Change to load MPID for secondary cores adding offset macro
BOOT_PARAM_MPID_OFFSET.
Currently the code load MPID for secondary cores from offset 0x0
of the struct arm64_cpu_boot_params, it's working as currently
the macro BOOT_PARAM_MPID_OFFSET has value 0x0, but when the
location of the member "mpid" is changed, it can result in SMP
booting failure and the build assert won't throw out any warning.
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
The ARM64 port is currently using SP_EL0 for everything: kernel threads,
user threads and exceptions. In addition when taking an exception the
exception code is still using the thread SP without relying on any
interrupt stack.
If from one hand this makes the context switch really quick because the
thread context is already on the thread stack so we have only to save
one register (SP) for the whole context, on the other hand the major
limitation introduced by this choice is that if for some reason the
thread SP is corrupted or pointing to some unaccessible location (for
example in case of stack overflow), the exception code is unable to
recover or even deal with it.
The usual way of dealing with this kind of problems is to use a
dedicated interrupt stack on SP_EL1 when servicing the exceptions. The
real drawback of this is that, in case of context switch, all the
context must be copied from the shared interrupt stack into a
thread-specific stack or structure, so it is really slow.
We use here an hybrid approach, sacrificing a bit of stack space for a
quicker context switch. While nothing really changes for kernel threads,
for user threads we now use the privileged stack (already present to
service syscalls) as interrupt stack.
When an exception arrives the code now switches to use SP_EL1 that for
user threads is always pointing inside the privileged portion of the
stack of the current running thread. This achieves two things: (1)
isolate exceptions and syscall code to use a stack that is isolated,
privileged and not accessible to user threads and (2) the thread SP is
not touched at all during exceptions, so it can be invalid or corrupted
without any direct consequence.
Signed-off-by: Carlo Caione <ccaione@baylibre.com>
The SMP boot code depends on physical CPU #0 to be first to boot and
subsequent CPUs to follow suit in a linear fashion. Let's decouple
physical and logical numbering so that any physical CPU can be the
boot CPU. This is based on a prior code proposal from
Jiafei Pan <Jiafei.Pan@nxp.com>.
This, however, was about to turn the boot code into some hairy mess.
So let's clean things up and simplify the code as well while at it.
Both the extension and the clean up aren't separate commits because
they actually depend on each other.
The BOOT_PARAM_*_OFFSET defines are locally hardcoded as there is no
point exposing the related structure widely. Build time assertions
ensure they don't go out of sync with the struct definition. And
vector_table.h is repurposed into boot.h to gather boot related
definitions.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Signed-off-by: Jiafei Pan <Jiafei.Pan@nxp.com>
Split ARM and ARM64 architectures.
Details:
- CONFIG_ARM64 is decoupled from CONFIG_ARM (not a subset anymore)
- Arch and include AArch64 files are in a dedicated directory
(arch/arm64 and include/arch/arm64)
- AArch64 boards and SoC are moved to soc/arm64 and boards/arm64
- AArch64-specific DTS files are moved to dts/arm64
- The A72 support for the bcm_vk/viper board is moved in the
boards/bcm_vk/viper directory
Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Hou Zhiqiang