Re: [PATCH AUTOSEL 4.19 134/191] efi: Make efi_rts_work accessible to efi page fault handler

On Sun, 10 Nov 2019 at 03:44, Sasha Levin sashal@kernel.org wrote:

From: Sai Praneeth sai.praneeth.prakhya@intel.com

[ Upstream commit 9dbbedaa6171247c4c7c40b83f05b200a117c2e0 ]

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 Signed-off-by: Sasha Levin sashal@kernel.org

NAK

Would it be possible to disregard all EFI patches for -stable unless they have a fixes tag? EFI subtly depends on lots of firmware quirks across various architectures, and so grabbing random patches and backporting them is really not a good idea in general.

---

drivers/firmware/efi/runtime-wrappers.c | 53 +++++-------------------- include/linux/efi.h | 36 +++++++++++++++++ 2 files changed, 45 insertions(+), 44 deletions(-)

diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c index 1606abead22cc..b31e3d3729a6d 100644 --- 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);                    \
  

@@ -191,18 +158,16 @@ extern struct semaphore __efi_uv_runtime_lock __alias(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);
  

@@ -260,8 +225,8 @@ 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 f43fc61fbe2c9..9d4c25090fd04 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1666,6 +1666,42 @@ 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;

-- 2.20.1