1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (C) 2017 Arm Ltd.
3 #define pr_fmt(fmt) "sdei: " fmt
6 #include <linux/acpi.h>
7 #include <linux/arm_sdei.h>
8 #include <linux/arm-smccc.h>
9 #include <linux/atomic.h>
10 #include <linux/bitops.h>
11 #include <linux/compiler.h>
12 #include <linux/cpuhotplug.h>
13 #include <linux/cpu.h>
14 #include <linux/cpu_pm.h>
15 #include <linux/errno.h>
16 #include <linux/hardirq.h>
17 #include <linux/kernel.h>
18 #include <linux/kprobes.h>
19 #include <linux/kvm_host.h>
20 #include <linux/list.h>
21 #include <linux/mutex.h>
22 #include <linux/notifier.h>
24 #include <linux/of_platform.h>
25 #include <linux/percpu.h>
26 #include <linux/platform_device.h>
28 #include <linux/ptrace.h>
29 #include <linux/preempt.h>
30 #include <linux/reboot.h>
31 #include <linux/slab.h>
32 #include <linux/smp.h>
33 #include <linux/spinlock.h>
34 #include <linux/uaccess.h>
37 * The call to use to reach the firmware.
39 static asmlinkage void (*sdei_firmware_call)(unsigned long function_id,
40 unsigned long arg0, unsigned long arg1,
41 unsigned long arg2, unsigned long arg3,
42 unsigned long arg4, struct arm_smccc_res *res);
44 /* entry point from firmware to arch asm code */
45 static unsigned long sdei_entry_point;
48 /* These three are protected by the sdei_list_lock */
49 struct list_head list;
57 /* This pointer is handed to firmware as the event argument. */
60 struct sdei_registered_event *registered;
62 /* CPU private events */
63 struct sdei_registered_event __percpu *private_registered;
67 /* Take the mutex for any API call or modification. Take the mutex first. */
68 static DEFINE_MUTEX(sdei_events_lock);
70 /* and then hold this when modifying the list */
71 static DEFINE_SPINLOCK(sdei_list_lock);
72 static LIST_HEAD(sdei_list);
74 /* Private events are registered/enabled via IPI passing one of these */
75 struct sdei_crosscall_args {
76 struct sdei_event *event;
81 #define CROSSCALL_INIT(arg, event) \
84 arg.first_error = 0; \
85 atomic_set(&arg.errors, 0); \
88 static inline int sdei_do_local_call(smp_call_func_t fn,
89 struct sdei_event *event)
91 struct sdei_crosscall_args arg;
93 CROSSCALL_INIT(arg, event);
96 return arg.first_error;
99 static inline int sdei_do_cross_call(smp_call_func_t fn,
100 struct sdei_event *event)
102 struct sdei_crosscall_args arg;
104 CROSSCALL_INIT(arg, event);
105 on_each_cpu(fn, &arg, true);
107 return arg.first_error;
111 sdei_cross_call_return(struct sdei_crosscall_args *arg, int err)
113 if (err && (atomic_inc_return(&arg->errors) == 1))
114 arg->first_error = err;
117 static int sdei_to_linux_errno(unsigned long sdei_err)
120 case SDEI_NOT_SUPPORTED:
122 case SDEI_INVALID_PARAMETERS:
128 case SDEI_OUT_OF_RESOURCE:
135 static int invoke_sdei_fn(unsigned long function_id, unsigned long arg0,
136 unsigned long arg1, unsigned long arg2,
137 unsigned long arg3, unsigned long arg4,
141 struct arm_smccc_res res;
143 if (sdei_firmware_call) {
144 sdei_firmware_call(function_id, arg0, arg1, arg2, arg3, arg4,
146 err = sdei_to_linux_errno(res.a0);
149 * !sdei_firmware_call means we failed to probe or called
150 * sdei_mark_interface_broken(). -EIO is not an error returned
151 * by sdei_to_linux_errno() and is used to suppress messages
155 res.a0 = SDEI_NOT_SUPPORTED;
163 NOKPROBE_SYMBOL(invoke_sdei_fn);
165 static struct sdei_event *sdei_event_find(u32 event_num)
167 struct sdei_event *e, *found = NULL;
169 lockdep_assert_held(&sdei_events_lock);
171 spin_lock(&sdei_list_lock);
172 list_for_each_entry(e, &sdei_list, list) {
173 if (e->event_num == event_num) {
178 spin_unlock(&sdei_list_lock);
183 int sdei_api_event_context(u32 query, u64 *result)
185 return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_CONTEXT, query, 0, 0, 0, 0,
188 NOKPROBE_SYMBOL(sdei_api_event_context);
190 static int sdei_api_event_get_info(u32 event, u32 info, u64 *result)
192 return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_GET_INFO, event, info, 0,
196 static struct sdei_event *sdei_event_create(u32 event_num,
197 sdei_event_callback *cb,
202 struct sdei_event *event;
203 struct sdei_registered_event *reg;
205 lockdep_assert_held(&sdei_events_lock);
207 event = kzalloc(sizeof(*event), GFP_KERNEL);
213 INIT_LIST_HEAD(&event->list);
214 event->event_num = event_num;
216 err = sdei_api_event_get_info(event_num, SDEI_EVENT_INFO_EV_PRIORITY,
220 event->priority = result;
222 err = sdei_api_event_get_info(event_num, SDEI_EVENT_INFO_EV_TYPE,
226 event->type = result;
228 if (event->type == SDEI_EVENT_TYPE_SHARED) {
229 reg = kzalloc(sizeof(*reg), GFP_KERNEL);
235 reg->event_num = event->event_num;
236 reg->priority = event->priority;
239 reg->callback_arg = cb_arg;
240 event->registered = reg;
243 struct sdei_registered_event __percpu *regs;
245 regs = alloc_percpu(struct sdei_registered_event);
251 for_each_possible_cpu(cpu) {
252 reg = per_cpu_ptr(regs, cpu);
254 reg->event_num = event->event_num;
255 reg->priority = event->priority;
257 reg->callback_arg = cb_arg;
260 event->private_registered = regs;
263 spin_lock(&sdei_list_lock);
264 list_add(&event->list, &sdei_list);
265 spin_unlock(&sdei_list_lock);
274 static void sdei_event_destroy_llocked(struct sdei_event *event)
276 lockdep_assert_held(&sdei_events_lock);
277 lockdep_assert_held(&sdei_list_lock);
279 list_del(&event->list);
281 if (event->type == SDEI_EVENT_TYPE_SHARED)
282 kfree(event->registered);
284 free_percpu(event->private_registered);
289 static void sdei_event_destroy(struct sdei_event *event)
291 spin_lock(&sdei_list_lock);
292 sdei_event_destroy_llocked(event);
293 spin_unlock(&sdei_list_lock);
296 static int sdei_api_get_version(u64 *version)
298 return invoke_sdei_fn(SDEI_1_0_FN_SDEI_VERSION, 0, 0, 0, 0, 0, version);
301 int sdei_mask_local_cpu(void)
305 WARN_ON_ONCE(preemptible());
307 err = invoke_sdei_fn(SDEI_1_0_FN_SDEI_PE_MASK, 0, 0, 0, 0, 0, NULL);
308 if (err && err != -EIO) {
309 pr_warn_once("failed to mask CPU[%u]: %d\n",
310 smp_processor_id(), err);
317 static void _ipi_mask_cpu(void *ignored)
319 sdei_mask_local_cpu();
322 int sdei_unmask_local_cpu(void)
326 WARN_ON_ONCE(preemptible());
328 err = invoke_sdei_fn(SDEI_1_0_FN_SDEI_PE_UNMASK, 0, 0, 0, 0, 0, NULL);
329 if (err && err != -EIO) {
330 pr_warn_once("failed to unmask CPU[%u]: %d\n",
331 smp_processor_id(), err);
338 static void _ipi_unmask_cpu(void *ignored)
340 sdei_unmask_local_cpu();
343 static void _ipi_private_reset(void *ignored)
347 err = invoke_sdei_fn(SDEI_1_0_FN_SDEI_PRIVATE_RESET, 0, 0, 0, 0, 0,
349 if (err && err != -EIO)
350 pr_warn_once("failed to reset CPU[%u]: %d\n",
351 smp_processor_id(), err);
354 static int sdei_api_shared_reset(void)
356 return invoke_sdei_fn(SDEI_1_0_FN_SDEI_SHARED_RESET, 0, 0, 0, 0, 0,
360 static void sdei_mark_interface_broken(void)
362 pr_err("disabling SDEI firmware interface\n");
363 on_each_cpu(&_ipi_mask_cpu, NULL, true);
364 sdei_firmware_call = NULL;
367 static int sdei_platform_reset(void)
371 on_each_cpu(&_ipi_private_reset, NULL, true);
372 err = sdei_api_shared_reset();
374 pr_err("Failed to reset platform: %d\n", err);
375 sdei_mark_interface_broken();
381 static int sdei_api_event_enable(u32 event_num)
383 return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_ENABLE, event_num, 0, 0, 0,
387 /* Called directly by the hotplug callbacks */
388 static void _local_event_enable(void *data)
391 struct sdei_crosscall_args *arg = data;
393 WARN_ON_ONCE(preemptible());
395 err = sdei_api_event_enable(arg->event->event_num);
397 sdei_cross_call_return(arg, err);
400 int sdei_event_enable(u32 event_num)
403 struct sdei_event *event;
405 mutex_lock(&sdei_events_lock);
406 event = sdei_event_find(event_num);
408 mutex_unlock(&sdei_events_lock);
414 if (event->type == SDEI_EVENT_TYPE_SHARED)
415 err = sdei_api_event_enable(event->event_num);
417 err = sdei_do_cross_call(_local_event_enable, event);
420 spin_lock(&sdei_list_lock);
421 event->reenable = true;
422 spin_unlock(&sdei_list_lock);
425 mutex_unlock(&sdei_events_lock);
430 static int sdei_api_event_disable(u32 event_num)
432 return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_DISABLE, event_num, 0, 0,
436 static void _ipi_event_disable(void *data)
439 struct sdei_crosscall_args *arg = data;
441 err = sdei_api_event_disable(arg->event->event_num);
443 sdei_cross_call_return(arg, err);
446 int sdei_event_disable(u32 event_num)
449 struct sdei_event *event;
451 mutex_lock(&sdei_events_lock);
452 event = sdei_event_find(event_num);
454 mutex_unlock(&sdei_events_lock);
458 spin_lock(&sdei_list_lock);
459 event->reenable = false;
460 spin_unlock(&sdei_list_lock);
462 if (event->type == SDEI_EVENT_TYPE_SHARED)
463 err = sdei_api_event_disable(event->event_num);
465 err = sdei_do_cross_call(_ipi_event_disable, event);
466 mutex_unlock(&sdei_events_lock);
471 static int sdei_api_event_unregister(u32 event_num)
473 return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_UNREGISTER, event_num, 0,
477 /* Called directly by the hotplug callbacks */
478 static void _local_event_unregister(void *data)
481 struct sdei_crosscall_args *arg = data;
483 WARN_ON_ONCE(preemptible());
485 err = sdei_api_event_unregister(arg->event->event_num);
487 sdei_cross_call_return(arg, err);
490 int sdei_event_unregister(u32 event_num)
493 struct sdei_event *event;
497 mutex_lock(&sdei_events_lock);
498 event = sdei_event_find(event_num);
500 pr_warn("Event %u not registered\n", event_num);
505 spin_lock(&sdei_list_lock);
506 event->reregister = false;
507 event->reenable = false;
508 spin_unlock(&sdei_list_lock);
510 if (event->type == SDEI_EVENT_TYPE_SHARED)
511 err = sdei_api_event_unregister(event->event_num);
513 err = sdei_do_cross_call(_local_event_unregister, event);
518 sdei_event_destroy(event);
520 mutex_unlock(&sdei_events_lock);
526 * unregister events, but don't destroy them as they are re-registered by
527 * sdei_reregister_shared().
529 static int sdei_unregister_shared(void)
532 struct sdei_event *event;
534 mutex_lock(&sdei_events_lock);
535 spin_lock(&sdei_list_lock);
536 list_for_each_entry(event, &sdei_list, list) {
537 if (event->type != SDEI_EVENT_TYPE_SHARED)
540 err = sdei_api_event_unregister(event->event_num);
544 spin_unlock(&sdei_list_lock);
545 mutex_unlock(&sdei_events_lock);
550 static int sdei_api_event_register(u32 event_num, unsigned long entry_point,
551 void *arg, u64 flags, u64 affinity)
553 return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_REGISTER, event_num,
554 (unsigned long)entry_point, (unsigned long)arg,
555 flags, affinity, NULL);
558 /* Called directly by the hotplug callbacks */
559 static void _local_event_register(void *data)
562 struct sdei_registered_event *reg;
563 struct sdei_crosscall_args *arg = data;
565 WARN_ON(preemptible());
567 reg = per_cpu_ptr(arg->event->private_registered, smp_processor_id());
568 err = sdei_api_event_register(arg->event->event_num, sdei_entry_point,
571 sdei_cross_call_return(arg, err);
574 int sdei_event_register(u32 event_num, sdei_event_callback *cb, void *arg)
577 struct sdei_event *event;
581 mutex_lock(&sdei_events_lock);
582 if (sdei_event_find(event_num)) {
583 pr_warn("Event %u already registered\n", event_num);
588 event = sdei_event_create(event_num, cb, arg);
590 err = PTR_ERR(event);
591 pr_warn("Failed to create event %u: %d\n", event_num, err);
596 if (event->type == SDEI_EVENT_TYPE_SHARED) {
597 err = sdei_api_event_register(event->event_num,
600 SDEI_EVENT_REGISTER_RM_ANY, 0);
602 err = sdei_do_cross_call(_local_event_register, event);
604 sdei_do_cross_call(_local_event_unregister, event);
608 sdei_event_destroy(event);
609 pr_warn("Failed to register event %u: %d\n", event_num, err);
613 spin_lock(&sdei_list_lock);
614 event->reregister = true;
615 spin_unlock(&sdei_list_lock);
619 mutex_unlock(&sdei_events_lock);
623 static int sdei_reregister_shared(void)
626 struct sdei_event *event;
628 mutex_lock(&sdei_events_lock);
629 spin_lock(&sdei_list_lock);
630 list_for_each_entry(event, &sdei_list, list) {
631 if (event->type != SDEI_EVENT_TYPE_SHARED)
634 if (event->reregister) {
635 err = sdei_api_event_register(event->event_num,
636 sdei_entry_point, event->registered,
637 SDEI_EVENT_REGISTER_RM_ANY, 0);
639 pr_err("Failed to re-register event %u\n",
641 sdei_event_destroy_llocked(event);
646 if (event->reenable) {
647 err = sdei_api_event_enable(event->event_num);
649 pr_err("Failed to re-enable event %u\n",
655 spin_unlock(&sdei_list_lock);
656 mutex_unlock(&sdei_events_lock);
661 static int sdei_cpuhp_down(unsigned int cpu)
663 struct sdei_event *event;
666 /* un-register private events */
667 spin_lock(&sdei_list_lock);
668 list_for_each_entry(event, &sdei_list, list) {
669 if (event->type == SDEI_EVENT_TYPE_SHARED)
672 err = sdei_do_local_call(_local_event_unregister, event);
674 pr_err("Failed to unregister event %u: %d\n",
675 event->event_num, err);
678 spin_unlock(&sdei_list_lock);
680 return sdei_mask_local_cpu();
683 static int sdei_cpuhp_up(unsigned int cpu)
685 struct sdei_event *event;
688 /* re-register/enable private events */
689 spin_lock(&sdei_list_lock);
690 list_for_each_entry(event, &sdei_list, list) {
691 if (event->type == SDEI_EVENT_TYPE_SHARED)
694 if (event->reregister) {
695 err = sdei_do_local_call(_local_event_register, event);
697 pr_err("Failed to re-register event %u: %d\n",
698 event->event_num, err);
702 if (event->reenable) {
703 err = sdei_do_local_call(_local_event_enable, event);
705 pr_err("Failed to re-enable event %u: %d\n",
706 event->event_num, err);
710 spin_unlock(&sdei_list_lock);
712 return sdei_unmask_local_cpu();
715 /* When entering idle, mask/unmask events for this cpu */
716 static int sdei_pm_notifier(struct notifier_block *nb, unsigned long action,
723 rv = sdei_mask_local_cpu();
726 case CPU_PM_ENTER_FAILED:
727 rv = sdei_unmask_local_cpu();
734 return notifier_from_errno(rv);
739 static struct notifier_block sdei_pm_nb = {
740 .notifier_call = sdei_pm_notifier,
743 static int sdei_device_suspend(struct device *dev)
745 on_each_cpu(_ipi_mask_cpu, NULL, true);
750 static int sdei_device_resume(struct device *dev)
752 on_each_cpu(_ipi_unmask_cpu, NULL, true);
758 * We need all events to be reregistered when we resume from hibernate.
760 * The sequence is freeze->thaw. Reboot. freeze->restore. We unregister
761 * events during freeze, then re-register and re-enable them during thaw
764 static int sdei_device_freeze(struct device *dev)
768 /* unregister private events */
769 cpuhp_remove_state(CPUHP_AP_ARM_SDEI_STARTING);
771 err = sdei_unregister_shared();
778 static int sdei_device_thaw(struct device *dev)
782 /* re-register shared events */
783 err = sdei_reregister_shared();
785 pr_warn("Failed to re-register shared events...\n");
786 sdei_mark_interface_broken();
790 err = cpuhp_setup_state(CPUHP_AP_ARM_SDEI_STARTING, "SDEI",
791 &sdei_cpuhp_up, &sdei_cpuhp_down);
793 pr_warn("Failed to re-register CPU hotplug notifier...\n");
798 static int sdei_device_restore(struct device *dev)
802 err = sdei_platform_reset();
806 return sdei_device_thaw(dev);
809 static const struct dev_pm_ops sdei_pm_ops = {
810 .suspend = sdei_device_suspend,
811 .resume = sdei_device_resume,
812 .freeze = sdei_device_freeze,
813 .thaw = sdei_device_thaw,
814 .restore = sdei_device_restore,
818 * Mask all CPUs and unregister all events on panic, reboot or kexec.
820 static int sdei_reboot_notifier(struct notifier_block *nb, unsigned long action,
824 * We are going to reset the interface, after this there is no point
825 * doing work when we take CPUs offline.
827 cpuhp_remove_state(CPUHP_AP_ARM_SDEI_STARTING);
829 sdei_platform_reset();
834 static struct notifier_block sdei_reboot_nb = {
835 .notifier_call = sdei_reboot_notifier,
838 static void sdei_smccc_smc(unsigned long function_id,
839 unsigned long arg0, unsigned long arg1,
840 unsigned long arg2, unsigned long arg3,
841 unsigned long arg4, struct arm_smccc_res *res)
843 arm_smccc_smc(function_id, arg0, arg1, arg2, arg3, arg4, 0, 0, res);
845 NOKPROBE_SYMBOL(sdei_smccc_smc);
847 static void sdei_smccc_hvc(unsigned long function_id,
848 unsigned long arg0, unsigned long arg1,
849 unsigned long arg2, unsigned long arg3,
850 unsigned long arg4, struct arm_smccc_res *res)
852 arm_smccc_hvc(function_id, arg0, arg1, arg2, arg3, arg4, 0, 0, res);
854 NOKPROBE_SYMBOL(sdei_smccc_hvc);
856 int sdei_register_ghes(struct ghes *ghes, sdei_event_callback *normal_cb,
857 sdei_event_callback *critical_cb)
862 sdei_event_callback *cb;
864 if (!IS_ENABLED(CONFIG_ACPI_APEI_GHES))
867 event_num = ghes->generic->notify.vector;
868 if (event_num == 0) {
870 * Event 0 is reserved by the specification for
876 err = sdei_api_event_get_info(event_num, SDEI_EVENT_INFO_EV_PRIORITY,
881 if (result == SDEI_EVENT_PRIORITY_CRITICAL)
886 err = sdei_event_register(event_num, cb, ghes);
888 err = sdei_event_enable(event_num);
893 int sdei_unregister_ghes(struct ghes *ghes)
897 u32 event_num = ghes->generic->notify.vector;
901 if (!IS_ENABLED(CONFIG_ACPI_APEI_GHES))
905 * The event may be running on another CPU. Disable it
906 * to stop new events, then try to unregister a few times.
908 err = sdei_event_disable(event_num);
912 for (i = 0; i < 3; i++) {
913 err = sdei_event_unregister(event_num);
914 if (err != -EINPROGRESS)
923 static int sdei_get_conduit(struct platform_device *pdev)
926 struct device_node *np = pdev->dev.of_node;
928 sdei_firmware_call = NULL;
930 if (of_property_read_string(np, "method", &method)) {
931 pr_warn("missing \"method\" property\n");
932 return SMCCC_CONDUIT_NONE;
935 if (!strcmp("hvc", method)) {
936 sdei_firmware_call = &sdei_smccc_hvc;
937 return SMCCC_CONDUIT_HVC;
938 } else if (!strcmp("smc", method)) {
939 sdei_firmware_call = &sdei_smccc_smc;
940 return SMCCC_CONDUIT_SMC;
943 pr_warn("invalid \"method\" property: %s\n", method);
944 } else if (!acpi_disabled) {
945 if (acpi_psci_use_hvc()) {
946 sdei_firmware_call = &sdei_smccc_hvc;
947 return SMCCC_CONDUIT_HVC;
949 sdei_firmware_call = &sdei_smccc_smc;
950 return SMCCC_CONDUIT_SMC;
954 return SMCCC_CONDUIT_NONE;
957 static int sdei_probe(struct platform_device *pdev)
963 conduit = sdei_get_conduit(pdev);
964 if (!sdei_firmware_call)
967 err = sdei_api_get_version(&ver);
969 pr_err("Failed to get SDEI version: %d\n", err);
970 sdei_mark_interface_broken();
974 pr_info("SDEIv%d.%d (0x%x) detected in firmware.\n",
975 (int)SDEI_VERSION_MAJOR(ver), (int)SDEI_VERSION_MINOR(ver),
976 (int)SDEI_VERSION_VENDOR(ver));
978 if (SDEI_VERSION_MAJOR(ver) != 1) {
979 pr_warn("Conflicting SDEI version detected.\n");
980 sdei_mark_interface_broken();
984 err = sdei_platform_reset();
988 sdei_entry_point = sdei_arch_get_entry_point(conduit);
989 if (!sdei_entry_point) {
990 /* Not supported due to hardware or boot configuration */
991 sdei_mark_interface_broken();
995 err = cpu_pm_register_notifier(&sdei_pm_nb);
997 pr_warn("Failed to register CPU PM notifier...\n");
1001 err = register_reboot_notifier(&sdei_reboot_nb);
1003 pr_warn("Failed to register reboot notifier...\n");
1007 err = cpuhp_setup_state(CPUHP_AP_ARM_SDEI_STARTING, "SDEI",
1008 &sdei_cpuhp_up, &sdei_cpuhp_down);
1010 pr_warn("Failed to register CPU hotplug notifier...\n");
1017 unregister_reboot_notifier(&sdei_reboot_nb);
1020 cpu_pm_unregister_notifier(&sdei_pm_nb);
1023 sdei_mark_interface_broken();
1027 static const struct of_device_id sdei_of_match[] = {
1028 { .compatible = "arm,sdei-1.0" },
1032 static struct platform_driver sdei_driver = {
1036 .of_match_table = sdei_of_match,
1038 .probe = sdei_probe,
1041 static bool __init sdei_present_acpi(void)
1044 struct acpi_table_header *sdei_table_header;
1049 status = acpi_get_table(ACPI_SIG_SDEI, 0, &sdei_table_header);
1050 if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
1051 const char *msg = acpi_format_exception(status);
1053 pr_info("Failed to get ACPI:SDEI table, %s\n", msg);
1055 if (ACPI_FAILURE(status))
1058 acpi_put_table(sdei_table_header);
1063 static int __init sdei_init(void)
1065 struct platform_device *pdev;
1068 ret = platform_driver_register(&sdei_driver);
1069 if (ret || !sdei_present_acpi())
1072 pdev = platform_device_register_simple(sdei_driver.driver.name,
1075 ret = PTR_ERR(pdev);
1076 platform_driver_unregister(&sdei_driver);
1077 pr_info("Failed to register ACPI:SDEI platform device %d\n",
1085 * On an ACPI system SDEI needs to be ready before HEST:GHES tries to register
1086 * its events. ACPI is initialised from a subsys_initcall(), GHES is initialised
1087 * by device_initcall(). We want to be called in the middle.
1089 subsys_initcall_sync(sdei_init);
1091 int sdei_event_handler(struct pt_regs *regs,
1092 struct sdei_registered_event *arg)
1095 mm_segment_t orig_addr_limit;
1096 u32 event_num = arg->event_num;
1099 * Save restore 'fs'.
1100 * The architecture's entry code save/restores 'fs' when taking an
1101 * exception from the kernel. This ensures addr_limit isn't inherited
1102 * if you interrupted something that allowed the uaccess routines to
1103 * access kernel memory.
1104 * Do the same here because this doesn't come via the same entry code.
1106 orig_addr_limit = force_uaccess_begin();
1108 err = arg->callback(event_num, regs, arg->callback_arg);
1110 pr_err_ratelimited("event %u on CPU %u failed with error: %d\n",
1111 event_num, smp_processor_id(), err);
1113 force_uaccess_end(orig_addr_limit);
1117 NOKPROBE_SYMBOL(sdei_event_handler);