Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 15 Nov 2023 11:14:12 +0530 | Subject | Re: [V14 3/8] drivers: perf: arm_pmuv3: Enable branch stack sampling framework | From | Anshuman Khandual <> |
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On 11/14/23 15:28, James Clark wrote: > > > On 14/11/2023 05:13, Anshuman Khandual wrote: >> Branch stack sampling support i.e capturing branch records during execution >> in core perf, rides along with normal HW events being scheduled on the PMU. >> This prepares ARMV8 PMU framework for branch stack support on relevant PMUs >> with required HW implementation. >> > > [...] > >> - All armv8pmu_branch_xxxx() stub definitions have been moved inside >> include/linux/perf/arm_pmuv3.h for easy access from both arm32 and >> arm64 platforms >> > > This causes lots of W=1 build errors because the prototypes are in > arm_pmuv3.h, but arm_brbe.c doesn't include it.
I guess these are the W=1 warnings you mentioned above.
drivers/perf/arm_brbe.c:11:6: warning: no previous prototype for ‘armv8pmu_branch_reset’ [-Wmissing-prototypes] 11 | void armv8pmu_branch_reset(void) | ^~~~~~~~~~~~~~~~~~~~~ drivers/perf/arm_brbe.c:190:6: warning: no previous prototype for ‘armv8pmu_branch_save’ [-Wmissing-prototypes] 190 | void armv8pmu_branch_save(struct arm_pmu *arm_pmu, void *ctx) | ^~~~~~~~~~~~~~~~~~~~ drivers/perf/arm_brbe.c:236:6: warning: no previous prototype for ‘armv8pmu_branch_attr_valid’ [-Wmissing-prototypes] 236 | bool armv8pmu_branch_attr_valid(struct perf_event *event) | ^~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/perf/arm_brbe.c:269:5: warning: no previous prototype for ‘armv8pmu_task_ctx_cache_alloc’ [-Wmissing-prototypes] 269 | int armv8pmu_task_ctx_cache_alloc(struct arm_pmu *arm_pmu) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/perf/arm_brbe.c:279:6: warning: no previous prototype for ‘armv8pmu_task_ctx_cache_free’ [-Wmissing-prototypes] 279 | void armv8pmu_task_ctx_cache_free(struct arm_pmu *arm_pmu) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/perf/arm_brbe.c:303:6: warning: no previous prototype for ‘armv8pmu_branch_probe’ [-Wmissing-prototypes] 303 | void armv8pmu_branch_probe(struct arm_pmu *armpmu) | ^~~~~~~~~~~~~~~~~~~~~ drivers/perf/arm_brbe.c:449:6: warning: no previous prototype for ‘armv8pmu_branch_enable’ [-Wmissing-prototypes] 449 | void armv8pmu_branch_enable(struct arm_pmu *arm_pmu) | ^~~~~~~~~~~~~~~~~~~~~~ drivers/perf/arm_brbe.c:474:6: warning: no previous prototype for ‘armv8pmu_branch_disable’ [-Wmissing-prototypes] 474 | void armv8pmu_branch_disable(void) | ^~~~~~~~~~~~~~~~~~~~~~~ drivers/perf/arm_brbe.c:717:6: warning: no previous prototype for ‘armv8pmu_branch_read’ [-Wmissing-prototypes] 717 | void armv8pmu_branch_read(struct pmu_hw_events *cpuc, struct perf_event *event)
Branch helpers are used in ARM PMU V3 driver i.e drivers/perf/arm_pmuv3.c. Whether the actual BRBE helper definitions, or their fallback stubs (when CONFIG_ARM64_BRBE is not enabled), need to be accessible from arm_pmuv3.c driver not from brbe.c implementations itself.
> > It seems like the main reason you can't include arm_brbe.h in arm32 code > is because there are a load of inline functions and references to > registers in there. But these are only used in arm_brbe.c, so they don't
Right, arm32 should not be exposed to BRBE internals via arm_brbe.h header.
> need to be in the header anyway.
Right, these are only used in arm_brbe.c
> > If you removed the code from the header and moved it to the source file > you could move the brbe prototypes to the brbe header and it would be a > bit cleaner and more idiomatic.
Alight, how about the following changes - build tested on arm32 and arm64.
- Move BRBE helpers from arm_brbe.h into arm_brbe.c - Move armv8_pmu_xxx() declaration inside arm_brbe.h for arm64 (CONFIG_ARM64_BRBE) - Move armv8_pmu_xxx() stub definitions inside arm_pmuv3.c for arm32 (!CONFIG_ARM64_BRBE) - Include arm_brbe.h header both in arm_pmuv3.c and arm_brbe.c
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