Commit 13e17c9f authored by Ian Rogers's avatar Ian Rogers Committed by Namhyung Kim
Browse files

perf build: Make libunwind opt-in rather than opt-out 



Having multiple unwinding libraries makes the perf code harder to
understand and we have unused/untested code paths.

Perf made BPF support an opt-out rather than opt-in feature. As libbpf
has a libelf dependency, elfutils that provides libelf will also
provide libdw. When libdw is present perf will use libdw unwinding
rather than libunwind unwinding even if libunwind support is compiled
in.

Rather than have libunwind built into perf and never used, explicitly
disable the support and make it opt-in.

Signed-off-by: default avatarIan Rogers <irogers@google.com>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/r/20241028193619.247727-1-irogers@google.com
Closes: https://lore.kernel.org/linux-perf-users/CAP-5=fUXkp-d7gkzX4eF+nbjb2978dZsiHZ9abGHN=BN1qAcbg@mail.gmail.com/


Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
parent aa5c9060

tools/perf/Makefile.config

+4 −0
Original line number Diff line number Diff line
@@ -95,6 +95,10 @@ ifneq ($(SRCARCH),$(filter $(SRCARCH),x86 arm arm64 powerpc s390 csky riscv loon 
  NO_LIBDW_DWARF_UNWIND := 1

endif



ifneq ($(LIBUNWIND),1)

  NO_LIBUNWIND := 1

endif



ifeq ($(LIBUNWIND_LIBS),)

  NO_LIBUNWIND := 1

endif

tools/perf/Makefile.perf

+1 −1
Original line number Diff line number Diff line
@@ -52,7 +52,7 @@ include ../scripts/utilities.mak 
#

# Define NO_LIBELF if you do not want libelf dependency (e.g. cross-builds)

#

# Define NO_LIBUNWIND if you do not want libunwind dependency for dwarf

# Define LIBUNWIND if you do not want libunwind dependency for dwarf

# backtrace post unwind.

#

# Define NO_BACKTRACE if you do not want stack backtrace debug feature

tools/perf/tests/make

+3 −3
Original line number Diff line number Diff line
@@ -81,7 +81,7 @@ make_no_gtk2 := NO_GTK2=1 
make_no_ui          := NO_SLANG=1 NO_GTK2=1

make_no_demangle    := NO_DEMANGLE=1

make_no_libelf      := NO_LIBELF=1

make_no_libunwind   := NO_LIBUNWIND=1

make_libunwind      := LIBUNWIND=1

make_no_libdw_dwarf_unwind := NO_LIBDW_DWARF_UNWIND=1

make_no_backtrace   := NO_BACKTRACE=1

make_no_libcapstone := NO_CAPSTONE=1
@@ -121,7 +121,7 @@ make_static := LDFLAGS=-static NO_PERF_READ_VDSO32=1 NO_PERF_READ_VDSOX3 


# all the NO_* variable combined

make_minimal        := NO_LIBPERL=1 NO_LIBPYTHON=1 NO_GTK2=1

make_minimal        += NO_DEMANGLE=1 NO_LIBELF=1 NO_LIBUNWIND=1 NO_BACKTRACE=1

make_minimal        += NO_DEMANGLE=1 NO_LIBELF=1 NO_BACKTRACE=1

make_minimal        += NO_LIBNUMA=1 NO_LIBAUDIT=1 NO_LIBBIONIC=1

make_minimal        += NO_LIBDW_DWARF_UNWIND=1 NO_AUXTRACE=1 NO_LIBBPF=1

make_minimal        += NO_LIBCRYPTO=1 NO_SDT=1 NO_JVMTI=1 NO_LIBZSTD=1
@@ -153,7 +153,7 @@ run += make_no_gtk2 
run += make_no_ui

run += make_no_demangle

run += make_no_libelf

run += make_no_libunwind

run += make_libunwind

run += make_no_libdw_dwarf_unwind

run += make_no_backtrace

run += make_no_libcapstone