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/cpuidle.h> 11 #include <asm/daifflags.h> 12 #include <asm/debug-monitors.h> 13 #include <asm/exec.h> 14 #include <asm/mte.h> 15 #include <asm/memory.h> 16 #include <asm/mmu_context.h> 17 #include <asm/smp_plat.h> 18 #include <asm/suspend.h> 19 20 /* 21 * This is allocated by cpu_suspend_init(), and used to store a pointer to 22 * the 'struct sleep_stack_data' the contains a particular CPUs state. 23 */ 24 unsigned long *sleep_save_stash; 25 26 /* 27 * This hook is provided so that cpu_suspend code can restore HW 28 * breakpoints as early as possible in the resume path, before reenabling 29 * debug exceptions. Code cannot be run from a CPU PM notifier since by the 30 * time the notifier runs debug exceptions might have been enabled already, 31 * with HW breakpoints registers content still in an unknown state. 32 */ 33 static int (*hw_breakpoint_restore)(unsigned int); 34 void __init cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int)) 35 { 36 /* Prevent multiple restore hook initializations */ 37 if (WARN_ON(hw_breakpoint_restore)) 38 return; 39 hw_breakpoint_restore = hw_bp_restore; 40 } 41 42 void notrace __cpu_suspend_exit(void) 43 { 44 unsigned int cpu = smp_processor_id(); 45 46 /* 47 * We are resuming from reset with the idmap active in TTBR0_EL1. 48 * We must uninstall the idmap and restore the expected MMU 49 * state before we can possibly return to userspace. 50 */ 51 cpu_uninstall_idmap(); 52 53 /* Restore CnP bit in TTBR1_EL1 */ 54 if (system_supports_cnp()) 55 cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir); 56 57 /* 58 * PSTATE was not saved over suspend/resume, re-enable any detected 59 * features that might not have been set correctly. 60 */ 61 __uaccess_enable_hw_pan(); 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 feature-specific configuration */ 79 ptrauth_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 struct arm_cpuidle_irq_context context; 95 96 /* Report any MTE async fault before going to suspend */ 97 mte_suspend_enter(); 98 99 /* 100 * From this point debug exceptions are disabled to prevent 101 * updates to mdscr register (saved and restored along with 102 * general purpose registers) from kernel debuggers. 103 */ 104 flags = local_daif_save(); 105 106 /* 107 * Function graph tracer state gets inconsistent when the kernel 108 * calls functions that never return (aka suspend finishers) hence 109 * disable graph tracing during their execution. 110 */ 111 pause_graph_tracing(); 112 113 /* 114 * Switch to using DAIF.IF instead of PMR in order to reliably 115 * resume if we're using pseudo-NMIs. 116 */ 117 arm_cpuidle_save_irq_context(&context); 118 119 if (__cpu_suspend_enter(&state)) { 120 /* Call the suspend finisher */ 121 ret = fn(arg); 122 123 /* 124 * Never gets here, unless the suspend finisher fails. 125 * Successful cpu_suspend() should return from cpu_resume(), 126 * returning through this code path is considered an error 127 * If the return value is set to 0 force ret = -EOPNOTSUPP 128 * to make sure a proper error condition is propagated 129 */ 130 if (!ret) 131 ret = -EOPNOTSUPP; 132 } else { 133 RCU_NONIDLE(__cpu_suspend_exit()); 134 } 135 136 arm_cpuidle_restore_irq_context(&context); 137 138 unpause_graph_tracing(); 139 140 /* 141 * Restore pstate flags. OS lock and mdscr have been already 142 * restored, so from this point onwards, debugging is fully 143 * reenabled if it was enabled when core started shutdown. 144 */ 145 local_daif_restore(flags); 146 147 return ret; 148 } 149 150 static int __init cpu_suspend_init(void) 151 { 152 /* ctx_ptr is an array of physical addresses */ 153 sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash), 154 GFP_KERNEL); 155 156 if (WARN_ON(!sleep_save_stash)) 157 return -ENOMEM; 158 159 return 0; 160 } 161 early_initcall(cpu_suspend_init); 162