aboutsummaryrefslogtreecommitdiff
path: root/arch/arm64/kernel/suspend.c
blob: 40f7b33a22dafce27c3491d181170760916aec04 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
#include <linux/percpu.h>
#include <linux/slab.h>
#include <asm/cacheflush.h>
#include <asm/debug-monitors.h>
#include <asm/pgtable.h>
#include <asm/memory.h>
#include <asm/mmu_context.h>
#include <asm/smp_plat.h>
#include <asm/suspend.h>
#include <asm/tlbflush.h>

extern int __cpu_suspend_enter(unsigned long arg, int (*fn)(unsigned long));
/*
 * This is called by __cpu_suspend_enter() to save the state, and do whatever
 * flushing is required to ensure that when the CPU goes to sleep we have
 * the necessary data available when the caches are not searched.
 *
 * ptr: CPU context virtual address
 * save_ptr: address of the location where the context physical address
 *           must be saved
 */
void notrace __cpu_suspend_save(struct cpu_suspend_ctx *ptr,
				phys_addr_t *save_ptr)
{
	*save_ptr = virt_to_phys(ptr);

	cpu_do_suspend(ptr);
	/*
	 * Only flush the context that must be retrieved with the MMU
	 * off. VA primitives ensure the flush is applied to all
	 * cache levels so context is pushed to DRAM.
	 */
	__flush_dcache_area(ptr, sizeof(*ptr));
	__flush_dcache_area(save_ptr, sizeof(*save_ptr));
}

/*
 * This hook is provided so that cpu_suspend code can restore HW
 * breakpoints as early as possible in the resume path, before reenabling
 * debug exceptions. Code cannot be run from a CPU PM notifier since by the
 * time the notifier runs debug exceptions might have been enabled already,
 * with HW breakpoints registers content still in an unknown state.
 */
void (*hw_breakpoint_restore)(void *);
void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
{
	/* Prevent multiple restore hook initializations */
	if (WARN_ON(hw_breakpoint_restore))
		return;
	hw_breakpoint_restore = hw_bp_restore;
}

/*
 * 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);

	/*
	 * 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();
		local_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);
	}

	/*
	 * 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;
}

struct sleep_save_sp sleep_save_sp;

static int __init cpu_suspend_init(void)
{
	void *ctx_ptr;

	/* ctx_ptr is an array of physical addresses */
	ctx_ptr = kcalloc(mpidr_hash_size(), sizeof(phys_addr_t), GFP_KERNEL);

	if (WARN_ON(!ctx_ptr))
		return -ENOMEM;

	sleep_save_sp.save_ptr_stash = ctx_ptr;
	sleep_save_sp.save_ptr_stash_phys = virt_to_phys(ctx_ptr);
	__flush_dcache_area(&sleep_save_sp, sizeof(struct sleep_save_sp));

	return 0;
}
early_initcall(cpu_suspend_init);