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0ae065a5d2
linux/tools/build/Makefile.feature
Arnaldo Carvalho de Melo 0ae065a5d2 perf build: Fix check for btf__load_from_kernel_by_id() in libbpf 
Avi Kivity reported a problem where the __weak
btf__load_from_kernel_by_id() in tools/perf/util/bpf-event.c was being
used and it called btf__get_from_id() in tools/lib/bpf/btf.c that in
turn called back to btf__load_from_kernel_by_id(), resulting in an
endless loop.

Fix this by adding a feature test to check if
btf__load_from_kernel_by_id() is available when building perf with
LIBBPF_DYNAMIC=1, and if not then provide the fallback to the old
btf__get_from_id(), that doesn't call back to btf__load_from_kernel_by_id()
since at that time it didn't exist at all.

Tested on Fedora 35 where we have libbpf-devel 0.4.0 with LIBBPF_DYNAMIC
where we don't have btf__load_from_kernel_by_id() and thus its feature
test fail, not defining HAVE_LIBBPF_BTF__LOAD_FROM_KERNEL_BY_ID:

  $ cat /tmp/build/perf-urgent/feature/test-libbpf-btf__load_from_kernel_by_id.make.output
  test-libbpf-btf__load_from_kernel_by_id.c: In function ‘main’:
  test-libbpf-btf__load_from_kernel_by_id.c:6:16: error: implicit declaration of function ‘btf__load_from_kernel_by_id’ [-Werror=implicit-function-declaration]
      6 |         return btf__load_from_kernel_by_id(20151128, NULL);
        |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~
  cc1: all warnings being treated as errors
  $

  $ nm /tmp/build/perf-urgent/perf | grep btf__load_from_kernel_by_id
  00000000005ba180 T btf__load_from_kernel_by_id
  $

  $ objdump --disassemble=btf__load_from_kernel_by_id -S /tmp/build/perf-urgent/perf

  /tmp/build/perf-urgent/perf:     file format elf64-x86-64
  <SNIP>
  00000000005ba180 <btf__load_from_kernel_by_id>:
  #include "record.h"
  #include "util/synthetic-events.h"

  #ifndef HAVE_LIBBPF_BTF__LOAD_FROM_KERNEL_BY_ID
  struct btf *btf__load_from_kernel_by_id(__u32 id)
  {
    5ba180:	55                   	push   %rbp
    5ba181:	48 89 e5             	mov    %rsp,%rbp
    5ba184:	48 83 ec 10          	sub    $0x10,%rsp
    5ba188:	64 48 8b 04 25 28 00 	mov    %fs:0x28,%rax
    5ba18f:	00 00
    5ba191:	48 89 45 f8          	mov    %rax,-0x8(%rbp)
    5ba195:	31 c0                	xor    %eax,%eax
         struct btf *btf;
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
         int err = btf__get_from_id(id, &btf);
    5ba197:	48 8d 75 f0          	lea    -0x10(%rbp),%rsi
    5ba19b:	e8 a0 57 e5 ff       	call   40f940 <btf__get_from_id@plt>
    5ba1a0:	89 c2                	mov    %eax,%edx
  #pragma GCC diagnostic pop

         return err ? ERR_PTR(err) : btf;
    5ba1a2:	48 98                	cltq
    5ba1a4:	85 d2                	test   %edx,%edx
    5ba1a6:	48 0f 44 45 f0       	cmove  -0x10(%rbp),%rax
  }
  <SNIP>

Fixes: 218e7b775d ("perf bpf: Provide a weak btf__load_from_kernel_by_id() for older libbpf versions")
Reported-by: Avi Kivity <avi@scylladb.com>
Link: https://lore.kernel.org/linux-perf-users/f0add43b-3de5-20c5-22c4-70aff4af959f@scylladb.com
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/linux-perf-users/YobjjFOblY4Xvwo7@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-05-20 09:45:41 -03:00

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# SPDX-License-Identifier: GPL-2.0-only
feature_dir := $(srctree)/tools/build/feature
ifneq ($(OUTPUT),)
OUTPUT_FEATURES = $(OUTPUT)feature/
$(shell mkdir -p $(OUTPUT_FEATURES))
endif
feature_check = $(eval $(feature_check_code))
define feature_check_code
feature-$(1) := $(shell $(MAKE) OUTPUT=$(OUTPUT_FEATURES) CC="$(CC)" CXX="$(CXX)" CFLAGS="$(EXTRA_CFLAGS) $(FEATURE_CHECK_CFLAGS-$(1))" CXXFLAGS="$(EXTRA_CXXFLAGS) $(FEATURE_CHECK_CXXFLAGS-$(1))" LDFLAGS="$(LDFLAGS) $(FEATURE_CHECK_LDFLAGS-$(1))" -C $(feature_dir) $(OUTPUT_FEATURES)test-$1.bin >/dev/null 2>/dev/null && echo 1 || echo 0)
endef
feature_set = $(eval $(feature_set_code))
define feature_set_code
feature-$(1) := 1
endef
#
# Build the feature check binaries in parallel, ignore errors, ignore return value and suppress output:
#
#
# Note that this is not a complete list of all feature tests, just
# those that are typically built on a fully configured system.
#
# [ Feature tests not mentioned here have to be built explicitly in
# the rule that uses them - an example for that is the 'bionic'
# feature check. ]
#
FEATURE_TESTS_BASIC := \
backtrace \
dwarf \
dwarf_getlocations \
eventfd \
fortify-source \
get_current_dir_name \
gettid \
glibc \
libbfd \
libbfd-buildid \
libcap \
libelf \
libelf-getphdrnum \
libelf-gelf_getnote \
libelf-getshdrstrndx \
libnuma \
numa_num_possible_cpus \
libperl \
libpython \
libslang \
libslang-include-subdir \
libtraceevent \
libtracefs \
libcrypto \
libunwind \
pthread-attr-setaffinity-np \
pthread-barrier \
reallocarray \
stackprotector-all \
timerfd \
libdw-dwarf-unwind \
zlib \
lzma \
get_cpuid \
bpf \
sched_getcpu \
sdt \
setns \
libaio \
libzstd \
disassembler-four-args \
file-handle
# FEATURE_TESTS_BASIC + FEATURE_TESTS_EXTRA is the complete list
# of all feature tests
FEATURE_TESTS_EXTRA := \
bionic \
compile-32 \
compile-x32 \
cplus-demangle \
gtk2 \
gtk2-infobar \
hello \
libbabeltrace \
libbfd-liberty \
libbfd-liberty-z \
libopencsd \
libunwind-x86 \
libunwind-x86_64 \
libunwind-arm \
libunwind-aarch64 \
libunwind-debug-frame \
libunwind-debug-frame-arm \
libunwind-debug-frame-aarch64 \
cxx \
llvm \
llvm-version \
clang \
libbpf \
libbpf-btf__load_from_kernel_by_id \
libpfm4 \
libdebuginfod \
clang-bpf-co-re
FEATURE_TESTS ?= $(FEATURE_TESTS_BASIC)
ifeq ($(FEATURE_TESTS),all)
FEATURE_TESTS := $(FEATURE_TESTS_BASIC) $(FEATURE_TESTS_EXTRA)
endif
FEATURE_DISPLAY ?= \
dwarf \
dwarf_getlocations \
glibc \
libbfd \
libbfd-buildid \
libcap \
libelf \
libnuma \
numa_num_possible_cpus \
libperl \
libpython \
libcrypto \
libunwind \
libdw-dwarf-unwind \
zlib \
lzma \
get_cpuid \
bpf \
libaio \
libzstd \
disassembler-four-args
# Set FEATURE_CHECK_(C|LD)FLAGS-all for all FEATURE_TESTS features.
# If in the future we need per-feature checks/flags for features not
# mentioned in this list we need to refactor this ;-).
set_test_all_flags = $(eval $(set_test_all_flags_code))
define set_test_all_flags_code
FEATURE_CHECK_CFLAGS-all += $(FEATURE_CHECK_CFLAGS-$(1))
FEATURE_CHECK_LDFLAGS-all += $(FEATURE_CHECK_LDFLAGS-$(1))
endef
$(foreach feat,$(FEATURE_TESTS),$(call set_test_all_flags,$(feat)))
#
# Special fast-path for the 'all features are available' case:
#
$(call feature_check,all,$(MSG))
#
# Just in case the build freshly failed, make sure we print the
# feature matrix:
#
ifeq ($(feature-all), 1)
#
# test-all.c passed - just set all the core feature flags to 1:
#
$(foreach feat,$(FEATURE_TESTS),$(call feature_set,$(feat)))
#
# test-all.c does not comprise these tests, so we need to
# for this case to get features proper values
#
$(call feature_check,compile-32)
$(call feature_check,compile-x32)
$(call feature_check,bionic)
$(call feature_check,libbabeltrace)
else
$(foreach feat,$(FEATURE_TESTS),$(call feature_check,$(feat)))
endif
#
# Print the result of the feature test:
#
feature_print_status = $(eval $(feature_print_status_code)) $(info $(MSG))
define feature_print_status_code
ifeq ($(feature-$(1)), 1)
MSG = $(shell printf '...%30s: [ \033[32mon\033[m ]' $(1))
else
MSG = $(shell printf '...%30s: [ \033[31mOFF\033[m ]' $(1))
endif
endef
feature_print_text = $(eval $(feature_print_text_code)) $(info $(MSG))
define feature_print_text_code
MSG = $(shell printf '...%30s: %s' $(1) $(2))
endef
#
# generates feature value assignment for name, like:
# $(call feature_assign,dwarf) == feature-dwarf=1
#
feature_assign = feature-$(1)=$(feature-$(1))
FEATURE_DUMP_FILENAME = $(OUTPUT)FEATURE-DUMP$(FEATURE_USER)
FEATURE_DUMP := $(shell touch $(FEATURE_DUMP_FILENAME); cat $(FEATURE_DUMP_FILENAME))
feature_dump_check = $(eval $(feature_dump_check_code))
define feature_dump_check_code
ifeq ($(findstring $(1),$(FEATURE_DUMP)),)
$(2) := 1
endif
endef
#
# First check if any test from FEATURE_DISPLAY
# and set feature_display := 1 if it does
$(foreach feat,$(FEATURE_DISPLAY),$(call feature_dump_check,$(call feature_assign,$(feat)),feature_display))
#
# Now also check if any other test changed,
# so we force FEATURE-DUMP generation
$(foreach feat,$(FEATURE_TESTS),$(call feature_dump_check,$(call feature_assign,$(feat)),feature_dump_changed))
# The $(feature_display) controls the default detection message
# output. It's set if:
# - detected features differes from stored features from
# last build (in $(FEATURE_DUMP_FILENAME) file)
# - one of the $(FEATURE_DISPLAY) is not detected
# - VF is enabled
ifeq ($(feature_dump_changed),1)
$(shell rm -f $(FEATURE_DUMP_FILENAME))
$(foreach feat,$(FEATURE_TESTS),$(shell echo "$(call feature_assign,$(feat))" >> $(FEATURE_DUMP_FILENAME)))
endif
feature_display_check = $(eval $(feature_check_display_code))
define feature_check_display_code
ifneq ($(feature-$(1)), 1)
feature_display := 1
endif
endef
$(foreach feat,$(FEATURE_DISPLAY),$(call feature_display_check,$(feat)))
ifeq ($(VF),1)
feature_display := 1
feature_verbose := 1
endif
feature_display_entries = $(eval $(feature_display_entries_code))
define feature_display_entries_code
ifeq ($(feature_display),1)
$(info )
$(info Auto-detecting system features:)
$(foreach feat,$(FEATURE_DISPLAY),$(call feature_print_status,$(feat),))
ifneq ($(feature_verbose),1)
$(info )
endif
endif
ifeq ($(feature_verbose),1)
TMP := $(filter-out $(FEATURE_DISPLAY),$(FEATURE_TESTS))
$(foreach feat,$(TMP),$(call feature_print_status,$(feat),))
$(info )
endif
endef
ifeq ($(FEATURE_DISPLAY_DEFERRED),)
$(call feature_display_entries)
endif
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