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/exec.h> 9 #include <asm/pgtable.h> 10 #include <asm/memory.h> 11 #include <asm/mmu_context.h> 12 #include <asm/smp_plat.h> 13 #include <asm/suspend.h> 14 #include <asm/tlbflush.h> 15 16 /* 17 * This is allocated by cpu_suspend_init(), and used to store a pointer to 18 * the 'struct sleep_stack_data' the contains a particular CPUs state. 19 */ 20 unsigned long *sleep_save_stash; 21 22 /* 23 * This hook is provided so that cpu_suspend code can restore HW 24 * breakpoints as early as possible in the resume path, before reenabling 25 * debug exceptions. Code cannot be run from a CPU PM notifier since by the 26 * time the notifier runs debug exceptions might have been enabled already, 27 * with HW breakpoints registers content still in an unknown state. 28 */ 29 static int (*hw_breakpoint_restore)(unsigned int); 30 void __init cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int)) 31 { 32 /* Prevent multiple restore hook initializations */ 33 if (WARN_ON(hw_breakpoint_restore)) 34 return; 35 hw_breakpoint_restore = hw_bp_restore; 36 } 37 38 void notrace __cpu_suspend_exit(void) 39 { 40 unsigned int cpu = smp_processor_id(); 41 42 /* 43 * We are resuming from reset with the idmap active in TTBR0_EL1. 44 * We must uninstall the idmap and restore the expected MMU 45 * state before we can possibly return to userspace. 46 */ 47 cpu_uninstall_idmap(); 48 49 /* 50 * Restore per-cpu offset before any kernel 51 * subsystem relying on it has a chance to run. 52 */ 53 set_my_cpu_offset(per_cpu_offset(cpu)); 54 55 /* 56 * PSTATE was not saved over suspend/resume, re-enable any detected 57 * features that might not have been set correctly. 58 */ 59 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, 60 CONFIG_ARM64_PAN)); 61 uao_thread_switch(current); 62 63 /* 64 * Restore HW breakpoint registers to sane values 65 * before debug exceptions are possibly reenabled 66 * through local_dbg_restore. 67 */ 68 if (hw_breakpoint_restore) 69 hw_breakpoint_restore(cpu); 70 } 71 72 /* 73 * cpu_suspend 74 * 75 * arg: argument to pass to the finisher function 76 * fn: finisher function pointer 77 * 78 */ 79 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) 80 { 81 int ret = 0; 82 unsigned long flags; 83 struct sleep_stack_data state; 84 85 /* 86 * From this point debug exceptions are disabled to prevent 87 * updates to mdscr register (saved and restored along with 88 * general purpose registers) from kernel debuggers. 89 */ 90 local_dbg_save(flags); 91 92 /* 93 * Function graph tracer state gets incosistent when the kernel 94 * calls functions that never return (aka suspend finishers) hence 95 * disable graph tracing during their execution. 96 */ 97 pause_graph_tracing(); 98 99 if (__cpu_suspend_enter(&state)) { 100 /* Call the suspend finisher */ 101 ret = fn(arg); 102 103 /* 104 * Never gets here, unless the suspend finisher fails. 105 * Successful cpu_suspend() should return from cpu_resume(), 106 * returning through this code path is considered an error 107 * If the return value is set to 0 force ret = -EOPNOTSUPP 108 * to make sure a proper error condition is propagated 109 */ 110 if (!ret) 111 ret = -EOPNOTSUPP; 112 } else { 113 __cpu_suspend_exit(); 114 } 115 116 unpause_graph_tracing(); 117 118 /* 119 * Restore pstate flags. OS lock and mdscr have been already 120 * restored, so from this point onwards, debugging is fully 121 * renabled if it was enabled when core started shutdown. 122 */ 123 local_dbg_restore(flags); 124 125 return ret; 126 } 127 128 static int __init cpu_suspend_init(void) 129 { 130 /* ctx_ptr is an array of physical addresses */ 131 sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash), 132 GFP_KERNEL); 133 134 if (WARN_ON(!sleep_save_stash)) 135 return -ENOMEM; 136 137 return 0; 138 } 139 early_initcall(cpu_suspend_init); 140