Re: [PATCH v9 10/18] arm64: kexec: cpu_soft_restart change argument types

[Pavel Tatashin]

On Wed, Apr 29, 2020 at 1:01 PM James Morse  wrote:
>
> Hi Pavel,
>
> On 26/03/2020 03:24, Pavel Tatashin wrote:
> > Change argument types from unsigned long to a more descriptive
> > phys_addr_t.
>
> For 'entry', which is a physical addresses, sure...
>
> > diff --git a/arch/arm64/kernel/cpu-reset.h b/arch/arm64/kernel/cpu-reset.h
> > index ed50e9587ad8..38cbd4068019 100644
> > --- a/arch/arm64/kernel/cpu-reset.h
> > +++ b/arch/arm64/kernel/cpu-reset.h
> > @@ -10,17 +10,17 @@
> >
> >  #include 
> >
> > -void __cpu_soft_restart(unsigned long el2_switch, unsigned long entry,
> > - unsigned long arg0, unsigned long arg1, unsigned long arg2);
>
> > +void __cpu_soft_restart(phys_addr_t el2_switch, phys_addr_t entry,
> > + phys_addr_t arg0, phys_addr_t arg1, phys_addr_t arg2);
>
> This looks weird because its re-using the hyp-stub API, because it might call 
> the hyp-stub
> from the idmap. entry is passed in, so this isn't tied to kexec. Without 
> tying it to
> kexec, how do you know arg2 is a physical address?
> I think it tried to be re-usable because 32bit has more users for this.

I will drop this patch. It was intended as a cleanup from suggestions
in earlier versions of this series, but I see it is not really needed.

Thank you,
Pasha

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Re: [PATCH v9 10/18] arm64: kexec: cpu_soft_restart change argument types

[James Morse]

Hi Pavel,

On 26/03/2020 03:24, Pavel Tatashin wrote:
> Change argument types from unsigned long to a more descriptive
> phys_addr_t.

For 'entry', which is a physical addresses, sure...

> diff --git a/arch/arm64/kernel/cpu-reset.h b/arch/arm64/kernel/cpu-reset.h
> index ed50e9587ad8..38cbd4068019 100644
> --- a/arch/arm64/kernel/cpu-reset.h
> +++ b/arch/arm64/kernel/cpu-reset.h
> @@ -10,17 +10,17 @@
>  
>  #include 
>  
> -void __cpu_soft_restart(unsigned long el2_switch, unsigned long entry,
> - unsigned long arg0, unsigned long arg1, unsigned long arg2);

> +void __cpu_soft_restart(phys_addr_t el2_switch, phys_addr_t entry,
> + phys_addr_t arg0, phys_addr_t arg1, phys_addr_t arg2);

This looks weird because its re-using the hyp-stub API, because it might call 
the hyp-stub
from the idmap. entry is passed in, so this isn't tied to kexec. Without tying 
it to
kexec, how do you know arg2 is a physical address?
I think it tried to be re-usable because 32bit has more users for this.

arg0-2 are unsigned long because the hyp-stub is just moving general purpose 
registers around.

This is to avoid casting?
Sure, its only got one caller. This thing evolved because the platform-has-EL2 
and
kdump-while-KVM-was-running code was bolted on as they were discovered.


> -static inline void __noreturn cpu_soft_restart(unsigned long entry,
> -unsigned long arg0,
> -unsigned long arg1,
> -unsigned long arg2)
> +static inline void __noreturn cpu_soft_restart(phys_addr_t entry,
> +phys_addr_t arg0,
> +phys_addr_t arg1,
> +phys_addr_t arg2)
>  {
>   typeof(__cpu_soft_restart) *restart;
>  
> - unsigned long el2_switch = !is_kernel_in_hyp_mode() &&
> + phys_addr_t el2_switch = !is_kernel_in_hyp_mode() &&
>   is_hyp_mode_available();

What on earth happened here!?


>   restart = (void *)__pa_symbol(__cpu_soft_restart);


Thanks,

James

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[PATCH v9 10/18] arm64: kexec: cpu_soft_restart change argument types

[Pavel Tatashin]

Change argument types from unsigned long to a more descriptive
phys_addr_t.

Signed-off-by: Pavel Tatashin 
---
 arch/arm64/kernel/cpu-reset.h | 14 +++---
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kernel/cpu-reset.h b/arch/arm64/kernel/cpu-reset.h
index ed50e9587ad8..38cbd4068019 100644
--- a/arch/arm64/kernel/cpu-reset.h
+++ b/arch/arm64/kernel/cpu-reset.h
@@ -10,17 +10,17 @@
 
 #include 
 
-void __cpu_soft_restart(unsigned long el2_switch, unsigned long entry,
-   unsigned long arg0, unsigned long arg1, unsigned long arg2);
+void __cpu_soft_restart(phys_addr_t el2_switch, phys_addr_t entry,
+   phys_addr_t arg0, phys_addr_t arg1, phys_addr_t arg2);
 
-static inline void __noreturn cpu_soft_restart(unsigned long entry,
-  unsigned long arg0,
-  unsigned long arg1,
-  unsigned long arg2)
+static inline void __noreturn cpu_soft_restart(phys_addr_t entry,
+  phys_addr_t arg0,
+  phys_addr_t arg1,
+  phys_addr_t arg2)
 {
typeof(__cpu_soft_restart) *restart;
 
-   unsigned long el2_switch = !is_kernel_in_hyp_mode() &&
+   phys_addr_t el2_switch = !is_kernel_in_hyp_mode() &&
is_hyp_mode_available();
restart = (void *)__pa_symbol(__cpu_soft_restart);
 
-- 
2.17.1


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