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 <linux/pgtable.h> 7 #include <asm/alternative.h> 8 #include <asm/cacheflush.h> 9 #include <asm/cpufeature.h> 10 #include <asm/daifflags.h> 11 #include <asm/debug-monitors.h> 12 #include <asm/exec.h> 13 #include <asm/mte.h> 14 #include <asm/memory.h> 15 #include <asm/mmu_context.h> 16 #include <asm/smp_plat.h> 17 #include <asm/suspend.h> 18 19 /* 20 * This is allocated by cpu_suspend_init(), and used to store a pointer to 21 * the 'struct sleep_stack_data' the contains a particular CPUs state. 22 */ 23 unsigned long *sleep_save_stash; 24 25 /* 26 * This hook is provided so that cpu_suspend code can restore HW 27 * breakpoints as early as possible in the resume path, before reenabling 28 * debug exceptions. Code cannot be run from a CPU PM notifier since by the 29 * time the notifier runs debug exceptions might have been enabled already, 30 * with HW breakpoints registers content still in an unknown state. 31 */ 32 static int (*hw_breakpoint_restore)(unsigned int); 33 void __init cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int)) 34 { 35 /* Prevent multiple restore hook initializations */ 36 if (WARN_ON(hw_breakpoint_restore)) 37 return; 38 hw_breakpoint_restore = hw_bp_restore; 39 } 40 41 void notrace __cpu_suspend_exit(void) 42 { 43 unsigned int cpu = smp_processor_id(); 44 45 /* 46 * We are resuming from reset with the idmap active in TTBR0_EL1. 47 * We must uninstall the idmap and restore the expected MMU 48 * state before we can possibly return to userspace. 49 */ 50 cpu_uninstall_idmap(); 51 52 /* Restore CnP bit in TTBR1_EL1 */ 53 if (system_supports_cnp()) 54 cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); 55 56 /* 57 * PSTATE was not saved over suspend/resume, re-enable any detected 58 * features that might not have been set correctly. 59 */ 60 __uaccess_enable_hw_pan(); 61 uao_thread_switch(current); 62 63 /* 64 * Restore HW breakpoint registers to sane values 65 * before debug exceptions are possibly reenabled 66 * by cpu_suspend()s local_daif_restore() call. 67 */ 68 if (hw_breakpoint_restore) 69 hw_breakpoint_restore(cpu); 70 71 /* 72 * On resume, firmware implementing dynamic mitigation will 73 * have turned the mitigation on. If the user has forcefully 74 * disabled it, make sure their wishes are obeyed. 75 */ 76 spectre_v4_enable_mitigation(NULL); 77 78 /* Restore additional MTE-specific configuration */ 79 mte_suspend_exit(); 80 } 81 82 /* 83 * cpu_suspend 84 * 85 * arg: argument to pass to the finisher function 86 * fn: finisher function pointer 87 * 88 */ 89 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) 90 { 91 int ret = 0; 92 unsigned long flags; 93 struct sleep_stack_data state; 94 95 /* 96 * From this point debug exceptions are disabled to prevent 97 * updates to mdscr register (saved and restored along with 98 * general purpose registers) from kernel debuggers. 99 */ 100 flags = local_daif_save(); 101 102 /* 103 * Function graph tracer state gets incosistent when the kernel 104 * calls functions that never return (aka suspend finishers) hence 105 * disable graph tracing during their execution. 106 */ 107 pause_graph_tracing(); 108 109 if (__cpu_suspend_enter(&state)) { 110 /* Call the suspend finisher */ 111 ret = fn(arg); 112 113 /* 114 * Never gets here, unless the suspend finisher fails. 115 * Successful cpu_suspend() should return from cpu_resume(), 116 * returning through this code path is considered an error 117 * If the return value is set to 0 force ret = -EOPNOTSUPP 118 * to make sure a proper error condition is propagated 119 */ 120 if (!ret) 121 ret = -EOPNOTSUPP; 122 } else { 123 __cpu_suspend_exit(); 124 } 125 126 unpause_graph_tracing(); 127 128 /* 129 * Restore pstate flags. OS lock and mdscr have been already 130 * restored, so from this point onwards, debugging is fully 131 * renabled if it was enabled when core started shutdown. 132 */ 133 local_daif_restore(flags); 134 135 return ret; 136 } 137 138 static int __init cpu_suspend_init(void) 139 { 140 /* ctx_ptr is an array of physical addresses */ 141 sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash), 142 GFP_KERNEL); 143 144 if (WARN_ON(!sleep_save_stash)) 145 return -ENOMEM; 146 147 return 0; 148 } 149 early_initcall(cpu_suspend_init); 150