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// SPDX-License-Identifier: GPL-2.0
/*
* lib/smp_processor_id.c
*
* DEBUG_PREEMPT variant of smp_processor_id().
*/
#include <linux/export.h>
#include <linux/kprobes.h>
#include <linux/sched.h>
noinstr static
unsigned int check_preemption_disabled(const char *what1, const char *what2)
{
int this_cpu = raw_smp_processor_id();
if (likely(preempt_count()))
goto out;
if (irqs_disabled())
goto out;
/*
* Kernel threads bound to a single CPU can safely use
* smp_processor_id():
*/
if (current->nr_cpus_allowed == 1)
goto out;
/*
* It is valid to assume CPU-locality during early bootup:
*/
if (system_state < SYSTEM_SCHEDULING)
goto out;
/*
* Avoid recursion:
*/
preempt_disable_notrace();
instrumentation_begin();
if (!printk_ratelimit())
goto out_enable;
printk(KERN_ERR "BUG: using %s%s() in preemptible [%08x] code: %s/%d\n",
what1, what2, preempt_count() - 1, current->comm, current->pid);
printk("caller is %pS\n", __builtin_return_address(0));
dump_stack();
out_enable:
instrumentation_end();
preempt_enable_no_resched_notrace();
out:
return this_cpu;
}
noinstr unsigned int debug_smp_processor_id(void)
{
return check_preemption_disabled("smp_processor_id", "");
}
EXPORT_SYMBOL(debug_smp_processor_id);
noinstr void __this_cpu_preempt_check(const char *op)
{
check_preemption_disabled("__this_cpu_", op);
}
EXPORT_SYMBOL(__this_cpu_preempt_check);
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