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s390: introduce text_poke_sync()
Introduce a text_poke_sync() similar to what x86 has. This can be used to execute a serializing instruction on all CPUs (including the current one). Note: according to the Principles of Operation an IPI (= interrupt) will already serialize a CPU, however it is better to be explicit. In addition on_each_cpu() makes sure that also the current CPU get serialized - just to make sure that possible preemption can prevent some theoretical case where a CPU will not be serialized. Therefore text_poke_sync() has to be used whenever code got modified, just to avoid to rely on implicit serialization. Also introduce text_poke_sync_lock() which will also disable CPU hotplug, to prevent that any CPU is just going online with a prefetched old version of a modified instruction. Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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arch/s390/include/asm/text-patching.h
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16
arch/s390/include/asm/text-patching.h
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@ -0,0 +1,16 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_S390_TEXT_PATCHING_H
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#define _ASM_S390_TEXT_PATCHING_H
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#include <asm/barrier.h>
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static __always_inline void sync_core(void)
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{
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bcr_serialize();
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}
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void text_poke_sync(void);
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void text_poke_sync_lock(void);
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#endif /* _ASM_S390_TEXT_PATCHING_H */
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@ -1,5 +1,8 @@
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/module.h>
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#include <linux/cpu.h>
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#include <linux/smp.h>
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#include <asm/text-patching.h>
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#include <asm/alternative.h>
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#include <asm/facility.h>
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#include <asm/nospec-branch.h>
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@ -110,3 +113,20 @@ void __init apply_alternative_instructions(void)
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{
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apply_alternatives(__alt_instructions, __alt_instructions_end);
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}
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static void do_sync_core(void *info)
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{
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sync_core();
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}
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void text_poke_sync(void)
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{
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on_each_cpu(do_sync_core, NULL, 1);
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}
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void text_poke_sync_lock(void)
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{
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cpus_read_lock();
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text_poke_sync();
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cpus_read_unlock();
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}
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