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    SubjectRe: [PATCH V6 08/15] ftrace: Add perf text poke events for ftrace trampolines
    Em Mon, Apr 27, 2020 at 10:23:05AM +0300, Adrian Hunter escreveu:
    > On 22/04/20 2:46 pm, Peter Zijlstra wrote:
    > > On Wed, Apr 22, 2020 at 10:39:06AM +0300, Adrian Hunter wrote:
    > >> On 21/04/20 4:45 pm, Peter Zijlstra wrote:
    > >>> On Sun, Apr 05, 2020 at 11:13:20PM +0300, Adrian Hunter wrote:
    > >>>> Add perf text poke events for ftrace trampolines when created and when
    > >>>> freed.
    > >>>
    > >>> Maybe also put in a little more detail on the various events. Because
    > >>> arch_ftrace_update_trampoline() can also generate text_poke_bp() events,
    > >>> to update an existing trampoline.
    > >>>
    > >>> A diagram, like with the kprobes thing perhaps.
    > >>
    > >> How about adding this:
    > >>
    > >> There can be 3 text_poke events for ftrace trampolines:
    > >>
    > >> 1. NULL -> trampoline
    > >> By ftrace_update_trampoline() when !ops->trampoline
    > >> Trampoline created
    > >>
    > >> 2. [e.g. on x86] CALL rel32 -> CALL rel32
    > >> By arch_ftrace_update_trampoline() when ops->trampoline and
    > >> ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP
    > >> [e.g. on x86] via text_poke_bp() which generates text poke events
    > >> Trampoline-called function target updated
    > >>
    > >> 3. trampoline -> NULL
    > >> By ftrace_trampoline_free() when ops->trampoline and
    > >> ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP
    > >> Trampoline freed
    > >
    > > Yes, very nice. Thanks!
    >
    > Arnaldo, do you have this patchset on your radar?

    Now it is, will look it into it,

    - Arnaldo

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