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Subject[PATCH 12/28] tools build: Add capability-related feature detection
Date
From: Igor Lubashev <ilubashe@akamai.com>

Add utilities to help checking capabilities of the running procss. Make
perf link with libcap, if it is available. If no libcap-dev[el], assume
no capabilities.

Committer testing:

$ make O=/tmp/build/perf -C tools/perf install-bin
make: Entering directory '/home/acme/git/perf/tools/perf'
BUILD: Doing 'make -j8' parallel build

Auto-detecting system features:
<SNIP>
... libbfd: [ on ]
... libcap: [ OFF ]
... libelf: [ on ]
<SNIP>
Makefile.config:833: No libcap found, disables capability support, please install libcap-devel/libcap-dev
<SNIP>
$ grep libcap /tmp/build/perf/FEATURE-DUMP
feature-libcap=0
$ cat /tmp/build/perf/feature/test-libcap.make.output
test-libcap.c:2:10: fatal error: sys/capability.h: No such file or directory
2 | #include <sys/capability.h>
| ^~~~~~~~~~~~~~~~~~
compilation terminated.
$

Now install libcap-devel and try again:

$ make O=/tmp/build/perf -C tools/perf install-bin
make: Entering directory '/home/acme/git/perf/tools/perf'
BUILD: Doing 'make -j8' parallel build
Warning: Kernel ABI header at 'tools/include/linux/bits.h' differs from latest version at 'include/linux/bits.h'
diff -u tools/include/linux/bits.h include/linux/bits.h
Warning: Kernel ABI header at 'tools/arch/x86/include/asm/cpufeatures.h' differs from latest version at 'arch/x86/include/asm/cpufeatures.h'
diff -u tools/arch/x86/include/asm/cpufeatures.h arch/x86/include/asm/cpufeatures.h

Auto-detecting system features:
<SNIP>
... libbfd: [ on ]
... libcap: [ on ]
... libelf: [ on ]
<SNIP>>
CC /tmp/build/perf/jvmti/libjvmti.o
<SNIP>>
$ grep libcap /tmp/build/perf/FEATURE-DUMP
feature-libcap=1
$ cat /tmp/build/perf/feature/test-libcap.make.output
$ ldd /tmp/build/perf/feature/test-libcap.make.bin
ldd: /tmp/build/perf/feature/test-libcap.make.bin: No such file or directory
$ ldd /tmp/build/perf/feature/test-libcap.bin
linux-vdso.so.1 (0x00007ffc35bfe000)
libcap.so.2 => /lib64/libcap.so.2 (0x00007ff9c62ff000)
libc.so.6 => /lib64/libc.so.6 (0x00007ff9c6139000)
/lib64/ld-linux-x86-64.so.2 (0x00007ff9c6326000)
$

Signed-off-by: Igor Lubashev <ilubashe@akamai.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
[ split from a larger patch ]
Link: http://lkml.kernel.org/r/8a1e76cf5c7c9796d0d4d240fbaa85305298aafa.1565188228.git.ilubashe@akamai.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/build/Makefile.feature | 2 ++
tools/build/feature/Makefile | 4 ++++
tools/build/feature/test-libcap.c | 20 ++++++++++++++++++++
tools/perf/Makefile.config | 11 +++++++++++
tools/perf/Makefile.perf | 2 ++
5 files changed, 39 insertions(+)
create mode 100644 tools/build/feature/test-libcap.c

diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 86b793dffbc4..8a19753cc26a 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -42,6 +42,7 @@ FEATURE_TESTS_BASIC := \
gtk2-infobar \
libaudit \
libbfd \
+ libcap \
libelf \
libelf-getphdrnum \
libelf-gelf_getnote \
@@ -110,6 +111,7 @@ FEATURE_DISPLAY ?= \
gtk2 \
libaudit \
libbfd \
+ libcap \
libelf \
libnuma \
numa_num_possible_cpus \
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 0658b8cd0e53..8499385365c0 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -20,6 +20,7 @@ FILES= \
test-libbfd-liberty.bin \
test-libbfd-liberty-z.bin \
test-cplus-demangle.bin \
+ test-libcap.bin \
test-libelf.bin \
test-libelf-getphdrnum.bin \
test-libelf-gelf_getnote.bin \
@@ -105,6 +106,9 @@ $(OUTPUT)test-fortify-source.bin:
$(OUTPUT)test-bionic.bin:
$(BUILD)

+$(OUTPUT)test-libcap.bin:
+ $(BUILD) -lcap
+
$(OUTPUT)test-libelf.bin:
$(BUILD) -lelf

diff --git a/tools/build/feature/test-libcap.c b/tools/build/feature/test-libcap.c
new file mode 100644
index 000000000000..d2a2e152195f
--- /dev/null
+++ b/tools/build/feature/test-libcap.c
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <sys/capability.h>
+#include <linux/capability.h>
+
+int main(void)
+{
+ cap_flag_value_t val;
+ cap_t caps = cap_get_proc();
+
+ if (!caps)
+ return 1;
+
+ if (cap_get_flag(caps, CAP_SYS_ADMIN, CAP_EFFECTIVE, &val) != 0)
+ return 1;
+
+ if (cap_free(caps) != 0)
+ return 1;
+
+ return 0;
+}
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index e4988f49ea79..9a06787fedc6 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -824,6 +824,17 @@ ifndef NO_LIBZSTD
endif
endif

+ifndef NO_LIBCAP
+ ifeq ($(feature-libcap), 1)
+ CFLAGS += -DHAVE_LIBCAP_SUPPORT
+ EXTLIBS += -lcap
+ $(call detected,CONFIG_LIBCAP)
+ else
+ msg := $(warning No libcap found, disables capability support, please install libcap-devel/libcap-dev);
+ NO_LIBCAP := 1
+ endif
+endif
+
ifndef NO_BACKTRACE
ifeq ($(feature-backtrace), 1)
CFLAGS += -DHAVE_BACKTRACE_SUPPORT
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 67512a12276b..f9807d8c005b 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -88,6 +88,8 @@ include ../scripts/utilities.mak
#
# Define NO_LIBBPF if you do not want BPF support
#
+# Define NO_LIBCAP if you do not want process capabilities considered by perf
+#
# Define NO_SDT if you do not want to define SDT event in perf tools,
# note that it doesn't disable SDT scanning support.
#
--
2.21.0
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