpo), \
[dispaltpcpr] "i" (lc_pcpr + LOWCORE_ALT_ADDRESS), \
[dispaltpcpo] "i" (lc_pcpo + LOWCORE_ALT_ADDRESS), \
"m" (((struct lowcore *)0)->percpu_offset) \
: "cc"); \
} \
} while (0)
#define this_cpu_add_4(pcp, val) arch_this_cpu_add(pcp, val, "laa", "asi", int)