Messages in this thread Patches in this message | | | Date | Thu, 24 Oct 2019 14:01:17 +0800 | From | Mao Han <> | Subject | Re: Perf-related compilation issues |
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On Wed, Oct 23, 2019 at 06:15:43PM +0300, Nick Kossifidis wrote: > Hello all, > > a) Compiling the current fixes branch with a minimal config I get the > following error: > > riscv64-unknown-linux-gnu-ld: arch/riscv/kernel/perf_callchain.o: in > function `.L0 ': > perf_callchain.c:(.text+0x16a): undefined reference to `walk_stackframe' > make: *** [Makefile:1074: vmlinux] Error 1 > > > I've removed the static delcaration of walk_stackframe on stackframe.c > and marked walk_stackframe as extern on perf_callchain.c to fix the > above issue. >
Beside the compile problem caused by: [PATCH v3 5/8] riscv: mark some code and data as file-static similar issue may happen when CONFIG_FRAME_POINTER is not defined. I didn't see the CONFIG_FRAME_POINTER in stacktrace.c, and the conditional for !CONFIG_FRAME_POINTER looks quite strange, keep adding the sp and read pc from that?
ksp = (unsigned long *)sp; while (!kstack_end(ksp)) { if (__kernel_text_address(pc) && unlikely(fn(pc, arg))) break; pc = (*ksp++) - 0x4; }
A conditional for perf_callchain_kernel might be properly to fix that. --- a/arch/riscv/kernel/perf_callchain.c +++ b/arch/riscv/kernel/perf_callchain.c +#ifdef CONFIG_FRAME_POINTER void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg); void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, @@ -92,3 +93,4 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, walk_stackframe(NULL, regs, fill_callchain, entry); } +#endif
> > b) Then If I compile the kernel without CONFIG_RISCV_BASE_PMU I get > > > ./arch/riscv/include/asm/perf_event.h:26:2: error: #error "Please > provide a valid RISCV_MAX_COUNTERS for the PMU." > #error "Please provide a valid RISCV_MAX_COUNTERS for the PMU." > > > I noticed that the only place where CONFIG_RISCV_BASE_PMU is checked is > on perf_event.h and only for this parameter that's not defined anywhere > else. So for now if one tries to compile the kernel without PMU the > kernel won't compile + I don't see how unsetting this saves code size as > the config description says. >
The content inside perf_event.h mostly relate to HW PMU. Other architectures normally put them inside perf_event.c or pmu.h, they are not compiled when CONFIG_PERF_EVENTS is selected and HW PMU is not selected, user can use software event under this configuration. Base pmu shouldn't be registed when it is defined in dts. I think it can be fixed by put the content inside perf_event.h into a riscv_pmu.h, only compile perf_event.c when CONFIG_RISCV_BASE_PMU is selected or add conditional inside it:
--- a/arch/riscv/kernel/perf_event.c +++ b/arch/riscv/kernel/perf_event.c @@ -474,12 +474,13 @@ int __init init_hw_perf_events(void) if (node) { of_id = of_match_node(riscv_pmu_of_ids, node); - if (of_id) + if (of_id) { riscv_pmu = of_id->data; + perf_pmu_register(riscv_pmu->pmu, "cpu", PERF_TYPE_RAW); + } of_node_put(node); } - perf_pmu_register(riscv_pmu->pmu, "cpu", PERF_TYPE_RAW); return 0; --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -38,7 +38,7 @@ obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o obj-$(CONFIG_DYNAMIC_FTRACE) += mcount-dyn.o -obj-$(CONFIG_PERF_EVENTS) += perf_event.o +obj-$(CONFIG_RISCV_BASE_PMU) += perf_event.o obj-$(CONFIG_PERF_EVENTS) += perf_callchain.o obj-$(CONFIG_HAVE_PERF_REGS) += perf_regs.o
Thanks, Mao Han
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