x86/resctrl: Drop __init/__exit on assorted symbols

Because ARM's MPAM controls are probed using MMIO, resctrl can't be
initialised until enough CPUs are online to have determined the system-wide
supported num_closid. Arm64 also supports 'late onlined secondaries', where
only a subset of CPUs are online during boot.

These two combine to mean the MPAM driver may not be able to initialise
resctrl until user-space has brought 'enough' CPUs online.

To allow MPAM to initialise resctrl after __init text has been free'd, remove
all the __init markings from resctrl.

The existing __exit markings cause these functions to be removed by the linker
as it has never been possible to build resctrl as a module. MPAM has an error
interrupt which causes the driver to reset and disable itself. Remove the
__exit markings to allow the MPAM driver to tear down resctrl when an error
occurs.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Tested-by: Fenghua Yu <fenghuay@nvidia.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Amit Singh Tomar <amitsinght@marvell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> # arm64
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/20250515165855.31452-10-james.morse@arm.com

arch/x86/kernel/cpu/resctrl/core.c

@@ -737,7 +737,7 @@ struct rdt_options {
 	bool	force_off, force_on;
 };
 
-static struct rdt_options rdt_options[]  __initdata = {
+static struct rdt_options rdt_options[]  __ro_after_init = {
 	RDT_OPT(RDT_FLAG_CMT,	    "cmt",	X86_FEATURE_CQM_OCCUP_LLC),
 	RDT_OPT(RDT_FLAG_MBM_TOTAL, "mbmtotal", X86_FEATURE_CQM_MBM_TOTAL),
 	RDT_OPT(RDT_FLAG_MBM_LOCAL, "mbmlocal", X86_FEATURE_CQM_MBM_LOCAL),
@@ -777,7 +777,7 @@ static int __init set_rdt_options(char *str)
 }
 __setup("rdt", set_rdt_options);
 
-bool __init rdt_cpu_has(int flag)
+bool rdt_cpu_has(int flag)
 {
 	bool ret = boot_cpu_has(flag);
 	struct rdt_options *o;
@@ -797,7 +797,7 @@ bool __init rdt_cpu_has(int flag)
 	return ret;
 }
 
-__init bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt)
+bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt)
 {
 	if (!rdt_cpu_has(X86_FEATURE_BMEC))
 		return false;

arch/x86/kernel/cpu/resctrl/internal.h

@@ -472,13 +472,13 @@ int alloc_rmid(u32 closid);
 void free_rmid(u32 closid, u32 rmid);
 int rdt_get_mon_l3_config(struct rdt_resource *r);
 void resctrl_mon_resource_exit(void);
-bool __init rdt_cpu_has(int flag);
+bool rdt_cpu_has(int flag);
 void mon_event_count(void *info);
 int rdtgroup_mondata_show(struct seq_file *m, void *arg);
 void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
 		    struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
 		    cpumask_t *cpumask, int evtid, int first);
-int __init resctrl_mon_resource_init(void);
+int resctrl_mon_resource_init(void);
 void mbm_setup_overflow_handler(struct rdt_mon_domain *dom,
 				unsigned long delay_ms,
 				int exclude_cpu);

arch/x86/kernel/cpu/resctrl/monitor.c

@@ -1204,7 +1204,7 @@ static __init int snc_get_config(void)
  *
  * Returns 0 for success, or -ENOMEM.
  */
-int __init resctrl_mon_resource_init(void)
+int resctrl_mon_resource_init(void)
 {
 	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
 	int ret;

arch/x86/kernel/cpu/resctrl/rdtgroup.c

@@ -4144,7 +4144,7 @@ static void rdtgroup_destroy_root(void)
 	rdtgroup_default.kn = NULL;
 }
 
-static void __init rdtgroup_setup_default(void)
+static void rdtgroup_setup_default(void)
 {
 	mutex_lock(&rdtgroup_mutex);
 
@@ -4376,7 +4376,7 @@ void resctrl_offline_cpu(unsigned int cpu)
  *
  * Return: 0 on success or -errno
  */
-int __init resctrl_init(void)
+int resctrl_init(void)
 {
 	int ret = 0;
 
@@ -4433,7 +4433,7 @@ int __init resctrl_init(void)
 	return ret;
 }
 
-static bool __exit resctrl_online_domains_exist(void)
+static bool resctrl_online_domains_exist(void)
 {
 	struct rdt_resource *r;
 
@@ -4471,7 +4471,7 @@ static bool __exit resctrl_online_domains_exist(void)
  * resctrl_arch_get_resource() must continue to return struct rdt_resources
  * with the correct rid field to ensure the filesystem can be unmounted.
  */
-void __exit resctrl_exit(void)
+void resctrl_exit(void)
 {
 	cpus_read_lock();
 	WARN_ON_ONCE(resctrl_online_domains_exist());

include/linux/resctrl.h

@@ -358,7 +358,7 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *r);
 u32 resctrl_arch_system_num_rmid_idx(void);
 int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
 
-__init bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);
+bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);
 
 /**
  * resctrl_arch_mon_event_config_write() - Write the config for an event.
@@ -514,7 +514,7 @@ void resctrl_arch_reset_all_ctrls(struct rdt_resource *r);
 extern unsigned int resctrl_rmid_realloc_threshold;
 extern unsigned int resctrl_rmid_realloc_limit;
 
-int __init resctrl_init(void);
-void __exit resctrl_exit(void);
+int resctrl_init(void);
+void resctrl_exit(void);
 
 #endif /* _RESCTRL_H */