Hi Stefan
From: Stefan Agner [mailto:stefan@agner.ch] Sent: mercredi 27 juin 2018 10:36 Subject: Re: [PATCH v1 1/5] ARM: PSCI: initialize stack pointer on secondary CPUs
On 24.06.2018 21:09, Stefan Agner wrote:
From: Stefan Agner stefan.agner@toradex.com
A proper stack is required to safely use C code in psci_arch_cpu_entry.
Patrick, I prefer to have your ack on this since you introduced psci_arch_cpu_entry.
As far as I can tell STM32MP1 uses C code in psci_arch_cpu_entry. The same function in i.MX 7's PSCI implementation the compiler actually pushed stuff on the (uninitialized) stack, which caused the newly brought up CPU to immediately crash.
Not sure if in your case the stack pointer is already setup by some other means or your compiler does not use the stack.
In any case, I think it is better to just setup the stack properly as done in this patch...
I expected that the secure stack is initialized by bootROM, but after check on 2018.07-rc2, I got a crash also with the stm32mp1 platform.
After code review, my behavior is clearly not safe: I don't sure that the initial BootROM stack is not overlapping the installed PSCI monitor code or data. So I agree: it is needed to initialize the stack in psci_cpu_entry.
Moreover after your patch the crash is solved for my platform stm32mp1.
Stefano, I think we really want patch 2/3 applied before the release since it fixes i.MX 7 PSCI. Right now the implementation is really broken and not PSCI 1.0 conformant. But patch 2/3 require this patch to be applied... Not sure how we should handle this.
-- Stefan
Acked-by: Patrick DELAUNAY Patrick.delaunay@st.com Tested-by: Patrick DELAUNAY Patrick.delaunay@st.com
Test done on stm32mp1 platform
Thanks! Patrick