1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/ftrace.h> 3 #include <linux/percpu.h> 4 #include <linux/slab.h> 5 #include <linux/uaccess.h> 6 #include <asm/alternative.h> 7 #include <asm/cacheflush.h> 8 #include <asm/cpufeature.h> 9 #include <asm/daifflags.h> 10 #include <asm/debug-monitors.h> 11 #include <asm/exec.h> 12 #include <asm/pgtable.h> 13 #include <asm/memory.h> 14 #include <asm/mmu_context.h> 15 #include <asm/smp_plat.h> 16 #include <asm/suspend.h> 17 18 /* 19 * This is allocated by cpu_suspend_init(), and used to store a pointer to 20 * the 'struct sleep_stack_data' the contains a particular CPUs state. 21 */ 22 unsigned long *sleep_save_stash; 23 24 /* 25 * This hook is provided so that cpu_suspend code can restore HW 26 * breakpoints as early as possible in the resume path, before reenabling 27 * debug exceptions. Code cannot be run from a CPU PM notifier since by the 28 * time the notifier runs debug exceptions might have been enabled already, 29 * with HW breakpoints registers content still in an unknown state. 30 */ 31 static int (*hw_breakpoint_restore)(unsigned int); 32 void __init cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int)) 33 { 34 /* Prevent multiple restore hook initializations */ 35 if (WARN_ON(hw_breakpoint_restore)) 36 return; 37 hw_breakpoint_restore = hw_bp_restore; 38 } 39 40 void notrace __cpu_suspend_exit(void) 41 { 42 unsigned int cpu = smp_processor_id(); 43 44 /* 45 * We are resuming from reset with the idmap active in TTBR0_EL1. 46 * We must uninstall the idmap and restore the expected MMU 47 * state before we can possibly return to userspace. 48 */ 49 cpu_uninstall_idmap(); 50 51 /* 52 * PSTATE was not saved over suspend/resume, re-enable any detected 53 * features that might not have been set correctly. 54 */ 55 __uaccess_enable_hw_pan(); 56 uao_thread_switch(current); 57 58 /* 59 * Restore HW breakpoint registers to sane values 60 * before debug exceptions are possibly reenabled 61 * by cpu_suspend()s local_daif_restore() call. 62 */ 63 if (hw_breakpoint_restore) 64 hw_breakpoint_restore(cpu); 65 } 66 67 /* 68 * cpu_suspend 69 * 70 * arg: argument to pass to the finisher function 71 * fn: finisher function pointer 72 * 73 */ 74 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) 75 { 76 int ret = 0; 77 unsigned long flags; 78 struct sleep_stack_data state; 79 80 /* 81 * From this point debug exceptions are disabled to prevent 82 * updates to mdscr register (saved and restored along with 83 * general purpose registers) from kernel debuggers. 84 */ 85 flags = local_daif_save(); 86 87 /* 88 * Function graph tracer state gets incosistent when the kernel 89 * calls functions that never return (aka suspend finishers) hence 90 * disable graph tracing during their execution. 91 */ 92 pause_graph_tracing(); 93 94 if (__cpu_suspend_enter(&state)) { 95 /* Call the suspend finisher */ 96 ret = fn(arg); 97 98 /* 99 * Never gets here, unless the suspend finisher fails. 100 * Successful cpu_suspend() should return from cpu_resume(), 101 * returning through this code path is considered an error 102 * If the return value is set to 0 force ret = -EOPNOTSUPP 103 * to make sure a proper error condition is propagated 104 */ 105 if (!ret) 106 ret = -EOPNOTSUPP; 107 } else { 108 __cpu_suspend_exit(); 109 } 110 111 unpause_graph_tracing(); 112 113 /* 114 * Restore pstate flags. OS lock and mdscr have been already 115 * restored, so from this point onwards, debugging is fully 116 * renabled if it was enabled when core started shutdown. 117 */ 118 local_daif_restore(flags); 119 120 return ret; 121 } 122 123 static int __init cpu_suspend_init(void) 124 { 125 /* ctx_ptr is an array of physical addresses */ 126 sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash), 127 GFP_KERNEL); 128 129 if (WARN_ON(!sleep_save_stash)) 130 return -ENOMEM; 131 132 return 0; 133 } 134 early_initcall(cpu_suspend_init); 135