LXR linux/arch/arm64/kernel/suspend.c

   1#include <linux/ftrace.h>
   2#include <linux/percpu.h>
   3#include <linux/slab.h>
   4#include <asm/cacheflush.h>
   5#include <asm/debug-monitors.h>
   6#include <asm/pgtable.h>
   7#include <asm/memory.h>
   8#include <asm/mmu_context.h>
   9#include <asm/smp_plat.h>
  10#include <asm/suspend.h>
  11#include <asm/tlbflush.h>
  12
  13/*
  14 * This is allocated by cpu_suspend_init(), and used to store a pointer to
  15 * the 'struct sleep_stack_data' the contains a particular CPUs state.
  16 */
  17unsigned long *sleep_save_stash;
  18
  19/*
  20 * This hook is provided so that cpu_suspend code can restore HW
  21 * breakpoints as early as possible in the resume path, before reenabling
  22 * debug exceptions. Code cannot be run from a CPU PM notifier since by the
  23 * time the notifier runs debug exceptions might have been enabled already,
  24 * with HW breakpoints registers content still in an unknown state.
  25 */
  26static void (*hw_breakpoint_restore)(void *);
  27void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
  28{
  29        /* Prevent multiple restore hook initializations */
  30        if (WARN_ON(hw_breakpoint_restore))
  31                return;
  32        hw_breakpoint_restore = hw_bp_restore;
  33}
  34
  35void notrace __cpu_suspend_exit(void)
  36{
  37        /*
  38         * We are resuming from reset with the idmap active in TTBR0_EL1.
  39         * We must uninstall the idmap and restore the expected MMU
  40         * state before we can possibly return to userspace.
  41         */
  42        cpu_uninstall_idmap();
  43
  44        /*
  45         * Restore per-cpu offset before any kernel
  46         * subsystem relying on it has a chance to run.
  47         */
  48        set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
  49
  50        /*
  51         * Restore HW breakpoint registers to sane values
  52         * before debug exceptions are possibly reenabled
  53         * through local_dbg_restore.
  54         */
  55        if (hw_breakpoint_restore)
  56                hw_breakpoint_restore(NULL);
  57}
  58
  59/*
  60 * cpu_suspend
  61 *
  62 * arg: argument to pass to the finisher function
  63 * fn: finisher function pointer
  64 *
  65 */
  66int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
  67{
  68        int ret = 0;
  69        unsigned long flags;
  70        struct sleep_stack_data state;
  71
  72        /*
  73         * From this point debug exceptions are disabled to prevent
  74         * updates to mdscr register (saved and restored along with
  75         * general purpose registers) from kernel debuggers.
  76         */
  77        local_dbg_save(flags);
  78
  79        /*
  80         * Function graph tracer state gets incosistent when the kernel
  81         * calls functions that never return (aka suspend finishers) hence
  82         * disable graph tracing during their execution.
  83         */
  84        pause_graph_tracing();
  85
  86        if (__cpu_suspend_enter(&state)) {
  87                /* Call the suspend finisher */
  88                ret = fn(arg);
  89
  90                /*
  91                 * Never gets here, unless the suspend finisher fails.
  92                 * Successful cpu_suspend() should return from cpu_resume(),
  93                 * returning through this code path is considered an error
  94                 * If the return value is set to 0 force ret = -EOPNOTSUPP
  95                 * to make sure a proper error condition is propagated
  96                 */
  97                if (!ret)
  98                        ret = -EOPNOTSUPP;
  99        } else {
 100                __cpu_suspend_exit();
 101        }
 102
 103        unpause_graph_tracing();
 104
 105        /*
 106         * Restore pstate flags. OS lock and mdscr have been already
 107         * restored, so from this point onwards, debugging is fully
 108         * renabled if it was enabled when core started shutdown.
 109         */
 110        local_dbg_restore(flags);
 111
 112        return ret;
 113}
 114
 115static int __init cpu_suspend_init(void)
 116{
 117        /* ctx_ptr is an array of physical addresses */
 118        sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash),
 119                                   GFP_KERNEL);
 120
 121        if (WARN_ON(!sleep_save_stash))
 122                return -ENOMEM;
 123
 124        return 0;
 125}
 126early_initcall(cpu_suspend_init);
 127