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Date:   Thu, 19 Oct 2023 12:45:08 -0700
From:   Manu Bretelle <chantr4@gmail.com>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>
Cc:     Ian Rogers <irogers@google.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, Fangrui Song <maskray@google.com>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Andi Kleen <ak@linux.intel.com>, Leo Yan <leo.yan@linaro.org>,
        Madhavan Srinivasan <maddy@linux.ibm.com>,
        Carsten Haitzler <carsten.haitzler@arm.com>,
        Ravi Bangoria <ravi.bangoria@amd.com>,
        "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
        Athira Rajeev <atrajeev@linux.vnet.ibm.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Yang Jihong <yangjihong1@huawei.com>,
        James Clark <james.clark@arm.com>,
        Tiezhu Yang <yangtiezhu@loongson.cn>,
        Eduard Zingerman <eddyz87@gmail.com>,
        Andrii Nakryiko <andrii@kernel.org>,
        Yonghong Song <yhs@fb.com>, Rob Herring <robh@kernel.org>,
        linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
        bpf@vger.kernel.org, llvm@lists.linux.dev,
        Wang Nan <wangnan0@huawei.com>,
        Wang ShaoBo <bobo.shaobowang@huawei.com>,
        YueHaibing <yuehaibing@huawei.com>,
        He Kuang <hekuang@huawei.com>,
        Brendan Gregg <brendan.d.gregg@gmail.com>,
        Quentin Monnet <quentin@isovalent.com>
Subject: Re: [PATCH v1 1/4] perf parse-events: Remove BPF event support
Message-ID: <ZTGHRAlQtF7Fq8vn@surya>
References: <20230810184853.2860737-1-irogers@google.com>
 <20230810184853.2860737-2-irogers@google.com>
 <ZNZJCWi9MT/HZdQ/@kernel.org>
 <ZNZWsAXg2px1sm2h@kernel.org>
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cc @quentin

On Fri, Aug 11, 2023 at 12:41:36PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Fri, Aug 11, 2023 at 11:43:22AM -0300, Arnaldo Carvalho de Melo escreveu:
> > Right now it is not applying due to some clash with other changes and
> > when I tried to apply it manually there were some formatting issues:
> > 
> > ⬢[acme@toolbox perf-tools-next]$ head ~/wb/1.patch
> > From SRS0=EALy=D3=flex--irogers.bounces.google.com=3IDHVZAcKBAUnwtljwxlttlqj.htrfhrjpjwsjq.twl@kernel.org Thu Aug 10 17:53:46 2023
> > Delivered-To: arnaldo.melo@gmail.com
> > Received: from imap.gmail.com [64.233.186.109]
> > 	by quaco with IMAP (fetchmail-6.4.37)
> > 	for <acme@localhost> (single-drop); Thu, 10 Aug 2023 17:53:46 -0300 (-03)
> > Received: by 2002:a0c:ab03:0:b0:63d:780e:9480 with SMTP id h3csp908198qvb;
> >  Thu, 10 Aug 2023 11:49:52 -0700 (PDT)
> > X-Google-Smtp-Source: AGHT+IH9N/knUCyQ0tQ2Q0XBH0gqf8A8DB8/37YHWAJDKBmz7AGSV9CvCKYDuE3EwxriZFBwtZMs
> > X-Received: by 2002:a4a:6b4f:0:b0:56c:b2ab:9820 with SMTP id
> >  h15-20020a4a6b4f000000b0056cb2ab9820mr2695332oof.8.1691693392493; Thu, 10 Aug
> > ⬢[acme@toolbox perf-tools-next]$ patch -p1 < ~/wb/1.patch
> > patching file tools/perf/Documentation/perf-config.txt
> > patch: **** malformed patch at line 234: ith
> > 
> > ⬢[acme@toolbox perf-tools-next]$
> > 
> > I'm trying to apply it manually.
> 
> I have this extracted from this patch as the first patch in the series:
> 
> >From adc61b5774a9de62f34d593f164ca02daa6fb44c Mon Sep 17 00:00:00 2001
> From: Ian Rogers <irogers@google.com>
> Date: Fri, 11 Aug 2023 12:19:48 -0300
> Subject: [PATCH 1/1] perf bpf: Remove support for embedding clang for
>  compiling BPF events (-e foo.c)
> 
> This never was in the default build for perf, is difficult to maintain
> as it uses clang/llvm internals so ditch it, keeping, for now, the
> external compilation of .c BPF into .o bytecode and its subsequent
> loading, that is also going to be removed, do it separately to help
> bisection and to properly document what is being removed and why.
> 
> Committer notes:
> 
> Extracted from a larger patch and removed some leftovers, namely
> deleting these now unused feature tests:
> 
>     tools/build/feature/test-clang.cpp
>     tools/build/feature/test-cxx.cpp
>     tools/build/feature/test-llvm-version.cpp
>     tools/build/feature/test-llvm.cpp
> 

This seem to have broken `llvm` feature detection for `bpftool`.

The feature detections are still available in `tools/build/Makefile.feature` [0]
but the .cpp files are gone.

`bpftool` still rely on the `llvm` feature:

    $ git --no-pager grep 'feature-llvm'
    tools/bpf/bpftool/Makefile:ifeq ($(feature-llvm),1)

The result of testing llvm feature is:

    $ cat tools/build/feature/test-llvm.make.output
    cc1plus: fatal error: test-llvm.cpp: No such file or directory
    compilation terminated.

With current head:

    make -j $((4*$(nproc))) -C tools/bpf/bpftool && ./tools/bpf/bpftool/bpftool --version
    ...
    Auto-detecting system features:
    ...                         clang-bpf-co-re: [ on  ]
    ...                                    llvm: [ OFF ]
    ...                                  libcap: [ on  ]
    ...                                  libbfd: [ on  ]
    ...
    ...
    ...
    bpftool v7.3.0
    using libbpf v1.3
    features: libbfd, skeletons

After applying

    git show 56b11a2126bf2f422831ecf6112b87a4485b221b  tools/build/feature | \
        patch -p1 -R

The feature gets properly detected again by:

    make -j $((4*$(nproc))) -C tools/bpf/bpftool && ./tools/bpf/bpftool/bpftool --version
    ...
    Auto-detecting system features:
    ...                         clang-bpf-co-re: [ on  ]
    ...                                    llvm: [ on  ]
    ...                                  libcap: [ on  ]
    ...                                  libbfd: [ on  ]
    ...
    ...
    bpftool v7.3.0
    using libbpf v1.3
    features: llvm, skeletons

     make  -C tools/bpf/bpftool

[0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/build/Makefile.feature?id=74e9347ebc5be452935fe4f3eddb150aa5a6f4fe#n99

> Testing the use of BPF events after applying this patch:
> 
> To use the external clang/llvm toolchain to compile a .c event and then
> use libbpf to load it, to get the syscalls:sys_enter_open* tracepoints
> and read the filename pointer, putting it into the ring buffer right
> after the usual tracepoint payload for 'perf trace' to then print it:
> 
>   [root@quaco ~]# perf trace -e /home/acme/git/perf-tools-next/tools/perf/examples/bpf/augmented_raw_syscalls.c,open* --max-events=10
>      0.000 systemd-oomd/959 openat(dfd: CWD, filename: "/proc/meminfo", flags: RDONLY|CLOEXEC) = 12
>      0.083 abrt-dump-jour/1453 openat(dfd: CWD, filename: "/var/log/journal/d6a97235307247e09f13f326fb607e3c/system.journal", flags: RDONLY|CLOEXEC|NONBLOCK) = 4
>      0.063 abrt-dump-jour/1454 openat(dfd: CWD, filename: "/var/log/journal/d6a97235307247e09f13f326fb607e3c/system.journal", flags: RDONLY|CLOEXEC|NONBLOCK) = 4
>      0.082 abrt-dump-jour/1455 openat(dfd: CWD, filename: "/var/log/journal/d6a97235307247e09f13f326fb607e3c/system.journal", flags: RDONLY|CLOEXEC|NONBLOCK) = 4
>    250.124 systemd-oomd/959 openat(dfd: CWD, filename: "/proc/meminfo", flags: RDONLY|CLOEXEC) = 12
>    250.521 systemd-oomd/959 openat(dfd: CWD, filename: "/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/app.slice/memory.pressure", flags: RDONLY|CLOEXEC) = 12
>    251.047 systemd-oomd/959 openat(dfd: CWD, filename: "/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/app.slice/memory.current", flags: RDONLY|CLOEXEC) = 12
>    251.162 systemd-oomd/959 openat(dfd: CWD, filename: "/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/app.slice/memory.min", flags: RDONLY|CLOEXEC) = 12
>    251.242 systemd-oomd/959 openat(dfd: CWD, filename: "/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/app.slice/memory.low", flags: RDONLY|CLOEXEC) = 12
>    251.353 systemd-oomd/959 openat(dfd: CWD, filename: "/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/app.slice/memory.swap.current", flags: RDONLY|CLOEXEC) = 12
>   [root@quaco ~]#
> 
> Same thing, but with a prebuilt .o BPF bytecode:
> 
>   [root@quaco ~]# perf trace -e /home/acme/git/perf-tools-next/tools/perf/examples/bpf/augmented_raw_syscalls.o,open* --max-events=10
>      0.000 systemd-oomd/959 openat(dfd: CWD, filename: "/proc/meminfo", flags: RDONLY|CLOEXEC) = 12
>      0.083 abrt-dump-jour/1453 openat(dfd: CWD, filename: "/var/log/journal/d6a97235307247e09f13f326fb607e3c/system.journal", flags: RDONLY|CLOEXEC|NONBLOCK) = 4
>      0.083 abrt-dump-jour/1455 openat(dfd: CWD, filename: "/var/log/journal/d6a97235307247e09f13f326fb607e3c/system.journal", flags: RDONLY|CLOEXEC|NONBLOCK) = 4
>      0.062 abrt-dump-jour/1454 openat(dfd: CWD, filename: "/var/log/journal/d6a97235307247e09f13f326fb607e3c/system.journal", flags: RDONLY|CLOEXEC|NONBLOCK) = 4
>    249.985 systemd-oomd/959 openat(dfd: CWD, filename: "/proc/meminfo", flags: RDONLY|CLOEXEC) = 12
>    466.763 thermald/1234 openat(dfd: CWD, filename: "/sys/class/powercap/intel-rapl/intel-rapl:0/intel-rapl:0:2/energy_uj") = 13
>    467.145 thermald/1234 openat(dfd: CWD, filename: "/sys/class/powercap/intel-rapl/intel-rapl:0/energy_uj") = 13
>    467.311 thermald/1234 openat(dfd: CWD, filename: "/sys/class/thermal/thermal_zone2/temp") = 13
>    500.040 cgroupify/24006 openat(dfd: 4, filename: ".", flags: RDONLY|CLOEXEC|DIRECTORY|NONBLOCK) = 5
>    500.295 cgroupify/24006 openat(dfd: 4, filename: "24616/cgroup.procs") = 5
>   [root@quaco ~]#
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Andi Kleen <ak@linux.intel.com>
> Cc: Andrii Nakryiko <andrii@kernel.org>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
> Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
> Cc: Carsten Haitzler <carsten.haitzler@arm.com>
> Cc: Eduard Zingerman <eddyz87@gmail.com>
> Cc: Fangrui Song <maskray@google.com>
> Cc: He Kuang <hekuang@huawei.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: James Clark <james.clark@arm.com>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Cc: Leo Yan <leo.yan@linaro.org>
> Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ravi Bangoria <ravi.bangoria@amd.com>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
> Cc: Tom Rix <trix@redhat.com>
> Cc: Wang Nan <wangnan0@huawei.com>
> Cc: Wang ShaoBo <bobo.shaobowang@huawei.com>
> Cc: Yang Jihong <yangjihong1@huawei.com>
> Cc: Yonghong Song <yhs@fb.com>
> Cc: YueHaibing <yuehaibing@huawei.com>
> Link: https://lore.kernel.org/lkml/
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
>  tools/build/feature/test-clang.cpp        |  28 ---
>  tools/build/feature/test-cxx.cpp          |  16 --
>  tools/build/feature/test-llvm-version.cpp |  12 --
>  tools/build/feature/test-llvm.cpp         |  14 --
>  tools/perf/Makefile.config                |  31 ---
>  tools/perf/Makefile.perf                  |  17 --
>  tools/perf/tests/Build                    |   1 -
>  tools/perf/tests/builtin-test.c           |   1 -
>  tools/perf/tests/clang.c                  |  32 ---
>  tools/perf/tests/make                     |   1 -
>  tools/perf/util/Build                     |   2 -
>  tools/perf/util/bpf-loader.c              |  15 +-
>  tools/perf/util/c++/Build                 |   5 -
>  tools/perf/util/c++/clang-c.h             |  43 -----
>  tools/perf/util/c++/clang-test.cpp        |  67 -------
>  tools/perf/util/c++/clang.cpp             | 225 ----------------------
>  tools/perf/util/c++/clang.h               |  27 ---
>  17 files changed, 4 insertions(+), 533 deletions(-)
>  delete mode 100644 tools/build/feature/test-clang.cpp
>  delete mode 100644 tools/build/feature/test-cxx.cpp
>  delete mode 100644 tools/build/feature/test-llvm-version.cpp
>  delete mode 100644 tools/build/feature/test-llvm.cpp
>  delete mode 100644 tools/perf/tests/clang.c
>  delete mode 100644 tools/perf/util/c++/Build
>  delete mode 100644 tools/perf/util/c++/clang-c.h
>  delete mode 100644 tools/perf/util/c++/clang-test.cpp
>  delete mode 100644 tools/perf/util/c++/clang.cpp
>  delete mode 100644 tools/perf/util/c++/clang.h
> 
> diff --git a/tools/build/feature/test-clang.cpp b/tools/build/feature/test-clang.cpp
> deleted file mode 100644
> index 7d87075cd1c5dd6e..0000000000000000
> --- a/tools/build/feature/test-clang.cpp
> +++ /dev/null
> @@ -1,28 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -#include "clang/Basic/Version.h"
> -#if CLANG_VERSION_MAJOR < 8
> -#include "clang/Basic/VirtualFileSystem.h"
> -#endif
> -#include "clang/Driver/Driver.h"
> -#include "clang/Frontend/TextDiagnosticPrinter.h"
> -#include "llvm/ADT/IntrusiveRefCntPtr.h"
> -#include "llvm/Support/ManagedStatic.h"
> -#if CLANG_VERSION_MAJOR >= 8
> -#include "llvm/Support/VirtualFileSystem.h"
> -#endif
> -#include "llvm/Support/raw_ostream.h"
> -
> -using namespace clang;
> -using namespace clang::driver;
> -
> -int main()
> -{
> -	IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
> -	IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
> -
> -	DiagnosticsEngine Diags(DiagID, &*DiagOpts);
> -	Driver TheDriver("test", "bpf-pc-linux", Diags);
> -
> -	llvm::llvm_shutdown();
> -	return 0;
> -}
> diff --git a/tools/build/feature/test-cxx.cpp b/tools/build/feature/test-cxx.cpp
> deleted file mode 100644
> index 396aaedd2418dd65..0000000000000000
> --- a/tools/build/feature/test-cxx.cpp
> +++ /dev/null
> @@ -1,16 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -#include <iostream>
> -#include <memory>
> -
> -static void print_str(std::string s)
> -{
> -	std::cout << s << std::endl;
> -}
> -
> -int main()
> -{
> -	std::string s("Hello World!");
> -	print_str(std::move(s));
> -	std::cout << "|" << s << "|" << std::endl;
> -	return 0;
> -}
> diff --git a/tools/build/feature/test-llvm-version.cpp b/tools/build/feature/test-llvm-version.cpp
> deleted file mode 100644
> index 8a091625446af985..0000000000000000
> --- a/tools/build/feature/test-llvm-version.cpp
> +++ /dev/null
> @@ -1,12 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -#include <cstdio>
> -#include "llvm/Config/llvm-config.h"
> -
> -#define NUM_VERSION (((LLVM_VERSION_MAJOR) << 16) + (LLVM_VERSION_MINOR << 8) + LLVM_VERSION_PATCH)
> -#define pass int main() {printf("%x\n", NUM_VERSION); return 0;}
> -
> -#if NUM_VERSION >= 0x030900
> -pass
> -#else
> -# error This LLVM is not tested yet.
> -#endif
> diff --git a/tools/build/feature/test-llvm.cpp b/tools/build/feature/test-llvm.cpp
> deleted file mode 100644
> index 88a3d1bdd9f6978e..0000000000000000
> --- a/tools/build/feature/test-llvm.cpp
> +++ /dev/null
> @@ -1,14 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -#include "llvm/Support/ManagedStatic.h"
> -#include "llvm/Support/raw_ostream.h"
> -#define NUM_VERSION (((LLVM_VERSION_MAJOR) << 16) + (LLVM_VERSION_MINOR << 8) + LLVM_VERSION_PATCH)
> -
> -#if NUM_VERSION < 0x030900
> -# error "LLVM version too low"
> -#endif
> -int main()
> -{
> -	llvm::errs() << "Hello World!\n";
> -	llvm::llvm_shutdown();
> -	return 0;
> -}
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index 1bf8dc53641fa093..e0592ed4c10f5904 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -1127,37 +1127,6 @@ ifndef NO_JVMTI
>    endif
>  endif
>  
> -USE_CXX = 0
> -USE_CLANGLLVM = 0
> -ifdef LIBCLANGLLVM
> -  $(call feature_check,cxx)
> -  ifneq ($(feature-cxx), 1)
> -    msg := $(warning No g++ found, disable clang and llvm support. Please install g++)
> -  else
> -    $(call feature_check,llvm)
> -    $(call feature_check,llvm-version)
> -    ifneq ($(feature-llvm), 1)
> -      msg := $(warning No suitable libLLVM found, disabling builtin clang and LLVM support. Please install llvm-dev(el) (>= 3.9.0))
> -    else
> -      $(call feature_check,clang)
> -      ifneq ($(feature-clang), 1)
> -        msg := $(warning No suitable libclang found, disabling builtin clang and LLVM support. Please install libclang-dev(el) (>= 3.9.0))
> -      else
> -        CFLAGS += -DHAVE_LIBCLANGLLVM_SUPPORT
> -        CXXFLAGS += -DHAVE_LIBCLANGLLVM_SUPPORT -I$(shell $(LLVM_CONFIG) --includedir)
> -        $(call detected,CONFIG_CXX)
> -        $(call detected,CONFIG_CLANGLLVM)
> -	USE_CXX = 1
> -	USE_LLVM = 1
> -	USE_CLANG = 1
> -        ifneq ($(feature-llvm-version),1)
> -          msg := $(warning This version of LLVM is not tested. May cause build errors)
> -        endif
> -      endif
> -    endif
> -  endif
> -endif
> -
>  ifndef NO_LIBPFM4
>    $(call feature_check,libpfm4)
>    ifeq ($(feature-libpfm4), 1)
> diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> index 0ed7ee0c1665a8cf..5370d7bf123e76af 100644
> --- a/tools/perf/Makefile.perf
> +++ b/tools/perf/Makefile.perf
> @@ -99,10 +99,6 @@ include ../scripts/utilities.mak
>  # Define NO_JVMTI_CMLR (debug only) if you do not want to process CMLR
>  # data for java source lines.
>  #
> -# Define LIBCLANGLLVM if you DO want builtin clang and llvm support.
> -# When selected, pass LLVM_CONFIG=/path/to/llvm-config to `make' if
> -# llvm-config is not in $PATH.
> -#
>  # Define CORESIGHT if you DO WANT support for CoreSight trace decoding.
>  #
>  # Define NO_AIO if you do not want support of Posix AIO based trace
> @@ -425,19 +421,6 @@ endif
>  EXTLIBS := $(call filter-out,$(EXCLUDE_EXTLIBS),$(EXTLIBS))
>  LIBS = -Wl,--whole-archive $(PERFLIBS) $(EXTRA_PERFLIBS) -Wl,--no-whole-archive -Wl,--start-group $(EXTLIBS) -Wl,--end-group
>  
> -ifeq ($(USE_CLANG), 1)
> -  LIBS += -L$(shell $(LLVM_CONFIG) --libdir) -lclang-cpp
> -endif
> -
> -ifeq ($(USE_LLVM), 1)
> -  LIBLLVM = $(shell $(LLVM_CONFIG) --libs all) $(shell $(LLVM_CONFIG) --system-libs)
> -  LIBS += -L$(shell $(LLVM_CONFIG) --libdir) $(LIBLLVM)
> -endif
> -
> -ifeq ($(USE_CXX), 1)
> -  LIBS += -lstdc++
> -endif
> -
>  export INSTALL SHELL_PATH
>  
>  ### Build rules
> diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
> index fb9ac5dc4079dab8..52df5923a8b9cc20 100644
> --- a/tools/perf/tests/Build
> +++ b/tools/perf/tests/Build
> @@ -51,7 +51,6 @@ perf-y += sdt.o
>  perf-y += is_printable_array.o
>  perf-y += bitmap.o
>  perf-y += perf-hooks.o
> -perf-y += clang.o
>  perf-y += unit_number__scnprintf.o
>  perf-y += mem2node.o
>  perf-y += maps.o
> diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
> index 6accb5442a731842..0f3691fd31c2536f 100644
> --- a/tools/perf/tests/builtin-test.c
> +++ b/tools/perf/tests/builtin-test.c
> @@ -108,7 +108,6 @@ static struct test_suite *generic_tests[] = {
>  	&suite__is_printable_array,
>  	&suite__bitmap_print,
>  	&suite__perf_hooks,
> -	&suite__clang,
>  	&suite__unit_number__scnprint,
>  	&suite__mem2node,
>  	&suite__time_utils,
> diff --git a/tools/perf/tests/clang.c b/tools/perf/tests/clang.c
> deleted file mode 100644
> index a7111005d5b9f481..0000000000000000
> --- a/tools/perf/tests/clang.c
> +++ /dev/null
> @@ -1,32 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -#include "tests.h"
> -#include "c++/clang-c.h"
> -#include <linux/kernel.h>
> -
> -#ifndef HAVE_LIBCLANGLLVM_SUPPORT
> -static int test__clang_to_IR(struct test_suite *test __maybe_unused,
> -			     int subtest __maybe_unused)
> -{
> -	return TEST_SKIP;
> -}
> -
> -static int test__clang_to_obj(struct test_suite *test __maybe_unused,
> -			      int subtest __maybe_unused)
> -{
> -	return TEST_SKIP;
> -}
> -#endif
> -
> -static struct test_case clang_tests[] = {
> -	TEST_CASE_REASON("builtin clang compile C source to IR", clang_to_IR,
> -			 "not compiled in"),
> -	TEST_CASE_REASON("builtin clang compile C source to ELF object",
> -			 clang_to_obj,
> -			 "not compiled in"),
> -	{ .name = NULL, }
> -};
> -
> -struct test_suite suite__clang = {
> -	.desc = "builtin clang support",
> -	.test_cases = clang_tests,
> -};
> diff --git a/tools/perf/tests/make b/tools/perf/tests/make
> index 58cf96d762d06a68..ea4c341f5af11741 100644
> --- a/tools/perf/tests/make
> +++ b/tools/perf/tests/make
> @@ -95,7 +95,6 @@ make_with_babeltrace:= LIBBABELTRACE=1
>  make_with_coresight := CORESIGHT=1
>  make_no_sdt	    := NO_SDT=1
>  make_no_syscall_tbl := NO_SYSCALL_TABLE=1
> -make_with_clangllvm := LIBCLANGLLVM=1
>  make_no_libpfm4     := NO_LIBPFM4=1
>  make_with_gtk2      := GTK2=1
>  make_refcnt_check   := EXTRA_CFLAGS="-DREFCNT_CHECKING=1"
> diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> index 9699e31ff4c04925..ff3b55c7ed43cdad 100644
> --- a/tools/perf/util/Build
> +++ b/tools/perf/util/Build
> @@ -232,8 +232,6 @@ perf-y += perf-hooks.o
>  perf-$(CONFIG_LIBBPF) += bpf-event.o
>  perf-$(CONFIG_LIBBPF) += bpf-utils.o
>  
> -perf-$(CONFIG_CXX) += c++/
> -
>  perf-$(CONFIG_LIBPFM4) += pfm.o
>  
>  CFLAGS_config.o   += -DETC_PERFCONFIG="BUILD_STR($(ETC_PERFCONFIG_SQ))"
> diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
> index 50e42698cbb721d1..b54e42f17926b17e 100644
> --- a/tools/perf/util/bpf-loader.c
> +++ b/tools/perf/util/bpf-loader.c
> @@ -26,7 +26,6 @@
>  #include "strfilter.h"
>  #include "util.h"
>  #include "llvm-utils.h"
> -#include "c++/clang-c.h"
>  #include "util/hashmap.h"
>  #include "asm/bug.h"
>  
> @@ -220,16 +219,10 @@ struct bpf_object *bpf__prepare_load(const char *filename, bool source)
>  		void *obj_buf;
>  		size_t obj_buf_sz;
>  
> -		perf_clang__init();
> -		err = perf_clang__compile_bpf(filename, &obj_buf, &obj_buf_sz);
> -		perf_clang__cleanup();
> -		if (err) {
> -			pr_debug("bpf: builtin compilation failed: %d, try external compiler\n", err);
> -			err = llvm__compile_bpf(filename, &obj_buf, &obj_buf_sz);
> -			if (err)
> -				return ERR_PTR(-BPF_LOADER_ERRNO__COMPILE);
> -		} else
> -			pr_debug("bpf: successful builtin compilation\n");
> +		err = llvm__compile_bpf(filename, &obj_buf, &obj_buf_sz);
> +		if (err)
> +			return ERR_PTR(-BPF_LOADER_ERRNO__COMPILE);
> +
>  		obj = bpf_object__open_mem(obj_buf, obj_buf_sz, &opts);
>  
>  		if (!IS_ERR_OR_NULL(obj) && llvm_param.dump_obj)
> diff --git a/tools/perf/util/c++/Build b/tools/perf/util/c++/Build
> deleted file mode 100644
> index 8610d032ac19d8c5..0000000000000000
> --- a/tools/perf/util/c++/Build
> +++ /dev/null
> @@ -1,5 +0,0 @@
> -perf-$(CONFIG_CLANGLLVM) += clang.o
> -perf-$(CONFIG_CLANGLLVM) += clang-test.o
> -
> -CXXFLAGS_clang.o += -Wno-unused-parameter
> -CXXFLAGS_clang-test.o += -Wno-unused-parameter
> diff --git a/tools/perf/util/c++/clang-c.h b/tools/perf/util/c++/clang-c.h
> deleted file mode 100644
> index d3731a876b6c10c5..0000000000000000
> --- a/tools/perf/util/c++/clang-c.h
> +++ /dev/null
> @@ -1,43 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0 */
> -#ifndef PERF_UTIL_CLANG_C_H
> -#define PERF_UTIL_CLANG_C_H
> -
> -#include <stddef.h>	/* for size_t */
> -
> -#ifdef __cplusplus
> -extern "C" {
> -#endif
> -
> -#ifdef HAVE_LIBCLANGLLVM_SUPPORT
> -extern void perf_clang__init(void);
> -extern void perf_clang__cleanup(void);
> -
> -struct test_suite;
> -extern int test__clang_to_IR(struct test_suite *test, int subtest);
> -extern int test__clang_to_obj(struct test_suite *test, int subtest);
> -
> -extern int perf_clang__compile_bpf(const char *filename,
> -				   void **p_obj_buf,
> -				   size_t *p_obj_buf_sz);
> -#else
> -
> -#include <errno.h>
> -#include <linux/compiler.h>	/* for __maybe_unused */
> -
> -static inline void perf_clang__init(void) { }
> -static inline void perf_clang__cleanup(void) { }
> -
> -static inline int
> -perf_clang__compile_bpf(const char *filename __maybe_unused,
> -			void **p_obj_buf __maybe_unused,
> -			size_t *p_obj_buf_sz __maybe_unused)
> -{
> -	return -ENOTSUP;
> -}
> -
> -#endif
> -
> -#ifdef __cplusplus
> -}
> -#endif
> -#endif
> diff --git a/tools/perf/util/c++/clang-test.cpp b/tools/perf/util/c++/clang-test.cpp
> deleted file mode 100644
> index a4683ca536973c04..0000000000000000
> --- a/tools/perf/util/c++/clang-test.cpp
> +++ /dev/null
> @@ -1,67 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -#include "clang.h"
> -#include "clang-c.h"
> -extern "C" {
> -#include "../util.h"
> -}
> -#include "llvm/IR/Function.h"
> -#include "llvm/IR/LLVMContext.h"
> -
> -#include <tests/llvm.h>
> -#include <string>
> -
> -class perf_clang_scope {
> -public:
> -	explicit perf_clang_scope() {perf_clang__init();}
> -	~perf_clang_scope() {perf_clang__cleanup();}
> -};
> -
> -static std::unique_ptr<llvm::Module>
> -__test__clang_to_IR(void)
> -{
> -	unsigned int kernel_version;
> -
> -	if (fetch_kernel_version(&kernel_version, NULL, 0))
> -		return std::unique_ptr<llvm::Module>(nullptr);
> -
> -	std::string cflag_kver("-DLINUX_VERSION_CODE=" +
> -				std::to_string(kernel_version));
> -
> -	std::unique_ptr<llvm::Module> M =
> -		perf::getModuleFromSource({cflag_kver.c_str()},
> -					  "perf-test.c",
> -					  test_llvm__bpf_base_prog);
> -	return M;
> -}
> -
> -extern "C" {
> -int test__clang_to_IR(struct test_suite *test __maybe_unused,
> -                      int subtest __maybe_unused)
> -{
> -	perf_clang_scope _scope;
> -
> -	auto M = __test__clang_to_IR();
> -	if (!M)
> -		return -1;
> -	for (llvm::Function& F : *M)
> -		if (F.getName() == "bpf_func__SyS_epoll_pwait")
> -			return 0;
> -	return -1;
> -}
> -
> -int test__clang_to_obj(struct test_suite *test __maybe_unused,
> -                       int subtest __maybe_unused)
> -{
> -	perf_clang_scope _scope;
> -
> -	auto M = __test__clang_to_IR();
> -	if (!M)
> -		return -1;
> -
> -	auto Buffer = perf::getBPFObjectFromModule(&*M);
> -	if (!Buffer)
> -		return -1;
> -	return 0;
> -}
> -
> -}
> diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp
> deleted file mode 100644
> index 1aad7d6d34aaa639..0000000000000000
> --- a/tools/perf/util/c++/clang.cpp
> +++ /dev/null
> @@ -1,225 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -/*
> - * llvm C frontend for perf. Support dynamically compile C file
> - *
> - * Inspired by clang example code:
> - * http://llvm.org/svn/llvm-project/cfe/trunk/examples/clang-interpreter/main.cpp
> - *
> - * Copyright (C) 2016 Wang Nan <wangnan0@huawei.com>
> - * Copyright (C) 2016 Huawei Inc.
> - */
> -
> -#include "clang/Basic/Version.h"
> -#include "clang/CodeGen/CodeGenAction.h"
> -#include "clang/Frontend/CompilerInvocation.h"
> -#include "clang/Frontend/CompilerInstance.h"
> -#include "clang/Frontend/TextDiagnosticPrinter.h"
> -#include "clang/Tooling/Tooling.h"
> -#include "llvm/IR/LegacyPassManager.h"
> -#include "llvm/IR/Module.h"
> -#include "llvm/Option/Option.h"
> -#include "llvm/Support/FileSystem.h"
> -#include "llvm/Support/ManagedStatic.h"
> -#if CLANG_VERSION_MAJOR >= 14
> -#include "llvm/MC/TargetRegistry.h"
> -#else
> -#include "llvm/Support/TargetRegistry.h"
> -#endif
> -#include "llvm/Support/TargetSelect.h"
> -#include "llvm/Target/TargetMachine.h"
> -#include "llvm/Target/TargetOptions.h"
> -#include <memory>
> -
> -#include "clang.h"
> -#include "clang-c.h"
> -
> -namespace perf {
> -
> -static std::unique_ptr<llvm::LLVMContext> LLVMCtx;
> -
> -using namespace clang;
> -
> -static CompilerInvocation *
> -createCompilerInvocation(llvm::opt::ArgStringList CFlags, StringRef& Path,
> -			 DiagnosticsEngine& Diags)
> -{
> -	llvm::opt::ArgStringList CCArgs {
> -		"-cc1",
> -		"-triple", "bpf-pc-linux",
> -		"-fsyntax-only",
> -		"-O2",
> -		"-nostdsysteminc",
> -		"-nobuiltininc",
> -		"-vectorize-loops",
> -		"-vectorize-slp",
> -		"-Wno-unused-value",
> -		"-Wno-pointer-sign",
> -		"-x", "c"};
> -
> -	CCArgs.append(CFlags.begin(), CFlags.end());
> -	CompilerInvocation *CI = tooling::newInvocation(&Diags, CCArgs
> -#if CLANG_VERSION_MAJOR >= 11
> -                                                        ,/*BinaryName=*/nullptr
> -#endif
> -                                                        );
> -
> -	FrontendOptions& Opts = CI->getFrontendOpts();
> -	Opts.Inputs.clear();
> -	Opts.Inputs.emplace_back(Path,
> -			FrontendOptions::getInputKindForExtension("c"));
> -	return CI;
> -}
> -
> -static std::unique_ptr<llvm::Module>
> -getModuleFromSource(llvm::opt::ArgStringList CFlags,
> -		    StringRef Path, IntrusiveRefCntPtr<vfs::FileSystem> VFS)
> -{
> -	CompilerInstance Clang;
> -	Clang.createDiagnostics();
> -
> -#if CLANG_VERSION_MAJOR < 9
> -	Clang.setVirtualFileSystem(&*VFS);
> -#else
> -	Clang.createFileManager(&*VFS);
> -#endif
> -
> -#if CLANG_VERSION_MAJOR < 4
> -	IntrusiveRefCntPtr<CompilerInvocation> CI =
> -		createCompilerInvocation(std::move(CFlags), Path,
> -					 Clang.getDiagnostics());
> -	Clang.setInvocation(&*CI);
> -#else
> -	std::shared_ptr<CompilerInvocation> CI(
> -		createCompilerInvocation(std::move(CFlags), Path,
> -					 Clang.getDiagnostics()));
> -	Clang.setInvocation(CI);
> -#endif
> -
> -	std::unique_ptr<CodeGenAction> Act(new EmitLLVMOnlyAction(&*LLVMCtx));
> -	if (!Clang.ExecuteAction(*Act))
> -		return std::unique_ptr<llvm::Module>(nullptr);
> -
> -	return Act->takeModule();
> -}
> -
> -std::unique_ptr<llvm::Module>
> -getModuleFromSource(llvm::opt::ArgStringList CFlags,
> -		    StringRef Name, StringRef Content)
> -{
> -	using namespace vfs;
> -
> -	llvm::IntrusiveRefCntPtr<OverlayFileSystem> OverlayFS(
> -			new OverlayFileSystem(getRealFileSystem()));
> -	llvm::IntrusiveRefCntPtr<InMemoryFileSystem> MemFS(
> -			new InMemoryFileSystem(true));
> -
> -	/*
> -	 * pushOverlay helps setting working dir for MemFS. Must call
> -	 * before addFile.
> -	 */
> -	OverlayFS->pushOverlay(MemFS);
> -	MemFS->addFile(Twine(Name), 0, llvm::MemoryBuffer::getMemBuffer(Content));
> -
> -	return getModuleFromSource(std::move(CFlags), Name, OverlayFS);
> -}
> -
> -std::unique_ptr<llvm::Module>
> -getModuleFromSource(llvm::opt::ArgStringList CFlags, StringRef Path)
> -{
> -	IntrusiveRefCntPtr<vfs::FileSystem> VFS(vfs::getRealFileSystem());
> -	return getModuleFromSource(std::move(CFlags), Path, VFS);
> -}
> -
> -std::unique_ptr<llvm::SmallVectorImpl<char>>
> -getBPFObjectFromModule(llvm::Module *Module)
> -{
> -	using namespace llvm;
> -
> -	std::string TargetTriple("bpf-pc-linux");
> -	std::string Error;
> -	const Target* Target = TargetRegistry::lookupTarget(TargetTriple, Error);
> -	if (!Target) {
> -		llvm::errs() << Error;
> -		return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);
> -	}
> -
> -	llvm::TargetOptions Opt;
> -	TargetMachine *TargetMachine =
> -		Target->createTargetMachine(TargetTriple,
> -					    "generic", "",
> -					    Opt, Reloc::Static);
> -
> -	Module->setDataLayout(TargetMachine->createDataLayout());
> -	Module->setTargetTriple(TargetTriple);
> -
> -	std::unique_ptr<SmallVectorImpl<char>> Buffer(new SmallVector<char, 0>());
> -	raw_svector_ostream ostream(*Buffer);
> -
> -	legacy::PassManager PM;
> -	bool NotAdded;
> -	NotAdded = TargetMachine->addPassesToEmitFile(PM, ostream
> -#if CLANG_VERSION_MAJOR >= 7
> -                                                      , /*DwoOut=*/nullptr
> -#endif
> -#if CLANG_VERSION_MAJOR < 10
> -                                                      , TargetMachine::CGFT_ObjectFile
> -#else
> -                                                      , llvm::CGFT_ObjectFile
> -#endif
> -                                                      );
> -	if (NotAdded) {
> -		llvm::errs() << "TargetMachine can't emit a file of this type\n";
> -		return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);
> -	}
> -	PM.run(*Module);
> -
> -	return Buffer;
> -}
> -
> -}
> -
> -extern "C" {
> -void perf_clang__init(void)
> -{
> -	perf::LLVMCtx.reset(new llvm::LLVMContext());
> -	LLVMInitializeBPFTargetInfo();
> -	LLVMInitializeBPFTarget();
> -	LLVMInitializeBPFTargetMC();
> -	LLVMInitializeBPFAsmPrinter();
> -}
> -
> -void perf_clang__cleanup(void)
> -{
> -	perf::LLVMCtx.reset(nullptr);
> -	llvm::llvm_shutdown();
> -}
> -
> -int perf_clang__compile_bpf(const char *filename,
> -			    void **p_obj_buf,
> -			    size_t *p_obj_buf_sz)
> -{
> -	using namespace perf;
> -
> -	if (!p_obj_buf || !p_obj_buf_sz)
> -		return -EINVAL;
> -
> -	llvm::opt::ArgStringList CFlags;
> -	auto M = getModuleFromSource(std::move(CFlags), filename);
> -	if (!M)
> -		return  -EINVAL;
> -	auto O = getBPFObjectFromModule(&*M);
> -	if (!O)
> -		return -EINVAL;
> -
> -	size_t size = O->size_in_bytes();
> -	void *buffer;
> -
> -	buffer = malloc(size);
> -	if (!buffer)
> -		return -ENOMEM;
> -	memcpy(buffer, O->data(), size);
> -	*p_obj_buf = buffer;
> -	*p_obj_buf_sz = size;
> -	return 0;
> -}
> -}
> diff --git a/tools/perf/util/c++/clang.h b/tools/perf/util/c++/clang.h
> deleted file mode 100644
> index 6ce33e22f23c084a..0000000000000000
> --- a/tools/perf/util/c++/clang.h
> +++ /dev/null
> @@ -1,27 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0 */
> -#ifndef PERF_UTIL_CLANG_H
> -#define PERF_UTIL_CLANG_H
> -
> -#include "llvm/ADT/StringRef.h"
> -#include "llvm/IR/LLVMContext.h"
> -#include "llvm/IR/Module.h"
> -#include "llvm/Option/Option.h"
> -#include <memory>
> -
> -namespace perf {
> -
> -using namespace llvm;
> -
> -std::unique_ptr<Module>
> -getModuleFromSource(opt::ArgStringList CFlags,
> -		    StringRef Name, StringRef Content);
> -
> -std::unique_ptr<Module>
> -getModuleFromSource(opt::ArgStringList CFlags,
> -		    StringRef Path);
> -
> -std::unique_ptr<llvm::SmallVectorImpl<char>>
> -getBPFObjectFromModule(llvm::Module *Module);
> -
> -}
> -#endif
> -- 
> 2.37.1
>