Executing thumb instructions on foundation model

Hello,

I want to execute thumb instructions on foundation model. Please suggest how this can be done. If I run the thumb instructions as it is, the trace shows them as undefined instructions. The test case I have used is as follows:

.section .text

.global _start

   _start:

.syntax unified 

.THUMB 

adc R7, R12, #0xad

The trace file generated shows that the instructions are not recognized:

---snip---

0 clk IT (0) 80000000 01fff04f O EL3h_s : DCI 0x01fff04f ; ? Undefined

0 clk E 80000000 00000084 CoreEvent_CURRENT_SPx_SYNC

0 clk R cpsr 000003cd

0 clk R ESR_EL3 02000000

0 clk R SPSR_EL3 000003cd

0 clk R ELR_EL3 0000000080000000

1 clk IT (1) 00000200 e7ff0010 O EL3h_s : DCI 0xe7ff0010 ; ? Undefined

1 clk E 00000200:0000000200 00000084 CoreEvent_CURRENT_SPx_SYNC

1 clk R cpsr 000003cd

1 clk R ESR_EL3 02000000

1 clk R SPSR_EL3 000003cd

1 clk R ELR_EL3 0000000000000200

2 clk IT (2) 00000200 e7ff0010 O EL3h_s : DCI 0xe7ff0010 ; ? Undefined

---snip---

I also tried changing mode by ERET instruction:

adc X23, X25, X5 //Is in A64 mode

MOV x0,#0x131

MSR SCR_EL3,x0  

MOV x1,#0x3c5 //Change to exception level EL1

adr X0, 22

MSR ELR_EL3,x0 //After ERET the control should go to last MOV

MSR SPSR_EL3, X1

MRS X1, SPSR_EL3

ERET //Should cause mode change to A32

MOV x0,#0x131

However, the ERET instruction is still not able to change mode:

7 clk IT (7) 8000001c d53e4001 O EL3h_s : MRS x1,SPSR_EL3

7 clk R X1 00000000000003C5

8 clk IT (8) 80000020 d69f03e0 O EL3h_s : ERET

8 clk R cpsr 001003cd

8 clk E 80000024:0080000024 00000084 CoreEvent_CURRENT_SPx_SYNC

8 clk R cpsr 000003cd

8 clk R ESR_EL3 3a000000

8 clk R SPSR_EL3 001003cd

8 clk R ELR_EL3 0000000080000024

9 clk IT (9) 00000200 e7ff0010 O EL3h_s : DCI 0xe7ff0010 ; ? Undefined

What is the correct way to execute thumb instructions on the Foundation model?

Thanks,

Deepti