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 */ 17 unsigned 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 */ 26 static void (*hw_breakpoint_restore)(void *); 27 void __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 35 void 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 */ 66 int 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 } 114 115 static 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 } 126 early_initcall(cpu_suspend_init); 127