2026-02-10 01:21:49 +00:00
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# traps.S
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.section .text
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.align 4 # mtvec requires 4-byte alignment
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.global trap_entry
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trap_entry:
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2026-02-11 22:56:25 +00:00
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# Create space on the stack for 32 registers (32 * 8 = 256 bytes)
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2026-02-10 01:21:49 +00:00
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addi sp, sp, -256
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2026-02-11 22:56:25 +00:00
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# Save all General Purpose Registers (GPRs)
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2026-02-10 01:21:49 +00:00
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sd ra, 0(sp)
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sd gp, 8(sp)
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sd tp, 16(sp)
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sd t0, 24(sp)
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sd t1, 32(sp)
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sd t2, 40(sp)
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sd s0, 48(sp)
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sd s1, 56(sp)
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sd a0, 64(sp)
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sd a1, 72(sp)
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sd a2, 80(sp)
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sd a3, 88(sp)
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sd a4, 96(sp)
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sd a5, 104(sp)
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sd a6, 112(sp)
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sd a7, 120(sp)
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sd s2, 128(sp)
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sd s3, 136(sp)
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sd s4, 144(sp)
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sd s5, 152(sp)
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sd s6, 160(sp)
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sd s7, 168(sp)
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sd s8, 176(sp)
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sd s9, 184(sp)
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sd s10, 192(sp)
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sd s11, 200(sp)
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sd t3, 208(sp)
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sd t4, 216(sp)
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sd t5, 224(sp)
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sd t6, 232(sp)
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2026-02-11 22:56:25 +00:00
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# Save mepc to the stack (using offset 240)
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csrr t0, mepc
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sd t0, 240(sp)
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# Call trap handler
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mv a0, sp # put the stack pointer to the first arg
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2026-02-10 01:21:49 +00:00
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call handle_trap
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2026-02-11 22:56:25 +00:00
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# restore mepc
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ld t0, 240(sp)
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csrw mepc, t0
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# Restore all GPRs
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2026-02-10 01:21:49 +00:00
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ld ra, 0(sp)
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ld gp, 8(sp)
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ld tp, 16(sp)
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ld t0, 24(sp)
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ld t1, 32(sp)
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ld t2, 40(sp)
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ld s0, 48(sp)
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ld s1, 56(sp)
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ld a0, 64(sp)
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ld a1, 72(sp)
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ld a2, 80(sp)
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ld a3, 88(sp)
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ld a4, 96(sp)
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ld a5, 104(sp)
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ld a6, 112(sp)
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ld a7, 120(sp)
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ld s2, 128(sp)
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ld s3, 136(sp)
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ld s4, 144(sp)
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ld s5, 152(sp)
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ld s6, 160(sp)
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ld s7, 168(sp)
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ld s8, 176(sp)
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ld s9, 184(sp)
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ld s10, 192(sp)
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ld s11, 200(sp)
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ld t3, 208(sp)
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ld t4, 216(sp)
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ld t5, 224(sp)
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ld t6, 232(sp)
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2026-02-11 22:56:25 +00:00
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# Shrink the stack back
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2026-02-10 01:21:49 +00:00
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addi sp, sp, 256
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2026-02-11 22:56:25 +00:00
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# Return from Machine-mode trap
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2026-02-10 01:21:49 +00:00
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mret
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