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-rw-r--r--drivers/firmware/efi/efi.c14
-rw-r--r--drivers/firmware/efi/runtime-wrappers.c202
-rw-r--r--include/linux/efi.h3
3 files changed, 204 insertions, 15 deletions
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 232f4915223b..1379a375dfa8 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -84,6 +84,8 @@ struct mm_struct efi_mm = {
.mmlist = LIST_HEAD_INIT(efi_mm.mmlist),
};
+struct workqueue_struct *efi_rts_wq;
+
static bool disable_runtime;
static int __init setup_noefi(char *arg)
{
@@ -337,6 +339,18 @@ static int __init efisubsys_init(void)
if (!efi_enabled(EFI_BOOT))
return 0;
+ /*
+ * Since we process only one efi_runtime_service() at a time, an
+ * ordered workqueue (which creates only one execution context)
+ * should suffice all our needs.
+ */
+ efi_rts_wq = alloc_ordered_workqueue("efi_rts_wq", 0);
+ if (!efi_rts_wq) {
+ pr_err("Creating efi_rts_wq failed, EFI runtime services disabled.\n");
+ clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+ return 0;
+ }
+
/* We register the efi directory at /sys/firmware/efi */
efi_kobj = kobject_create_and_add("efi", firmware_kobj);
if (!efi_kobj) {
diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
index ae54870b2788..aa66cbf23512 100644
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -1,6 +1,15 @@
/*
* runtime-wrappers.c - Runtime Services function call wrappers
*
+ * Implementation summary:
+ * -----------------------
+ * 1. When user/kernel thread requests to execute efi_runtime_service(),
+ * enqueue work to efi_rts_wq.
+ * 2. Caller thread waits for completion until the work is finished
+ * because it's dependent on the return status and execution of
+ * efi_runtime_service().
+ * For instance, get_variable() and get_next_variable().
+ *
* Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
*
* Split off from arch/x86/platform/efi/efi.c
@@ -22,6 +31,9 @@
#include <linux/mutex.h>
#include <linux/semaphore.h>
#include <linux/stringify.h>
+#include <linux/workqueue.h>
+#include <linux/completion.h>
+
#include <asm/efi.h>
/*
@@ -33,6 +45,76 @@
#define __efi_call_virt(f, args...) \
__efi_call_virt_pointer(efi.systab->runtime, f, args)
+/* efi_runtime_service() function identifiers */
+enum efi_rts_ids {
+ GET_TIME,
+ SET_TIME,
+ GET_WAKEUP_TIME,
+ SET_WAKEUP_TIME,
+ GET_VARIABLE,
+ GET_NEXT_VARIABLE,
+ SET_VARIABLE,
+ QUERY_VARIABLE_INFO,
+ GET_NEXT_HIGH_MONO_COUNT,
+ UPDATE_CAPSULE,
+ QUERY_CAPSULE_CAPS,
+};
+
+/*
+ * efi_runtime_work: Details of EFI Runtime Service work
+ * @arg<1-5>: EFI Runtime Service function arguments
+ * @status: Status of executing EFI Runtime Service
+ * @efi_rts_id: EFI Runtime Service function identifier
+ * @efi_rts_comp: Struct used for handling completions
+ */
+struct efi_runtime_work {
+ void *arg1;
+ void *arg2;
+ void *arg3;
+ void *arg4;
+ void *arg5;
+ efi_status_t status;
+ struct work_struct work;
+ enum efi_rts_ids efi_rts_id;
+ struct completion efi_rts_comp;
+};
+
+/*
+ * efi_queue_work: Queue efi_runtime_service() and wait until it's done
+ * @rts: efi_runtime_service() function identifier
+ * @rts_arg<1-5>: efi_runtime_service() function arguments
+ *
+ * Accesses to efi_runtime_services() are serialized by a binary
+ * semaphore (efi_runtime_lock) and caller waits until the work is
+ * finished, hence _only_ one work is queued at a time and the caller
+ * thread waits for completion.
+ */
+#define efi_queue_work(_rts, _arg1, _arg2, _arg3, _arg4, _arg5) \
+({ \
+ struct efi_runtime_work efi_rts_work; \
+ efi_rts_work.status = EFI_ABORTED; \
+ \
+ init_completion(&efi_rts_work.efi_rts_comp); \
+ INIT_WORK_ONSTACK(&efi_rts_work.work, efi_call_rts); \
+ efi_rts_work.arg1 = _arg1; \
+ efi_rts_work.arg2 = _arg2; \
+ efi_rts_work.arg3 = _arg3; \
+ efi_rts_work.arg4 = _arg4; \
+ efi_rts_work.arg5 = _arg5; \
+ efi_rts_work.efi_rts_id = _rts; \
+ \
+ /* \
+ * queue_work() returns 0 if work was already on queue, \
+ * _ideally_ this should never happen. \
+ */ \
+ if (queue_work(efi_rts_wq, &efi_rts_work.work)) \
+ wait_for_completion(&efi_rts_work.efi_rts_comp); \
+ else \
+ pr_err("Failed to queue work to efi_rts_wq.\n"); \
+ \
+ efi_rts_work.status; \
+})
+
void efi_call_virt_check_flags(unsigned long flags, const char *call)
{
unsigned long cur_flags, mismatch;
@@ -90,13 +172,98 @@ void efi_call_virt_check_flags(unsigned long flags, const char *call)
*/
static DEFINE_SEMAPHORE(efi_runtime_lock);
+/*
+ * Calls the appropriate efi_runtime_service() with the appropriate
+ * arguments.
+ *
+ * Semantics followed by efi_call_rts() to understand efi_runtime_work:
+ * 1. If argument was a pointer, recast it from void pointer to original
+ * pointer type.
+ * 2. If argument was a value, recast it from void pointer to original
+ * pointer type and dereference it.
+ */
+static void efi_call_rts(struct work_struct *work)
+{
+ struct efi_runtime_work *efi_rts_work;
+ void *arg1, *arg2, *arg3, *arg4, *arg5;
+ efi_status_t status = EFI_NOT_FOUND;
+
+ efi_rts_work = container_of(work, struct efi_runtime_work, work);
+ arg1 = efi_rts_work->arg1;
+ arg2 = efi_rts_work->arg2;
+ arg3 = efi_rts_work->arg3;
+ arg4 = efi_rts_work->arg4;
+ arg5 = efi_rts_work->arg5;
+
+ switch (efi_rts_work->efi_rts_id) {
+ case GET_TIME:
+ status = efi_call_virt(get_time, (efi_time_t *)arg1,
+ (efi_time_cap_t *)arg2);
+ break;
+ case SET_TIME:
+ status = efi_call_virt(set_time, (efi_time_t *)arg1);
+ break;
+ case GET_WAKEUP_TIME:
+ status = efi_call_virt(get_wakeup_time, (efi_bool_t *)arg1,
+ (efi_bool_t *)arg2, (efi_time_t *)arg3);
+ break;
+ case SET_WAKEUP_TIME:
+ status = efi_call_virt(set_wakeup_time, *(efi_bool_t *)arg1,
+ (efi_time_t *)arg2);
+ break;
+ case GET_VARIABLE:
+ status = efi_call_virt(get_variable, (efi_char16_t *)arg1,
+ (efi_guid_t *)arg2, (u32 *)arg3,
+ (unsigned long *)arg4, (void *)arg5);
+ break;
+ case GET_NEXT_VARIABLE:
+ status = efi_call_virt(get_next_variable, (unsigned long *)arg1,
+ (efi_char16_t *)arg2,
+ (efi_guid_t *)arg3);
+ break;
+ case SET_VARIABLE:
+ status = efi_call_virt(set_variable, (efi_char16_t *)arg1,
+ (efi_guid_t *)arg2, *(u32 *)arg3,
+ *(unsigned long *)arg4, (void *)arg5);
+ break;
+ case QUERY_VARIABLE_INFO:
+ status = efi_call_virt(query_variable_info, *(u32 *)arg1,
+ (u64 *)arg2, (u64 *)arg3, (u64 *)arg4);
+ break;
+ case GET_NEXT_HIGH_MONO_COUNT:
+ status = efi_call_virt(get_next_high_mono_count, (u32 *)arg1);
+ break;
+ case UPDATE_CAPSULE:
+ status = efi_call_virt(update_capsule,
+ (efi_capsule_header_t **)arg1,
+ *(unsigned long *)arg2,
+ *(unsigned long *)arg3);
+ break;
+ case QUERY_CAPSULE_CAPS:
+ status = efi_call_virt(query_capsule_caps,
+ (efi_capsule_header_t **)arg1,
+ *(unsigned long *)arg2, (u64 *)arg3,
+ (int *)arg4);
+ break;
+ default:
+ /*
+ * Ideally, we should never reach here because a caller of this
+ * function should have put the right efi_runtime_service()
+ * function identifier into efi_rts_work->efi_rts_id
+ */
+ pr_err("Requested executing invalid EFI Runtime Service.\n");
+ }
+ efi_rts_work->status = status;
+ complete(&efi_rts_work->efi_rts_comp);
+}
+
static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
{
efi_status_t status;
if (down_interruptible(&efi_runtime_lock))
return EFI_ABORTED;
- status = efi_call_virt(get_time, tm, tc);
+ status = efi_queue_work(GET_TIME, tm, tc, NULL, NULL, NULL);
up(&efi_runtime_lock);
return status;
}
@@ -107,7 +274,7 @@ static efi_status_t virt_efi_set_time(efi_time_t *tm)
if (down_interruptible(&efi_runtime_lock))
return EFI_ABORTED;
- status = efi_call_virt(set_time, tm);
+ status = efi_queue_work(SET_TIME, tm, NULL, NULL, NULL, NULL);
up(&efi_runtime_lock);
return status;
}
@@ -120,7 +287,8 @@ static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled,
if (down_interruptible(&efi_runtime_lock))
return EFI_ABORTED;
- status = efi_call_virt(get_wakeup_time, enabled, pending, tm);
+ status = efi_queue_work(GET_WAKEUP_TIME, enabled, pending, tm, NULL,
+ NULL);
up(&efi_runtime_lock);
return status;
}
@@ -131,7 +299,8 @@ static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
if (down_interruptible(&efi_runtime_lock))
return EFI_ABORTED;
- status = efi_call_virt(set_wakeup_time, enabled, tm);
+ status = efi_queue_work(SET_WAKEUP_TIME, &enabled, tm, NULL, NULL,
+ NULL);
up(&efi_runtime_lock);
return status;
}
@@ -146,8 +315,8 @@ static efi_status_t virt_efi_get_variable(efi_char16_t *name,
if (down_interruptible(&efi_runtime_lock))
return EFI_ABORTED;
- status = efi_call_virt(get_variable, name, vendor, attr, data_size,
- data);
+ status = efi_queue_work(GET_VARIABLE, name, vendor, attr, data_size,
+ data);
up(&efi_runtime_lock);
return status;
}
@@ -160,7 +329,8 @@ static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
if (down_interruptible(&efi_runtime_lock))
return EFI_ABORTED;
- status = efi_call_virt(get_next_variable, name_size, name, vendor);
+ status = efi_queue_work(GET_NEXT_VARIABLE, name_size, name, vendor,
+ NULL, NULL);
up(&efi_runtime_lock);
return status;
}
@@ -175,8 +345,8 @@ static efi_status_t virt_efi_set_variable(efi_char16_t *name,
if (down_interruptible(&efi_runtime_lock))
return EFI_ABORTED;
- status = efi_call_virt(set_variable, name, vendor, attr, data_size,
- data);
+ status = efi_queue_work(SET_VARIABLE, name, vendor, &attr, &data_size,
+ data);
up(&efi_runtime_lock);
return status;
}
@@ -210,8 +380,8 @@ static efi_status_t virt_efi_query_variable_info(u32 attr,
if (down_interruptible(&efi_runtime_lock))
return EFI_ABORTED;
- status = efi_call_virt(query_variable_info, attr, storage_space,
- remaining_space, max_variable_size);
+ status = efi_queue_work(QUERY_VARIABLE_INFO, &attr, storage_space,
+ remaining_space, max_variable_size, NULL);
up(&efi_runtime_lock);
return status;
}
@@ -242,7 +412,8 @@ static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
if (down_interruptible(&efi_runtime_lock))
return EFI_ABORTED;
- status = efi_call_virt(get_next_high_mono_count, count);
+ status = efi_queue_work(GET_NEXT_HIGH_MONO_COUNT, count, NULL, NULL,
+ NULL, NULL);
up(&efi_runtime_lock);
return status;
}
@@ -272,7 +443,8 @@ static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules,
if (down_interruptible(&efi_runtime_lock))
return EFI_ABORTED;
- status = efi_call_virt(update_capsule, capsules, count, sg_list);
+ status = efi_queue_work(UPDATE_CAPSULE, capsules, &count, &sg_list,
+ NULL, NULL);
up(&efi_runtime_lock);
return status;
}
@@ -289,8 +461,8 @@ static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
if (down_interruptible(&efi_runtime_lock))
return EFI_ABORTED;
- status = efi_call_virt(query_capsule_caps, capsules, count, max_size,
- reset_type);
+ status = efi_queue_work(QUERY_CAPSULE_CAPS, capsules, &count,
+ max_size, reset_type, NULL);
up(&efi_runtime_lock);
return status;
}
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 56add823f190..8ba0cdd244b2 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1651,4 +1651,7 @@ struct linux_efi_tpm_eventlog {
extern int efi_tpm_eventlog_init(void);
+/* Workqueue to queue EFI Runtime Services */
+extern struct workqueue_struct *efi_rts_wq;
+
#endif /* _LINUX_EFI_H */
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.