1 #include <linux/ftrace.h>
2 #include <linux/percpu.h>
3 #include <linux/slab.h>
4 #include <asm/alternative.h>
5 #include <asm/cacheflush.h>
6 #include <asm/cpufeature.h>
7 #include <asm/debug-monitors.h>
8 #include <asm/pgtable.h>
9 #include <asm/memory.h>
10 #include <asm/mmu_context.h>
11 #include <asm/smp_plat.h>
12 #include <asm/suspend.h>
13 #include <asm/tlbflush.h>
15 extern int __cpu_suspend_enter(unsigned long arg, int (*fn)(unsigned long));
17 * This is called by __cpu_suspend_enter() to save the state, and do whatever
18 * flushing is required to ensure that when the CPU goes to sleep we have
19 * the necessary data available when the caches are not searched.
21 * ptr: CPU context virtual address
22 * save_ptr: address of the location where the context physical address
25 void notrace __cpu_suspend_save(struct cpu_suspend_ctx *ptr,
26 phys_addr_t *save_ptr)
28 *save_ptr = virt_to_phys(ptr);
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.
36 __flush_dcache_area(ptr, sizeof(*ptr));
37 __flush_dcache_area(save_ptr, sizeof(*save_ptr));
41 * This hook is provided so that cpu_suspend code can restore HW
42 * breakpoints as early as possible in the resume path, before reenabling
43 * debug exceptions. Code cannot be run from a CPU PM notifier since by the
44 * time the notifier runs debug exceptions might have been enabled already,
45 * with HW breakpoints registers content still in an unknown state.
47 static void (*hw_breakpoint_restore)(void *);
48 void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
50 /* Prevent multiple restore hook initializations */
51 if (WARN_ON(hw_breakpoint_restore))
53 hw_breakpoint_restore = hw_bp_restore;
59 * arg: argument to pass to the finisher function
60 * fn: finisher function pointer
63 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
65 struct mm_struct *mm = current->active_mm;
70 * From this point debug exceptions are disabled to prevent
71 * updates to mdscr register (saved and restored along with
72 * general purpose registers) from kernel debuggers.
74 local_dbg_save(flags);
77 * Function graph tracer state gets incosistent when the kernel
78 * calls functions that never return (aka suspend finishers) hence
79 * disable graph tracing during their execution.
81 pause_graph_tracing();
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.
89 ret = __cpu_suspend_enter(arg, fn);
92 * We are resuming from reset with TTBR0_EL1 set to the
93 * idmap to enable the MMU; set the TTBR0 to the reserved
94 * page tables to prevent speculative TLB allocations, flush
95 * the local tlb and set the default tcr_el1.t0sz so that
96 * the TTBR0 address space set-up is properly restored.
97 * If the current active_mm != &init_mm we entered cpu_suspend
98 * with mappings in TTBR0 that must be restored, so we switch
99 * them back to complete the address space configuration
100 * restoration before returning.
102 cpu_set_reserved_ttbr0();
103 local_flush_tlb_all();
104 cpu_set_default_tcr_t0sz();
107 cpu_switch_mm(mm->pgd, mm);
110 * Restore per-cpu offset before any kernel
111 * subsystem relying on it has a chance to run.
113 set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
116 * PSTATE was not saved over suspend/resume, re-enable any
117 * detected features that might not have been set correctly.
119 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,
123 * Restore HW breakpoint registers to sane values
124 * before debug exceptions are possibly reenabled
125 * through local_dbg_restore.
127 if (hw_breakpoint_restore)
128 hw_breakpoint_restore(NULL);
131 unpause_graph_tracing();
134 * Restore pstate flags. OS lock and mdscr have been already
135 * restored, so from this point onwards, debugging is fully
136 * renabled if it was enabled when core started shutdown.
138 local_dbg_restore(flags);
143 struct sleep_save_sp sleep_save_sp;
145 static int __init cpu_suspend_init(void)
149 /* ctx_ptr is an array of physical addresses */
150 ctx_ptr = kcalloc(mpidr_hash_size(), sizeof(phys_addr_t), GFP_KERNEL);
152 if (WARN_ON(!ctx_ptr))
155 sleep_save_sp.save_ptr_stash = ctx_ptr;
156 sleep_save_sp.save_ptr_stash_phys = virt_to_phys(ctx_ptr);
157 __flush_dcache_area(&sleep_save_sp, sizeof(struct sleep_save_sp));
161 early_initcall(cpu_suspend_init);