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s390/percpu: Provide arch_this_cpu_write() implementation

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Provide an s390 specific implementation of arch_this_cpu_write()
instead of the generic variant. The generic variant uses a quite
expensive raw_local_irq_save() / raw_local_irq_restore() pair.

Get rid of this by providing an own variant which makes use of the new
percpu code section infrastructure.

With this the text size of the kernel image is reduced by ~1k (defconfig).

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 07:57:02 +02:00 committed by Alexander Gordeev
parent 9858c19a66
commit 4a9d66c670
1 changed files with 30 additions and 0 deletions
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30
arch/s390/include/asm/percpu.h
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@ -279,6 +279,36 @@ do { \
#define this_cpu_read_4(pcp) arch_this_cpu_read(pcp, "llgf")
#define this_cpu_read_8(pcp) arch_this_cpu_read(pcp, "lg")
#define arch_this_cpu_write(pcp, val, op) \
do { \
unsigned long lc_pcpr, lc_pcpo; \
typedef typeof(pcp) pcp_op_T__; \
pcp_op_T__ *ptr__, val__ = (val); \
\
lc_pcpr = offsetof(struct lowcore, percpu_register); \
lc_pcpo = offsetof(struct lowcore, percpu_offset); \
ptr__ = PERCPU_PTR(&(pcp)); \
asm_inline volatile( \
MVIY_PERCPU("%[disppcpr]", "%[dispaltpcpr]", "%[ptr__]")\
AG_ALT("%[disppcpo]", "%[dispaltpcpo]", "%[ptr__]") \
op " %[val__],0(%[ptr__])\n" \
MVIY_ALT("%[disppcpr]", "%[dispaltpcpr]") \
: [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_write_1(pcp, val) arch_this_cpu_write(pcp, val, "stc")
#define this_cpu_write_2(pcp, val) arch_this_cpu_write(pcp, val, "sth")
#define this_cpu_write_4(pcp, val) arch_this_cpu_write(pcp, val, "st")
#define this_cpu_write_8(pcp, val) arch_this_cpu_write(pcp, val, "stg")
#define arch_this_cpu_cmpxchg(pcp, oval, nval) \
({ \
typedef typeof(pcp) pcp_op_T__; \