29 Aug
2018
29 Aug
'18
3:17 p.m.
Hi Yanyan,
According to your advice，I modified the avail_p_regs[] in hardware.h file
as tk1. 1 MiB starting from 0x37f00000 is reserved for monitor mode.
{ /* .start = */ 0x10000000, /* .end = */ 0x37f00000}
And then
#define MON_PA_START (0x10000000 + 0x27f00000)
#define MON_PA_SIZE (1 << 20)
#define MON_PA_END (MON_PA_START + MON_PA_SIZE)
#define MON_PA_STACK (MON_PA_END - 0x10)
#define MON_VECTOR_START (MON_PA_START)
set sp:
asm volatile ("cps %0\n\t"
"isb\n"
"mov sp, %1\n\t"
::"I"(MONITOR_MODE),"r"(MON_PA_STACK));
copy monitor mode vector 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 used the arm_monitor_vector provided by the source code in monitor.S and
just didn't perform the operation 'blx r0'. I think the it can jump to
smc_handler and return successfully.
#define VECTOR_BASE 0x37f00000
#define STACK_TOP (VECTOR_BASE + (1 << 20) - 0x10)
arm_monitor_vector:
ldr pc, [pc, #28]
ldr pc, [pc, #24]
ldr pc, [pc, #16]
ldr pc, [pc, #16]
ldr pc, [pc, #12]
ldr pc, [pc, #8]
ldr pc, [pc, #4]
ldr pc, [pc, #0]
smc_handler_addr:
.word VECTOR_BASE + (smc_handler - arm_monitor_vector)//0x1000002c
smc_halt_addr:
.word VECTOR_BASE + (smc_halt - arm_monitor_vector)
smc_stack:
.word STACK_TOP
smc_handler:
/* always have a valid stack */
ldr sp, [pc, #-12]
push {lr}
//blx r0
isb
mrc p15, 0, r5, c1, c1, 0
/* set the NS bit */
orr r5, r5, #1
mcr p15, 0, r5, c1, c1, 0
pop {lr}
isb
movs pc, lr
However, the problem still exists. And I have another question that why set
the sp in monitor mode to sp in SVC mode.
asm volatile ("mov r8, sp\n\t"
"cps %0\n\t"
"isb\n"
"mov sp, r8\n\t"
::"I"(MONITOR_MODE));
Thank you,
Dongxu Ji
<Yanyan.Shen(a)data61.csiro.au> 于2018年8月28日周二 下午10:10写道：
Hi Dongxu,
As you can see, the arm_monitor_vector uses PC-relative addressing so that
the code can be moved around in memory. I think ldr pc, =smc_handler
breaks this. Also, please set the NS bit in SCR to 1 before returning.
To reserve a memory region for the monitor-mode code and data, I suggest
you modify the avail_p_regs[] in kernel/include/plat/imx6/plat/machine/hardware.h
file. See the kernel/include/plat/tk1/plat/machine/hardware.h as an example.
Regards,
Yanyan
------------------------------
*From:* Dongxu Ji <jidongxu1993(a)gmail.com>
*Sent:* Wednesday, August 29, 2018 12:02 AM
*To:* devel(a)sel4.systems; Shen, Yanyan (Data61, Kensington NSW)
*Subject:* Fwd: [seL4] SMC in seL4
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
<Yanyan.Shen(a)data61.csiro.au> 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 <devel-bounces(a)sel4.systems> on behalf of 冀东旭 <
> jidongxu1993(a)gmail.com>
> *Sent:* Tuesday, August 28, 2018 1:02 PM
> *To:* devel(a)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
>
>