[PATCH 1/3] perf build: Fix cross-arch build failures by isolating auxtrace objects
Ian Rogers
irogers at google.com
Wed May 13 09:37:49 PDT 2026
On Wed, May 13, 2026 at 9:32 AM guanli <guanli.oerv at isrc.iscas.ac.cn> wrote:
>
> Hi Ian,
>
> Thanks a lot for the quick and detailed review!
>
> Regarding Patch 1/3 and 3/3 (the auxtrace decoupling):
> I completely misunderstood the design goal of perf for cross-platform trace analysis. My apologies for that. I encountered build errors on RISC-V with GCC 14 when it tried to compile files like intel-pt.c, and I incorrectly assumed they shouldn't be built for RISC-V at all.
> I will drop this approach entirely. I'll go back to the original build logs to find the exact GCC 14 compilation errors in those decoders on RISC-V, and I will try to fix those specific issues instead. I'll make sure to include the exact compiler error messages in the next patch.
>
> Regarding Patch 2/3 (the const qualifier):
> You are right, casting it to (char *) is not the proper way to handle it. I will check the perf-tools-next branch as you suggested. If it hasn't been fixed there, I will submit a v2 that properly preserves the const semantics.
>
> Thanks again for pointing me in the right direction!
No worries, thanks for sending fixes and glad to clean up the intent
in the tool. I'm actually trying to push more with this cross-platform
direction, and increase RISC-V support in this series that I'm
currently rebasing:
https://lore.kernel.org/linux-perf-users/20260413024805.1316480-1-irogers@google.com/
I'll be cheeky and add you to the cc list as maybe you can help with
building/testing :-)
Thanks,
Ian
> Best regards,
> Li Guan
>
>
> > -----原始邮件-----
> > 发件人: "Ian Rogers" <irogers at google.com>
> > 发送时间: 2026-05-14 00:14:59 (星期四)
> > 收件人: "Li Guan" <guanli.oerv at isrc.iscas.ac.cn>
> > 抄送: acme at kernel.org, namhyung at kernel.org, adrian.hunter at intel.com, palmer at dabbelt.com, pjw at kernel.org, linux-perf-users at vger.kernel.org, linux-riscv at lists.infradead.org, linux-kernel at vger.kernel.org
> > 主题: Re: [PATCH 1/3] perf build: Fix cross-arch build failures by isolating auxtrace objects
> >
> > On Wed, May 13, 2026 at 8:50 AM Li Guan <guanli.oerv at isrc.iscas.ac.cn> wrote:
> > >
> > > Currently, tools/perf/util/Build hardcodes architecture-specific hardware
> > > tracing objects (e.g., intel-pt.o, arm-spe.o, cs-etm-base.o) into the
> > > generic perf-util-y list. When compiling on architectures that lack
> > > these features (such as RISC-V), the compiler skips generating these
> > > objects, causing the linker to fail with "No such file or directory"
> > > or undefined references.
> >
> > So it is intentional to build these into the perf binary so that you
> > may generate a perf.data file on an x86 or ARM machine and then
> > analyze it on an RISC-V machine. I'm not sure how you've managed to
> > break the build, you didn't provide a message, but the build expects
> > these decoders for cross-platform support.
> >
> > > Fix this by decoupling the architecture-specific hardware tracing drivers
> > > from the generic build process:
> > > 1. In Makefile.config, explicitly export CONFIG_PERF_XYZ feature flags
> > > only for their corresponding target architectures.
> > > 2. In util/Build, conditionally link these hardware tracing objects
> > > based on the newly exported feature flags.
> > > 3. In util/auxtrace.c, provide __weak stub functions returning -ENOSYS
> > > for the arch-specific processing routines. This ensures successful
> > > linking and graceful degradation when specific drivers are omitted.
> >
> > This is a complete misunderstanding of the code, please don't
> > implement this. If anything, more code should move out of the
> > tools/perf/arch directory and into tools/perf/util guarded by
> > perf_env's arch or e_machine values for cross platform support.
> >
> > Thanks,
> > Ian
> >
> > > Signed-off-by: Li Guan <guanli.oerv at isrc.iscas.ac.cn>
> > > ---
> > > tools/perf/Makefile.config | 21 ++++++++++++
> > > tools/perf/util/Build | 20 +++++------
> > > tools/perf/util/auxtrace.c | 70 ++++++++++++++++++++++++++++++++++++++
> > > tools/perf/util/auxtrace.h | 6 ++++
> > > 4 files changed, 107 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> > > index 06d7a3f999..13f4b98b2e 100644
> > > --- a/tools/perf/Makefile.config
> > > +++ b/tools/perf/Makefile.config
> > > @@ -107,6 +107,27 @@ ifeq ($(SRCARCH),loongarch)
> > > endif
> > > endif
> > >
> > > +ifndef NO_AUXTRACE
> > > + ifeq ($(SRCARCH),x86)
> > > + $(call detected,CONFIG_PERF_INTEL_PT)
> > > + $(call detected,CONFIG_PERF_AMD_PT)
> > > + endif
> > > +
> > > + ifeq ($(SRCARCH),arm64)
> > > + $(call detected,CONFIG_PERF_ARM_SPE)
> > > + $(call detected,CONFIG_PERF_HISI_PTT)
> > > + $(call detected,CONFIG_PERF_CS_ETM)
> > > + endif
> > > +
> > > + ifeq ($(SRCARCH),s390)
> > > + $(call detected,CONFIG_PERF_S390_CPUMSF)
> > > + endif
> > > +endif
> > > +
> > > +ifeq ($(SRCARCH),arm64)
> > > + $(call detected,CONFIG_PERF_ARM64_UNWIND_SUPPORT)
> > > +endif
> > > +
> > > ifeq ($(ARCH),s390)
> > > CFLAGS += -fPIC
> > > endif
> > > diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> > > index 70cc91d008..79ade6066d 100644
> > > --- a/tools/perf/util/Build
> > > +++ b/tools/perf/util/Build
> > > @@ -132,21 +132,21 @@ perf-util-$(CONFIG_LIBTRACEEVENT) += kvm-stat.o
> > > perf-util-y += kvm-stat-arch/
> > > perf-util-y += lock-contention.o
> > > perf-util-y += auxtrace.o
> > > -perf-util-y += intel-pt-decoder/
> > > -perf-util-y += intel-pt.o
> > > -perf-util-y += intel-bts.o
> > > -perf-util-y += arm-spe.o
> > > -perf-util-y += arm-spe-decoder/
> > > -perf-util-y += hisi-ptt.o
> > > -perf-util-y += hisi-ptt-decoder/
> > > -perf-util-y += s390-cpumsf.o
> > > +perf-util-$(CONFIG_PERF_INTEL_PT) += intel-pt-decoder/
> > > +perf-util-$(CONFIG_PERF_INTEL_PT) += intel-pt.o
> > > +perf-util-$(CONFIG_PERF_INTEL_PT) += intel-bts.o
> > > +perf-util-$(CONFIG_PERF_ARM_SPE) += arm-spe.o
> > > +perf-util-$(CONFIG_PERF_ARM_SPE) += arm-spe-decoder/
> > > +perf-util-$(CONFIG_PERF_HISI_PTT) += hisi-ptt.o
> > > +perf-util-$(CONFIG_PERF_HISI_PTT) += hisi-ptt-decoder/
> > > +perf-util-$(CONFIG_PERF_S390_CPUMSF) += s390-cpumsf.o
> > > perf-util-y += powerpc-vpadtl.o
> > >
> > > ifdef CONFIG_LIBOPENCSD
> > > perf-util-y += cs-etm.o
> > > perf-util-y += cs-etm-decoder/
> > > endif
> > > -perf-util-y += cs-etm-base.o
> > > +perf-util-$(CONFIG_PERF_CS_ETM) += cs-etm-base.o
> > >
> > > perf-util-y += parse-branch-options.o
> > > perf-util-y += parse-regs-options.o
> > > @@ -168,7 +168,7 @@ perf-util-y += clockid.o
> > > perf-util-y += list_sort.o
> > > perf-util-y += mutex.o
> > > perf-util-y += sharded_mutex.o
> > > -perf-util-y += intel-tpebs.o
> > > +perf-util-$(CONFIG_PERF_INTEL_PT) += intel-tpebs.o
> > >
> > > perf-util-$(CONFIG_PERF_BPF_SKEL) += bpf_counter.o
> > > perf-util-$(CONFIG_PERF_BPF_SKEL) += bpf_counter_cgroup.o
> > > diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
> > > index a224687ffb..f6e426c3c5 100644
> > > --- a/tools/perf/util/auxtrace.c
> > > +++ b/tools/perf/util/auxtrace.c
> > > @@ -51,6 +51,7 @@
> > > #include "cs-etm.h"
> > > #include "intel-pt.h"
> > > #include "intel-bts.h"
> > > +#include "intel-tpebs.h"
> > > #include "arm-spe.h"
> > > #include "hisi-ptt.h"
> > > #include "s390-cpumsf.h"
> > > @@ -2960,3 +2961,72 @@ bool auxtrace__evsel_is_auxtrace(struct perf_session *session,
> > >
> > > return session->auxtrace->evsel_is_auxtrace(session, evsel);
> > > }
> > > +
> > > +/*
> > > + * Stub functions for architecture-specific features to support cross-platform building.
> > > + * These weak symbols are overridden by strong symbols when the corresponding
> > > + * architecture-specific code is compiled in.
> > > + */
> > > +#ifndef HAVE_ARCH_X86_64_SUPPORT
> > > +int __weak intel_pt_process_auxtrace_info(union perf_event *event __maybe_unused,
> > > + struct perf_session *session __maybe_unused)
> > > +{
> > > + return -EOPNOTSUPP;
> > > +}
> > > +
> > > +int __weak intel_bts_process_auxtrace_info(union perf_event *event __maybe_unused,
> > > + struct perf_session *session __maybe_unused)
> > > +{
> > > + return -EOPNOTSUPP;
> > > +}
> > > +
> > > +int __weak evsel__tpebs_open(struct evsel *evsel __maybe_unused)
> > > +{
> > > + return -EOPNOTSUPP;
> > > +}
> > > +
> > > +void __weak evsel__tpebs_close(struct evsel *evsel __maybe_unused)
> > > +{
> > > +}
> > > +
> > > +int __weak evsel__tpebs_read(struct evsel *evsel __maybe_unused,
> > > + int cpu_map_idx __maybe_unused,
> > > + int thread __maybe_unused)
> > > +{
> > > + return -EOPNOTSUPP;
> > > +}
> > > +
> > > +int __weak insn_decode(void *insn __maybe_unused, const void *kaddr __maybe_unused,
> > > + int len __maybe_unused, int mode __maybe_unused)
> > > +{
> > > + return -EOPNOTSUPP;
> > > +}
> > > +#endif
> > > +
> > > +#ifndef HAVE_ARCH_ARM64_SUPPORT
> > > +int __weak arm_spe_process_auxtrace_info(union perf_event *event __maybe_unused,
> > > + struct perf_session *session __maybe_unused)
> > > +{
> > > + return -EOPNOTSUPP;
> > > +}
> > > +
> > > +int __weak hisi_ptt_process_auxtrace_info(union perf_event *event __maybe_unused,
> > > + struct perf_session *session __maybe_unused)
> > > +{
> > > + return -EOPNOTSUPP;
> > > +}
> > > +
> > > +int __weak cs_etm__process_auxtrace_info(union perf_event *event __maybe_unused,
> > > + struct perf_session *session __maybe_unused)
> > > +{
> > > + return -EOPNOTSUPP;
> > > +}
> > > +#endif
> > > +
> > > +#ifndef HAVE_ARCH_S390_SUPPORT
> > > +int __weak s390_cpumsf_process_auxtrace_info(union perf_event *event __maybe_unused,
> > > + struct perf_session *session __maybe_unused)
> > > +{
> > > + return -EOPNOTSUPP;
> > > +}
> > > +#endif
> > > diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
> > > index 6947f3f284..474e9445b4 100644
> > > --- a/tools/perf/util/auxtrace.h
> > > +++ b/tools/perf/util/auxtrace.h
> > > @@ -699,4 +699,10 @@ void itrace_synth_opts__clear_time_range(struct itrace_synth_opts *opts)
> > > opts->range_num = 0;
> > > }
> > >
> > > +/*
> > > + * Prototypes for architecture-specific functions that require weak stubs
> > > + * to support cross-platform builds on non-x86 architectures.
> > > + */
> > > +int insn_decode(void *insn, const void *kaddr, int len, int mode);
> > > +
> > > #endif
> > > --
> > > 2.54.0
> > >
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