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 <linux/cpuidle.h> 8 #include <asm/alternative.h> 9 #include <asm/cacheflush.h> 10 #include <asm/cpufeature.h> 11 #include <asm/cpuidle.h> 12 #include <asm/daifflags.h> 13 #include <asm/debug-monitors.h> 14 #include <asm/exec.h> 15 #include <asm/fpsimd.h> 16 #include <asm/mte.h> 17 #include <asm/memory.h> 18 #include <asm/mmu_context.h> 19 #include <asm/smp_plat.h> 20 #include <asm/suspend.h> 21 22 /* 23 * This is allocated by cpu_suspend_init(), and used to store a pointer to 24 * the 'struct sleep_stack_data' the contains a particular CPUs state. 25 */ 26 unsigned long *sleep_save_stash; 27 28 /* 29 * This hook is provided so that cpu_suspend code can restore HW 30 * breakpoints as early as possible in the resume path, before reenabling 31 * debug exceptions. Code cannot be run from a CPU PM notifier since by the 32 * time the notifier runs debug exceptions might have been enabled already, 33 * with HW breakpoints registers content still in an unknown state. 34 */ 35 static int (*hw_breakpoint_restore)(unsigned int); 36 void __init cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int)) 37 { 38 /* Prevent multiple restore hook initializations */ 39 if (WARN_ON(hw_breakpoint_restore)) 40 return; 41 hw_breakpoint_restore = hw_bp_restore; 42 } 43 44 void notrace __cpu_suspend_exit(void) 45 { 46 unsigned int cpu = smp_processor_id(); 47 48 mte_suspend_exit(); 49 50 /* 51 * We are resuming from reset with the idmap active in TTBR0_EL1. 52 * We must uninstall the idmap and restore the expected MMU 53 * state before we can possibly return to userspace. 54 */ 55 cpu_uninstall_idmap(); 56 57 /* Restore CnP bit in TTBR1_EL1 */ 58 if (system_supports_cnp()) 59 cpu_enable_swapper_cnp(); 60 61 /* 62 * PSTATE was not saved over suspend/resume, re-enable any detected 63 * features that might not have been set correctly. 64 */ 65 if (alternative_has_cap_unlikely(ARM64_HAS_DIT)) 66 set_pstate_dit(1); 67 __uaccess_enable_hw_pan(); 68 69 /* 70 * Restore HW breakpoint registers to sane values 71 * before debug exceptions are possibly reenabled 72 * by cpu_suspend()s local_daif_restore() call. 73 */ 74 if (hw_breakpoint_restore) 75 hw_breakpoint_restore(cpu); 76 77 /* 78 * On resume, firmware implementing dynamic mitigation will 79 * have turned the mitigation on. If the user has forcefully 80 * disabled it, make sure their wishes are obeyed. 81 */ 82 spectre_v4_enable_mitigation(NULL); 83 84 sme_suspend_exit(); 85 86 /* Restore additional feature-specific configuration */ 87 ptrauth_suspend_exit(); 88 } 89 90 /* 91 * cpu_suspend 92 * 93 * arg: argument to pass to the finisher function 94 * fn: finisher function pointer 95 * 96 */ 97 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) 98 { 99 int ret = 0; 100 unsigned long flags; 101 struct sleep_stack_data state; 102 103 /* 104 * Some portions of CPU state (e.g. PSTATE.{PAN,DIT}) are initialized 105 * before alternatives are patched, but are only restored by 106 * __cpu_suspend_exit() after alternatives are patched. To avoid 107 * accidentally losing these bits we must not attempt to suspend until 108 * after alternatives have been patched. 109 */ 110 WARN_ON(!system_capabilities_finalized()); 111 112 /* Report any MTE async fault before going to suspend */ 113 mte_suspend_enter(); 114 115 /* 116 * From this point debug exceptions are disabled to prevent 117 * updates to mdscr register (saved and restored along with 118 * general purpose registers) from kernel debuggers. 119 * 120 * Strictly speaking the trace_hardirqs_off() here is superfluous, 121 * hardirqs should be firmly off by now. This really ought to use 122 * something like raw_local_daif_save(). 123 * 124 * This also unmasks interrupts in PMR in order to reliably 125 * resume if we're using pseudo-NMIs. 126 */ 127 flags = local_daif_save(); 128 129 /* 130 * Function graph tracer state gets inconsistent when the kernel 131 * calls functions that never return (aka suspend finishers) hence 132 * disable graph tracing during their execution. 133 */ 134 pause_graph_tracing(); 135 136 ct_cpuidle_enter(); 137 138 if (__cpu_suspend_enter(&state)) { 139 /* Call the suspend finisher */ 140 ret = fn(arg); 141 142 /* 143 * Never gets here, unless the suspend finisher fails. 144 * Successful cpu_suspend() should return from cpu_resume(), 145 * returning through this code path is considered an error 146 * If the return value is set to 0 force ret = -EOPNOTSUPP 147 * to make sure a proper error condition is propagated 148 */ 149 if (!ret) 150 ret = -EOPNOTSUPP; 151 152 ct_cpuidle_exit(); 153 } else { 154 ct_cpuidle_exit(); 155 __cpu_suspend_exit(); 156 } 157 158 unpause_graph_tracing(); 159 160 /* 161 * Restore pstate flags. OS lock and mdscr have been already 162 * restored, so from this point onwards, debugging is fully 163 * reenabled if it was enabled when core started shutdown. 164 */ 165 local_daif_restore(flags); 166 167 return ret; 168 } 169 170 static int __init cpu_suspend_init(void) 171 { 172 /* ctx_ptr is an array of physical addresses */ 173 sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash), 174 GFP_KERNEL); 175 176 if (WARN_ON(!sleep_save_stash)) 177 return -ENOMEM; 178 179 return 0; 180 } 181 early_initcall(cpu_suspend_init); 182