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 int (*hw_breakpoint_restore)(unsigned int); 27 void __init cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int)) 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 unsigned int cpu = smp_processor_id(); 38 39 /* 40 * We are resuming from reset with the idmap active in TTBR0_EL1. 41 * We must uninstall the idmap and restore the expected MMU 42 * state before we can possibly return to userspace. 43 */ 44 cpu_uninstall_idmap(); 45 46 /* 47 * Restore per-cpu offset before any kernel 48 * subsystem relying on it has a chance to run. 49 */ 50 set_my_cpu_offset(per_cpu_offset(cpu)); 51 52 /* 53 * Restore HW breakpoint registers to sane values 54 * before debug exceptions are possibly reenabled 55 * through local_dbg_restore. 56 */ 57 if (hw_breakpoint_restore) 58 hw_breakpoint_restore(cpu); 59 } 60 61 /* 62 * cpu_suspend 63 * 64 * arg: argument to pass to the finisher function 65 * fn: finisher function pointer 66 * 67 */ 68 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) 69 { 70 int ret = 0; 71 unsigned long flags; 72 struct sleep_stack_data state; 73 74 /* 75 * From this point debug exceptions are disabled to prevent 76 * updates to mdscr register (saved and restored along with 77 * general purpose registers) from kernel debuggers. 78 */ 79 local_dbg_save(flags); 80 81 /* 82 * Function graph tracer state gets incosistent when the kernel 83 * calls functions that never return (aka suspend finishers) hence 84 * disable graph tracing during their execution. 85 */ 86 pause_graph_tracing(); 87 88 if (__cpu_suspend_enter(&state)) { 89 /* Call the suspend finisher */ 90 ret = fn(arg); 91 92 /* 93 * Never gets here, unless the suspend finisher fails. 94 * Successful cpu_suspend() should return from cpu_resume(), 95 * returning through this code path is considered an error 96 * If the return value is set to 0 force ret = -EOPNOTSUPP 97 * to make sure a proper error condition is propagated 98 */ 99 if (!ret) 100 ret = -EOPNOTSUPP; 101 } else { 102 __cpu_suspend_exit(); 103 } 104 105 unpause_graph_tracing(); 106 107 /* 108 * Restore pstate flags. OS lock and mdscr have been already 109 * restored, so from this point onwards, debugging is fully 110 * renabled if it was enabled when core started shutdown. 111 */ 112 local_dbg_restore(flags); 113 114 return ret; 115 } 116 117 static int __init cpu_suspend_init(void) 118 { 119 /* ctx_ptr is an array of physical addresses */ 120 sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash), 121 GFP_KERNEL); 122 123 if (WARN_ON(!sleep_save_stash)) 124 return -ENOMEM; 125 126 return 0; 127 } 128 early_initcall(cpu_suspend_init); 129