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>
15 #include <asm/memory.h>
16 #include <asm/mmu_context.h>
17 #include <asm/smp_plat.h>
18 #include <asm/suspend.h>
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.
24 unsigned long *sleep_save_stash;
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.
33 static int (*hw_breakpoint_restore)(unsigned int);
34 void __init cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int))
36 /* Prevent multiple restore hook initializations */
37 if (WARN_ON(hw_breakpoint_restore))
39 hw_breakpoint_restore = hw_bp_restore;
42 void notrace __cpu_suspend_exit(void)
44 unsigned int cpu = smp_processor_id();
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.
51 cpu_uninstall_idmap();
53 /* Restore CnP bit in TTBR1_EL1 */
54 if (system_supports_cnp())
55 cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
58 * PSTATE was not saved over suspend/resume, re-enable any detected
59 * features that might not have been set correctly.
61 __uaccess_enable_hw_pan();
64 * Restore HW breakpoint registers to sane values
65 * before debug exceptions are possibly reenabled
66 * by cpu_suspend()s local_daif_restore() call.
68 if (hw_breakpoint_restore)
69 hw_breakpoint_restore(cpu);
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.
76 spectre_v4_enable_mitigation(NULL);
78 /* Restore additional feature-specific configuration */
79 ptrauth_suspend_exit();
85 * arg: argument to pass to the finisher function
86 * fn: finisher function pointer
89 int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
93 struct sleep_stack_data state;
94 struct arm_cpuidle_irq_context context;
96 /* Report any MTE async fault before going to suspend */
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.
104 flags = local_daif_save();
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.
111 pause_graph_tracing();
114 * Switch to using DAIF.IF instead of PMR in order to reliably
115 * resume if we're using pseudo-NMIs.
117 arm_cpuidle_save_irq_context(&context);
119 if (__cpu_suspend_enter(&state)) {
120 /* Call the suspend finisher */
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
133 RCU_NONIDLE(__cpu_suspend_exit());
136 arm_cpuidle_restore_irq_context(&context);
138 unpause_graph_tracing();
141 * Restore pstate flags. OS lock and mdscr have been already
142 * restored, so from this point onwards, debugging is fully
143 * renabled if it was enabled when core started shutdown.
145 local_daif_restore(flags);
150 static int __init cpu_suspend_init(void)
152 /* ctx_ptr is an array of physical addresses */
153 sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash),
156 if (WARN_ON(!sleep_save_stash))
161 early_initcall(cpu_suspend_init);