[PATCH 1/3] perf build: Fix cross-arch build failures by isolating auxtrace objects
guanli
guanli.oerv at isrc.iscas.ac.cn
Wed May 13 09:31:54 PDT 2026
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!
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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