* Perf-related compilation issues
@ 2019-10-23 15:15 Nick Kossifidis
2019-10-23 23:52 ` Alan Kao
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Nick Kossifidis @ 2019-10-23 15:15 UTC (permalink / raw)
To: linux-riscv
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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.
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.
Since I'm not familiar with the perf code how should I approach this ?
Is the fix on a correct ? How should we handle b ?
Thanks a lot in advance.
Regards,
Nick
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* Re: Perf-related compilation issues
2019-10-23 15:15 Perf-related compilation issues Nick Kossifidis
@ 2019-10-23 23:52 ` Alan Kao
2019-10-24 2:23 ` Paul Walmsley
2019-10-24 6:01 ` Mao Han
2 siblings, 0 replies; 4+ messages in thread
From: Alan Kao @ 2019-10-23 23:52 UTC (permalink / raw)
To: Nick Kossifidis; +Cc: linux-riscv
Hi Nick,
Thanks for pointing out this.
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.
>
>
> 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."
>
The check was meant to warn new PMU developers that they should provide
this parameter for their 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.
Sorry for the inconvenience.
Will something like this help?
...
#ifdef CONFIG_RISCV_BASE_PMU
#define RISCV_MAX_COUNTERS 2
#endif
+ #ifndef CONFIG_PERF_EVENTS
+ #define RISCV_MAX_COUNTERS 0
+ #endif
#ifndef RISCV_MAX_COUNTERS
#error "Please provide a valid RISCV_MAX_COUNTERS for the PMU."
#endif
...
>
>
> Since I'm not familiar with the perf code how should I approach this ?
> Is the fix on a correct ? How should we handle b ?
>
> Thanks a lot in advance.
>
> Regards,
> Nick
> pub 2048R/F2823DEF 2019-05-13 Nick Kossifidis <mick@ics.forth.gr>
> sub 2048R/F84F263E 2019-05-13 [expires: 2020-05-12]
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* Re: Perf-related compilation issues
2019-10-23 15:15 Perf-related compilation issues Nick Kossifidis
2019-10-23 23:52 ` Alan Kao
@ 2019-10-24 2:23 ` Paul Walmsley
2019-10-24 6:01 ` Mao Han
2 siblings, 0 replies; 4+ messages in thread
From: Paul Walmsley @ 2019-10-24 2:23 UTC (permalink / raw)
To: Nick Kossifidis; +Cc: linux-riscv
On Wed, 23 Oct 2019, Nick Kossifidis wrote:
> 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.
Greentime found the same issue:
https://lore.kernel.org/linux-riscv/CAEbi=3dk0R3HMnqsK1mSm2bewecdHm279f9zEq1pHWLPo9tdAg@mail.gmail.com/
Will fix this in the upcoming revision of these patches.
- Paul
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* Re: Perf-related compilation issues
2019-10-23 15:15 Perf-related compilation issues Nick Kossifidis
2019-10-23 23:52 ` Alan Kao
2019-10-24 2:23 ` Paul Walmsley
@ 2019-10-24 6:01 ` Mao Han
2 siblings, 0 replies; 4+ messages in thread
From: Mao Han @ 2019-10-24 6:01 UTC (permalink / raw)
To: Nick Kossifidis; +Cc: linux-riscv, linux-kernel
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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2019-10-23 23:52 ` Alan Kao
2019-10-24 2:23 ` Paul Walmsley
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