[PATCH v2 0/8] perf build: Support building with Clang

[PATCH v2 0/8] perf build: Support building with Clang

[Leo Yan]

This series adds support for building perf with Clang, following the
discussion in [1]. Because the Android NDK uses Clang by default,
enabling Clang builds naturally covers Android as well.

The series is organized as follows:

  - Patches 1–2: Fix two bugs found with Clang.
  - Patches 3–6: Correct CROSS_ARCH and dismiss Clang build warnings.
  - Patches 7–8: Enable Clang in the Makefile and update the
    documentation.

Testing:

  - Clang 15.0.7 on Ubuntu 22.04.5: native and cross-compiling (aarch64)
  - Clang 18.1.3 on Ubuntu 24.04.2: native and cross-compiling (aarch64)
  - Android NDK r27d (latest LTS): cross-compiling (aarch64)

[1] https://lore.kernel.org/linux-perf-users/20240715143342.52236-1-leo.yan@arm.com/

---
Changes in v2:
- Dropped the patch for dismissing warning in bpftool.
- Refined the document. (Ian)
- Link to v1: https://lore.kernel.org/r/20250925-perf_build_android_ndk-v1-0-8b35aadde3dc@arm.com

---
Leo Yan (8):
      tools build: Align warning options with perf
      perf python: split Clang options when invoking Popen
      perf: build: Correct CROSS_ARCH for clang
      perf test coresight: Dismiss clang warning for memcpy thread
      perf test coresight: Dismiss clang warning for thread loop
      perf test coresight: Dismiss clang warning for unroll loop thread
      perf build: Support build with clang
      perf docs: Document building with Clang

 tools/build/feature/Makefile                       |  6 +-
 tools/perf/Documentation/Build.txt                 | 15 ++++
 tools/perf/Documentation/android.txt               | 80 ++--------------------
 tools/perf/Makefile.config                         | 32 ++++++++-
 tools/perf/Makefile.perf                           |  2 +-
 .../shell/coresight/memcpy_thread/memcpy_thread.c  |  2 +
 .../shell/coresight/thread_loop/thread_loop.c      |  4 +-
 .../unroll_loop_thread/unroll_loop_thread.c        |  4 +-
 tools/perf/util/setup.py                           |  5 +-
 9 files changed, 67 insertions(+), 83 deletions(-)
---
base-commit: c17dda8013495d8132c976cbf349be9949d0fbd1
change-id: 20250915-perf_build_android_ndk-500b53bea895

Best regards,
-- 
Leo Yan <leo.yan@arm.com>

[PATCH v2 1/8] tools build: Align warning options with perf

[Leo Yan]

The feature test programs are built without enabling '-Wall -Werror'
options. As a result, a feature may appear to be available, but later
building in perf can fail with stricter checks.

Make the feature test program use the same warning options as perf.

Fixes: 1925459b4d92 ("tools build: Fix feature Makefile issues with 'O='")
Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 tools/build/feature/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index b41a42818d8ac232ade78ecb41363d26ce2a9471..bd615a708a0aa89ddbe87401f04bd736e384a9c4 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -316,10 +316,10 @@ $(OUTPUT)test-libcapstone.bin:
 	$(BUILD) # -lcapstone provided by $(FEATURE_CHECK_LDFLAGS-libcapstone)
 
 $(OUTPUT)test-compile-32.bin:
-	$(CC) -m32 -o $@ test-compile.c
+	$(CC) -m32 -Wall -Werror -o $@ test-compile.c
 
 $(OUTPUT)test-compile-x32.bin:
-	$(CC) -mx32 -o $@ test-compile.c
+	$(CC) -mx32 -Wall -Werror -o $@ test-compile.c
 
 $(OUTPUT)test-zlib.bin:
 	$(BUILD) -lz

-- 
2.34.1

[PATCH v2 2/8] perf python: split Clang options when invoking Popen

[Leo Yan]

When passing a list to subprocess.Popen, each element maps to one argv
token. Current code bundles multiple Clang flags into a single element,
something like:

  cmd = ['clang',
         '--target=x86_64-linux-gnu -fintegrated-as -Wno-cast-function-type-mismatch',
	 'test-hello.c']

So Clang only sees one long, invalid option instead of separate flags,
as a result, the script cannot capture any log via PIPE.

Fix this by using shlex.split() to separate the string so each option
becomes its own argv element. The fixed list will be:

  cmd = ['clang',
         '--target=x86_64-linux-gnu',
	 '-fintegrated-as',
	 '-Wno-cast-function-type-mismatch',
	 'test-hello.c']

Fixes: 09e6f9f98370 ("perf python: Fix splitting CC into compiler and options")
Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 tools/perf/util/setup.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
index dd289d15acfd62ff058bbaed7e565bb958e3a3c8..9cae2c472f4ad4d9579e8528b8bb0152df6fe20e 100644
--- a/tools/perf/util/setup.py
+++ b/tools/perf/util/setup.py
@@ -1,6 +1,7 @@
 from os import getenv, path
 from subprocess import Popen, PIPE
 from re import sub
+import shlex
 
 cc = getenv("CC")
 assert cc, "Environment variable CC not set"
@@ -22,7 +23,9 @@ assert srctree, "Environment variable srctree, for the Linux sources, not set"
 src_feature_tests  = f'{srctree}/tools/build/feature'
 
 def clang_has_option(option):
-    cc_output = Popen([cc, cc_options + option, path.join(src_feature_tests, "test-hello.c") ], stderr=PIPE).stderr.readlines()
+    cmd = shlex.split(f"{cc} {cc_options} {option}")
+    cmd.append(path.join(src_feature_tests, "test-hello.c"))
+    cc_output = Popen(cmd, stderr=PIPE).stderr.readlines()
     return [o for o in cc_output if ((b"unknown argument" in o) or (b"is not supported" in o) or (b"unknown warning option" in o))] == [ ]
 
 if cc_is_clang:

-- 
2.34.1

[PATCH v2 3/8] perf: build: Correct CROSS_ARCH for clang

[Leo Yan]

Clang's -dumpmachine outputs "aarch64-unknown-linux-gnu", which does not
match the MultiArch convention. This prevents the build system from
detecting installed packages.

Fix by stripping the trailing '-' from CROSS_COMPILE when setting
CROSS_ARCH.

Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 tools/build/feature/Makefile | 2 +-
 tools/perf/Makefile.perf     | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index bd615a708a0aa89ddbe87401f04bd736e384a9c4..214ccaee69181cce1f8e736b85c8dc940efa6c19 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -94,7 +94,7 @@ else
   # paths are used instead.
   ifdef CROSS_COMPILE
     ifeq ($(PKG_CONFIG_LIBDIR)$(PKG_CONFIG_PATH)$(PKG_CONFIG_SYSROOT_DIR),)
-      CROSS_ARCH = $(shell $(CC) -dumpmachine)
+      CROSS_ARCH = $(notdir $(CROSS_COMPILE:%-=%))
       PKG_CONFIG_LIBDIR := /usr/local/$(CROSS_ARCH)/lib/pkgconfig/
       PKG_CONFIG_LIBDIR := $(PKG_CONFIG_LIBDIR):/usr/local/lib/$(CROSS_ARCH)/pkgconfig/
       PKG_CONFIG_LIBDIR := $(PKG_CONFIG_LIBDIR):/usr/lib/$(CROSS_ARCH)/pkgconfig/
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index e2150acc2c13325f93a2d5cd4a60b4a6bfeedc94..47bc9d8a91df90535408c427909bcb3f7cd50970 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -194,7 +194,7 @@ else
   # paths are used instead.
   ifdef CROSS_COMPILE
     ifeq ($(PKG_CONFIG_LIBDIR)$(PKG_CONFIG_PATH)$(PKG_CONFIG_SYSROOT_DIR),)
-      CROSS_ARCH = $(shell $(CC) -dumpmachine)
+      CROSS_ARCH = $(notdir $(CROSS_COMPILE:%-=%))
       PKG_CONFIG_LIBDIR := /usr/local/$(CROSS_ARCH)/lib/pkgconfig/
       PKG_CONFIG_LIBDIR := $(PKG_CONFIG_LIBDIR):/usr/local/lib/$(CROSS_ARCH)/pkgconfig/
       PKG_CONFIG_LIBDIR := $(PKG_CONFIG_LIBDIR):/usr/lib/$(CROSS_ARCH)/pkgconfig/

-- 
2.34.1

[PATCH v2 4/8] perf test coresight: Dismiss clang warning for memcpy thread

[Leo Yan]

clang-18.1.3 on Ubuntu 24.04.2 reports warning:

  memcpy_thread.c:30:1: warning: non-void function does not return a value in all control paths [-Wreturn-type]
     30 | }
        | ^

Dismiss the warning with returning NULL from the thread function.

Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 tools/perf/tests/shell/coresight/memcpy_thread/memcpy_thread.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/perf/tests/shell/coresight/memcpy_thread/memcpy_thread.c b/tools/perf/tests/shell/coresight/memcpy_thread/memcpy_thread.c
index 5f886cd09e6b3a62b5690dade94f1f8cae3279d2..7e879217be30a86431989dbf1f36d2134ef259cc 100644
--- a/tools/perf/tests/shell/coresight/memcpy_thread/memcpy_thread.c
+++ b/tools/perf/tests/shell/coresight/memcpy_thread/memcpy_thread.c
@@ -27,6 +27,8 @@ static void *thrfn(void *arg)
 	}
 	for (i = 0; i < len; i++)
 		memcpy(dst, src, a->size * 1024);
+
+	return NULL;
 }
 
 static pthread_t new_thr(void *(*fn) (void *arg), void *arg)

-- 
2.34.1

[PATCH v2 5/8] perf test coresight: Dismiss clang warning for thread loop

[Leo Yan]

clang-18.1.3 on Ubuntu 24.04.2 reports warning:

  thread_loop.c:41:23: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
     41 |                 : /* in */ [i] "r" (i), [len] "r" (len)
        |                                     ^
  thread_loop.c:37:8: note: use constraint modifier "w"
     37 |                 "add %[i], %[i], #1\n"
        |                      ^~~~
        |                      %w[i]
  thread_loop.c:41:23: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
     41 |                 : /* in */ [i] "r" (i), [len] "r" (len)
        |                                     ^
  thread_loop.c:37:14: note: use constraint modifier "w"
     37 |                 "add %[i], %[i], #1\n"
        |                            ^~~~
        |                            %w[i]
  thread_loop.c:41:23: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
     41 |                 : /* in */ [i] "r" (i), [len] "r" (len)
        |                                     ^
  thread_loop.c:38:8: note: use constraint modifier "w"
     38 |                 "cmp %[i], %[len]\n"
        |                      ^~~~
        |                      %w[i]
  thread_loop.c:41:38: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
     41 |                 : /* in */ [i] "r" (i), [len] "r" (len)
        |                                                    ^
  thread_loop.c:38:14: note: use constraint modifier "w"
     38 |                 "cmp %[i], %[len]\n"
        |                            ^~~~~~
        |                            %w[len]

Use the modifier "w" for 32-bit register access.

Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 tools/perf/tests/shell/coresight/thread_loop/thread_loop.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/tests/shell/coresight/thread_loop/thread_loop.c b/tools/perf/tests/shell/coresight/thread_loop/thread_loop.c
index e05a559253ca9d9366ad321d520349042fb07fca..86f3f548b00631682767665fc5e9d5b8551a3634 100644
--- a/tools/perf/tests/shell/coresight/thread_loop/thread_loop.c
+++ b/tools/perf/tests/shell/coresight/thread_loop/thread_loop.c
@@ -34,8 +34,8 @@ static void *thrfn(void *arg)
 	}
 	asm volatile(
 		"loop:\n"
-		"add %[i], %[i], #1\n"
-		"cmp %[i], %[len]\n"
+		"add %w[i], %w[i], #1\n"
+		"cmp %w[i], %w[len]\n"
 		"blt loop\n"
 		: /* out */
 		: /* in */ [i] "r" (i), [len] "r" (len)

-- 
2.34.1

[PATCH v2 6/8] perf test coresight: Dismiss clang warning for unroll loop thread

[Leo Yan]

clang-18.1.3 on Ubuntu 24.04.2 reports warning:

  unroll_loop_thread.c:35:25: warning: value size does not match register size specified by the constraint and modifier [-Wasm-operand-widths]
     35 |                         : /* in */ [in] "r" (in)
        |                                              ^
  unroll_loop_thread.c:39:1: warning: non-void function does not return a value [-Wreturn-type]
     39 | }
        | ^

Use the modifier "w" for 32-bit register access and return NULL at the
end of thread function.

Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 .../tests/shell/coresight/unroll_loop_thread/unroll_loop_thread.c     | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/tests/shell/coresight/unroll_loop_thread/unroll_loop_thread.c b/tools/perf/tests/shell/coresight/unroll_loop_thread/unroll_loop_thread.c
index 0fc7bf1a25af3607b40f091f62176134ddb7f9f6..8f4e1c985ca38ab545a05189432a14a6d888d34c 100644
--- a/tools/perf/tests/shell/coresight/unroll_loop_thread/unroll_loop_thread.c
+++ b/tools/perf/tests/shell/coresight/unroll_loop_thread/unroll_loop_thread.c
@@ -20,7 +20,7 @@ static void *thrfn(void *arg)
 	for (i = 0; i < 10000; i++) {
 		asm volatile (
 // force an unroll of thia add instruction so we can test long runs of code
-#define SNIP1 "add %[in], %[in], #1\n"
+#define SNIP1 "add %w[in], %w[in], #1\n"
 // 10
 #define SNIP2 SNIP1 SNIP1 SNIP1 SNIP1 SNIP1 SNIP1 SNIP1 SNIP1 SNIP1 SNIP1
 // 100
@@ -36,6 +36,8 @@ static void *thrfn(void *arg)
 			: /* clobber */
 		);
 	}
+
+	return NULL;
 }
 
 static pthread_t new_thr(void *(*fn) (void *arg), void *arg)

-- 
2.34.1

[PATCH v2 7/8] perf build: Support build with clang

[Leo Yan]

Add support for building perf with clang. For cross compilation, the
Makefile dynamically selects target flag for corresponding arch.

This patch has been verified on x86_64 machine with Ubuntu distro, it
can build successfully for native target, and for cross building Arm64
and s390.

Example: native build on x86_64 / Ubuntu machine:

  $ HOSTCC=clang CC=clang CXX=clang++ make -C tools/perf

Example: cross building s390 target on x86_64 / Ubuntu machine:

  # Install x390x cross toolchain and headers
  $ sudo apt-get install gcc-s390x-linux-gnu g++-s390x-linux-gnu \
         libc6-dev-s390x-cross linux-libc-dev-s390x-cross

  # Build with clang
  $ HOSTCC=clang CC=clang CXX=clang++ \
    ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- \
    make -C tools/perf NO_LIBELF=1 NO_LIBTRACEEVENT=1 NO_LIBPYTHON=1

Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 tools/perf/Makefile.config | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 5a5832ee7b53c604ec0d90c5ca7e2bee5bfa6a17..a2b5c291a364cbf331c16384764520dfe330a04c 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -23,8 +23,38 @@ HOSTCFLAGS := $(filter-out -Wnested-externs,$(EXTRA_WARNINGS))
 # borrowed from kernel headers depends on it, e.g. put_unaligned_*().
 CFLAGS += -fno-strict-aliasing
 
-# Enabled Wthread-safety analysis for clang builds.
+# Set target flag and options when using clang as compiler.
 ifeq ($(CC_NO_CLANG), 0)
+  CLANG_TARGET_FLAGS_arm	:= arm-linux-gnueabi
+  CLANG_TARGET_FLAGS_arm64	:= aarch64-linux-gnu
+  CLANG_TARGET_FLAGS_m68k	:= m68k-linux-gnu
+  CLANG_TARGET_FLAGS_mips	:= mipsel-linux-gnu
+  CLANG_TARGET_FLAGS_powerpc	:= powerpc64le-linux-gnu
+  CLANG_TARGET_FLAGS_riscv	:= riscv64-linux-gnu
+  CLANG_TARGET_FLAGS_s390	:= s390x-linux-gnu
+  CLANG_TARGET_FLAGS_x86	:= x86_64-linux-gnu
+
+  # Default to host architecture if ARCH is not explicitly given.
+  ifeq ($(ARCH),)
+    CLANG_TARGET_FLAGS := $(shell $(CLANG) -print-target-triple)
+  else
+    CLANG_TARGET_FLAGS := $(CLANG_TARGET_FLAGS_$(ARCH))
+  endif
+
+  ifeq ($(CROSS_COMPILE),)
+    ifeq ($(CLANG_TARGET_FLAGS),)
+      $(error Specify CROSS_COMPILE or add CLANG_TARGET_FLAGS for $(ARCH))
+    else
+      CLANG_FLAGS += --target=$(CLANG_TARGET_FLAGS)
+    endif # CLANG_TARGET_FLAGS
+  else
+    CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%))
+  endif # CROSS_COMPILE
+
+  CC := $(CLANG) $(CLANG_FLAGS) -fintegrated-as
+  CXX := $(CXX) $(CLANG_FLAGS) -fintegrated-as
+
+  # Enabled Wthread-safety analysis for clang builds.
   CFLAGS += -Wthread-safety
 endif
 

-- 
2.34.1

[PATCH v2 8/8] perf docs: Document building with Clang

[Leo Yan]

Add example commands for building perf with Clang.

Since recent Android NDK releases use Clang as the default compiler, a
separate Android specific document is no longer needed; point to the
general build documentation instead.

Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 tools/perf/Documentation/Build.txt   | 15 +++++++
 tools/perf/Documentation/android.txt | 80 +++---------------------------------
 2 files changed, 21 insertions(+), 74 deletions(-)

diff --git a/tools/perf/Documentation/Build.txt b/tools/perf/Documentation/Build.txt
index 83dc87c662b63ecc17553a15cc15a6b8d6f01d83..57b226e7fc2f8e849dfe58b3af31891f58dfd0af 100644
--- a/tools/perf/Documentation/Build.txt
+++ b/tools/perf/Documentation/Build.txt
@@ -99,3 +99,18 @@ configuration paths for cross building:
 In this case, the variable PKG_CONFIG_SYSROOT_DIR can be used alongside the
 variable PKG_CONFIG_LIBDIR or PKG_CONFIG_PATH to prepend the sysroot path to
 the library paths for cross compilation.
+
+5) Build with Clang
+===================
+By default, the makefile uses GCC as compiler. With specifying environment
+variables HOSTCC, CC and CXX, it allows to build perf with Clang.
+
+Using Clang for a native build:
+
+  $ HOSTCC=clang CC=clang CXX=clang++ make -C tools/perf
+
+Specifying ARCH and CROSS_COMPILE for cross compilation:
+
+  $ HOSTCC=clang CC=clang CXX=clang++ \
+    ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- \
+    make -C tools/perf
diff --git a/tools/perf/Documentation/android.txt b/tools/perf/Documentation/android.txt
index 24a59998fc91e814ad96f658d3481d88d798b60c..3f3cc7ac3d139c5517ec9458f13c06249c701429 100644
--- a/tools/perf/Documentation/android.txt
+++ b/tools/perf/Documentation/android.txt
@@ -1,78 +1,10 @@
 How to compile perf for Android
-=========================================
+===============================
 
-I. Set the Android NDK environment
-------------------------------------------------
+There are two ways to build perf and run it on Android:
 
-(a). Use the Android NDK
-------------------------------------------------
-1. You need to download and install the Android Native Development Kit (NDK).
-Set the NDK variable to point to the path where you installed the NDK:
-  export NDK=/path/to/android-ndk
+- Method 1: Build perf with static linking. See Build.txt, section
+  "4) Cross compilation" for how to build a static perf binary.
 
-2. Set cross-compiling environment variables for NDK toolchain and sysroot.
-For arm:
-  export NDK_TOOLCHAIN=${NDK}/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/arm-linux-androideabi-
-  export NDK_SYSROOT=${NDK}/platforms/android-24/arch-arm
-For x86:
-  export NDK_TOOLCHAIN=${NDK}/toolchains/x86-4.9/prebuilt/linux-x86_64/bin/i686-linux-android-
-  export NDK_SYSROOT=${NDK}/platforms/android-24/arch-x86
-
-This method is only tested for Android NDK versions Revision 11b and later.
-perf uses some bionic enhancements that are not included in prior NDK versions.
-You can use method (b) described below instead.
-
-(b). Use the Android source tree
------------------------------------------------
-1. Download the master branch of the Android source tree.
-Set the environment for the target you want using:
-  source build/envsetup.sh
-  lunch
-
-2. Build your own NDK sysroot to contain latest bionic changes and set the
-NDK sysroot environment variable.
-  cd ${ANDROID_BUILD_TOP}/ndk
-For arm:
-  ./build/tools/build-ndk-sysroot.sh --abi=arm
-  export NDK_SYSROOT=${ANDROID_BUILD_TOP}/ndk/build/platforms/android-3/arch-arm
-For x86:
-  ./build/tools/build-ndk-sysroot.sh --abi=x86
-  export NDK_SYSROOT=${ANDROID_BUILD_TOP}/ndk/build/platforms/android-3/arch-x86
-
-3. Set the NDK toolchain environment variable.
-For arm:
-  export NDK_TOOLCHAIN=${ANDROID_TOOLCHAIN}/arm-linux-androideabi-
-For x86:
-  export NDK_TOOLCHAIN=${ANDROID_TOOLCHAIN}/i686-linux-android-
-
-II. Compile perf for Android
-------------------------------------------------
-You need to run make with the NDK toolchain and sysroot defined above:
-For arm:
-  make WERROR=0 ARCH=arm CROSS_COMPILE=${NDK_TOOLCHAIN} EXTRA_CFLAGS="-pie --sysroot=${NDK_SYSROOT}"
-For x86:
-  make WERROR=0 ARCH=x86 CROSS_COMPILE=${NDK_TOOLCHAIN} EXTRA_CFLAGS="-pie --sysroot=${NDK_SYSROOT}"
-
-III. Install perf
------------------------------------------------
-You need to connect to your Android device/emulator using adb.
-Install perf using:
-  adb push perf /data/perf
-
-If you also want to use perf-archive you need busybox tools for Android.
-For installing perf-archive, you first need to replace #!/bin/bash with #!/system/bin/sh:
-  sed 's/#!\/bin\/bash/#!\/system\/bin\/sh/g' perf-archive >> /tmp/perf-archive
-  chmod +x /tmp/perf-archive
-  adb push /tmp/perf-archive /data/perf-archive
-
-IV. Environment settings for running perf
-------------------------------------------------
-Some perf features need environment variables to run properly.
-You need to set these before running perf on the target:
-  adb shell
-  # PERF_PAGER=cat
-
-IV. Run perf
-------------------------------------------------
-Run perf on your device/emulator to which you previously connected using adb:
-  # ./data/perf
+- Method 2: Download the Android NDK and use the bundled Clang to
+  build perf. See Build.txt, section "5) Build with clang" for details.

-- 
2.34.1

Re: [PATCH v2 0/8] perf build: Support building with Clang

[Ian Rogers]

On Tue, Sep 30, 2025 at 9:55 AM Leo Yan <leo.yan@arm.com> wrote:
>
> This series adds support for building perf with Clang, following the
> discussion in [1]. Because the Android NDK uses Clang by default,
> enabling Clang builds naturally covers Android as well.
>
> The series is organized as follows:
>
>   - Patches 1–2: Fix two bugs found with Clang.
>   - Patches 3–6: Correct CROSS_ARCH and dismiss Clang build warnings.
>   - Patches 7–8: Enable Clang in the Makefile and update the
>     documentation.
>
> Testing:
>
>   - Clang 15.0.7 on Ubuntu 22.04.5: native and cross-compiling (aarch64)
>   - Clang 18.1.3 on Ubuntu 24.04.2: native and cross-compiling (aarch64)
>   - Android NDK r27d (latest LTS): cross-compiling (aarch64)
>
> [1] https://lore.kernel.org/linux-perf-users/20240715143342.52236-1-leo.yan@arm.com/
>
> ---
> Changes in v2:
> - Dropped the patch for dismissing warning in bpftool.
> - Refined the document. (Ian)
> - Link to v1: https://lore.kernel.org/r/20250925-perf_build_android_ndk-v1-0-8b35aadde3dc@arm.com

Reviewed-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> ---
> Leo Yan (8):
>       tools build: Align warning options with perf
>       perf python: split Clang options when invoking Popen
>       perf: build: Correct CROSS_ARCH for clang
>       perf test coresight: Dismiss clang warning for memcpy thread
>       perf test coresight: Dismiss clang warning for thread loop
>       perf test coresight: Dismiss clang warning for unroll loop thread
>       perf build: Support build with clang
>       perf docs: Document building with Clang
>
>  tools/build/feature/Makefile                       |  6 +-
>  tools/perf/Documentation/Build.txt                 | 15 ++++
>  tools/perf/Documentation/android.txt               | 80 ++--------------------
>  tools/perf/Makefile.config                         | 32 ++++++++-
>  tools/perf/Makefile.perf                           |  2 +-
>  .../shell/coresight/memcpy_thread/memcpy_thread.c  |  2 +
>  .../shell/coresight/thread_loop/thread_loop.c      |  4 +-
>  .../unroll_loop_thread/unroll_loop_thread.c        |  4 +-
>  tools/perf/util/setup.py                           |  5 +-
>  9 files changed, 67 insertions(+), 83 deletions(-)
> ---
> base-commit: c17dda8013495d8132c976cbf349be9949d0fbd1
> change-id: 20250915-perf_build_android_ndk-500b53bea895
>
> Best regards,
> --
> Leo Yan <leo.yan@arm.com>
>

Re: [PATCH v2 0/8] perf build: Support building with Clang

[Arnaldo Carvalho de Melo]

On Tue, Sep 30, 2025 at 11:14:30AM -0700, Ian Rogers wrote:
> On Tue, Sep 30, 2025 at 9:55 AM Leo Yan <leo.yan@arm.com> wrote:
> >
> > This series adds support for building perf with Clang, following the
> > discussion in [1]. Because the Android NDK uses Clang by default,
> > enabling Clang builds naturally covers Android as well.
> >
> > The series is organized as follows:
> >
> >   - Patches 1–2: Fix two bugs found with Clang.
> >   - Patches 3–6: Correct CROSS_ARCH and dismiss Clang build warnings.
> >   - Patches 7–8: Enable Clang in the Makefile and update the
> >     documentation.
> >
> > Testing:
> >
> >   - Clang 15.0.7 on Ubuntu 22.04.5: native and cross-compiling (aarch64)
> >   - Clang 18.1.3 on Ubuntu 24.04.2: native and cross-compiling (aarch64)
> >   - Android NDK r27d (latest LTS): cross-compiling (aarch64)
> >
> > [1] https://lore.kernel.org/linux-perf-users/20240715143342.52236-1-leo.yan@arm.com/
> >
> > ---
> > Changes in v2:
> > - Dropped the patch for dismissing warning in bpftool.
> > - Refined the document. (Ian)
> > - Link to v1: https://lore.kernel.org/r/20250925-perf_build_android_ndk-v1-0-8b35aadde3dc@arm.com
> 
> Reviewed-by: Ian Rogers <irogers@google.com>

Thanks, applied to perf-tools-next,

- Arnaldo

Re: [PATCH v2 0/8] perf build: Support building with Clang

[Arnaldo Carvalho de Melo]

On Tue, Sep 30, 2025 at 05:54:48PM +0100, Leo Yan wrote:
> This series adds support for building perf with Clang, following the
> discussion in [1]. Because the Android NDK uses Clang by default,
> enabling Clang builds naturally covers Android as well.
> 
> The series is organized as follows:
> 
>   - Patches 1–2: Fix two bugs found with Clang.
>   - Patches 3–6: Correct CROSS_ARCH and dismiss Clang build warnings.
>   - Patches 7–8: Enable Clang in the Makefile and update the
>     documentation.
> 
> Testing:
> 
>   - Clang 15.0.7 on Ubuntu 22.04.5: native and cross-compiling (aarch64)
>   - Clang 18.1.3 on Ubuntu 24.04.2: native and cross-compiling (aarch64)
>   - Android NDK r27d (latest LTS): cross-compiling (aarch64)

  LD      /tmp/build/perf/util/perf-util-in.o
  LD      /tmp/build/perf/perf-util-in.o
  AR      /tmp/build/perf/libperf-util.a
  CC      /tmp/build/perf/pmu-events/pmu-events.o
  LD      /tmp/build/perf/pmu-events/pmu-events-in.o
  AR      /tmp/build/perf/libpmu-events.a
  LINK    /tmp/build/perf/perf
make: Leaving directory '/git/perf-6.17.0-rc6/tools/perf'
+ rm -rf /tmp/build/perf
+ mkdir /tmp/build/perf
+ make 'ARCH=' 'CROSS_COMPILE=' 'EXTRA_CFLAGS=' -C tools/perf 'O=/tmp/build/perf' 'CC=clang'
make: Entering directory '/git/perf-6.17.0-rc6/tools/perf'
  BUILD:   Doing 'make -j28' parallel build
Makefile.config:494: *** No gnu/libc-version.h found, please install glibc-dev[el].  Stop.
make[1]: *** [Makefile.perf:289: sub-make] Error 2
make: *** [Makefile:76: all] Error 2
make: Leaving directory '/git/perf-6.17.0-rc6/tools/perf'
+ exit 1
toolsbuilder@five:~$ cat dm.log/alpine\:3.22

Re: [PATCH v2 0/8] perf build: Support building with Clang

[Leo Yan]

On Wed, Oct 01, 2025 at 11:21:20AM -0300, Arnaldo Carvalho de Melo wrote:
> On Tue, Sep 30, 2025 at 05:54:48PM +0100, Leo Yan wrote:
> > This series adds support for building perf with Clang, following the
> > discussion in [1]. Because the Android NDK uses Clang by default,
> > enabling Clang builds naturally covers Android as well.
> > 
> > The series is organized as follows:
> > 
> >   - Patches 1–2: Fix two bugs found with Clang.
> >   - Patches 3–6: Correct CROSS_ARCH and dismiss Clang build warnings.
> >   - Patches 7–8: Enable Clang in the Makefile and update the
> >     documentation.
> > 
> > Testing:
> > 
> >   - Clang 15.0.7 on Ubuntu 22.04.5: native and cross-compiling (aarch64)
> >   - Clang 18.1.3 on Ubuntu 24.04.2: native and cross-compiling (aarch64)
> >   - Android NDK r27d (latest LTS): cross-compiling (aarch64)
> 
>   LD      /tmp/build/perf/util/perf-util-in.o
>   LD      /tmp/build/perf/perf-util-in.o
>   AR      /tmp/build/perf/libperf-util.a
>   CC      /tmp/build/perf/pmu-events/pmu-events.o
>   LD      /tmp/build/perf/pmu-events/pmu-events-in.o
>   AR      /tmp/build/perf/libpmu-events.a
>   LINK    /tmp/build/perf/perf
> make: Leaving directory '/git/perf-6.17.0-rc6/tools/perf'
> + rm -rf /tmp/build/perf
> + mkdir /tmp/build/perf
> + make 'ARCH=' 'CROSS_COMPILE=' 'EXTRA_CFLAGS=' -C tools/perf 'O=/tmp/build/perf' 'CC=clang'
> make: Entering directory '/git/perf-6.17.0-rc6/tools/perf'
>   BUILD:   Doing 'make -j28' parallel build
> Makefile.config:494: *** No gnu/libc-version.h found, please install glibc-dev[el].  Stop.
> make[1]: *** [Makefile.perf:289: sub-make] Error 2
> make: *** [Makefile:76: all] Error 2
> make: Leaving directory '/git/perf-6.17.0-rc6/tools/perf'
> + exit 1
> toolsbuilder@five:~$ cat dm.log/alpine\:3.22

A quick look: the build cannot find both libelf (feature-libelf=0) and
glibc (feature-glibc=0), thus lead to build failure. It is good to
know what the reason for the feature building failures:

  tools/perf/feature/test-libelf.make.output
  tools/perf/feature/test-glibc.make.output

I am not surprised for the failure of libelf (this is common case
that the package is not installed by default in a distro), but it is a
bit confused for the glibc feature failure.

It seems the issue occurs on Alpine 3.22, but the highest version
supported in container-build is 3.21 [1]. Could you confirm whether
the issue reproduces on other distros or versions?

Thanks,
Leo

[1] https://github.com/acmel/linux-tools-container-builds/tree/main/alpine

Re: [PATCH v2 0/8] perf build: Support building with Clang

[Arnaldo Carvalho de Melo]

On Wed, Oct 01, 2025 at 04:22:17PM +0100, Leo Yan wrote:
> On Wed, Oct 01, 2025 at 11:21:20AM -0300, Arnaldo Carvalho de Melo wrote:
> > On Tue, Sep 30, 2025 at 05:54:48PM +0100, Leo Yan wrote:
> > > This series adds support for building perf with Clang, following the
> > > discussion in [1]. Because the Android NDK uses Clang by default,
> > > enabling Clang builds naturally covers Android as well.
> > > 
> > > The series is organized as follows:
> > > 
> > >   - Patches 1–2: Fix two bugs found with Clang.
> > >   - Patches 3–6: Correct CROSS_ARCH and dismiss Clang build warnings.
> > >   - Patches 7–8: Enable Clang in the Makefile and update the
> > >     documentation.
> > > 
> > > Testing:
> > > 
> > >   - Clang 15.0.7 on Ubuntu 22.04.5: native and cross-compiling (aarch64)
> > >   - Clang 18.1.3 on Ubuntu 24.04.2: native and cross-compiling (aarch64)
> > >   - Android NDK r27d (latest LTS): cross-compiling (aarch64)
> > 
> >   LD      /tmp/build/perf/util/perf-util-in.o
> >   LD      /tmp/build/perf/perf-util-in.o
> >   AR      /tmp/build/perf/libperf-util.a
> >   CC      /tmp/build/perf/pmu-events/pmu-events.o
> >   LD      /tmp/build/perf/pmu-events/pmu-events-in.o
> >   AR      /tmp/build/perf/libpmu-events.a
> >   LINK    /tmp/build/perf/perf
> > make: Leaving directory '/git/perf-6.17.0-rc6/tools/perf'
> > + rm -rf /tmp/build/perf
> > + mkdir /tmp/build/perf
> > + make 'ARCH=' 'CROSS_COMPILE=' 'EXTRA_CFLAGS=' -C tools/perf 'O=/tmp/build/perf' 'CC=clang'
> > make: Entering directory '/git/perf-6.17.0-rc6/tools/perf'
> >   BUILD:   Doing 'make -j28' parallel build
> > Makefile.config:494: *** No gnu/libc-version.h found, please install glibc-dev[el].  Stop.
> > make[1]: *** [Makefile.perf:289: sub-make] Error 2
> > make: *** [Makefile:76: all] Error 2
> > make: Leaving directory '/git/perf-6.17.0-rc6/tools/perf'
> > + exit 1
> > toolsbuilder@five:~$ cat dm.log/alpine\:3.22
 
> A quick look: the build cannot find both libelf (feature-libelf=0) and
> glibc (feature-glibc=0), thus lead to build failure. It is good to
> know what the reason for the feature building failures:
 
>   tools/perf/feature/test-libelf.make.output
>   tools/perf/feature/test-glibc.make.output
 
> I am not surprised for the failure of libelf (this is common case
> that the package is not installed by default in a distro), but it is a
> bit confused for the glibc feature failure.
 
> It seems the issue occurs on Alpine 3.22, but the highest version
> supported in container-build is 3.21 [1]. Could you confirm whether
> the issue reproduces on other distros or versions?

It was in all alpine versions I have containers to test on:

toolsbuilder@five:~$ grep FAIL dm.log.old/summary 
   3    71.85 almalinux:9-i386              : FAIL clang version 17.0.6 (AlmaLinux OS Foundation 17.0.6-5.el9)
   5    78.60 alpine:3.16                   : FAIL gcc version 11.2.1 20220219 (Alpine 11.2.1_git20220219) 
   6    59.77 alpine:3.17                   : FAIL gcc version 12.2.1 20220924 (Alpine 12.2.1_git20220924-r4) 
   7    56.89 alpine:3.18                   : FAIL gcc version 12.2.1 20220924 (Alpine 12.2.1_git20220924-r10) 
   8    60.86 alpine:3.19                   : FAIL gcc version 13.2.1 20231014 (Alpine 13.2.1_git20231014) 
   9    60.18 alpine:3.20                   : FAIL gcc version 13.2.1 20240309 (Alpine 13.2.1_git20240309) 
  10    64.58 alpine:3.22                   : FAIL gcc version 14.2.0 (Alpine 14.2.0) 
  11    63.36 alpine:edge                   : FAIL gcc version 14.2.0 (Alpine 14.2.0) 
toolsbuilder@five:~$

  GEN     /tmp/build/perf/python/perf.cpython-312-x86_64-linux-musl.so
make: Leaving directory '/git/perf-6.17.0-rc6/tools/perf'
+ rm -rf /tmp/build/perf
+ mkdir /tmp/build/perf
+ make 'ARCH=' 'CROSS_COMPILE=' 'EXTRA_CFLAGS=' -C tools/perf 'O=/tmp/build/perf' 'CC=clang'
make: Entering directory '/git/perf-6.17.0-rc6/tools/perf'
  BUILD:   Doing 'make -j28' parallel build
Makefile.config:494: *** No gnu/libc-version.h found, please install glibc-dev[el].  Stop.
make[1]: *** [Makefile.perf:289: sub-make] Error 2
make: *** [Makefile:76: all] Error 2
make: Leaving directory '/git/perf-6.17.0-rc6/tools/perf'
+ exit 1
toolsbuilder@five:~
$

lemme try to reapply those patches and get the
tools/perf/feature/test-libelf.make.output and
tools/perf/feature/test-glibc.make.output files.

- Arnaldo

Re: [PATCH v2 0/8] perf build: Support building with Clang

[Leo Yan]

On Wed, Oct 01, 2025 at 03:25:56PM -0300, Arnaldo Carvalho de Melo wrote:

[...]

> It was in all alpine versions I have containers to test on:
> 
> toolsbuilder@five:~$ grep FAIL dm.log.old/summary 
>    3    71.85 almalinux:9-i386              : FAIL clang version 17.0.6 (AlmaLinux OS Foundation 17.0.6-5.el9)
>    5    78.60 alpine:3.16                   : FAIL gcc version 11.2.1 20220219 (Alpine 11.2.1_git20220219) 
>    6    59.77 alpine:3.17                   : FAIL gcc version 12.2.1 20220924 (Alpine 12.2.1_git20220924-r4) 
>    7    56.89 alpine:3.18                   : FAIL gcc version 12.2.1 20220924 (Alpine 12.2.1_git20220924-r10) 
>    8    60.86 alpine:3.19                   : FAIL gcc version 13.2.1 20231014 (Alpine 13.2.1_git20231014) 
>    9    60.18 alpine:3.20                   : FAIL gcc version 13.2.1 20240309 (Alpine 13.2.1_git20240309) 
>   10    64.58 alpine:3.22                   : FAIL gcc version 14.2.0 (Alpine 14.2.0) 
>   11    63.36 alpine:edge                   : FAIL gcc version 14.2.0 (Alpine 14.2.0) 
> toolsbuilder@five:~$
> 
>   GEN     /tmp/build/perf/python/perf.cpython-312-x86_64-linux-musl.so
> make: Leaving directory '/git/perf-6.17.0-rc6/tools/perf'
> + rm -rf /tmp/build/perf
> + mkdir /tmp/build/perf
> + make 'ARCH=' 'CROSS_COMPILE=' 'EXTRA_CFLAGS=' -C tools/perf 'O=/tmp/build/perf' 'CC=clang'
> make: Entering directory '/git/perf-6.17.0-rc6/tools/perf'
>   BUILD:   Doing 'make -j28' parallel build
> Makefile.config:494: *** No gnu/libc-version.h found, please install glibc-dev[el].  Stop.
> make[1]: *** [Makefile.perf:289: sub-make] Error 2
> make: *** [Makefile:76: all] Error 2
> make: Leaving directory '/git/perf-6.17.0-rc6/tools/perf'
> + exit 1
> toolsbuilder@five:~
> $
> 
> lemme try to reapply those patches and get the
> tools/perf/feature/test-libelf.make.output and
> tools/perf/feature/test-glibc.make.output files.

That is fine.  I have reproduced at my side, will look into.

Thanks,
Leo

Re: [PATCH v2 0/8] perf build: Support building with Clang

[Leo Yan]

On Wed, Oct 01, 2025 at 07:32:56PM +0100, Leo Yan wrote:

[...]

> > + make 'ARCH=' 'CROSS_COMPILE=' 'EXTRA_CFLAGS=' -C tools/perf 'O=/tmp/build/perf' 'CC=clang'
> > make: Entering directory '/git/perf-6.17.0-rc6/tools/perf'
> >   BUILD:   Doing 'make -j28' parallel build
> > Makefile.config:494: *** No gnu/libc-version.h found, please install glibc-dev[el].  Stop.

It does not set correctly --target as x86_64-alpine-linux-musl if
distros are using musl libc.

Now running the container build for updated code.  Once pass test,
I will send new series.

Thanks,
Leo

Re: [PATCH v2 0/8] perf build: Support building with Clang

[Arnaldo Carvalho de Melo]

On Wed, Oct 01, 2025 at 09:20:50PM +0100, Leo Yan wrote:
> On Wed, Oct 01, 2025 at 07:32:56PM +0100, Leo Yan wrote:
> 
> [...]
> 
> > > + make 'ARCH=' 'CROSS_COMPILE=' 'EXTRA_CFLAGS=' -C tools/perf 'O=/tmp/build/perf' 'CC=clang'
> > > make: Entering directory '/git/perf-6.17.0-rc6/tools/perf'
> > >   BUILD:   Doing 'make -j28' parallel build
> > > Makefile.config:494: *** No gnu/libc-version.h found, please install glibc-dev[el].  Stop.
> 
> It does not set correctly --target as x86_64-alpine-linux-musl if
> distros are using musl libc.
> 
> Now running the container build for updated code.  Once pass test,
> I will send new series.

Thanks for spotting the problem after taking the trouble of starting a
container! Hopefully that will save time for other people trying to
cross-build perf.

Cheers,

- Arnaldo