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SubjectRe: [PATCHv2 0/8] hw_breakpoint: Breakpoint modification fixes and new modify ioctl
PING

thanks,
jirka

On Wed, Nov 29, 2017 at 09:38:45AM +0100, Jiri Olsa 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
>
> thanks,
> jirka
>
>
> [1] https://marc.info/?l=linux-kernel&m=151012255331565&w=2
> [2] https://marc.info/?l=linux-man&m=151172469807302&w=2
> ---
> 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

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