diff options
| author | Christian Krinitsin <mail@krinitsin.com> | 2025-05-21 21:21:26 +0200 |
|---|---|---|
| committer | Christian Krinitsin <mail@krinitsin.com> | 2025-05-21 21:21:26 +0200 |
| commit | 4b927bc37359dec23f67d3427fc982945f24f404 (patch) | |
| tree | 245449ef9146942dc7fffd0235b48b7e70a00bf2 /gitlab/issues/target_riscv/host_missing/accel_TCG/1060.toml | |
| parent | aa8bd79cec7bf6790ddb01d156c2ef2201abbaab (diff) | |
| download | emulator-bug-study-4b927bc37359dec23f67d3427fc982945f24f404.tar.gz emulator-bug-study-4b927bc37359dec23f67d3427fc982945f24f404.zip | |
add gitlab issues in toml format
Diffstat (limited to 'gitlab/issues/target_riscv/host_missing/accel_TCG/1060.toml')
| -rw-r--r-- | gitlab/issues/target_riscv/host_missing/accel_TCG/1060.toml | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/gitlab/issues/target_riscv/host_missing/accel_TCG/1060.toml b/gitlab/issues/target_riscv/host_missing/accel_TCG/1060.toml new file mode 100644 index 00000000..d1603567 --- /dev/null +++ b/gitlab/issues/target_riscv/host_missing/accel_TCG/1060.toml @@ -0,0 +1,41 @@ +id = 1060 +title = "RISC-V: mtval/stval is not correctly set to the instruction itself on illegal instructions" +state = "closed" +created_at = "2022-06-03T19:27:05.176Z" +closed_at = "2022-07-03T04:38:37.975Z" +labels = ["Closed::Fixed", "accel: TCG", "target: riscv"] +url = "https://gitlab.com/qemu-project/qemu/-/issues/1060" +host-os = "NixOS unstable, git commit 692517bf851f2d8d999f0ad50f53fa1d2dd5c8f9" +host-arch = "x86-64" +qemu-version = "7.0.0" +guest-os = "n/a" +guest-arch = "n/a" +description = """QEMU 7.0 claims to support `stval`/`mtval` for illegal instructions, but `mtval`/`stval` is actually set to `0`""" +reproduce = """1. Assemble and link `mtval-illegal.elf`. The code simply sets up a trap handler and generates an illegal instruction exception + +2. Start QEMU with: + + ``` + qemu-system-riscv64 -cpu rv64,h=off -bios mtval-illegal.elf -nographic -icount shift=0 -s -S + ``` + +3. Attach with GDB: + + ``` + gdb mtval-illegal.elf + + # Within GDB + target extended-remote :1234 + break trap + disp $mtval + + # Keep single stepping until breakpoint + stepi + ``` + +4. When control flow reaches `trap`, `mtval` is written with `0` instead of the encoding of `csrw time, x0` (`0xc0101073`)""" +additional = """Writing `0` to `mtval` on a illegal instruction trap is allowed by the specs, but since the [changelog of QEMU 7.0][changelog] says it should be supported, I would consider it a bug. + +[changelog]: https://wiki.qemu.org/ChangeLog/7.0#RISC-V + +I encountered this when trying to figure out why my program worked with QEMU 6 but breaks with QEMU 7. It's more complicated, but in that case I managed to get `mtval` written with neither `0` nor the actual illegal instruction, but a different illegal instruction. I will try gathering up all the dependencies and write down the steps to reproduce if needed and if I find the time.""" |
