[Query] How to pass reboot arguments to secure firmware with PSCI spec

[Query] How to pass reboot arguments to secure firmware with PSCI spec

[Jisheng Zhang]

Hi Catalin and Will,

I noticed that the following commit implement reboot via. PSCI SYSTEM_RESET
function. So my question is how to handle the reboot arguments? 


> static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
> {
>       invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);

How to pass cmd to secure firmware?

> }

Thanks in advance,
Jisheng

commit e71246a23acbc89e9cb4ebf1558d60e65733479f
Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Date:   Thu Apr 17 14:38:41 2014 -0400

    PSCI: Add initial support for PSCIv0.2 functions
    
    The PSCIv0.2 spec defines standard values of function IDs
    and introduces a few new functions. Detect version of PSCI
    and appropriately select the right PSCI functions.
    
    Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
    Reviewed-by: Rob Herring <robh@kernel.org>
    Acked-by: Catalin Marinas <catalin.marinas@arm.com>

[Query] How to pass reboot arguments to secure firmware with PSCI spec

[Sudeep Holla]

On 01/08/14 11:06, Jisheng Zhang wrote:
> Hi Catalin and Will,
>
> I noticed that the following commit implement reboot via. PSCI SYSTEM_RESET
> function. So my question is how to handle the reboot arguments?
>

What reboot arguments do you want to handle ?

>
>> static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
>> {
>>        invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
>
> How to pass cmd to secure firmware?
>

What cmd do you want to pass ? The function id is already handled. What
else do you want to pass ?

If you see PSCI v0.2 spec, the SYSTEM_RESET and SYSTEM_SHUTDOWN takes no
parameters.

Regards,
Sudeep

[Query] How to pass reboot arguments to secure firmware with PSCI spec

[Jisheng Zhang]

Hi Sudeep,

On Fri, 1 Aug 2014 03:21:12 -0700
Sudeep Holla <sudeep.holla@arm.com> wrote:

> 
> 
> On 01/08/14 11:06, Jisheng Zhang wrote:
> > Hi Catalin and Will,
> >
> > I noticed that the following commit implement reboot via. PSCI
> > SYSTEM_RESET function. So my question is how to handle the reboot
> > arguments?
> >
> 
> What reboot arguments do you want to handle ?

man 2 reboot

...

int reboot(int magic, int magic2, int cmd, void *arg);

...

I want to pass "void *arg" to secure firmware.


> 
> >
> >> static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
> >> {
> >>        invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
> >
> > How to pass cmd to secure firmware?
> >
> 
> What cmd do you want to pass ? The function id is already handled. What
> else do you want to pass ?

the "const char *cmd", usually this is the "abc" if user type "reboot abc"
under shell.

For example, android usually type "reboot recovery", the "recovery" will be
passed to next boot kernel boot args.

> 
> If you see PSCI v0.2 spec, the SYSTEM_RESET and SYSTEM_SHUTDOWN takes no
> parameters.

Yes. I know it. That's why I need your help/suggestions about how to handle
the situation above.

Thanks for your input,
Jisheng

[Query] How to pass reboot arguments to secure firmware with PSCI spec

[Sudeep Holla]

On 01/08/14 12:02, Jisheng Zhang wrote:
> Hi Sudeep,
>
> On Fri, 1 Aug 2014 03:21:12 -0700
> Sudeep Holla <sudeep.holla@arm.com> wrote:
>
>>
>>
>> On 01/08/14 11:06, Jisheng Zhang wrote:
>>> Hi Catalin and Will,
>>>
>>> I noticed that the following commit implement reboot via. PSCI
>>> SYSTEM_RESET function. So my question is how to handle the reboot
>>> arguments?
>>>
>>
>> What reboot arguments do you want to handle ?
>
> man 2 reboot
>
> ...
>
> int reboot(int magic, int magic2, int cmd, void *arg);
>
> ...
>
> I want to pass "void *arg" to secure firmware.
>
>

Why ? What will secure firmware do with that ? I can't think of any
use of those arguments in the secure firmware esp. the example you have
given below. Why should secure firmware know that you are booting in
recovery mode.

And you can't do that with PSCI, the specification has no provisions
and if do that it's violation.

>>
>>>
>>>> static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
>>>> {
>>>>         invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
>>>
>>> How to pass cmd to secure firmware?
>>>
>>
>> What cmd do you want to pass ? The function id is already handled. What
>> else do you want to pass ?
>
> the "const char *cmd", usually this is the "abc" if user type "reboot abc"
> under shell.
>
> For example, android usually type "reboot recovery", the "recovery" will be
> passed to next boot kernel boot args.
>

How did you had manage to pass these information in absence of
PSCI(i..e. other methods) ?

IIUC it's typically write to non-volatile memory indicating the reboot
reason(at-least in Android devices) through some reboot notifiers.

You can still do that now even with PSCI right ?

Yes