diff options
Diffstat (limited to 'arch/arm64/kernel/suspend.c')
| -rw-r--r-- | arch/arm64/kernel/suspend.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c new file mode 100644 index 0000000000..0fbdf5fe64 --- /dev/null +++ b/arch/arm64/kernel/suspend.c @@ -0,0 +1,175 @@ +// 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 <linux/cpuidle.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(); + + mte_suspend_exit(); + + /* + * 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), idmap_pg_dir); + + /* + * PSTATE was not saved over suspend/resume, re-enable any detected + * features that might not have been set correctly. + */ + if (cpus_have_const_cap(ARM64_HAS_DIT)) + set_pstate_dit(1); + __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 */ + 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. + * + * Strictly speaking the trace_hardirqs_off() here is superfluous, + * hardirqs should be firmly off by now. This really ought to use + * something like raw_local_daif_save(). + */ + 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); + + ct_cpuidle_enter(); + + 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; + + ct_cpuidle_exit(); + } else { + ct_cpuidle_exit(); + __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 + * reenabled 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); |