Re: x86: do_debug PTRACE_SINGLESTEP broken by 08d68323d1f0c34452e614263b212ca556dae47f
Oleg Nesterov wrote: On 12/18, Roland McGrath wrote: Please find the trivial test-case below. It hangs, because PTRACE_SINGLESTEP doesn't trigger the trap. 2.6.33-rc1 x86-64 works for me with either -m64 or -m32 version of that test. (not sure this matters, but I did the testing under kvm) Apparently it does. You should hack some printks into do_debug() and see how kvm is differing from real hardware. (Actually you can probably do this with a notifier added by a module, not that you are shy about recompiling!) Probably kvm's emulation of the hardware behavior wrt the DR6 bits is not sufficiently faithful. Conceivably, kvm is being consistent with some older hardware and we have encoded assumptions that only newer hardware meets. But I'd guess it's just a plain kvm bug. OK, thanks. Hmm. Now I see how wrong I was when I said this code is obviously wrong ;) I'll add the debugging printk's and report the output. Sorry for delay, can't do this today. Can't reproduce, runs fine here with with 2.6.33-rc1 as both hostguest and qemu-kvm latest git. Host uses kvm-intel. Can you specify your setup in more details? Which host kernel did you use, which qemu-kvm version? Are you on AMD or Intel? Any specific guest kernel config switch that may influence this? Jan signature.asc Description: OpenPGP digital signature
Re: [PATCH 6/7] implement utrace-ptrace
On Mon, Dec 21, 2009 at 07:18:37PM +0530, Ananth N Mavinakayanahalli wrote: On Fri, Dec 18, 2009 at 02:11:40AM +0100, Oleg Nesterov wrote: The patch adds the new file, kernel/ptrace-utrace.c, which contains the new implementation of ptrace over utrace. This file is not compiled until we have CONFIG_UTRACE option, will be added by the next utrace core patch. It's supposed to be an invisible implementation change, nothing should change to userland when CONFIG_UTRACE is enabled. Signed-off-by: Roland McGrath rol...@redhat.com Signed-off-by: Oleg Nesterov o...@redhat.com --- Oleg, ptrace/utrace performs better with the ptrace-tests [1] testsuite (1 failure vs. 3 with vanilla ptrace [1]). The gdb testsuite also has no regressions. In fact, the results on the gdb testsuite are identical. Forgot to mention the tests were on powerpc.
Re: [PATCH 6/7] implement utrace-ptrace
On Fri, Dec 18, 2009 at 02:11:40AM +0100, Oleg Nesterov wrote: The patch adds the new file, kernel/ptrace-utrace.c, which contains the new implementation of ptrace over utrace. This file is not compiled until we have CONFIG_UTRACE option, will be added by the next utrace core patch. It's supposed to be an invisible implementation change, nothing should change to userland when CONFIG_UTRACE is enabled. Signed-off-by: Roland McGrath rol...@redhat.com Signed-off-by: Oleg Nesterov o...@redhat.com --- Oleg, ptrace/utrace performs better with the ptrace-tests [1] testsuite (1 failure vs. 3 with vanilla ptrace [1]). The gdb testsuite also has no regressions. In fact, the results on the gdb testsuite are identical. Ananth [1] http://sourceware.org/systemtap/wiki/utrace/tests [2] detach-stopped and stopped-attach-transparency are the additional failures. syscall-reset fails in both cases.
Re: x86: do_debug PTRACE_SINGLESTEP broken by 08d68323d1f0c34452e614263b212ca556dae47f
On 12/21, Jan Kiszka wrote: Oleg Nesterov wrote: Hmm. Now I see how wrong I was when I said this code is obviously wrong ;) Yes, it is easy to blame the code you don't understand. My apologies to all. I'll add the debugging printk's and report the output. Sorry for delay, can't do this today. Can't reproduce, runs fine here with with 2.6.33-rc1 as both hostguest and qemu-kvm latest git. Host uses kvm-intel. Everything runs fine under 2.6.32 as a _host_ kernel. Previously I did the testing under 2.6.26.5-45.fc9. Sorry for noise, thanks all for your help. Oleg.
Re: x86: do_debug PTRACE_SINGLESTEP broken by 08d68323d1f0c34452e614263b212ca556dae47f
Oleg Nesterov wrote: On 12/21, Jan Kiszka wrote: Oleg Nesterov wrote: Hmm. Now I see how wrong I was when I said this code is obviously wrong ;) Yes, it is easy to blame the code you don't understand. My apologies to all. I'll add the debugging printk's and report the output. Sorry for delay, can't do this today. Can't reproduce, runs fine here with with 2.6.33-rc1 as both hostguest and qemu-kvm latest git. Host uses kvm-intel. Everything runs fine under 2.6.32 as a _host_ kernel. Previously I did the testing under 2.6.26.5-45.fc9. Makes sense: that kernel (most probably) predates any debug register virtualization in kvm. Sorry for noise, thanks all for your help. Never mind. Jan signature.asc Description: OpenPGP digital signature
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Re: new Fedora 13 utrace kernel
The utrace patch looks suspicious in utrace.h, which cause the compilation
failure without CONFIG_UTRACE. I have confirmed that the git tree looks sane.
+static inline void utrace_init_task(struct task_struct *child)
+{
+}
+{
+}
Oops! That snafu got fixed on the main branch but I forgot to put the
fix on the 2.6.32/utrace branch too. Fixed now.
Thanks,
Roland
