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| author | Heiko Carstens <hca@linux.ibm.com> | 2026-05-26 07:57:01 +0200 |
|---|---|---|
| committer | Alexander Gordeev <agordeev@linux.ibm.com> | 2026-06-03 15:32:47 +0200 |
| commit | 9858c19a66386cb2553480643f2d4565993d1cd8 (patch) | |
| tree | 24483ceee1ec27829d198e20fa853a5e6367795b | |
| parent | ee8cefbfb0718bfe1460cf2ba72722c51f6789eb (diff) | |
s390/percpu: Provide arch_this_cpu_read() implementation
Provide an s390 specific implementation of arch_this_cpu_read() instead
of the generic variant. The generic variant uses preempt_disable() /
preempt_enable() pair and READ_ONCE().
Get rid of the preempt_disable() / preempt_enable() pairs 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). Also 87 generated preempt_schedule_notrace() function
calls within the kernel image (modules not counted) are 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>
| -rw-r--r-- | arch/s390/include/asm/percpu.h | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h index 5e0185e5960b..83195a5dc409 100644 --- a/arch/s390/include/asm/percpu.h +++ b/arch/s390/include/asm/percpu.h @@ -248,6 +248,37 @@ do { \ #endif /* MARCH_HAS_Z196_FEATURES */ +#define arch_this_cpu_read(pcp, op) \ +({ \ + unsigned long lc_pcpr, lc_pcpo, res__; \ + typedef typeof(pcp) pcp_op_T__; \ + pcp_op_T__ *ptr__; \ + \ + 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 " %[res__],0(%[ptr__])\n" \ + MVIY_ALT("%[disppcpr]", "%[dispaltpcpr]") \ + : [res__] "=&d" (res__), [ptr__] "+&a" (ptr__), \ + "=m" (((struct lowcore *)0)->percpu_register) \ + : [disppcpr] "i" (lc_pcpr), \ + [disppcpo] "i" (lc_pcpo), \ + [dispaltpcpr] "i" (lc_pcpr + LOWCORE_ALT_ADDRESS), \ + [dispaltpcpo] "i" (lc_pcpo + LOWCORE_ALT_ADDRESS), \ + "m" (*ptr__), \ + "m" (((struct lowcore *)0)->percpu_offset) \ + : "cc"); \ + (pcp_op_T__)res__; \ +}) + +#define this_cpu_read_1(pcp) arch_this_cpu_read(pcp, "llgc") +#define this_cpu_read_2(pcp) arch_this_cpu_read(pcp, "llgh") +#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_cmpxchg(pcp, oval, nval) \ ({ \ typedef typeof(pcp) pcp_op_T__; \ |