[PATCH v8 05/21] x86/resctrl: Drop __init/__exit on assorted symbols

James Morse
2025-04-11T16:43:30Z

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>
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>
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>
---
Changes since v4:
* Earlier __init marker removal migrated here.
---
arch/x86/kernel/cpu/resctrl/core.c | 6 +++---
arch/x86/kernel/cpu/resctrl/internal.h | 4 ++--
arch/x86/kernel/cpu/resctrl/monitor.c | 2 +-
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 6 +++---
include/linux/resctrl.h | 6 +++---
5 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index cf29681d01e0..31538c65d9a2 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/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;
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index eaae99602b61..36a862a4832f 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -486,13 +486,13 @@ 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);
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index a93ed7d2a160..73e3fe4f4c87 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/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;
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 3f9c37637d7e..d1cffbc21115 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -4140,7 +4140,7 @@ 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);

@@ -4372,7 +4372,7 @@ 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;

@@ -4436,7 +4436,7 @@ int __init resctrl_init(void)
* Resctrl files and structures are removed from kernfs to prevent further
* configuration.
*/
-void __exit resctrl_exit(void)
+void resctrl_exit(void)
{
mutex_lock(&rdtgroup_mutex);
resctrl_fs_teardown();
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 880351ca3dfc..b8f8240050b4 100644
--- a/include/linux/resctrl.h
+++ b/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 */
--
2.20.1