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
13extern int __cpu_suspend_enter(unsigned long arg, int (*fn)(unsigned long));
14/*
15 * This is called by __cpu_suspend_enter() to save the state, and do whatever
16 * flushing is required to ensure that when the CPU goes to sleep we have
17 * the necessary data available when the caches are not searched.
18 *
19 * ptr: CPU context virtual address
20 * save_ptr: address of the location where the context physical address
21 *           must be saved
22 */
23void notrace __cpu_suspend_save(struct cpu_suspend_ctx *ptr,
24				phys_addr_t *save_ptr)
25{
26	*save_ptr = virt_to_phys(ptr);
27
28	cpu_do_suspend(ptr);
29	/*
30	 * Only flush the context that must be retrieved with the MMU
31	 * off. VA primitives ensure the flush is applied to all
32	 * cache levels so context is pushed to DRAM.
33	 */
34	__flush_dcache_area(ptr, sizeof(*ptr));
35	__flush_dcache_area(save_ptr, sizeof(*save_ptr));
36}
37
38/*
39 * This hook is provided so that cpu_suspend code can restore HW
40 * breakpoints as early as possible in the resume path, before reenabling
41 * debug exceptions. Code cannot be run from a CPU PM notifier since by the
42 * time the notifier runs debug exceptions might have been enabled already,
43 * with HW breakpoints registers content still in an unknown state.
44 */
45static void (*hw_breakpoint_restore)(void *);
46void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
47{
48	/* Prevent multiple restore hook initializations */
49	if (WARN_ON(hw_breakpoint_restore))
50		return;
51	hw_breakpoint_restore = hw_bp_restore;
52}
53
54/*
55 * cpu_suspend
56 *
57 * arg: argument to pass to the finisher function
58 * fn: finisher function pointer
59 *
60 */
61int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
62{
63	struct mm_struct *mm = current->active_mm;
64	int ret;
65	unsigned long flags;
66
67	/*
68	 * From this point debug exceptions are disabled to prevent
69	 * updates to mdscr register (saved and restored along with
70	 * general purpose registers) from kernel debuggers.
71	 */
72	local_dbg_save(flags);
73
74	/*
75	 * Function graph tracer state gets incosistent when the kernel
76	 * calls functions that never return (aka suspend finishers) hence
77	 * disable graph tracing during their execution.
78	 */
79	pause_graph_tracing();
80
81	/*
82	 * mm context saved on the stack, it will be restored when
83	 * the cpu comes out of reset through the identity mapped
84	 * page tables, so that the thread address space is properly
85	 * set-up on function return.
86	 */
87	ret = __cpu_suspend_enter(arg, fn);
88	if (ret == 0) {
89		/*
90		 * We are resuming from reset with TTBR0_EL1 set to the
91		 * idmap to enable the MMU; set the TTBR0 to the reserved
92		 * page tables to prevent speculative TLB allocations, flush
93		 * the local tlb and set the default tcr_el1.t0sz so that
94		 * the TTBR0 address space set-up is properly restored.
95		 * If the current active_mm != &init_mm we entered cpu_suspend
96		 * with mappings in TTBR0 that must be restored, so we switch
97		 * them back to complete the address space configuration
98		 * restoration before returning.
99		 */
100		cpu_set_reserved_ttbr0();
101		local_flush_tlb_all();
102		cpu_set_default_tcr_t0sz();
103
104		if (mm != &init_mm)
105			cpu_switch_mm(mm->pgd, mm);
106
107		/*
108		 * Restore per-cpu offset before any kernel
109		 * subsystem relying on it has a chance to run.
110		 */
111		set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
112
113		/*
114		 * Restore HW breakpoint registers to sane values
115		 * before debug exceptions are possibly reenabled
116		 * through local_dbg_restore.
117		 */
118		if (hw_breakpoint_restore)
119			hw_breakpoint_restore(NULL);
120	}
121
122	unpause_graph_tracing();
123
124	/*
125	 * Restore pstate flags. OS lock and mdscr have been already
126	 * restored, so from this point onwards, debugging is fully
127	 * renabled if it was enabled when core started shutdown.
128	 */
129	local_dbg_restore(flags);
130
131	return ret;
132}
133
134struct sleep_save_sp sleep_save_sp;
135
136static int __init cpu_suspend_init(void)
137{
138	void *ctx_ptr;
139
140	/* ctx_ptr is an array of physical addresses */
141	ctx_ptr = kcalloc(mpidr_hash_size(), sizeof(phys_addr_t), GFP_KERNEL);
142
143	if (WARN_ON(!ctx_ptr))
144		return -ENOMEM;
145
146	sleep_save_sp.save_ptr_stash = ctx_ptr;
147	sleep_save_sp.save_ptr_stash_phys = virt_to_phys(ctx_ptr);
148	__flush_dcache_area(&sleep_save_sp, sizeof(struct sleep_save_sp));
149
150	return 0;
151}
152early_initcall(cpu_suspend_init);
153