perf: Add wrappers for invoking guest callbacks

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Add helpers for the guest callbacks to prepare for burying the callbacks
behind a Kconfig (it's a lot easier to provide a few stubs than to #ifdef
piles of code), and also to prepare for converting the callbacks to
static_call().  perf_instruction_pointer() in particular will have subtle
semantics with static_call(), as the "no callbacks" case will return 0 if
the callbacks are unregistered between querying guest state and getting
the IP.  Implement the change now to avoid a functional change when adding
static_call() support, and because the new helper needs to return
_something_ in this case.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-8-seanjc@google.com

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Sean Christopherson 2021-11-11 02:07:28 +00:00 • committed by Peter Zijlstra

parent b9f5621c95

commit 1c3430516b

4 changed files with 35 additions and 25 deletions

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16

arch/arm64/kernel/perf_callchain.c

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15

arch/x86/events/core.c

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5

arch/x86/events/intel/core.c

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24

include/linux/perf_event.h

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