/*
* This is the secondary CPU boot entry. We're using this CPUs
* idle thread stack, but a set of temporary page tables.
*/
asmlinkage void secondary_start_kernel(void)
{
struct mm_struct *mm = &init_mm;
unsigned int cpu = smp_processor_id();
/*
* All kernel threads share the same mm context; grab a
* reference and switch to it.
*/
atomic_inc(&mm->mm_count);
current->active_mm = mm;
cpumask_set_cpu(cpu, mm_cpumask(mm));
set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
printk("CPU%u: Booted secondary processor\n", cpu);
/*
* TTBR0 is only used for the identity mapping at this stage. Make it
* point to zero page to avoid speculatively fetching new entries.
*/
cpu_set_reserved_ttbr0();
flush_tlb_all();
cpu_set_default_tcr_t0sz();
preempt_disable();
trace_hardirqs_off();
if (cpu_ops[cpu]->cpu_postboot)
cpu_ops[cpu]->cpu_postboot();
/*
* Log the CPU info before it is marked online and might get read.
*/
cpuinfo_store_cpu();
/*
* Enable GIC and timers.
*/
notify_cpu_starting(cpu);
smp_store_cpu_info(cpu);
/*
* OK, now it's safe to let the boot CPU continue. Wait for
* the CPU migration code to notice that the CPU is online
* before we continue.
*/
set_cpu_online(cpu, true);
complete(&cpu_running);
local_dbg_enable();
local_irq_enable();
local_async_enable();
/*
* OK, it's off to the idle thread for us
*/
cpu_startup_entry(CPUHP_ONLINE);
}
/*
* cpu_suspend
*
* arg: argument to pass to the finisher function
* fn: finisher function pointer
*
*/
int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
{
struct mm_struct *mm = current->active_mm;
int ret;
unsigned long flags;
/*
* From this point debug exceptions are disabled to prevent
* updates to mdscr register (saved and restored along with
* general purpose registers) from kernel debuggers.
*/
local_dbg_save(flags);
/*
* Function graph tracer state gets incosistent when the kernel
* calls functions that never return (aka suspend finishers) hence
* disable graph tracing during their execution.
*/
pause_graph_tracing();
/*
* mm context saved on the stack, it will be restored when
* the cpu comes out of reset through the identity mapped
* page tables, so that the thread address space is properly
* set-up on function return.
*/
ret = __cpu_suspend_enter(arg, fn);
if (ret == 0) {
/*
* We are resuming from reset with TTBR0_EL1 set to the
* idmap to enable the MMU; set the TTBR0 to the reserved
* page tables to prevent speculative TLB allocations, flush
* the local tlb and set the default tcr_el1.t0sz so that
* the TTBR0 address space set-up is properly restored.
* If the current active_mm != &init_mm we entered cpu_suspend
* with mappings in TTBR0 that must be restored, so we switch
* them back to complete the address space configuration
* restoration before returning.
*/
cpu_set_reserved_ttbr0();
flush_tlb_all();
cpu_set_default_tcr_t0sz();
if (mm != &init_mm)
cpu_switch_mm(mm->pgd, mm);
/*
* Restore per-cpu offset before any kernel
* subsystem relying on it has a chance to run.
*/
set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
/*
* Restore HW breakpoint registers to sane values
* before debug exceptions are possibly reenabled
* through local_dbg_restore.
*/
if (hw_breakpoint_restore)
hw_breakpoint_restore(NULL);
}
unpause_graph_tracing();
/*
* Restore pstate flags. OS lock and mdscr have been already
* restored, so from this point onwards, debugging is fully
* renabled if it was enabled when core started shutdown.
*/
local_dbg_restore(flags);
return ret;
}
