Messages in this thread | | | Date | Mon, 12 Mar 2018 12:20:41 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCHv2 0/8] hw_breakpoint: Breakpoint modification fixes and new modify ioctl |
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* Jiri Olsa <jolsa@kernel.org> wrote:
> hi, > Milind Chabbi introduced new ioctl interface to change > live breakpoint [1]. It allows to change its bp_addr, > bp_len and bp_type throught new ioctl for perf breakpoint > event. > > We already have a kernel interface for this via > modify_user_hw_breakpoint function. This function however > does not update the breakpoint slot counts. > > So when the same functionality was exposed to user space > (Milind's change), with simple test program I could put wrong > slots count on arm server [2] and ended up with no breakpoints > available on the system. Note it's not an issue on x86, because > it shares slot single counter for both data and inst types > (CONFIG_HAVE_MIXED_BREAKPOINTS_REGS). > > This patchset contains my fixes for keeping breakpoint slots > count updated. On top of it there's Milind's change for new > _IOC_MODIFY_ATTRIBUTES ioctl interface to change a breakpoint. > > As I mentioned above there're kernel users of > modify_user_hw_breakpoint function, all ptrace related > AFAICS, which could got broken.. so cc-ing Oleg ;-) > > I ran gdb and strace tests suites and got same amount of > skip/fail tests as when I run them on unpatched machine, > so I assume nothing new got broken. > > It's also available in here: > https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git > perf/bp > > v2 changes: > - added check for the rest of the perf_event_attr fields > to be the same as for kernel event > > Jiri Olsa (7): > hw_breakpoint: Pass bp_type directly as find_slot_idx argument > hw_breakpoint: Pass bp_type argument to __reserve_bp_slot|__release_bp_slot > hw_breakpoint: Add modify_bp_slot function > hw_breakpoint: Factor out __modify_user_hw_breakpoint function > hw_breakpoint: Add perf_event_attr fields check in __modify_user_hw_breakpoint > perf/core: Move perf_event_attr::sample_max_stack into perf_copy_attr > perf tests: Add breakpoint accounting/modify test > > Milind Chabbi (1): > perf/core: fast breakpoint modification via _IOC_MODIFY_ATTRIBUTES. > > include/linux/hw_breakpoint.h | 7 +++++ > include/uapi/linux/perf_event.h | 2 ++ > kernel/events/core.c | 53 +++++++++++++++++++++++++++++-- > kernel/events/hw_breakpoint.c | 115 ++++++++++++++++++++++++++++++++++++++++++++++++------------------- > tools/include/uapi/linux/perf_event.h | 2 ++ > tools/perf/tests/Build | 1 + > tools/perf/tests/bp_account.c | 195 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > tools/perf/tests/builtin-test.c | 4 +++ > tools/perf/tests/tests.h | 1 + > 9 files changed, 344 insertions(+), 36 deletions(-) > create mode 100644 tools/perf/tests/bp_account.c
Sorry about the late response - I suppose we could try this feature, but the tooling patches don't apply anymore. Mind re-sending a merged version, on top of latest -tip or so?
Thanks,
Ingo
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