| // SPDX-License-Identifier: GPL-2.0 |
| #include <linux/ftrace.h> |
| #include <linux/percpu.h> |
| #include <linux/slab.h> |
| #include <linux/uaccess.h> |
| #include <linux/pgtable.h> |
| #include <asm/alternative.h> |
| #include <asm/cacheflush.h> |
| #include <asm/cpufeature.h> |
| #include <asm/cpuidle.h> |
| #include <asm/daifflags.h> |
| #include <asm/debug-monitors.h> |
| #include <asm/exec.h> |
| #include <asm/mte.h> |
| #include <asm/memory.h> |
| #include <asm/mmu_context.h> |
| #include <asm/smp_plat.h> |
| #include <asm/suspend.h> |
| |
| /* |
| * This is allocated by cpu_suspend_init(), and used to store a pointer to |
| * the 'struct sleep_stack_data' the contains a particular CPUs state. |
| */ |
| unsigned long *sleep_save_stash; |
| |
| /* |
| * This hook is provided so that cpu_suspend code can restore HW |
| * breakpoints as early as possible in the resume path, before reenabling |
| * debug exceptions. Code cannot be run from a CPU PM notifier since by the |
| * time the notifier runs debug exceptions might have been enabled already, |
| * with HW breakpoints registers content still in an unknown state. |
| */ |
| static int (*hw_breakpoint_restore)(unsigned int); |
| void __init cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int)) |
| { |
| /* Prevent multiple restore hook initializations */ |
| if (WARN_ON(hw_breakpoint_restore)) |
| return; |
| hw_breakpoint_restore = hw_bp_restore; |
| } |
| |
| void notrace __cpu_suspend_exit(void) |
| { |
| unsigned int cpu = smp_processor_id(); |
| |
| /* |
| * We are resuming from reset with the idmap active in TTBR0_EL1. |
| * We must uninstall the idmap and restore the expected MMU |
| * state before we can possibly return to userspace. |
| */ |
| cpu_uninstall_idmap(); |
| |
| /* Restore CnP bit in TTBR1_EL1 */ |
| if (system_supports_cnp()) |
| cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); |
| |
| /* |
| * PSTATE was not saved over suspend/resume, re-enable any detected |
| * features that might not have been set correctly. |
| */ |
| __uaccess_enable_hw_pan(); |
| |
| /* |
| * Restore HW breakpoint registers to sane values |
| * before debug exceptions are possibly reenabled |
| * by cpu_suspend()s local_daif_restore() call. |
| */ |
| if (hw_breakpoint_restore) |
| hw_breakpoint_restore(cpu); |
| |
| /* |
| * On resume, firmware implementing dynamic mitigation will |
| * have turned the mitigation on. If the user has forcefully |
| * disabled it, make sure their wishes are obeyed. |
| */ |
| spectre_v4_enable_mitigation(NULL); |
| |
| /* Restore additional feature-specific configuration */ |
| mte_suspend_exit(); |
| ptrauth_suspend_exit(); |
| } |
| |
| /* |
| * cpu_suspend |
| * |
| * arg: argument to pass to the finisher function |
| * fn: finisher function pointer |
| * |
| */ |
| int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) |
| { |
| int ret = 0; |
| unsigned long flags; |
| struct sleep_stack_data state; |
| struct arm_cpuidle_irq_context context; |
| |
| /* Report any MTE async fault before going to suspend */ |
| mte_suspend_enter(); |
| |
| /* |
| * From this point debug exceptions are disabled to prevent |
| * updates to mdscr register (saved and restored along with |
| * general purpose registers) from kernel debuggers. |
| */ |
| flags = local_daif_save(); |
| |
| /* |
| * Function graph tracer state gets inconsistent when the kernel |
| * calls functions that never return (aka suspend finishers) hence |
| * disable graph tracing during their execution. |
| */ |
| pause_graph_tracing(); |
| |
| /* |
| * Switch to using DAIF.IF instead of PMR in order to reliably |
| * resume if we're using pseudo-NMIs. |
| */ |
| arm_cpuidle_save_irq_context(&context); |
| |
| if (__cpu_suspend_enter(&state)) { |
| /* Call the suspend finisher */ |
| ret = fn(arg); |
| |
| /* |
| * Never gets here, unless the suspend finisher fails. |
| * Successful cpu_suspend() should return from cpu_resume(), |
| * returning through this code path is considered an error |
| * If the return value is set to 0 force ret = -EOPNOTSUPP |
| * to make sure a proper error condition is propagated |
| */ |
| if (!ret) |
| ret = -EOPNOTSUPP; |
| } else { |
| RCU_NONIDLE(__cpu_suspend_exit()); |
| } |
| |
| arm_cpuidle_restore_irq_context(&context); |
| |
| unpause_graph_tracing(); |
| |
| /* |
| * Restore pstate flags. OS lock and mdscr have been already |
| * restored, so from this point onwards, debugging is fully |
| * renabled if it was enabled when core started shutdown. |
| */ |
| local_daif_restore(flags); |
| |
| return ret; |
| } |
| |
| static int __init cpu_suspend_init(void) |
| { |
| /* ctx_ptr is an array of physical addresses */ |
| sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash), |
| GFP_KERNEL); |
| |
| if (WARN_ON(!sleep_save_stash)) |
| return -ENOMEM; |
| |
| return 0; |
| } |
| early_initcall(cpu_suspend_init); |