arch/arm64/kernel/suspend.c

   1 #include <linux/percpu.h>
   2 #include <linux/slab.h>
   3 #include <asm/cacheflush.h>
   4 #include <asm/cpu_ops.h>
   5 #include <asm/debug-monitors.h>
   6 #include <asm/pgtable.h>
   7 #include <asm/memory.h>
   8 #include <asm/smp_plat.h>
   9 #include <asm/suspend.h>
  10 #include <asm/tlbflush.h>
  11
  12 extern int __cpu_suspend(unsigned long);
  13 /*
  14  * This is called by __cpu_suspend() to save the state, and do whatever
  15  * flushing is required to ensure that when the CPU goes to sleep we have
  16  * the necessary data available when the caches are not searched.
  17  *
  18  * @arg: Argument to pass to suspend operations
  19  * @ptr: CPU context virtual address
  20  * @save_ptr: address of the location where the context physical address
  21  *            must be saved
  22  */
  23 int __cpu_suspend_finisher(unsigned long arg, struct cpu_suspend_ctx *ptr,
  24                            phys_addr_t *save_ptr)
  25 {
  26         int cpu = smp_processor_id();
  27
  28         *save_ptr = virt_to_phys(ptr);
  29
  30         cpu_do_suspend(ptr);
  31         /*
  32          * Only flush the context that must be retrieved with the MMU
  33          * off. VA primitives ensure the flush is applied to all
  34          * cache levels so context is pushed to DRAM.
  35          */
  36         __flush_dcache_area(ptr, sizeof(*ptr));
  37         __flush_dcache_area(save_ptr, sizeof(*save_ptr));
  38
  39         return cpu_ops[cpu]->cpu_suspend(arg);
  40 }
  41
  42 /*
  43  * This hook is provided so that cpu_suspend code can restore HW
  44  * breakpoints as early as possible in the resume path, before reenabling
  45  * debug exceptions. Code cannot be run from a CPU PM notifier since by the
  46  * time the notifier runs debug exceptions might have been enabled already,
  47  * with HW breakpoints registers content still in an unknown state.
  48  */
  49 void (*hw_breakpoint_restore)(void *);
  50 void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
  51 {
  52         /* Prevent multiple restore hook initializations */
  53         if (WARN_ON(hw_breakpoint_restore))
  54                 return;
  55         hw_breakpoint_restore = hw_bp_restore;
  56 }
  57
  58 /**
  59  * cpu_suspend
  60  *
  61  * @arg: argument to pass to the finisher function
  62  */
  63 int cpu_suspend(unsigned long arg)
  64 {
  65         struct mm_struct *mm = current->active_mm;
  66         int ret, cpu = smp_processor_id();
  67         unsigned long flags;
  68
  69         /*
  70          * If cpu_ops have not been registered or suspend
  71          * has not been initialized, cpu_suspend call fails early.
  72          */
  73         if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_suspend)
  74                 return -EOPNOTSUPP;
  75
  76         /*
  77          * From this point debug exceptions are disabled to prevent
  78          * updates to mdscr register (saved and restored along with
  79          * general purpose registers) from kernel debuggers.
  80          */
  81         local_dbg_save(flags);
  82
  83         /*
  84          * mm context saved on the stack, it will be restored when
  85          * the cpu comes out of reset through the identity mapped
  86          * page tables, so that the thread address space is properly
  87          * set-up on function return.
  88          */
  89         ret = __cpu_suspend(arg);
  90         if (ret == 0) {
  91                 cpu_switch_mm(mm->pgd, mm);
  92                 flush_tlb_all();
  93
  94                 /*
  95                  * Restore per-cpu offset before any kernel
  96                  * subsystem relying on it has a chance to run.
  97                  */
  98                 set_my_cpu_offset(per_cpu_offset(cpu));
  99
 100                 /*
 101                  * Restore HW breakpoint registers to sane values
 102                  * before debug exceptions are possibly reenabled
 103                  * through local_dbg_restore.
 104                  */
 105                 if (hw_breakpoint_restore)
 106                         hw_breakpoint_restore(NULL);
 107         }
 108
 109         /*
 110          * Restore pstate flags. OS lock and mdscr have been already
 111          * restored, so from this point onwards, debugging is fully
 112          * renabled if it was enabled when core started shutdown.
 113          */
 114         local_dbg_restore(flags);
 115
 116         return ret;
 117 }
 118
 119 extern struct sleep_save_sp sleep_save_sp;
 120 extern phys_addr_t sleep_idmap_phys;
 121
 122 static int cpu_suspend_init(void)
 123 {
 124         void *ctx_ptr;
 125
 126         /* ctx_ptr is an array of physical addresses */
 127         ctx_ptr = kcalloc(mpidr_hash_size(), sizeof(phys_addr_t), GFP_KERNEL);
 128
 129         if (WARN_ON(!ctx_ptr))
 130                 return -ENOMEM;
 131
 132         sleep_save_sp.save_ptr_stash = ctx_ptr;
 133         sleep_save_sp.save_ptr_stash_phys = virt_to_phys(ctx_ptr);
 134         sleep_idmap_phys = virt_to_phys(idmap_pg_dir);
 135         __flush_dcache_area(&sleep_save_sp, sizeof(struct sleep_save_sp));
 136         __flush_dcache_area(&sleep_idmap_phys, sizeof(sleep_idmap_phys));
 137
 138         return 0;
 139 }
 140 early_initcall(cpu_suspend_init);