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    SubjectRe: [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
    >

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