Revert "firmware: arm_sdei: Fix sleep from invalid context BUG"

This reverts commit 48ac727ea4.

It is not needed in Android systems, and it breaks the ABI for no real
reason, so revert it.

Bug: 161946584
Change-Id: I0ee2f63bbf65ff04dea4434438e4ece97406f7a1
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/firmware/arm_sdei.c

@@ -44,8 +44,6 @@ static asmlinkage void (*sdei_firmware_call)(unsigned long function_id,
 /* entry point from firmware to arch asm code */
 static unsigned long sdei_entry_point;
 
-static int sdei_hp_state;
-
 struct sdei_event {
 	/* These three are protected by the sdei_list_lock */
 	struct list_head	list;
@@ -307,6 +305,8 @@ int sdei_mask_local_cpu(void)
 {
 	int err;
 
+	WARN_ON_ONCE(preemptible());
+
 	err = invoke_sdei_fn(SDEI_1_0_FN_SDEI_PE_MASK, 0, 0, 0, 0, 0, NULL);
 	if (err && err != -EIO) {
 		pr_warn_once("failed to mask CPU[%u]: %d\n",
@@ -319,7 +319,6 @@ int sdei_mask_local_cpu(void)
 
 static void _ipi_mask_cpu(void *ignored)
 {
-	WARN_ON_ONCE(preemptible());
 	sdei_mask_local_cpu();
 }
 
@@ -327,6 +326,8 @@ int sdei_unmask_local_cpu(void)
 {
 	int err;
 
+	WARN_ON_ONCE(preemptible());
+
 	err = invoke_sdei_fn(SDEI_1_0_FN_SDEI_PE_UNMASK, 0, 0, 0, 0, 0, NULL);
 	if (err && err != -EIO) {
 		pr_warn_once("failed to unmask CPU[%u]: %d\n",
@@ -339,7 +340,6 @@ int sdei_unmask_local_cpu(void)
 
 static void _ipi_unmask_cpu(void *ignored)
 {
-	WARN_ON_ONCE(preemptible());
 	sdei_unmask_local_cpu();
 }
 
@@ -347,8 +347,6 @@ static void _ipi_private_reset(void *ignored)
 {
 	int err;
 
-	WARN_ON_ONCE(preemptible());
-
 	err = invoke_sdei_fn(SDEI_1_0_FN_SDEI_PRIVATE_RESET, 0, 0, 0, 0, 0,
 			     NULL);
 	if (err && err != -EIO)
@@ -395,6 +393,8 @@ static void _local_event_enable(void *data)
 	int err;
 	struct sdei_crosscall_args *arg = data;
 
+	WARN_ON_ONCE(preemptible());
+
 	err = sdei_api_event_enable(arg->event->event_num);
 
 	sdei_cross_call_return(arg, err);
@@ -485,6 +485,8 @@ static void _local_event_unregister(void *data)
 	int err;
 	struct sdei_crosscall_args *arg = data;
 
+	WARN_ON_ONCE(preemptible());
+
 	err = sdei_api_event_unregister(arg->event->event_num);
 
 	sdei_cross_call_return(arg, err);
@@ -573,6 +575,8 @@ static void _local_event_register(void *data)
 	struct sdei_registered_event *reg;
 	struct sdei_crosscall_args *arg = data;
 
+	WARN_ON(preemptible());
+
 	reg = per_cpu_ptr(arg->event->private_registered, smp_processor_id());
 	err = sdei_api_event_register(arg->event->event_num, sdei_entry_point,
 				      reg, 0, 0);
@@ -752,8 +756,6 @@ static int sdei_pm_notifier(struct notifier_block *nb, unsigned long action,
 {
 	int rv;
 
-	WARN_ON_ONCE(preemptible());
-
 	switch (action) {
 	case CPU_PM_ENTER:
 		rv = sdei_mask_local_cpu();
@@ -802,7 +804,7 @@ static int sdei_device_freeze(struct device *dev)
 	int err;
 
 	/* unregister private events */
-	cpuhp_remove_state(sdei_entry_point);
+	cpuhp_remove_state(CPUHP_AP_ARM_SDEI_STARTING);
 
 	err = sdei_unregister_shared();
 	if (err)
@@ -823,15 +825,12 @@ static int sdei_device_thaw(struct device *dev)
 		return err;
 	}
 
-	err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "SDEI",
+	err = cpuhp_setup_state(CPUHP_AP_ARM_SDEI_STARTING, "SDEI",
 				&sdei_cpuhp_up, &sdei_cpuhp_down);
-	if (err < 0) {
+	if (err)
 		pr_warn("Failed to re-register CPU hotplug notifier...\n");
-		return err;
-	}
 
-	sdei_hp_state = err;
+	return err;
-	return 0;
 }
 
 static int sdei_device_restore(struct device *dev)
@@ -863,7 +862,7 @@ static int sdei_reboot_notifier(struct notifier_block *nb, unsigned long action,
 	 * We are going to reset the interface, after this there is no point
 	 * doing work when we take CPUs offline.
 	 */
-	cpuhp_remove_state(sdei_hp_state);
+	cpuhp_remove_state(CPUHP_AP_ARM_SDEI_STARTING);
 
 	sdei_platform_reset();
 
@@ -1045,15 +1044,13 @@ static int sdei_probe(struct platform_device *pdev)
 		goto remove_cpupm;
 	}
 
-	err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "SDEI",
+	err = cpuhp_setup_state(CPUHP_AP_ARM_SDEI_STARTING, "SDEI",
 				&sdei_cpuhp_up, &sdei_cpuhp_down);
-	if (err < 0) {
+	if (err) {
 		pr_warn("Failed to register CPU hotplug notifier...\n");
 		goto remove_reboot;
 	}
 
-	sdei_hp_state = err;
-
 	return 0;
 
 remove_reboot:

include/linux/cpuhotplug.h

@@ -110,6 +110,7 @@ enum cpuhp_state {
 	CPUHP_AP_PERF_X86_CSTATE_STARTING,
 	CPUHP_AP_PERF_XTENSA_STARTING,
 	CPUHP_AP_MIPS_OP_LOONGSON3_STARTING,
+	CPUHP_AP_ARM_SDEI_STARTING,
 	CPUHP_AP_ARM_VFP_STARTING,
 	CPUHP_AP_ARM64_DEBUG_MONITORS_STARTING,
 	CPUHP_AP_PERF_ARM_HW_BREAKPOINT_STARTING,