https://bugzilla.kernel.org/show_bug.cgi?id=218339 Bug ID: 218339 Summary: kernel goes unresponsive if single-stepping over an instruction which writes to an address for which a hardware read/write watchpoint has been set Product: Virtualization Version: unspecified Hardware: All OS: Linux Status: NEW Severity: normal Priority: P3 Component: kvm Assignee: virtualization_kvm@xxxxxxxxxxxxxxxxxxxx Reporter: anthony.louis.eden@xxxxxxxxx Regression: No In a debian QEMU/KVM virtual machine, run `gdb` on any executable (e.g. `/usr/bin/ls`). Run the program by typing `starti`. Proceed to `_dl_start` (i.e. `break _dl_start`, `continue`). When you get there disassemble the function (i.e. `disas`). Find an instruction that's going to be executed for which you can compute the address in memory it will write to. Run the program to that instruction (i.e. `break *0xINSN`, `continue`). When you're on that instruction, set a read/write watchpoint on the address it will write to, then single-step (i.e. `stepi`) and the kernel will go unresponsive. >(gdb) x/1i $pc >=> 0x7ffff7fe6510 <_dl_start+48>: mov %rdi,-0x88(%rbp) >(gdb) x/1wx $rbp-0x88 >0x7fffffffec28: 0x00000000 >(gdb) awatch *0x7fffffffec28 >Hardware access (read/write) watchpoint 2: *0x7fffffffec28 >(gdb) stepi Looking with `journalctl`, I cannot find anything printed to dmesg. The kernel of the guest inside the virtual machine is Debian 6.1.0-15-amd64. The kernel of the host running qemu-system-x86_64 is Archlinux 6.6.7-arch1-1. gdb is version 13.1. -- You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.
