* blink, fp should not be always cleared
* clean up code format
* use a better way to save and restore ER_SEC_STAT
Signed-off-by: Wayne Ren <wei.ren@synopsys.com>
The new thread stack layout is as follow:
|---------------------|
| user stack |
|---------------------|
| stack guard (opt.) |
|---------------------|
| privilege stack |
-----------------------
For MPUv2
* user stack is aligned to the power of 2 of user stack size
* the stack guard is 2048 bytes
* the default size of privileg stack is 256 bytes.
For user thread, the following MPU regions are needded
* one region for user stack, no need of stack guard for user stack
* one region for stack guard when stack guard is enbaled
* regions for memory domain.
For kernel thread, the stack guard region will be at the top, adn
The user stack and privilege stack will be merged.
MPUv3 is the same as V2's layout, except no need of power of 2
alignment.
* reimplement the user mode enter function. Now it's possible for
kernel thread to drop privileg to user thread.
* add a separate entry for user thread
* bug fixes in the cleanup of regs when go to user mode
Signed-off-by: Wayne Ren <wei.ren@synopsys.com>
scrub all the regs of kernel context before returnning to userspace.
For sys call, ro is not cleared as it's a return value of sys call.
Signed-off-by: Wayne Ren <wei.ren@synopsys.com>
Enable us bit to check user mode more efficienly.
US is read as zero in user mode. This will allow use mode sleep
instructions, and it enables a form of denial-of-service attack
by putting the processor in sleep mode, but since interrupt
level/mask can't be set from user space that's not worse than
executing a loop without yielding.
Signed-off-by: Wayne Ren <wei.ren@synopsys.com>
* add the implementation of syscall
* based on 'trap_s' intruction, id = 3
* add the privilege stack
* the privilege stack is allocted with thread stack
* for the kernel thread, the privilege stack is also a
part of thread stack, the start of stack can be configured
as stack guard
* for the user thread, no stack guard, when the user stack is
overflow, it will fall into kernel memory area which requires
kernel privilege, privilege violation will be raised
* modify the linker template and add MPU_ADDR_ALIGN
* add user space corresponding codes in mpu
* the user sp aux reg will be part of thread context
* When user thread is interruptted for the 1st time, the context is
saved in user stack (U bit of IRQ_CTLR is set to 1). When nest
interrupt comes, the context is saved in thread's privilege stack
* the arc_mpu_regions.c is moved to board folder, as it's board
specific
* the above codes have been tested through tests/kernel/mem_protect/
userspace for MPU version 2
Signed-off-by: Wayne Ren <wei.ren@synopsys.com>
Wayne Ren