efi: Make efi_rts_work accessible to efi page fault handler

After the kernel has booted, if any accesses by firmware causes a page
fault, the efi page fault handler would freeze efi_rts_wq and schedules
a new process. To do this, the efi page fault handler needs
efi_rts_work. Hence, make it accessible.

There will be no race conditions in accessing this structure, because
all the calls to efi runtime services are already serialized.

Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
Suggested-by: Matt Fleming <matt@codeblueprint.co.uk>
Based-on-code-from: Ricardo Neri <ricardo.neri@intel.com>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
index aa66cbf23512af3c6e9195cd5b3471533a8f8e42..b18b2d864c2c39a743c8850c921962de870881ef 100644 (file)
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -45,39 +45,7 @@
 #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;
-};
+struct efi_runtime_work efi_rts_work;
 
 /*
  * efi_queue_work:     Queue efi_runtime_service() and wait until it's done
@@ -91,7 +59,6 @@ struct efi_runtime_work {
  */
 #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);                    \
@@ -184,18 +151,16 @@ static DEFINE_SEMAPHORE(efi_runtime_lock);
  */
 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;
+       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) {
+       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);
@@ -253,8 +218,8 @@ static void efi_call_rts(struct work_struct *work)
                 */
                pr_err("Requested executing invalid EFI Runtime Service.\n");
        }
-       efi_rts_work->status = status;
-       complete(&efi_rts_work->efi_rts_comp);
+       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)

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 22e4de9d370004bd5a65f56ab9d2084ac56f79dc..a929d2bf41fa5598be1b7a979c58f24833fe0f47 100644 (file)
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1662,6 +1662,42 @@ struct linux_efi_tpm_eventlog {
 
 extern int efi_tpm_eventlog_init(void);
 
+/* 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;
+};
+
+extern struct efi_runtime_work efi_rts_work;
+
 /* Workqueue to queue EFI Runtime Services */
 extern struct workqueue_struct *efi_rts_wq;