On 10/19/21 4:24 PM, Arnaldo Carvalho de Melo wrote:
Em Mon, Oct 18, 2021 at 10:57:43AM +0100, Douglas Raillard escreveu:
On 10/15/21 3:20 PM, Arnaldo Carvalho de Melo wrote:
Em Fri, Oct 15, 2021 at 10:22:43AM -0300, Arnaldo Carvalho de Melo escreveu:
Em Fri, Oct 15, 2021 at 10:18:41AM -0300, Arnaldo Carvalho de Melo escreveu:
CMake Error at cmake/modules/FindDWARF.cmake:103 (message):
Could NOT find some ELF and DWARF libraries, please install the missing
packages
Call Stack (most recent call first):
CMakeLists.txt:64 (find_package)
-- Configuring incomplete, errors occurred!
See also "/var/home/acme/git/pahole/build/CMakeFiles/CMakeOutput.log".
⬢[acme@toolbox build]$
Which means I don't have those static library files, will try installing
them.
I'm trying with the latest fedora that comes with static libraries,
fedora:32, and there I noticed that we need to look for libzstd as well,
I added it manually to:
target_link_libraries(dwarves ${DWARF_LIBRARIES} ${ZLIB_LIBRARIES} ${LIBBPF_LIBRARIES} ${ARGP_LIBRARY} ${OBSTACK_LIBRARY} ${BZ2_LIBRARY} ${LZMA_LIBRARY} -lzstd)
[root@cc85f3a7b96f dwarves-1.22]# rpm -qa | grep -- -static
zlib-static-1.2.11-21.fc32.x86_64
glibc-static-2.31-6.fc32.x86_64
elfutils-devel-static-0.183-1.fc32.x86_64
xz-static-5.2.5-1.fc32.x86_64
libxcrypt-static-4.4.20-2.fc32.x86_64
libzstd-static-1.4.9-1.fc32.x86_64
elfutils-libelf-devel-static-0.183-1.fc32.x86_64
bzip2-static-1.0.8-2.fc32.x86_64
[root@cc85f3a7b96f dwarves-1.22]# cat /etc/fedora-release
Fedora release 32 (Thirty Two)
[root@cc85f3a7b96f dwarves-1.22]#
now I'm at:
/usr/bin/ld: /usr/lib/gcc/x86_64-redhat-linux/10/../../../../lib64/libdw.a(debuginfod-client.o): in function `__libdwfl_debuginfod_init':
(.text.startup[.text.startup.group]+0x1b): undefined reference to `dlopen'
/usr/bin/ld: (.text.startup[.text.startup.group]+0x36): undefined reference to `dlsym'
/usr/bin/ld: (.text.startup[.text.startup.group]+0x4f): undefined reference to `dlsym'
/usr/bin/ld: (.text.startup[.text.startup.group]+0x68): undefined reference to `dlsym'
/usr/bin/ld: (.text.startup[.text.startup.group]+0x81): undefined reference to `dlsym'
/usr/bin/ld: (.text.startup[.text.startup.group]+0xe0): undefined reference to `dlclose'
that needs some more magic that I already forgot :-\
When trying on Ubuntu it also appeared that find_library() for libebl
was also needed, but not on Alpine Linux so I did not include it, as it
does not seem necessary on Alpine. I'm not sure how we want to go about
these:
1) Take the union of all the dependencies that seem to be necessary and
deal gracefully in CMakeLists.txt with failure to find a lib. This will
result in linker error if a lib is actually necessary and not found.
2) Select a blessed distro for static building and only maintain that
3) Find some cmake builtin "magic" so that the user can point at
existing lib that seem to not be detected on their distro. I'm quite
rusty in cmake so maybe there is a better way than sprinkling
find_library() everywhere.
So far I opted for approach 2) with Alpine, as building on e.g. Ubuntu
will not work in any case, because glibc does not support static linking
(it kind of does until it does not anymore). Alpine uses the musl libc
which supports static linking.
As for the dlopen/dlsym/dlclose issue I'm not sure. Maybe these symbols
are just not present in static glibc ? The binary I produced on Alpine
did not seem to segfault [1]. If you want to give it a go, this scripts
set it up in ~20s:
https://github.com/alpinelinux/alpine-chroot-install
Packages: bash gcc git make cmake musl-dev zlib-static bzip2-static
libelf-static libbpf-dev musl-obstack-dev argp-standalone linux-headers
I'll try with this later, thing is, I want to build on the CI for pahole
that Andrii put in place in the libbpf repo, so we need to check how to
build this static build.
I tried to make it work on Ubuntu and came up with that. It is quite stinky
and does not result in a fully static build, but it's probably as close we can
get to it using glibc, and it does not segfault:
ldd pahole
linux-vdso.so.1 (0x00007ffd9b7e2000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f049a55e000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f049a53b000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f049a349000)
/lib/ld64.so.1 => /lib64/ld-linux-x86-64.so.2 (0x00007f049a584000)
Subject: [PATCH] CMakeLists.txt: Allow pseudo-static build on Ubuntu
Allow STATIC_LINK=ON on Ubuntu by:
* providing libebl
* avoiding a trailing -Wl,-Bstatic that makes the resulting binary
segfault
* dynamically link to libdl. Static linking to that lib would impose
that the same glibc version used for linking is present on the
runtime system, which is not very safe and would mislead into
thinking the binary is safe to use everywhere.
Apart from that, all the other libraries are statically linked to the
executable.
Note: the user might need a symlink /lib/ld64.so.1 => /lib64/ld-linux-x86-64.so.2
The ld option --dynamic-linker=file is supposed to allow fixing that,
but it's unfortunately ignored when used with -static.
---
CMakeLists.txt | 18 ++++++++++++++++--
cmake/modules/FindDWARF.cmake | 8 ++++++++
2 files changed, 24 insertions(+), 2 deletions(-)
diff --git a/CMakeLists.txt b/CMakeLists.txt
index ba467bf..adb6d74 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,6 +2,11 @@ project(pahole C)
cmake_minimum_required(VERSION 2.8.12)
cmake_policy(SET CMP0005 NEW)
+execute_process(COMMAND lsb_release -si
+ OUTPUT_VARIABLE LINUX_DISTRO
+ OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+
option(LIBBPF_EMBEDDED "Use the embedded version of libbpf instead of searching it via pkg-config" ON)
if (NOT LIBBPF_EMBEDDED)
find_package(PkgConfig REQUIRED)
@@ -127,7 +132,12 @@ endif()
add_library(dwarves ${dwarves_LIB_SRCS})
set_target_properties(dwarves PROPERTIES VERSION 1.0.0 SOVERSION 1)
set_target_properties(dwarves PROPERTIES INTERFACE_LINK_LIBRARIES "")
-target_link_libraries(dwarves ${DWARF_LIBRARIES} ${ZLIB_LIBRARIES} ${LIBBPF_LIBRARIES} ${ARGP_LIBRARY} ${OBSTACK_LIBRARY} ${BZ2_LIBRARY} ${LZMA_LIBRARY})
+target_link_libraries(dwarves ${DWARF_LIBRARIES} ${ZLIB_LIBRARIES} ${LIBBPF_LIBRARIES} ${ARGP_LIBRARY} ${OBSTACK_LIBRARY} ${BZ2_LIBRARY} ${LZMA_LIBRARY} ${EBL_LIBRARY})
+# On non-musl systems, we need to link to libdl in order to get
+# dlopen/dlclose/dlsym, as required by libdwfl and libebl
+if (LINUX_DISTRO STREQUAL "Ubuntu")
+ target_link_libraries(dwarves dl)
+endif()
set(dwarves_emit_LIB_SRCS dwarves_emit.c)
add_library(dwarves_emit ${dwarves_emit_LIB_SRCS})
@@ -201,4 +211,8 @@ install(FILES lib/Makefile lib/ctracer_relay.c lib/ctracer_relay.h lib/linux.bla
# Avoid having a trailing -Wl,-Bdynamic that will make some linkers think we
# need to link against a DSO for the libc.
get_property(TARGETS DIRECTORY PROPERTY BUILDSYSTEM_TARGETS)
-set_target_properties(${TARGETS} PROPERTIES LINK_SEARCH_END_STATIC ${STATIC_LINK})
+# If we use a trailing -Wl,-Bstatic on ubuntu, the binary will segfault for some
+# reasons ...
+if (NOT LINUX_DISTRO STREQUAL "Ubuntu")
+ set_target_properties(${TARGETS} PROPERTIES LINK_SEARCH_END_STATIC ${STATIC_LINK})
+endif()
diff --git a/cmake/modules/FindDWARF.cmake b/cmake/modules/FindDWARF.cmake
index 1b4ac49..cd1f265 100644
--- a/cmake/modules/FindDWARF.cmake
+++ b/cmake/modules/FindDWARF.cmake
@@ -27,6 +27,14 @@ find_path(LIBDW_INCLUDE_DIR elfutils/libdw.h
~/usr/local/include
)
+# This does not seem to be necessary on Alpine Linux
+if (LINUX_DISTRO STREQUAL "Ubuntu")
+ find_library(EBL_LIBRARY
+ NAMES ebl
+ PATHS /usr/lib /usr/local/lib /usr/lib64 /usr/local/lib64 ~/usr/local/lib ~/usr/local/lib64
+ )
+endif()
+
find_library(DWARF_LIBRARY
NAMES dw dwarf
PATHS /usr/lib /usr/local/lib /usr/lib64 /usr/local/lib64 ~/usr/local/lib ~/usr/local/lib64
--
2.25.1
