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 mte_suspend_exit(); 47 48 /* 49 * We are resuming from reset with the idmap active in TTBR0_EL1. 50 * We must uninstall the idmap and restore the expected MMU 51 * state before we can possibly return to userspace. 52 */ 53 cpu_uninstall_idmap(); 54 55 /* Restore CnP bit in TTBR1_EL1 */ 56 if (system_supports_cnp()) 57 cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir); 58 59 /* 60 * PSTATE was not saved over suspend/resume, re-enable any detected 61 * features that might not have been set correctly. 62 */ 63 if (cpus_have_const_cap(ARM64_HAS_DIT)) 64 set_pstate_dit(1); 65 __uaccess_enable_hw_pan(); 66 67 /* 68 * Restore HW breakpoint registers to sane values 69 * before debug exceptions are possibly reenabled 70 * by cpu_suspend()s local_daif_restore() call. 71 */ 72 if (hw_breakpoint_restore) 73 hw_breakpoint_restore(cpu); 74 75 /* 76 * On resume, firmware implementing dynamic mitigation will 77 * have turned the mitigation on. If the user has forcefully 78 * disabled it, make sure their wishes are obeyed. 79 */ 80 spectre_v4_enable_mitigation(NULL); 81 82 /* Restore additional feature-specific configuration */ 83 ptrauth_suspend_exit(); 84 } 85 86 /* 87 * cpu_suspend 88 * 89 * arg: argument to pass to the finisher function 90 * fn: finisher function pointer 91 * 92 */ 93 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) 94 { 95 int ret = 0; 96 unsigned long flags; 97 struct sleep_stack_data state; 98 struct arm_cpuidle_irq_context context; 99 100 /* Report any MTE async fault before going to suspend */ 101 mte_suspend_enter(); 102 103 /* 104 * From this point debug exceptions are disabled to prevent 105 * updates to mdscr register (saved and restored along with 106 * general purpose registers) from kernel debuggers. 107 */ 108 flags = local_daif_save(); 109 110 /* 111 * Function graph tracer state gets inconsistent when the kernel 112 * calls functions that never return (aka suspend finishers) hence 113 * disable graph tracing during their execution. 114 */ 115 pause_graph_tracing(); 116 117 /* 118 * Switch to using DAIF.IF instead of PMR in order to reliably 119 * resume if we're using pseudo-NMIs. 120 */ 121 arm_cpuidle_save_irq_context(&context); 122 123 if (__cpu_suspend_enter(&state)) { 124 /* Call the suspend finisher */ 125 ret = fn(arg); 126 127 /* 128 * Never gets here, unless the suspend finisher fails. 129 * Successful cpu_suspend() should return from cpu_resume(), 130 * returning through this code path is considered an error 131 * If the return value is set to 0 force ret = -EOPNOTSUPP 132 * to make sure a proper error condition is propagated 133 */ 134 if (!ret) 135 ret = -EOPNOTSUPP; 136 } else { 137 RCU_NONIDLE(__cpu_suspend_exit()); 138 } 139 140 arm_cpuidle_restore_irq_context(&context); 141 142 unpause_graph_tracing(); 143 144 /* 145 * Restore pstate flags. OS lock and mdscr have been already 146 * restored, so from this point onwards, debugging is fully 147 * reenabled if it was enabled when core started shutdown. 148 */ 149 local_daif_restore(flags); 150 151 return ret; 152 } 153 154 static int __init cpu_suspend_init(void) 155 { 156 /* ctx_ptr is an array of physical addresses */ 157 sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash), 158 GFP_KERNEL); 159 160 if (WARN_ON(!sleep_save_stash)) 161 return -ENOMEM; 162 163 return 0; 164 } 165 early_initcall(cpu_suspend_init); 166