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 62 /* 63 * Restore HW breakpoint registers to sane values 64 * before debug exceptions are possibly reenabled 65 * by cpu_suspend()s local_daif_restore() call. 66 */ 67 if (hw_breakpoint_restore) 68 hw_breakpoint_restore(cpu); 69 70 /* 71 * On resume, firmware implementing dynamic mitigation will 72 * have turned the mitigation on. If the user has forcefully 73 * disabled it, make sure their wishes are obeyed. 74 */ 75 spectre_v4_enable_mitigation(NULL); 76 77 /* Restore additional MTE-specific configuration */ 78 mte_suspend_exit(); 79 } 80 81 /* 82 * cpu_suspend 83 * 84 * arg: argument to pass to the finisher function 85 * fn: finisher function pointer 86 * 87 */ 88 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) 89 { 90 int ret = 0; 91 unsigned long flags; 92 struct sleep_stack_data state; 93 94 /* 95 * From this point debug exceptions are disabled to prevent 96 * updates to mdscr register (saved and restored along with 97 * general purpose registers) from kernel debuggers. 98 */ 99 flags = local_daif_save(); 100 101 /* 102 * Function graph tracer state gets incosistent when the kernel 103 * calls functions that never return (aka suspend finishers) hence 104 * disable graph tracing during their execution. 105 */ 106 pause_graph_tracing(); 107 108 if (__cpu_suspend_enter(&state)) { 109 /* Call the suspend finisher */ 110 ret = fn(arg); 111 112 /* 113 * Never gets here, unless the suspend finisher fails. 114 * Successful cpu_suspend() should return from cpu_resume(), 115 * returning through this code path is considered an error 116 * If the return value is set to 0 force ret = -EOPNOTSUPP 117 * to make sure a proper error condition is propagated 118 */ 119 if (!ret) 120 ret = -EOPNOTSUPP; 121 } else { 122 __cpu_suspend_exit(); 123 } 124 125 unpause_graph_tracing(); 126 127 /* 128 * Restore pstate flags. OS lock and mdscr have been already 129 * restored, so from this point onwards, debugging is fully 130 * renabled if it was enabled when core started shutdown. 131 */ 132 local_daif_restore(flags); 133 134 return ret; 135 } 136 137 static int __init cpu_suspend_init(void) 138 { 139 /* ctx_ptr is an array of physical addresses */ 140 sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash), 141 GFP_KERNEL); 142 143 if (WARN_ON(!sleep_save_stash)) 144 return -ENOMEM; 145 146 return 0; 147 } 148 early_initcall(cpu_suspend_init); 149