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/memory.h> 14 #include <asm/mmu_context.h> 15 #include <asm/smp_plat.h> 16 #include <asm/suspend.h> 17 18 /* 19 * This is allocated by cpu_suspend_init(), and used to store a pointer to 20 * the 'struct sleep_stack_data' the contains a particular CPUs state. 21 */ 22 unsigned long *sleep_save_stash; 23 24 /* 25 * This hook is provided so that cpu_suspend code can restore HW 26 * breakpoints as early as possible in the resume path, before reenabling 27 * debug exceptions. Code cannot be run from a CPU PM notifier since by the 28 * time the notifier runs debug exceptions might have been enabled already, 29 * with HW breakpoints registers content still in an unknown state. 30 */ 31 static int (*hw_breakpoint_restore)(unsigned int); 32 void __init cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int)) 33 { 34 /* Prevent multiple restore hook initializations */ 35 if (WARN_ON(hw_breakpoint_restore)) 36 return; 37 hw_breakpoint_restore = hw_bp_restore; 38 } 39 40 void notrace __cpu_suspend_exit(void) 41 { 42 unsigned int cpu = smp_processor_id(); 43 44 /* 45 * We are resuming from reset with the idmap active in TTBR0_EL1. 46 * We must uninstall the idmap and restore the expected MMU 47 * state before we can possibly return to userspace. 48 */ 49 cpu_uninstall_idmap(); 50 51 /* Restore CnP bit in TTBR1_EL1 */ 52 if (system_supports_cnp()) 53 cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); 54 55 /* 56 * PSTATE was not saved over suspend/resume, re-enable any detected 57 * features that might not have been set correctly. 58 */ 59 __uaccess_enable_hw_pan(); 60 uao_thread_switch(current); 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 if (arm64_get_ssbd_state() == ARM64_SSBD_FORCE_DISABLE) 76 arm64_set_ssbd_mitigation(false); 77 } 78 79 /* 80 * cpu_suspend 81 * 82 * arg: argument to pass to the finisher function 83 * fn: finisher function pointer 84 * 85 */ 86 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) 87 { 88 int ret = 0; 89 unsigned long flags; 90 struct sleep_stack_data state; 91 92 /* 93 * From this point debug exceptions are disabled to prevent 94 * updates to mdscr register (saved and restored along with 95 * general purpose registers) from kernel debuggers. 96 */ 97 flags = local_daif_save(); 98 99 /* 100 * Function graph tracer state gets incosistent when the kernel 101 * calls functions that never return (aka suspend finishers) hence 102 * disable graph tracing during their execution. 103 */ 104 pause_graph_tracing(); 105 106 if (__cpu_suspend_enter(&state)) { 107 /* Call the suspend finisher */ 108 ret = fn(arg); 109 110 /* 111 * Never gets here, unless the suspend finisher fails. 112 * Successful cpu_suspend() should return from cpu_resume(), 113 * returning through this code path is considered an error 114 * If the return value is set to 0 force ret = -EOPNOTSUPP 115 * to make sure a proper error condition is propagated 116 */ 117 if (!ret) 118 ret = -EOPNOTSUPP; 119 } else { 120 __cpu_suspend_exit(); 121 } 122 123 unpause_graph_tracing(); 124 125 /* 126 * Restore pstate flags. OS lock and mdscr have been already 127 * restored, so from this point onwards, debugging is fully 128 * renabled if it was enabled when core started shutdown. 129 */ 130 local_daif_restore(flags); 131 132 return ret; 133 } 134 135 static int __init cpu_suspend_init(void) 136 { 137 /* ctx_ptr is an array of physical addresses */ 138 sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash), 139 GFP_KERNEL); 140 141 if (WARN_ON(!sleep_save_stash)) 142 return -ENOMEM; 143 144 return 0; 145 } 146 early_initcall(cpu_suspend_init); 147