[seL4] Fwd: SMC in seL4

29 Aug 2018

      Hi  Yanyan,
1. It doesn't set the NS bit to 1 in SCR(I just want it to return without
do anything). The arm_monitor_vector and the smc_handler():

arm_monitor_vector:
    ldr pc, [pc, #28]
    ldr pc, [pc, #24]
    ldr pc, =smc_handler
    ldr pc, [pc, #16]
    ldr pc, [pc, #12]
    ldr pc, [pc, #8]
    ldr pc, [pc, #4]
    ldr pc, [pc, #0]

smc_handler:
    movs pc, lr

2. I didn't do any extra work other than the boot log:

..........
ELF-loader started on CPU: ARM Ltd. Cortex-A9 r2p10

  paddr=[20000000..203fbfff]

ELF-loading image 'kernel'

  paddr=[10000000..10026fff]

  vaddr=[e0000000..e0026fff]

  virt_entry=e0000000

ELF-loading image 'sel4test-driver'

  paddr=[10027000..10500fff]

  vaddr=[8000..4e1fff]

  virt_entry=25a6c

Enabling MMU and paging

Jumping to kernel-image entry point...

3. The initialization operations in platform_init.c:
set sp:
#define MONITOR_MODE        (0x16)
#define MON_VECTOR_START    (0x11000000)
#define VECTOR_BASE     0x11000000
#define STACK_TOP       (VECTOR_BASE + (1 << 12) - 0x10)

asm volatile ( "mrs r1, cpsr\n\t"
                      "cps %0\n\t"
                      "isb\n"
                      "mov sp, %1\n\t"
                      "msr cpsr, r1\n\t"
                     ::"I"(MONITOR_MODE),"r"(STACK_TOP));

copy monitor mode vector to MON_VECTOR_START  and write into MVBAR:
uint32_t size = arm_monitor_vector_end - arm_monitor_vector;
    printf("Copy monitor mode vector from %x to %x size %x\n",
(arm_monitor_vector), MON_VECTOR_START, size);
    memcpy((void *)MON_VECTOR_START, (void *)(arm_monitor_vector), size);
        asm volatile ("dmb\n isb\n");
        asm volatile ("mcr p15, 0, %0, c12, c0, 1"::"r"(MON_VECTOR_START));

I enter into SVC mode by software interrupt and call the function smc():
                  asm (".arch_extension sec\n");
     asm volatile ("stmfd    sp!, {r3-r11, lr}\n\t"
                   "dsb\n"
                   "smc #0\n"
                   "ldmfd    sp!, {r3-r11, pc}");

and then the problem arises.

Thank you,
Dongxu Ji

 于2018年8月28日周二 下午8:30写道：
...
Hi,
The smc_handle() in monitor.S, it does nothing but "movs pc, lr".
Does it set the NS bit to 1 in SCR?
Also, what did you do to ensure that 0x11000000 is not used by the kernel?
Could you share the code (if possible) so that I could better understand
the problem.
Regards,
Yanyan
------------------------------
*From:* Devel  on behalf of 冀东旭 <
jidongxu1993@gmail.com>
*Sent:* Tuesday, August 28, 2018 1:02 PM
*To:* devel@sel4.systems
*Subject:* [seL4] SMC in seL4
Hello,
I'm porting sel4 to imx6q sabrelite as the trusted OS in trustzone.  I initialize the monitor mode by setting the sp to  STACK_TOP and copying arm_monitor_vector to MON_VECTOR_START according to the functions "install_monitor_hook()" and "switch_to_mon_mode()" in "platform_init.c".
#define VECTOR_BASE     0x11000000(addr is not used by the seL4 kernel)
#define STACK_TOP       (VECTOR_BASE + (1 << 12) - 0x10)
#define MON_VECTOR_START    0x11000000(The VECTOR_BASE is the same as MON_VECTOR_START)
The smc_handle() in monitor.S, it does nothing but "movs pc, lr".  After calling smc in SVC mode, it hangs without any log.  If I comment the "smc #0", it can return the caller successfully in usr mode.
stmfd    sp!, {r3-r11, lr}
    dsb
    smc #0
    ldmfd    sp!, {r3-r11, pc}
Is the sp in monitor mode appropriate? Or I need to do something else in initialization operations?  What's wrong with it?  Do you have any ideas?
Thank you!
Dongxu Ji