| Richard Henderson | b97028b | 2022-06-04 23:10:02 +0000 | [diff] [blame] | 1 | .option norvc |
| 2 | |
| 3 | .text |
| 4 | .global _start |
| 5 | _start: |
| 6 | lla t0, trap |
| 7 | csrw mtvec, t0 |
| 8 | |
| 9 | # These are all illegal instructions |
| 10 | csrw time, x0 |
| 11 | .insn i CUSTOM_0, 0, x0, x0, 0x321 |
| 12 | csrw time, x0 |
| 13 | .insn i CUSTOM_0, 0, x0, x0, 0x123 |
| 14 | csrw cycle, x0 |
| 15 | |
| 16 | # Success! |
| 17 | li a0, 0 |
| 18 | j _exit |
| 19 | |
| 20 | trap: |
| 21 | # When an instruction traps, compare it to the insn in memory. |
| 22 | csrr t0, mepc |
| 23 | csrr t1, mtval |
| 24 | lwu t2, 0(t0) |
| 25 | bne t1, t2, fail |
| 26 | |
| 27 | # Skip the insn and continue. |
| 28 | addi t0, t0, 4 |
| 29 | csrw mepc, t0 |
| 30 | mret |
| 31 | |
| 32 | fail: |
| 33 | li a0, 1 |
| 34 | |
| 35 | # Exit code in a0 |
| 36 | _exit: |
| 37 | lla a1, semiargs |
| 38 | li t0, 0x20026 # ADP_Stopped_ApplicationExit |
| 39 | sd t0, 0(a1) |
| 40 | sd a0, 8(a1) |
| 41 | li a0, 0x20 # TARGET_SYS_EXIT_EXTENDED |
| 42 | |
| 43 | # Semihosting call sequence |
| 44 | .balign 16 |
| 45 | slli zero, zero, 0x1f |
| 46 | ebreak |
| 47 | srai zero, zero, 0x7 |
| 48 | j . |
| 49 | |
| 50 | .data |
| 51 | .balign 16 |
| 52 | semiargs: |
| 53 | .space 16 |
