qemu-system-riscv32 cpu_transaction_failed cause Infinite loop when write mstatus ~"target: riscv" Description of problem: I wanna run FreeRTOS riscv, and use the FreeRTOS/Demo/RISC-V-Qemu-virt_GCC/Makefile to build elf.\ When qemu execute to write mstatus as 0x1888(enable Interrupt, MIE:1, MIP:1, MPP:3), there is no response.\ https://github.com/FreeRTOS/FreeRTOS-Kernel/blob/main/portable/GCC/RISC-V/portASM.S\ line 274: csrrw x0, mstatus, x5 /* Interrupts enabled from here! */\ opcode is hex 30029073\n I use pstack to trace qemu thread, there is only one thread is active, and cpu loading is 100%.\ then I use gdb attatch to trace the active thread, and it has a loop\ cpu_loop_exit call siglongjmp and back to sigsetjmp in cpu_exec (cpu=cpu@entry=0x55e2294e4070) at ../accel/tcg/cpu-exec.c:936 Steps to reproduce: 1.download FreeRTOS and build FreeRTOS/Demo/RISC-V-Qemu-virt_GCC\ 2.run qemu with gdb\ 3.hang when writing mstatus Additional information: I find that my issue occur when mtvec is zero and timer interrupt occur when writing mstatus(riscv_cpu_do_interrupt)\ Although it should jump to 0x0 rather then hanging in while loop.\ expected flow :cpu_handle_interrupt->check_for_breakpoints->break\ actually flow: cpu_handle_interrupt->check_for_breakpoints->infinite loop\ Qemu build command: ``` ./configure --target-list=riscv32-softmmu && make ``` pstack for qemu (only need to debug Thread 3) ``` Thread 3 (Thread 0x7f83af6d3640 (LWP 5093) "qemu-system-ris"): #0 0x000055cb31b1769f in riscv_cpu_exec_interrupt () #1 0x0000000000000000 in () Thread 2 (Thread 0x7f83b0119640 (LWP 5092) "qemu-system-ris"): #0 0x00007f83b0400a3d in syscall () at /lib/x86_64-linux-gnu/libc.so.6 #1 0x000055cb31e0bd52 in qemu_event_wait () #2 0x0000000000000000 in () Thread 1 (Thread 0x7f83b011ac00 (LWP 5090) "qemu-system-ris"): #0 0x00007f83b03fae7e in ppoll () at /lib/x86_64-linux-gnu/libc.so.6 #1 0x00007f83b0752500 in () at /lib/x86_64-linux-gnu/libglib-2.0.so.0 #2 0x000055cb33241b30 in () #3 0x0000000000000005 in () #4 0x0000000000000000 in () ``` backtrace for the infinite loop ``` (gdb) bt #0 cpu_loop_exit (cpu=0x55e2294e4070) at ../accel/tcg/cpu-exec-common.c:65 #1 0x000055e2274efde4 in cpu_loop_exit_restore (cpu=cpu@entry=0x55e2294e4070, pc=pc@entry=0) at ../accel/tcg/cpu-exec-common.c:76 #2 0x000055e22737fff1 in riscv_cpu_do_transaction_failed (cs=0x55e2294e4070, physaddr=, addr=0, size=, access_type=MMU_INST_FETCH, mmu_idx=, attrs=..., response=2, retaddr=0) at ../target/riscv/cpu_helper.c:1165 #3 0x000055e2274fa4a7 in cpu_transaction_failed (retaddr=0, response=2, attrs=..., mmu_idx=3, access_type=MMU_INST_FETCH, size=, addr=0, physaddr=, cpu=0x55e2294e4070) at ../accel/tcg/cputlb.c:1344 #4 io_readx (env=env@entry=0x55e2294e53d0, full=full@entry=0x7fd90c029410, mmu_idx=3, addr=addr@entry=0, retaddr=retaddr@entry=0, access_type=access_type@entry=MMU_INST_FETCH, op=MO_16) at ../accel/tcg/cputlb.c:1380 #5 0x000055e2274fba28 in load_helper (full_load=, code_read=true, op=MO_16, retaddr=0, oi=19, addr=0, env=0x55e2294e53d0) at ../accel/tcg/cputlb.c:1970 #6 full_lduw_code (env=env@entry=0x55e2294e53d0, addr=addr@entry=0, oi=19, retaddr=0) at ../accel/tcg/cputlb.c:2606 #7 0x000055e22750827b in cpu_lduw_code (env=env@entry=0x55e2294e53d0, addr=addr@entry=0) at ../accel/tcg/cputlb.c:2612 #8 0x000055e2274f87fa in translator_lduw (env=env@entry=0x55e2294e53d0, db=db@entry=0x7fd913dfe5a0, pc=0) at ../accel/tcg/translator.c:216 #9 0x000055e2273e423a in riscv_tr_translate_insn (dcbase=0x7fd913dfe5a0, cpu=) at ../target/riscv/translate.c:1158 #10 0x000055e2274f83d3 in translator_loop (cpu=cpu@entry=0x55e2294e4070, tb=tb@entry=0x7fd91c000240 , max_insns=, pc=pc@entry=0, host_pc=host_pc@entry=0x55e2274efe74 , ops=ops@entry=0x55e227a75c80 , db=0x7fd913dfe5a0) at ../accel/tcg/translator.c:96 #11 0x000055e227411760 in gen_intermediate_code (cs=cs@entry=0x55e2294e4070, tb=tb@entry=0x7fd91c000240 , max_insns=, pc=pc@entry=0, host_pc=host_pc@entry=0x55e2274efe74 ) at ../target/riscv/translate.c:1240 #12 0x000055e2274f6954 in setjmp_gen_code (env=env@entry=0x55e2294e53d0, tb=tb@entry=0x7fd91c000240 , pc=pc@entry=0, host_pc=0x55e2274efe74 , max_insns=max_insns@entry=0x7fd913dfe744, ti=) at ../accel/tcg/translate-all.c:761 #13 0x000055e2274f7294 in tb_gen_code (cpu=cpu@entry=0x55e2294e4070, pc=0, cs_base=0, flags=1085443, cflags=, cflags@entry=-16777216) at ../accel/tcg/translate-all.c:841 #14 0x000055e2274f10cf in cpu_exec (cpu=cpu@entry=0x55e2294e4070) at ../accel/tcg/cpu-exec.c:1006 #15 0x000055e22750a904 in tcg_cpus_exec (cpu=cpu@entry=0x55e2294e4070) at ../accel/tcg/tcg-accel-ops.c:69 #16 0x000055e22750aa57 in mttcg_cpu_thread_fn (arg=arg@entry=0x55e2294e4070) at ../accel/tcg/tcg-accel-ops-mttcg.c:95 #17 0x000055e227674b21 in qemu_thread_start (args=) at ../util/qemu-thread-posix.c:505 #18 0x00007fd9611a9b43 in start_thread (arg=) at ./nptl/pthread_create.c:442 #19 0x00007fd96123ba00 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81 ``` disassembly code ``` 80001ac6 : 80001ac6: 85c1a103 lw sp,-1956(gp) # 800809fc 80001aca: 4102 lw sp,0(sp) 80001acc: 4082 lw ra,0(sp) 80001ace: 43c2 lw t2,16(sp) 80001ad0: 4452 lw s0,20(sp) 80001ad2: 44e2 lw s1,24(sp) 80001ad4: 4572 lw a0,28(sp) 80001ad6: 5582 lw a1,32(sp) 80001ad8: 5612 lw a2,36(sp) 80001ada: 56a2 lw a3,40(sp) 80001adc: 5732 lw a4,44(sp) 80001ade: 57c2 lw a5,48(sp) 80001ae0: 5852 lw a6,52(sp) 80001ae2: 58e2 lw a7,56(sp) 80001ae4: 5972 lw s2,60(sp) 80001ae6: 4986 lw s3,64(sp) 80001ae8: 4a16 lw s4,68(sp) 80001aea: 4aa6 lw s5,72(sp) 80001aec: 4b36 lw s6,76(sp) 80001aee: 4bc6 lw s7,80(sp) 80001af0: 4c56 lw s8,84(sp) 80001af2: 4ce6 lw s9,88(sp) 80001af4: 4d76 lw s10,92(sp) 80001af6: 5d86 lw s11,96(sp) 80001af8: 5e16 lw t3,100(sp) 80001afa: 5ea6 lw t4,104(sp) 80001afc: 5f36 lw t5,108(sp) 80001afe: 5fc6 lw t6,112(sp) 80001b00: 52d6 lw t0,116(sp) 80001b02: 0007f317 auipc t1,0x7f 80001b06: ea232303 lw t1,-350(t1) # 800809a4 80001b0a: 00532023 sw t0,0(t1) 80001b0e: 52e6 lw t0,120(sp) 80001b10: 02a1 addi t0,t0,8 80001b12: 30029073 csrw mstatus,t0 <--- hang on this line 80001b16: 42a2 lw t0,8(sp) 80001b18: 4332 lw t1,12(sp) 80001b1a: 07c10113 addi sp,sp,124 80001b1e: 8082 ret ``` ``` (gdb) bt #0 cpu_loop_exit (cpu=cpu@entry=0x564cd884b070) at ../accel/tcg/cpu-exec-common.c:65 #1 0x0000564cd6685631 in helper_lookup_tb_ptr (env=0x564cd884c3d0) at ../accel/tcg/cpu-exec.c:400 #2 0x00007f55dc00014c in code_gen_buffer () #3 0x0000564cd668521b in cpu_tb_exec (cpu=cpu@entry=0x564cd884b070, itb=itb@entry=0x7f55dc000040 , tb_exit=tb_exit@entry=0x7f56235f67ec) at ../accel/tcg/cpu-exec.c:438 #4 0x0000564cd6685cfb in cpu_loop_exec_tb (tb_exit=0x7f56235f67ec, last_tb=, pc=, tb=0x7f55dc000040 , cpu=0x564cd884b070) at ../accel/tcg/cpu-exec.c:868 #5 cpu_exec (cpu=cpu@entry=0x564cd884b070) at ../accel/tcg/cpu-exec.c:1032 #6 0x0000564cd669f904 in tcg_cpus_exec (cpu=cpu@entry=0x564cd884b070) at ../accel/tcg/tcg-accel-ops.c:69 #7 0x0000564cd669fa57 in mttcg_cpu_thread_fn (arg=arg@entry=0x564cd884b070) at ../accel/tcg/tcg-accel-ops-mttcg.c:95 #8 0x0000564cd6809b21 in qemu_thread_start (args=) at ../util/qemu-thread-posix.c:505 #9 0x00007f562429ab43 in start_thread (arg=) at ./nptl/pthread_create.c:442 #10 0x00007f562432ca00 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81 ``` I also build a very simple elf for qemu-virt-platform, just contain boot-loader and write mstatus as 0x1888, it can't reproduce.\ I also build different qemu version such v6.0.0, it still can reproduce.\ I has modify the march to the most simple arch:rv32i, is still can reproduce. ~"target: riscv"